package golite

import (
	"context"
	"database/sql"
	"database/sql/driver"
	"errors"
	"fmt"
	"io"
	"math"
	"net/url"
	"reflect"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"
	"unsafe"
	"syscall"
)

/*
Premises:
- FTS5
- (default) foreign keys
- ICU
- (default) AUTOVACUUM
- SQLITE_THREADSAFE
- column metadata
*/

/*
#include <stdlib.h>
#include <sqlite3.h>

void         stepTrampoline(sqlite3_context*, int, sqlite3_value**);
void         doneTrampoline(sqlite3_context*);
int       compareTrampoline(void*, int, char*, int, char*);
int    commitHookTrampoline(void*);
void rollbackHookTrampoline(void*);
void   updateHookTrampoline(void*, int, char*, char*, sqlite3_int64);
*/
import "C"



// SQLiteBackup implement interface of Backup.
type SQLiteBackup struct {
	b *C.sqlite3_backup
}

// Backup make backup from src to dest.
func (destConn *SQLiteConn) Backup(dest string, srcConn *SQLiteConn, src string) (*SQLiteBackup, error) {
	destptr := C.CString(dest)
	defer C.free(unsafe.Pointer(destptr))
	srcptr := C.CString(src)
	defer C.free(unsafe.Pointer(srcptr))

	if b := C.sqlite3_backup_init(destConn.db, destptr, srcConn.db, srcptr); b != nil {
		bb := &SQLiteBackup{b: b}
		runtime.SetFinalizer(bb, (*SQLiteBackup).Finish)
		return bb, nil
	}
	return nil, destConn.lastError()
}

// Step to backs up for one step. Calls the underlying `sqlite3_backup_step`
// function.  This function returns a boolean indicating if the backup is done
// and an error signalling any other error. Done is returned if the underlying
// C function returns SQLITE_DONE (Code 101)
func (b *SQLiteBackup) Step(p int) (bool, error) {
	ret := C.sqlite3_backup_step(b.b, C.int(p))
	if ret == C.SQLITE_DONE {
		return true, nil
	} else if ret != 0 && ret != C.SQLITE_LOCKED && ret != C.SQLITE_BUSY {
		return false, Error{Code: ErrNo(ret)}
	}
	return false, nil
}

// Remaining return whether have the rest for backup.
func (b *SQLiteBackup) Remaining() int {
	return int(C.sqlite3_backup_remaining(b.b))
}

// PageCount return count of pages.
func (b *SQLiteBackup) PageCount() int {
	return int(C.sqlite3_backup_pagecount(b.b))
}

// Finish close backup.
func (b *SQLiteBackup) Finish() error {
	return b.Close()
}

// Close close backup.
func (b *SQLiteBackup) Close() error {
	ret := C.sqlite3_backup_finish(b.b)

	// sqlite3_backup_finish() never fails, it just returns the
	// error code from previous operations, so clean up before
	// checking and returning an error
	b.b = nil
	runtime.SetFinalizer(b, nil)

	if ret != 0 {
		return Error{Code: ErrNo(ret)}
	}
	return nil
}

//export stepTrampoline
func stepTrampoline(
	ctx *C.sqlite3_context,
	argc C.int,
	argv **C.sqlite3_value,
) {
	const size = (math.MaxInt32 - 1) /
		unsafe.Sizeof((*C.sqlite3_value)(nil))
	args := (*[size]*C.sqlite3_value)(unsafe.Pointer(argv))
	slice := args[:int(argc):int(argc)]
	lookupHandle(C.sqlite3_user_data(ctx)).(*aggInfo).Step(ctx, slice)
}

//export doneTrampoline
func doneTrampoline(ctx *C.sqlite3_context) {
	lookupHandle(C.sqlite3_user_data(ctx)).(*aggInfo).Done(ctx)
}

//export compareTrampoline
func compareTrampoline(
	handlePtr unsafe.Pointer,
	la C.int,
	a *C.char,
	lb C.int,
	b *C.char,
) C.int {
	cmpFn := lookupHandle(handlePtr).(func(string, string) int)
	return C.int(cmpFn(C.GoStringN(a, la), C.GoStringN(b, lb)))
}

//export commitHookTrampoline
func commitHookTrampoline(handle unsafe.Pointer) C.int {
	return C.int(lookupHandle(handle).(func() int)())
}

//export rollbackHookTrampoline
func rollbackHookTrampoline(handle unsafe.Pointer) {
	lookupHandle(handle).(func())()
}

//export updateHookTrampoline
func updateHookTrampoline(
	handle unsafe.Pointer,
	op C.int,
	db *C.char,
	table *C.char,
	rowid int64,
) {
	lookupHandle(handle).(func(int, string, string, int64))(
		int(op),
		C.GoString(db),
		C.GoString(table),
		int64(rowid),
	)
}

// Use handles to avoid passing Go pointers to C.
type handleVal struct {
	db  *SQLiteConn
	val any
}

var handleLock sync.Mutex
var handleVals = make(map[unsafe.Pointer]handleVal)

func newHandle(db *SQLiteConn, v any) unsafe.Pointer {
	val := handleVal{db: db, val: v}
	p := C.malloc(C.size_t(1))
	if p == nil {
		panic("can't allocate 'cgo-pointer hack index pointer': ptr == nil")
	}
	{
		handleLock.Lock()
		defer handleLock.Unlock()
		handleVals[p] = val
	}
	return p
}

func lookupHandleVal(handle unsafe.Pointer) handleVal {
	handleLock.Lock()
	defer handleLock.Unlock()
	return handleVals[handle]
}

func lookupHandle(handle unsafe.Pointer) any {
	return lookupHandleVal(handle).val
}

func deleteHandles(db *SQLiteConn) {
	handleLock.Lock()
	defer handleLock.Unlock()
	for handle, val := range handleVals {
		if val.db == db {
			delete(handleVals, handle)
			C.free(handle)
		}
	}
}

type callbackArgConverter func(*C.sqlite3_value) (reflect.Value, error)

type callbackArgCast struct {
	f   callbackArgConverter
	typ reflect.Type
}

func (c callbackArgCast) Run(v *C.sqlite3_value) (reflect.Value, error) {
	val, err := c.f(v)
	if err != nil {
		return reflect.Value{}, err
	}
	if !val.Type().ConvertibleTo(c.typ) {
		return reflect.Value{}, fmt.Errorf("cannot convert %s to %s", val.Type(), c.typ)
	}
	return val.Convert(c.typ), nil
}

func callbackArgInt64(v *C.sqlite3_value) (reflect.Value, error) {
	if C.sqlite3_value_type(v) != C.SQLITE_INTEGER {
		return reflect.Value{}, fmt.Errorf("argument must be an INTEGER")
	}
	return reflect.ValueOf(int64(C.sqlite3_value_int64(v))), nil
}

func callbackArgBool(v *C.sqlite3_value) (reflect.Value, error) {
	if C.sqlite3_value_type(v) != C.SQLITE_INTEGER {
		return reflect.Value{}, fmt.Errorf("argument must be an INTEGER")
	}
	i := int64(C.sqlite3_value_int64(v))
	val := false
	if i != 0 {
		val = true
	}
	return reflect.ValueOf(val), nil
}

func callbackArgFloat64(v *C.sqlite3_value) (reflect.Value, error) {
	if C.sqlite3_value_type(v) != C.SQLITE_FLOAT {
		return reflect.Value{}, fmt.Errorf("argument must be a FLOAT")
	}
	return reflect.ValueOf(float64(C.sqlite3_value_double(v))), nil
}

func callbackArgBytes(v *C.sqlite3_value) (reflect.Value, error) {
	switch C.sqlite3_value_type(v) {
	case C.SQLITE_BLOB:
		l := C.sqlite3_value_bytes(v)
		p := C.sqlite3_value_blob(v)
		return reflect.ValueOf(C.GoBytes(p, l)), nil
	case C.SQLITE_TEXT:
		l := C.sqlite3_value_bytes(v)
		c := unsafe.Pointer(C.sqlite3_value_text(v))
		return reflect.ValueOf(C.GoBytes(c, l)), nil
	default:
		return reflect.Value{}, fmt.Errorf("argument must be BLOB or TEXT")
	}
}

func callbackArgString(v *C.sqlite3_value) (reflect.Value, error) {
	switch C.sqlite3_value_type(v) {
	case C.SQLITE_BLOB:
		l := C.sqlite3_value_bytes(v)
		p := (*C.char)(C.sqlite3_value_blob(v))
		return reflect.ValueOf(C.GoStringN(p, l)), nil
	case C.SQLITE_TEXT:
		c := (*C.char)(unsafe.Pointer(C.sqlite3_value_text(v)))
		return reflect.ValueOf(C.GoString(c)), nil
	default:
		return reflect.Value{}, fmt.Errorf("argument must be BLOB or TEXT")
	}
}

func callbackArgGeneric(v *C.sqlite3_value) (reflect.Value, error) {
	switch C.sqlite3_value_type(v) {
	case C.SQLITE_INTEGER:
		return callbackArgInt64(v)
	case C.SQLITE_FLOAT:
		return callbackArgFloat64(v)
	case C.SQLITE_TEXT:
		return callbackArgString(v)
	case C.SQLITE_BLOB:
		return callbackArgBytes(v)
	case C.SQLITE_NULL:
		// Interpret NULL as a nil byte slice.
		var ret []byte
		return reflect.ValueOf(ret), nil
	default:
		panic("unreachable")
	}
}

func callbackArg(typ reflect.Type) (callbackArgConverter, error) {
	switch typ.Kind() {
	case reflect.Interface:
		if typ.NumMethod() != 0 {
			return nil, errors.New("the only supported interface type is any")
		}
		return callbackArgGeneric, nil
	case reflect.Slice:
		if typ.Elem().Kind() != reflect.Uint8 {
			return nil, errors.New("the only supported slice type is []byte")
		}
		return callbackArgBytes, nil
	case reflect.String:
		return callbackArgString, nil
	case reflect.Bool:
		return callbackArgBool, nil
	case reflect.Int64:
		return callbackArgInt64, nil
	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Int, reflect.Uint:
		c := callbackArgCast{callbackArgInt64, typ}
		return c.Run, nil
	case reflect.Float64:
		return callbackArgFloat64, nil
	case reflect.Float32:
		c := callbackArgCast{callbackArgFloat64, typ}
		return c.Run, nil
	default:
		return nil, fmt.Errorf("don't know how to convert to %s", typ)
	}
}

func callbackConvertArgs(argv []*C.sqlite3_value, converters []callbackArgConverter, variadic callbackArgConverter) ([]reflect.Value, error) {
	var args []reflect.Value

	if len(argv) < len(converters) {
		return nil, fmt.Errorf("function requires at least %d arguments", len(converters))
	}

	for i, arg := range argv[:len(converters)] {
		v, err := converters[i](arg)
		if err != nil {
			return nil, err
		}
		args = append(args, v)
	}

	if variadic != nil {
		for _, arg := range argv[len(converters):] {
			v, err := variadic(arg)
			if err != nil {
				return nil, err
			}
			args = append(args, v)
		}
	}
	return args, nil
}

type callbackRetConverter func(*C.sqlite3_context, reflect.Value) error

func callbackRetInteger(ctx *C.sqlite3_context, v reflect.Value) error {
	switch v.Type().Kind() {
	case reflect.Int64:
	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Int, reflect.Uint:
		v = v.Convert(reflect.TypeOf(int64(0)))
	case reflect.Bool:
		b := v.Interface().(bool)
		if b {
			v = reflect.ValueOf(int64(1))
		} else {
			v = reflect.ValueOf(int64(0))
		}
	default:
		return fmt.Errorf("cannot convert %s to INTEGER", v.Type())
	}

	C.sqlite3_result_int64(ctx, C.sqlite3_int64(v.Interface().(int64)))
	return nil
}

func callbackRetFloat(ctx *C.sqlite3_context, v reflect.Value) error {
	switch v.Type().Kind() {
	case reflect.Float64:
	case reflect.Float32:
		v = v.Convert(reflect.TypeOf(float64(0)))
	default:
		return fmt.Errorf("cannot convert %s to FLOAT", v.Type())
	}

	C.sqlite3_result_double(ctx, C.double(v.Interface().(float64)))
	return nil
}

func callbackRetBlob(ctx *C.sqlite3_context, v reflect.Value) error {
	if v.Type().Kind() != reflect.Slice || v.Type().Elem().Kind() != reflect.Uint8 {
		return fmt.Errorf("cannot convert %s to BLOB", v.Type())
	}
	i := v.Interface()
	if i == nil || len(i.([]byte)) == 0 {
		C.sqlite3_result_null(ctx)
	} else {
		bs := i.([]byte)
		C.sqlite3_result_blob(
			ctx,
			unsafe.Pointer(&bs[0]),
			C.int(len(bs)),
			C.SQLITE_TRANSIENT,
		)
	}
	return nil
}

func callbackRetText(ctx *C.sqlite3_context, v reflect.Value) error {
	if v.Type().Kind() != reflect.String {
		return fmt.Errorf("cannot convert %s to TEXT", v.Type())
	}
	C.sqlite3_result_text(
		ctx,
		C.CString(v.Interface().(string)),
		-1,
		(*[0]byte)(unsafe.Pointer(C.free)),
	)
	return nil
}

func callbackRetNil(ctx *C.sqlite3_context, v reflect.Value) error {
	return nil
}

func callbackRetGeneric(ctx *C.sqlite3_context, v reflect.Value) error {
	if v.IsNil() {
		C.sqlite3_result_null(ctx)
		return nil
	}

	cb, err := callbackRet(v.Elem().Type())
	if err != nil {
		return err
	}

	return cb(ctx, v.Elem())
}

func callbackRet(typ reflect.Type) (callbackRetConverter, error) {
	switch typ.Kind() {
	case reflect.Interface:
		errorInterface := reflect.TypeOf((*error)(nil)).Elem()
		if typ.Implements(errorInterface) {
			return callbackRetNil, nil
		}

		if typ.NumMethod() == 0 {
			return callbackRetGeneric, nil
		}

		fallthrough
	case reflect.Slice:
		if typ.Elem().Kind() != reflect.Uint8 {
			return nil, errors.New("the only supported slice type is []byte")
		}
		return callbackRetBlob, nil
	case reflect.String:
		return callbackRetText, nil
	case reflect.Bool, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Int, reflect.Uint:
		return callbackRetInteger, nil
	case reflect.Float32, reflect.Float64:
		return callbackRetFloat, nil
	default:
		return nil, fmt.Errorf("don't know how to convert to %s", typ)
	}
}

func callbackError(ctx *C.sqlite3_context, err error) {
	cstr := C.CString(err.Error())
	defer C.free(unsafe.Pointer(cstr))
	C.sqlite3_result_error(ctx, cstr, C.int(-1))
}

// FIXME: remove this
// Test support code. Tests are not allowed to import "C", so we can't
// declare any functions that use C.sqlite3_value.
func callbackSyntheticForTests(v reflect.Value, err error) callbackArgConverter {
	return func(*C.sqlite3_value) (reflect.Value, error) {
		return v, err
	}
}

// Extracted from Go database/sql source code
// Type conversions for Scan.

var errNilPtr = errors.New("destination pointer is nil") // embedded in descriptive error

// convertAssign copies to dest the value in src, converting it if possible.
// An error is returned if the copy would result in loss of information.
// dest should be a pointer type.
func convertAssign(dest, src any) error {
	// Common cases, without reflect.
	switch s := src.(type) {
	case string:
		switch d := dest.(type) {
		case *string:
			if d == nil {
				return errNilPtr
			}
			*d = s
			return nil
		case *[]byte:
			if d == nil {
				return errNilPtr
			}
			*d = []byte(s)
			return nil
		case *sql.RawBytes:
			if d == nil {
				return errNilPtr
			}
			*d = append((*d)[:0], s...)
			return nil
		}
	case []byte:
		switch d := dest.(type) {
		case *string:
			if d == nil {
				return errNilPtr
			}
			*d = string(s)
			return nil
		case *any:
			if d == nil {
				return errNilPtr
			}
			*d = cloneBytes(s)
			return nil
		case *[]byte:
			if d == nil {
				return errNilPtr
			}
			*d = cloneBytes(s)
			return nil
		case *sql.RawBytes:
			if d == nil {
				return errNilPtr
			}
			*d = s
			return nil
		}
	case time.Time:
		switch d := dest.(type) {
		case *time.Time:
			*d = s
			return nil
		case *string:
			*d = s.Format(time.RFC3339Nano)
			return nil
		case *[]byte:
			if d == nil {
				return errNilPtr
			}
			*d = []byte(s.Format(time.RFC3339Nano))
			return nil
		case *sql.RawBytes:
			if d == nil {
				return errNilPtr
			}
			*d = s.AppendFormat((*d)[:0], time.RFC3339Nano)
			return nil
		}
	case nil:
		switch d := dest.(type) {
		case *any:
			if d == nil {
				return errNilPtr
			}
			*d = nil
			return nil
		case *[]byte:
			if d == nil {
				return errNilPtr
			}
			*d = nil
			return nil
		case *sql.RawBytes:
			if d == nil {
				return errNilPtr
			}
			*d = nil
			return nil
		}
	}

	var sv reflect.Value

	switch d := dest.(type) {
	case *string:
		sv = reflect.ValueOf(src)
		switch sv.Kind() {
		case reflect.Bool,
			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
			reflect.Float32, reflect.Float64:
			*d = asString(src)
			return nil
		}
	case *[]byte:
		sv = reflect.ValueOf(src)
		if b, ok := asBytes(nil, sv); ok {
			*d = b
			return nil
		}
	case *sql.RawBytes:
		sv = reflect.ValueOf(src)
		if b, ok := asBytes([]byte(*d)[:0], sv); ok {
			*d = sql.RawBytes(b)
			return nil
		}
	case *bool:
		bv, err := driver.Bool.ConvertValue(src)
		if err == nil {
			*d = bv.(bool)
		}
		return err
	case *any:
		*d = src
		return nil
	}

	if scanner, ok := dest.(sql.Scanner); ok {
		return scanner.Scan(src)
	}

	dpv := reflect.ValueOf(dest)
	if dpv.Kind() != reflect.Ptr {
		return errors.New("destination not a pointer")
	}
	if dpv.IsNil() {
		return errNilPtr
	}

	if !sv.IsValid() {
		sv = reflect.ValueOf(src)
	}

	dv := reflect.Indirect(dpv)
	if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
		switch b := src.(type) {
		case []byte:
			dv.Set(reflect.ValueOf(cloneBytes(b)))
		default:
			dv.Set(sv)
		}
		return nil
	}

	if dv.Kind() == sv.Kind() && sv.Type().ConvertibleTo(dv.Type()) {
		dv.Set(sv.Convert(dv.Type()))
		return nil
	}

	// The following conversions use a string value as an intermediate representation
	// to convert between various numeric types.
	//
	// This also allows scanning into user defined types such as "type Int int64".
	// For symmetry, also check for string destination types.
	switch dv.Kind() {
	case reflect.Ptr:
		if src == nil {
			dv.Set(reflect.Zero(dv.Type()))
			return nil
		}
		dv.Set(reflect.New(dv.Type().Elem()))
		return convertAssign(dv.Interface(), src)
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		s := asString(src)
		i64, err := strconv.ParseInt(s, 10, dv.Type().Bits())
		if err != nil {
			err = strconvErr(err)
			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
		}
		dv.SetInt(i64)
		return nil
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		s := asString(src)
		u64, err := strconv.ParseUint(s, 10, dv.Type().Bits())
		if err != nil {
			err = strconvErr(err)
			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
		}
		dv.SetUint(u64)
		return nil
	case reflect.Float32, reflect.Float64:
		s := asString(src)
		f64, err := strconv.ParseFloat(s, dv.Type().Bits())
		if err != nil {
			err = strconvErr(err)
			return fmt.Errorf("converting driver.Value type %T (%q) to a %s: %v", src, s, dv.Kind(), err)
		}
		dv.SetFloat(f64)
		return nil
	case reflect.String:
		switch v := src.(type) {
		case string:
			dv.SetString(v)
			return nil
		case []byte:
			dv.SetString(string(v))
			return nil
		}
	}

	return fmt.Errorf("unsupported Scan, storing driver.Value type %T into type %T", src, dest)
}

func strconvErr(err error) error {
	if ne, ok := err.(*strconv.NumError); ok {
		return ne.Err
	}
	return err
}

func cloneBytes(b []byte) []byte {
	if b == nil {
		return nil
	}
	c := make([]byte, len(b))
	copy(c, b)
	return c
}

func asString(src any) string {
	switch v := src.(type) {
	case string:
		return v
	case []byte:
		return string(v)
	}
	rv := reflect.ValueOf(src)
	switch rv.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return strconv.FormatInt(rv.Int(), 10)
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return strconv.FormatUint(rv.Uint(), 10)
	case reflect.Float64:
		return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
	case reflect.Float32:
		return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
	case reflect.Bool:
		return strconv.FormatBool(rv.Bool())
	}
	return fmt.Sprintf("%v", src)
}

func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
	switch rv.Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return strconv.AppendInt(buf, rv.Int(), 10), true
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return strconv.AppendUint(buf, rv.Uint(), 10), true
	case reflect.Float32:
		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
	case reflect.Float64:
		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
	case reflect.Bool:
		return strconv.AppendBool(buf, rv.Bool()), true
	case reflect.String:
		s := rv.String()
		return append(buf, s...), true
	}
	return
}

/*
Package sqlite3 provides interface to SQLite3 databases.

This works as a driver for database/sql.

Installation

	go get github.com/mattn/go-sqlite3

# Supported Types

Currently, go-sqlite3 supports the following data types.

	+------------------------------+
	|go        | sqlite3           |
	|----------|-------------------|
	|nil       | null              |
	|int       | integer           |
	|int64     | integer           |
	|float64   | float             |
	|bool      | integer           |
	|[]byte    | blob              |
	|string    | text              |
	|time.Time | timestamp/datetime|
	+------------------------------+

# SQLite3 Extension

You can write your own extension module for sqlite3. For example, below is an
extension for a Regexp matcher operation.

	#include <pcre.h>
	#include <string.h>
	#include <stdio.h>
	#include <sqlite3ext.h>

	SQLITE_EXTENSION_INIT1
	static void regexp_func(sqlite3_context *context, int argc, sqlite3_value **argv) {
	  if (argc >= 2) {
	    const char *target  = (const char *)sqlite3_value_text(argv[1]);
	    const char *pattern = (const char *)sqlite3_value_text(argv[0]);
	    const char* errstr = NULL;
	    int erroff = 0;
	    int vec[500];
	    int n, rc;
	    pcre* re = pcre_compile(pattern, 0, &errstr, &erroff, NULL);
	    rc = pcre_exec(re, NULL, target, strlen(target), 0, 0, vec, 500);
	    if (rc <= 0) {
	      sqlite3_result_error(context, errstr, 0);
	      return;
	    }
	    sqlite3_result_int(context, 1);
	  }
	}

	int sqlite3_extension_init(sqlite3 *db, char **errmsg,
	      const sqlite3_api_routines *api) {
	  SQLITE_EXTENSION_INIT2(api);
	  return sqlite3_create_function(db, "regexp", 2, SQLITE_UTF8,
	      (void*)db, regexp_func, NULL, NULL);
	}

It needs to be built as a so/dll shared library. And you need to register
the extension module like below.

	sql.Register("sqlite3_with_extensions",
		&sqlite3.SQLiteDriver{
			Extensions: []string{
				"sqlite3_mod_regexp",
			},
		})

Then, you can use this extension.

	rows, err := db.Query("select text from mytable where name regexp '^golang'")

# Connection Hook

You can hook and inject your code when the connection is established by setting
ConnectHook to get the SQLiteConn.

	sql.Register("sqlite3_with_hook_example",
			&sqlite3.SQLiteDriver{
					ConnectHook: func(conn *sqlite3.SQLiteConn) error {
						sqlite3conn = append(sqlite3conn, conn)
						return nil
					},
			})

You can also use database/sql.Conn.Raw (Go >= 1.13):

	conn, err := db.Conn(context.Background())
	// if err != nil { ... }
	defer conn.Close()
	err = conn.Raw(func (driverConn any) error {
		sqliteConn := driverConn.(*sqlite3.SQLiteConn)
		// ... use sqliteConn
	})
	// if err != nil { ... }

# Go SQlite3 Extensions

If you want to register Go functions as SQLite extension functions
you can make a custom driver by calling RegisterFunction from
ConnectHook.

	regex = func(re, s string) (bool, error) {
		return regexp.MatchString(re, s)
	}
	sql.Register("sqlite3_extended",
			&sqlite3.SQLiteDriver{
					ConnectHook: func(conn *sqlite3.SQLiteConn) error {
						return conn.RegisterFunc("regexp", regex, true)
					},
			})

You can then use the custom driver by passing its name to sql.Open.

	var i int
	conn, err := sql.Open("sqlite3_extended", "./foo.db")
	if err != nil {
		panic(err)
	}
	err = db.QueryRow(`SELECT regexp("foo.*", "seafood")`).Scan(&i)
	if err != nil {
		panic(err)
	}

See the documentation of RegisterFunc for more details.
*/

// ErrNo inherit errno.
type ErrNo int

// ErrNoMask is mask code.
const ErrNoMask C.int = 0xff

// ErrNoExtended is extended errno.
type ErrNoExtended int

// Error implement sqlite error code.
type Error struct {
	Code         ErrNo         /* The error code returned by SQLite */
	ExtendedCode ErrNoExtended /* The extended error code returned by SQLite */
	SystemErrno  syscall.Errno /* The system errno returned by the OS through SQLite, if applicable */
	err          string        /* The error string returned by sqlite3_errmsg(),
	this usually contains more specific details. */
}

// result codes from http://www.sqlite.org/c3ref/c_abort.html
var (
	ErrError      = ErrNo(1)  /* SQL error or missing database */
	ErrInternal   = ErrNo(2)  /* Internal logic error in SQLite */
	ErrPerm       = ErrNo(3)  /* Access permission denied */
	ErrAbort      = ErrNo(4)  /* Callback routine requested an abort */
	ErrBusy       = ErrNo(5)  /* The database file is locked */
	ErrLocked     = ErrNo(6)  /* A table in the database is locked */
	ErrNomem      = ErrNo(7)  /* A malloc() failed */
	ErrReadonly   = ErrNo(8)  /* Attempt to write a readonly database */
	ErrInterrupt  = ErrNo(9)  /* Operation terminated by sqlite3_interrupt() */
	ErrIoErr      = ErrNo(10) /* Some kind of disk I/O error occurred */
	ErrCorrupt    = ErrNo(11) /* The database disk image is malformed */
	ErrNotFound   = ErrNo(12) /* Unknown opcode in sqlite3_file_control() */
	ErrFull       = ErrNo(13) /* Insertion failed because database is full */
	ErrCantOpen   = ErrNo(14) /* Unable to open the database file */
	ErrProtocol   = ErrNo(15) /* Database lock protocol error */
	ErrEmpty      = ErrNo(16) /* Database is empty */
	ErrSchema     = ErrNo(17) /* The database schema changed */
	ErrTooBig     = ErrNo(18) /* String or BLOB exceeds size limit */
	ErrConstraint = ErrNo(19) /* Abort due to constraint violation */
	ErrMismatch   = ErrNo(20) /* Data type mismatch */
	ErrMisuse     = ErrNo(21) /* Library used incorrectly */
	ErrNoLFS      = ErrNo(22) /* Uses OS features not supported on host */
	ErrAuth       = ErrNo(23) /* Authorization denied */
	ErrFormat     = ErrNo(24) /* Auxiliary database format error */
	ErrRange      = ErrNo(25) /* 2nd parameter to sqlite3_bind out of range */
	ErrNotADB     = ErrNo(26) /* File opened that is not a database file */
	ErrNotice     = ErrNo(27) /* Notifications from sqlite3_log() */
	ErrWarning    = ErrNo(28) /* Warnings from sqlite3_log() */
)

// Error return error message from errno.
func (err ErrNo) Error() string {
	return Error{Code: err}.Error()
}

// Extend return extended errno.
func (err ErrNo) Extend(by int) ErrNoExtended {
	return ErrNoExtended(int(err) | (by << 8))
}

// Error return error message that is extended code.
func (err ErrNoExtended) Error() string {
	return Error{Code: ErrNo(C.int(err) & ErrNoMask), ExtendedCode: err}.Error()
}

func (err Error) Error() string {
	var str string
	if err.err != "" {
		str = err.err
	} else {
		str = C.GoString(C.sqlite3_errstr(C.int(err.Code)))
	}
	if err.SystemErrno != 0 {
		str += ": " + err.SystemErrno.Error()
	}
	return str
}

// result codes from http://www.sqlite.org/c3ref/c_abort_rollback.html
var (
	ErrIoErrRead              = ErrIoErr.Extend(1)
	ErrIoErrShortRead         = ErrIoErr.Extend(2)
	ErrIoErrWrite             = ErrIoErr.Extend(3)
	ErrIoErrFsync             = ErrIoErr.Extend(4)
	ErrIoErrDirFsync          = ErrIoErr.Extend(5)
	ErrIoErrTruncate          = ErrIoErr.Extend(6)
	ErrIoErrFstat             = ErrIoErr.Extend(7)
	ErrIoErrUnlock            = ErrIoErr.Extend(8)
	ErrIoErrRDlock            = ErrIoErr.Extend(9)
	ErrIoErrDelete            = ErrIoErr.Extend(10)
	ErrIoErrBlocked           = ErrIoErr.Extend(11)
	ErrIoErrNoMem             = ErrIoErr.Extend(12)
	ErrIoErrAccess            = ErrIoErr.Extend(13)
	ErrIoErrCheckReservedLock = ErrIoErr.Extend(14)
	ErrIoErrLock              = ErrIoErr.Extend(15)
	ErrIoErrClose             = ErrIoErr.Extend(16)
	ErrIoErrDirClose          = ErrIoErr.Extend(17)
	ErrIoErrSHMOpen           = ErrIoErr.Extend(18)
	ErrIoErrSHMSize           = ErrIoErr.Extend(19)
	ErrIoErrSHMLock           = ErrIoErr.Extend(20)
	ErrIoErrSHMMap            = ErrIoErr.Extend(21)
	ErrIoErrSeek              = ErrIoErr.Extend(22)
	ErrIoErrDeleteNoent       = ErrIoErr.Extend(23)
	ErrIoErrMMap              = ErrIoErr.Extend(24)
	ErrIoErrGetTempPath       = ErrIoErr.Extend(25)
	ErrIoErrConvPath          = ErrIoErr.Extend(26)
	ErrLockedSharedCache      = ErrLocked.Extend(1)
	ErrBusyRecovery           = ErrBusy.Extend(1)
	ErrBusySnapshot           = ErrBusy.Extend(2)
	ErrCantOpenNoTempDir      = ErrCantOpen.Extend(1)
	ErrCantOpenIsDir          = ErrCantOpen.Extend(2)
	ErrCantOpenFullPath       = ErrCantOpen.Extend(3)
	ErrCantOpenConvPath       = ErrCantOpen.Extend(4)
	ErrCorruptVTab            = ErrCorrupt.Extend(1)
	ErrReadonlyRecovery       = ErrReadonly.Extend(1)
	ErrReadonlyCantLock       = ErrReadonly.Extend(2)
	ErrReadonlyRollback       = ErrReadonly.Extend(3)
	ErrReadonlyDbMoved        = ErrReadonly.Extend(4)
	ErrAbortRollback          = ErrAbort.Extend(2)
	ErrConstraintCheck        = ErrConstraint.Extend(1)
	ErrConstraintCommitHook   = ErrConstraint.Extend(2)
	ErrConstraintForeignKey   = ErrConstraint.Extend(3)
	ErrConstraintFunction     = ErrConstraint.Extend(4)
	ErrConstraintNotNull      = ErrConstraint.Extend(5)
	ErrConstraintPrimaryKey   = ErrConstraint.Extend(6)
	ErrConstraintTrigger      = ErrConstraint.Extend(7)
	ErrConstraintUnique       = ErrConstraint.Extend(8)
	ErrConstraintVTab         = ErrConstraint.Extend(9)
	ErrConstraintRowID        = ErrConstraint.Extend(10)
	ErrNoticeRecoverWAL       = ErrNotice.Extend(1)
	ErrNoticeRecoverRollback  = ErrNotice.Extend(2)
	ErrWarningAutoIndex       = ErrWarning.Extend(1)
)

// FIXME: remove this
// SQLiteTimestampFormats is timestamp formats understood by both this module
// and SQLite.  The first format in the slice will be used when saving time
// values into the database. When parsing a string from a timestamp or datetime
// column, the formats are tried in order.
var SQLiteTimestampFormats = []string{
	// By default, store timestamps with whatever timezone they come with.
	// When parsed, they will be returned with the same timezone.
	"2006-01-02 15:04:05.999999999-07:00",
	"2006-01-02T15:04:05.999999999-07:00",
	"2006-01-02 15:04:05.999999999",
	"2006-01-02T15:04:05.999999999",
	"2006-01-02 15:04:05",
	"2006-01-02T15:04:05",
	"2006-01-02 15:04",
	"2006-01-02T15:04",
	"2006-01-02",
}

const (
	columnDate      string = "date"
	columnDatetime  string = "datetime"
	columnTimestamp string = "timestamp"
)

var driverName = "sqlite3"
func init() {
	sql.Register(driverName, &SQLiteDriver{})
}

// Version returns SQLite library version information.
func LibVersion() (libVersion string, libVersionNumber int, sourceID string) {
	libVersion = C.GoString(C.sqlite3_libversion())
	libVersionNumber = int(C.sqlite3_libversion_number())
	sourceID = C.GoString(C.sqlite3_sourceid())
	return libVersion, libVersionNumber, sourceID
}

const (
	// used by update hook
	SQLITE_DELETE = C.SQLITE_DELETE
	SQLITE_INSERT = C.SQLITE_INSERT
	SQLITE_UPDATE = C.SQLITE_UPDATE
)

// Standard File Control Opcodes
// See: https://www.sqlite.org/c3ref/c_fcntl_begin_atomic_write.html
const (
	SQLITE_FCNTL_LOCKSTATE             = int(1)
	SQLITE_FCNTL_GET_LOCKPROXYFILE     = int(2)
	SQLITE_FCNTL_SET_LOCKPROXYFILE     = int(3)
	SQLITE_FCNTL_LAST_ERRNO            = int(4)
	SQLITE_FCNTL_SIZE_HINT             = int(5)
	SQLITE_FCNTL_CHUNK_SIZE            = int(6)
	SQLITE_FCNTL_FILE_POINTER          = int(7)
	SQLITE_FCNTL_SYNC_OMITTED          = int(8)
	SQLITE_FCNTL_WIN32_AV_RETRY        = int(9)
	SQLITE_FCNTL_PERSIST_WAL           = int(10)
	SQLITE_FCNTL_OVERWRITE             = int(11)
	SQLITE_FCNTL_VFSNAME               = int(12)
	SQLITE_FCNTL_POWERSAFE_OVERWRITE   = int(13)
	SQLITE_FCNTL_PRAGMA                = int(14)
	SQLITE_FCNTL_BUSYHANDLER           = int(15)
	SQLITE_FCNTL_TEMPFILENAME          = int(16)
	SQLITE_FCNTL_MMAP_SIZE             = int(18)
	SQLITE_FCNTL_TRACE                 = int(19)
	SQLITE_FCNTL_HAS_MOVED             = int(20)
	SQLITE_FCNTL_SYNC                  = int(21)
	SQLITE_FCNTL_COMMIT_PHASETWO       = int(22)
	SQLITE_FCNTL_WIN32_SET_HANDLE      = int(23)
	SQLITE_FCNTL_WAL_BLOCK             = int(24)
	SQLITE_FCNTL_ZIPVFS                = int(25)
	SQLITE_FCNTL_RBU                   = int(26)
	SQLITE_FCNTL_VFS_POINTER           = int(27)
	SQLITE_FCNTL_JOURNAL_POINTER       = int(28)
	SQLITE_FCNTL_WIN32_GET_HANDLE      = int(29)
	SQLITE_FCNTL_PDB                   = int(30)
	SQLITE_FCNTL_BEGIN_ATOMIC_WRITE    = int(31)
	SQLITE_FCNTL_COMMIT_ATOMIC_WRITE   = int(32)
	SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE = int(33)
	SQLITE_FCNTL_LOCK_TIMEOUT          = int(34)
	SQLITE_FCNTL_DATA_VERSION          = int(35)
	SQLITE_FCNTL_SIZE_LIMIT            = int(36)
	SQLITE_FCNTL_CKPT_DONE             = int(37)
	SQLITE_FCNTL_RESERVE_BYTES         = int(38)
	SQLITE_FCNTL_CKPT_START            = int(39)
	SQLITE_FCNTL_EXTERNAL_READER       = int(40)
	SQLITE_FCNTL_CKSM_FILE             = int(41)
)

// SQLiteDriver implements driver.Driver.
type SQLiteDriver struct {
	ConnectHook func(*SQLiteConn) error
}

// SQLiteConn implements driver.Conn.
type SQLiteConn struct {
	mu          sync.Mutex
	db          *C.sqlite3
	loc         *time.Location
	txlock      string
	funcs       []*functionInfo
	aggregators []*aggInfo
}

// SQLiteTx implements driver.Tx.
type SQLiteTx struct {
	c *SQLiteConn
}

// SQLiteStmt implements driver.Stmt.
type SQLiteStmt struct {
	mu     sync.Mutex
	c      *SQLiteConn
	s      *C.sqlite3_stmt
	t      string
	closed bool
	cls    bool
}

// SQLiteResult implements sql.Result.
type SQLiteResult struct {
	id      int64
	changes int64
}

// SQLiteRows implements driver.Rows.
type SQLiteRows struct {
	s        *SQLiteStmt
	nc       int
	cols     []string
	decltype []string
	cls      bool
	closed   bool
	ctx      context.Context // no better alternative to pass context into Next() method
}

type functionInfo struct {
	f                 reflect.Value
	argConverters     []callbackArgConverter
	variadicConverter callbackArgConverter
	retConverter      callbackRetConverter
}

func (fi *functionInfo) Call(ctx *C.sqlite3_context, argv []*C.sqlite3_value) {
	args, err := callbackConvertArgs(argv, fi.argConverters, fi.variadicConverter)
	if err != nil {
		callbackError(ctx, err)
		return
	}

	ret := fi.f.Call(args)

	if len(ret) == 2 && ret[1].Interface() != nil {
		callbackError(ctx, ret[1].Interface().(error))
		return
	}

	err = fi.retConverter(ctx, ret[0])
	if err != nil {
		callbackError(ctx, err)
		return
	}
}

type aggInfo struct {
	constructor reflect.Value

	// Active aggregator objects for aggregations in flight. The
	// aggregators are indexed by a counter stored in the aggregation
	// user data space provided by sqlite.
	active map[int64]reflect.Value
	next   int64

	stepArgConverters     []callbackArgConverter
	stepVariadicConverter callbackArgConverter

	doneRetConverter callbackRetConverter
}

func (ai *aggInfo) agg(ctx *C.sqlite3_context) (int64, reflect.Value, error) {
	aggIdx := (*int64)(C.sqlite3_aggregate_context(ctx, C.int(8)))
	if *aggIdx == 0 {
		*aggIdx = ai.next
		ret := ai.constructor.Call(nil)
		if len(ret) == 2 && ret[1].Interface() != nil {
			return 0, reflect.Value{}, ret[1].Interface().(error)
		}
		if ret[0].IsNil() {
			return 0, reflect.Value{}, errors.New("aggregator constructor returned nil state")
		}
		ai.next++
		ai.active[*aggIdx] = ret[0]
	}
	return *aggIdx, ai.active[*aggIdx], nil
}

func (ai *aggInfo) Step(ctx *C.sqlite3_context, argv []*C.sqlite3_value) {
	_, agg, err := ai.agg(ctx)
	if err != nil {
		callbackError(ctx, err)
		return
	}

	args, err := callbackConvertArgs(argv, ai.stepArgConverters, ai.stepVariadicConverter)
	if err != nil {
		callbackError(ctx, err)
		return
	}

	ret := agg.MethodByName("Step").Call(args)
	if len(ret) == 1 && ret[0].Interface() != nil {
		callbackError(ctx, ret[0].Interface().(error))
		return
	}
}

func (ai *aggInfo) Done(ctx *C.sqlite3_context) {
	idx, agg, err := ai.agg(ctx)
	if err != nil {
		callbackError(ctx, err)
		return
	}
	defer func() { delete(ai.active, idx) }()

	ret := agg.MethodByName("Done").Call(nil)
	if len(ret) == 2 && ret[1].Interface() != nil {
		callbackError(ctx, ret[1].Interface().(error))
		return
	}

	err = ai.doneRetConverter(ctx, ret[0])
	if err != nil {
		callbackError(ctx, err)
		return
	}
}

// Commit transaction.
func (tx *SQLiteTx) Commit() error {
	_, err := tx.c.exec(context.Background(), "COMMIT", nil)
	if err != nil {
		// sqlite3 may leave the transaction open in this scenario.
		// However, database/sql considers the transaction complete once we
		// return from Commit() - we must clean up to honour its semantics.
		// We don't know if the ROLLBACK is strictly necessary, but according
		// to sqlite's docs, there is no harm in calling ROLLBACK unnecessarily.
		tx.c.exec(context.Background(), "ROLLBACK", nil)
	}
	return err
}

// Rollback transaction.
func (tx *SQLiteTx) Rollback() error {
	_, err := tx.c.exec(context.Background(), "ROLLBACK", nil)
	return err
}

// RegisterCollation makes a Go function available as a collation.
//
// cmp receives two UTF-8 strings, a and b. The result should be 0 if
// a==b, -1 if a < b, and +1 if a > b.
//
// cmp must always return the same result given the same
// inputs. Additionally, it must have the following properties for all
// strings A, B and C: if A==B then B==A; if A==B and B==C then A==C;
// if A<B then B>A; if A<B and B<C then A<C.
//
// If cmp does not obey these constraints, sqlite3's behavior is
// undefined when the collation is used.
func (c *SQLiteConn) RegisterCollation(name string, cmp func(string, string) int) error {
	handle := newHandle(c, cmp)
	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))
	rv := C.sqlite3_create_collation(c.db, cname, C.SQLITE_UTF8, handle, (*[0]byte)(unsafe.Pointer(C.compareTrampoline)))
	if rv != C.SQLITE_OK {
		return c.lastError()
	}
	return nil
}

func (c *SQLiteConn) RegisterCommitHook(callback func() int) {
	if callback == nil {
		C.sqlite3_commit_hook(c.db, nil, nil)
	} else {
		C.sqlite3_commit_hook(c.db, (*[0]byte)(C.commitHookTrampoline), newHandle(c, callback))
	}
}

func (c *SQLiteConn) RegisterRollbackHook(callback func()) {
	if callback == nil {
		C.sqlite3_rollback_hook(c.db, nil, nil)
	} else {
		C.sqlite3_rollback_hook(c.db, (*[0]byte)(C.rollbackHookTrampoline), newHandle(c, callback))
	}
}

func (c *SQLiteConn) RegisterUpdateHook(callback func(int, string, string, int64)) {
	if callback == nil {
		C.sqlite3_update_hook(c.db, nil, nil)
	} else {
		C.sqlite3_update_hook(c.db, (*[0]byte)(C.updateHookTrampoline), newHandle(c, callback))
	}
}

// RegisterAggregator makes a Go type available as a SQLite aggregation function.
//
// Because aggregation is incremental, it's implemented in Go with a
// type that has 2 methods: func Step(values) accumulates one row of
// data into the accumulator, and func Done() ret finalizes and
// returns the aggregate value. "values" and "ret" may be any type
// supported by RegisterFunc.
//
// RegisterAggregator takes as implementation a constructor function
// that constructs an instance of the aggregator type each time an
// aggregation begins. The constructor must return a pointer to a
// type, or an interface that implements Step() and Done().
//
// The constructor function and the Step/Done methods may optionally
// return an error in addition to their other return values.
//
// See _example/go_custom_funcs for a detailed example.
func (c *SQLiteConn) RegisterAggregator(name string, impl any, pure bool) error {
	var ai aggInfo
	ai.constructor = reflect.ValueOf(impl)
	t := ai.constructor.Type()
	if t.Kind() != reflect.Func {
		return errors.New("non-function passed to RegisterAggregator")
	}
	if t.NumOut() != 1 && t.NumOut() != 2 {
		return errors.New("SQLite aggregator constructors must return 1 or 2 values")
	}
	if t.NumOut() == 2 && !t.Out(1).Implements(reflect.TypeOf((*error)(nil)).Elem()) {
		return errors.New("Second return value of SQLite function must be error")
	}
	if t.NumIn() != 0 {
		return errors.New("SQLite aggregator constructors must not have arguments")
	}

	agg := t.Out(0)
	switch agg.Kind() {
	case reflect.Ptr, reflect.Interface:
	default:
		return errors.New("SQlite aggregator constructor must return a pointer object")
	}
	stepFn, found := agg.MethodByName("Step")
	if !found {
		return errors.New("SQlite aggregator doesn't have a Step() function")
	}
	step := stepFn.Type
	if step.NumOut() != 0 && step.NumOut() != 1 {
		return errors.New("SQlite aggregator Step() function must return 0 or 1 values")
	}
	if step.NumOut() == 1 && !step.Out(0).Implements(reflect.TypeOf((*error)(nil)).Elem()) {
		return errors.New("type of SQlite aggregator Step() return value must be error")
	}

	stepNArgs := step.NumIn()
	start := 0
	if agg.Kind() == reflect.Ptr {
		// Skip over the method receiver
		stepNArgs--
		start++
	}
	if step.IsVariadic() {
		stepNArgs--
	}
	for i := start; i < start+stepNArgs; i++ {
		conv, err := callbackArg(step.In(i))
		if err != nil {
			return err
		}
		ai.stepArgConverters = append(ai.stepArgConverters, conv)
	}
	if step.IsVariadic() {
		conv, err := callbackArg(step.In(start + stepNArgs).Elem())
		if err != nil {
			return err
		}
		ai.stepVariadicConverter = conv
		// Pass -1 to sqlite so that it allows any number of
		// arguments. The call helper verifies that the minimum number
		// of arguments is present for variadic functions.
		stepNArgs = -1
	}

	doneFn, found := agg.MethodByName("Done")
	if !found {
		return errors.New("SQlite aggregator doesn't have a Done() function")
	}
	done := doneFn.Type
	doneNArgs := done.NumIn()
	if agg.Kind() == reflect.Ptr {
		// Skip over the method receiver
		doneNArgs--
	}
	if doneNArgs != 0 {
		return errors.New("SQlite aggregator Done() function must have no arguments")
	}
	if done.NumOut() != 1 && done.NumOut() != 2 {
		return errors.New("SQLite aggregator Done() function must return 1 or 2 values")
	}
	if done.NumOut() == 2 && !done.Out(1).Implements(reflect.TypeOf((*error)(nil)).Elem()) {
		return errors.New("second return value of SQLite aggregator Done() function must be error")
	}

	conv, err := callbackRet(done.Out(0))
	if err != nil {
		return err
	}
	ai.doneRetConverter = conv
	ai.active = make(map[int64]reflect.Value)
	ai.next = 1

	// ai must outlast the database connection, or we'll have dangling pointers.
	c.aggregators = append(c.aggregators, &ai)

	cname := C.CString(name)
	defer C.free(unsafe.Pointer(cname))
	opts := C.SQLITE_UTF8
	if pure {
		opts |= C.SQLITE_DETERMINISTIC
	}
	rv := C.sqlite3_create_function(
		c.db,
		cname,
		C.int(stepNArgs),
		C.int(opts),
		newHandle(c, &ai),
		nil,
		(*[0]byte)(C.stepTrampoline),
		(*[0]byte)(C.doneTrampoline),
	)
	if rv != C.SQLITE_OK {
		return c.lastError()
	}
	return nil
}

// AutoCommit return which currently auto commit or not.
func (c *SQLiteConn) AutoCommit() bool {
	c.mu.Lock()
	defer c.mu.Unlock()
	return int(C.sqlite3_get_autocommit(c.db)) != 0
}

func (c *SQLiteConn) lastError() error {
	return lastError(c.db)
}

// Note: may be called with db == nil
func lastError(db *C.sqlite3) error {
	rv := C.sqlite3_errcode(db) // returns SQLITE_NOMEM if db == nil
	if rv == C.SQLITE_OK {
		return nil
	}
	extrv := C.sqlite3_extended_errcode(db)    // returns SQLITE_NOMEM if db == nil
	errStr := C.GoString(C.sqlite3_errmsg(db)) // returns "out of memory" if db == nil

	// https://www.sqlite.org/c3ref/system_errno.html
	// sqlite3_system_errno is only meaningful if the error code was SQLITE_CANTOPEN,
	// or it was SQLITE_IOERR and the extended code was not SQLITE_IOERR_NOMEM
	var systemErrno syscall.Errno
	if rv == C.SQLITE_CANTOPEN || (rv == C.SQLITE_IOERR && extrv != C.SQLITE_IOERR_NOMEM) {
		systemErrno = syscall.Errno(C.sqlite3_system_errno(db))
	}

	return Error{
		Code:         ErrNo(rv),
		ExtendedCode: ErrNoExtended(extrv),
		SystemErrno:  systemErrno,
		err:          errStr,
	}
}

// Exec implements Execer.
func (c *SQLiteConn) Exec(query string, args []driver.Value) (driver.Result, error) {
	list := make([]driver.NamedValue, len(args))
	for i, v := range args {
		list[i] = driver.NamedValue{
			Ordinal: i + 1,
			Value:   v,
		}
	}
	return c.exec(context.Background(), query, list)
}

func (c *SQLiteConn) exec(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
	start := 0
	for {
		s, err := c.prepare(ctx, query)
		if err != nil {
			return nil, err
		}
		var res driver.Result
		if s.(*SQLiteStmt).s != nil {
			stmtArgs := make([]driver.NamedValue, 0, len(args))
			na := s.NumInput()
			if len(args)-start < na {
				s.Close()
				return nil, fmt.Errorf("not enough args to execute query: want %d got %d", na, len(args))
			}
			// consume the number of arguments used in the current
			// statement and append all named arguments not
			// contained therein
			if len(args[start:start+na]) > 0 {
				stmtArgs = append(stmtArgs, args[start:start+na]...)
				for i := range args {
					if (i < start || i >= na) && args[i].Name != "" {
						stmtArgs = append(stmtArgs, args[i])
					}
				}
				for i := range stmtArgs {
					stmtArgs[i].Ordinal = i + 1
				}
			}
			res, err = s.(*SQLiteStmt).exec(ctx, stmtArgs)
			if err != nil && err != driver.ErrSkip {
				s.Close()
				return nil, err
			}
			start += na
		}
		tail := s.(*SQLiteStmt).t
		s.Close()
		if tail == "" {
			if res == nil {
				// https://github.com/mattn/go-sqlite3/issues/963
				res = &SQLiteResult{0, 0}
			}
			return res, nil
		}
		query = tail
	}
}

// Query implements Queryer.
func (c *SQLiteConn) Query(query string, args []driver.Value) (driver.Rows, error) {
	list := make([]driver.NamedValue, len(args))
	for i, v := range args {
		list[i] = driver.NamedValue{
			Ordinal: i + 1,
			Value:   v,
		}
	}
	return c.query(context.Background(), query, list)
}

func (c *SQLiteConn) query(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
	start := 0
	for {
		stmtArgs := make([]driver.NamedValue, 0, len(args))
		s, err := c.prepare(ctx, query)
		if err != nil {
			return nil, err
		}
		s.(*SQLiteStmt).cls = true
		na := s.NumInput()
		if len(args)-start < na {
			return nil, fmt.Errorf("not enough args to execute query: want %d got %d", na, len(args)-start)
		}
		// consume the number of arguments used in the current
		// statement and append all named arguments not contained
		// therein
		stmtArgs = append(stmtArgs, args[start:start+na]...)
		for i := range args {
			if (i < start || i >= na) && args[i].Name != "" {
				stmtArgs = append(stmtArgs, args[i])
			}
		}
		for i := range stmtArgs {
			stmtArgs[i].Ordinal = i + 1
		}
		rows, err := s.(*SQLiteStmt).query(ctx, stmtArgs)
		if err != nil && err != driver.ErrSkip {
			s.Close()
			return rows, err
		}
		start += na
		tail := s.(*SQLiteStmt).t
		if tail == "" {
			return rows, nil
		}
		rows.Close()
		s.Close()
		query = tail
	}
}

// Begin transaction.
func (c *SQLiteConn) Begin() (driver.Tx, error) {
	return c.begin(context.Background())
}

func (c *SQLiteConn) begin(ctx context.Context) (driver.Tx, error) {
	if _, err := c.exec(ctx, c.txlock, nil); err != nil {
		return nil, err
	}
	return &SQLiteTx{c}, nil
}

// Open database and return a new connection.
//
// A pragma can take either zero or one argument.
// The argument is may be either in parentheses or it may be separated from
// the pragma name by an equal sign. The two syntaxes yield identical results.
// In many pragmas, the argument is a boolean. The boolean can be one of:
//
//	1 yes true on
//	0 no false off
//
// You can specify a DSN string using a URI as the filename.
//
//	test.db
//	file:test.db?cache=shared&mode=memory
//	:memory:
//	file::memory:
//
//	mode
//	  Access mode of the database.
//	  https://www.sqlite.org/c3ref/open.html
//	  Values:
//	   - ro
//	   - rw
//	   - rwc
//	   - memory
//
//	cache
//	  SQLite Shared-Cache Mode
//	  https://www.sqlite.org/sharedcache.html
//	  Values:
//	    - shared
//	    - private
//
//	immutable=Boolean
//	  The immutable parameter is a boolean query parameter that indicates
//	  that the database file is stored on read-only media. When immutable is set,
//	  SQLite assumes that the database file cannot be changed,
//	  even by a process with higher privilege,
//	  and so the database is opened read-only and all locking and change detection is disabled.
//	  Caution: Setting the immutable property on a database file that
//	  does in fact change can result in incorrect query results and/or SQLITE_CORRUPT errors.
//
// go-sqlite3 adds the following query parameters to those used by SQLite:
//
//	_loc=XXX
//	  Specify location of time format. It's possible to specify "auto".
//
//	_mutex=XXX
//	  Specify mutex mode. XXX can be "no", "full".
//
//	_txlock=XXX
//	  Specify locking behavior for transactions.  XXX can be "immediate",
//	  "deferred", "exclusive".
//
//	_auto_vacuum=X | _vacuum=X
//	  0 | none - Auto Vacuum disabled
//	  1 | full - Auto Vacuum FULL
//	  2 | incremental - Auto Vacuum Incremental
//
//	_busy_timeout=XXX"| _timeout=XXX
//	  Specify value for sqlite3_busy_timeout.
//
//	_case_sensitive_like=Boolean | _cslike=Boolean
//	  https://www.sqlite.org/pragma.html#pragma_case_sensitive_like
//	  Default or disabled the LIKE operation is case-insensitive.
//	  When enabling this options behaviour of LIKE will become case-sensitive.
//
//	_defer_foreign_keys=Boolean | _defer_fk=Boolean
//	  Defer Foreign Keys until outermost transaction is committed.
//
//	_ignore_check_constraints=Boolean
//	  This pragma enables or disables the enforcement of CHECK constraints.
//	  The default setting is off, meaning that CHECK constraints are enforced by default.
//
//	_locking_mode=X | _locking=X
//	  Sets the database connection locking-mode.
//	  The locking-mode is either NORMAL or EXCLUSIVE.
//	  https://www.sqlite.org/pragma.html#pragma_locking_mode
//
//	_query_only=Boolean
//	  The query_only pragma prevents all changes to database files when enabled.
//
//	_recursive_triggers=Boolean | _rt=Boolean
//	  Enable or disable recursive triggers.
//
//	_writable_schema=Boolean
//	  When this pragma is on, the SQLITE_MASTER tables in which database
//	  can be changed using ordinary UPDATE, INSERT, and DELETE statements.
//	  Warning: misuse of this pragma can easily result in a corrupt database file.
func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
	if C.sqlite3_threadsafe() == 0 {
		return nil, errors.New("sqlite library was not compiled for thread-safe operation")
	}

	var pkey string

	// Options
	var loc *time.Location
	mutex := C.int(C.SQLITE_OPEN_FULLMUTEX)
	txlock := "BEGIN"

	// PRAGMA's
	autoVacuum := -1
	busyTimeout := 5000
	caseSensitiveLike := -1
	deferForeignKeys := -1
	ignoreCheckConstraints := -1
	lockingMode := "NORMAL"
	queryOnly := -1
	recursiveTriggers := -1
	writableSchema := -1
	vfsName := ""
	var cacheSize *int64

	pos := strings.IndexRune(dsn, '?')
	if pos >= 1 {
		params, err := url.ParseQuery(dsn[pos+1:])
		if err != nil {
			return nil, err
		}

		// _loc
		if val := params.Get("_loc"); val != "" {
			switch strings.ToLower(val) {
			case "auto":
				loc = time.Local
			default:
				loc, err = time.LoadLocation(val)
				if err != nil {
					return nil, fmt.Errorf("Invalid _loc: %v: %v", val, err)
				}
			}
		}

		// _mutex
		if val := params.Get("_mutex"); val != "" {
			switch strings.ToLower(val) {
			case "no":
				mutex = C.SQLITE_OPEN_NOMUTEX
			case "full":
				mutex = C.SQLITE_OPEN_FULLMUTEX
			default:
				return nil, fmt.Errorf("Invalid _mutex: %v", val)
			}
		}

		// _txlock
		if val := params.Get("_txlock"); val != "" {
			switch strings.ToLower(val) {
			case "immediate":
				txlock = "BEGIN IMMEDIATE"
			case "exclusive":
				txlock = "BEGIN EXCLUSIVE"
			case "deferred":
				txlock = "BEGIN"
			default:
				return nil, fmt.Errorf("Invalid _txlock: %v", val)
			}
		}

		// Auto Vacuum (_vacuum)
		//
		// https://www.sqlite.org/pragma.html#pragma_auto_vacuum
		//
		pkey = "" // Reset pkey
		if _, ok := params["_auto_vacuum"]; ok {
			pkey = "_auto_vacuum"
		}
		if _, ok := params["_vacuum"]; ok {
			pkey = "_vacuum"
		}
		if val := params.Get(pkey); val != "" {
			switch strings.ToLower(val) {
			case "0", "none":
				autoVacuum = 0
			case "1", "full":
				autoVacuum = 1
			case "2", "incremental":
				autoVacuum = 2
			default:
				return nil, fmt.Errorf("Invalid _auto_vacuum: %v, expecting value of '0 NONE 1 FULL 2 INCREMENTAL'", val)
			}
		}

		// Busy Timeout (_busy_timeout)
		//
		// https://www.sqlite.org/pragma.html#pragma_busy_timeout
		//
		pkey = "" // Reset pkey
		if _, ok := params["_busy_timeout"]; ok {
			pkey = "_busy_timeout"
		}
		if _, ok := params["_timeout"]; ok {
			pkey = "_timeout"
		}
		if val := params.Get(pkey); val != "" {
			iv, err := strconv.ParseInt(val, 10, 64)
			if err != nil {
				return nil, fmt.Errorf("Invalid _busy_timeout: %v: %v", val, err)
			}
			busyTimeout = int(iv)
		}

		// Case Sensitive Like (_cslike)
		//
		// https://www.sqlite.org/pragma.html#pragma_case_sensitive_like
		//
		pkey = "" // Reset pkey
		if _, ok := params["_case_sensitive_like"]; ok {
			pkey = "_case_sensitive_like"
		}
		if _, ok := params["_cslike"]; ok {
			pkey = "_cslike"
		}
		if val := params.Get(pkey); val != "" {
			switch strings.ToLower(val) {
			case "0", "no", "false", "off":
				caseSensitiveLike = 0
			case "1", "yes", "true", "on":
				caseSensitiveLike = 1
			default:
				return nil, fmt.Errorf("Invalid _case_sensitive_like: %v, expecting boolean value of '0 1 false true no yes off on'", val)
			}
		}

		// Defer Foreign Keys (_defer_foreign_keys | _defer_fk)
		//
		// https://www.sqlite.org/pragma.html#pragma_defer_foreign_keys
		//
		pkey = "" // Reset pkey
		if _, ok := params["_defer_foreign_keys"]; ok {
			pkey = "_defer_foreign_keys"
		}
		if _, ok := params["_defer_fk"]; ok {
			pkey = "_defer_fk"
		}
		if val := params.Get(pkey); val != "" {
			switch strings.ToLower(val) {
			case "0", "no", "false", "off":
				deferForeignKeys = 0
			case "1", "yes", "true", "on":
				deferForeignKeys = 1
			default:
				return nil, fmt.Errorf("Invalid _defer_foreign_keys: %v, expecting boolean value of '0 1 false true no yes off on'", val)
			}
		}

		// Ignore CHECK Constrains (_ignore_check_constraints)
		//
		// https://www.sqlite.org/pragma.html#pragma_ignore_check_constraints
		//
		if val := params.Get("_ignore_check_constraints"); val != "" {
			switch strings.ToLower(val) {
			case "0", "no", "false", "off":
				ignoreCheckConstraints = 0
			case "1", "yes", "true", "on":
				ignoreCheckConstraints = 1
			default:
				return nil, fmt.Errorf("Invalid _ignore_check_constraints: %v, expecting boolean value of '0 1 false true no yes off on'", val)
			}
		}

		// Locking Mode (_locking)
		//
		// https://www.sqlite.org/pragma.html#pragma_locking_mode
		//
		pkey = "" // Reset pkey
		if _, ok := params["_locking_mode"]; ok {
			pkey = "_locking_mode"
		}
		if _, ok := params["_locking"]; ok {
			pkey = "_locking"
		}
		if val := params.Get(pkey); val != "" {
			switch strings.ToUpper(val) {
			case "NORMAL", "EXCLUSIVE":
				lockingMode = strings.ToUpper(val)
			default:
				return nil, fmt.Errorf("Invalid _locking_mode: %v, expecting value of 'NORMAL EXCLUSIVE", val)
			}
		}

		// Query Only (_query_only)
		//
		// https://www.sqlite.org/pragma.html#pragma_query_only
		//
		if val := params.Get("_query_only"); val != "" {
			switch strings.ToLower(val) {
			case "0", "no", "false", "off":
				queryOnly = 0
			case "1", "yes", "true", "on":
				queryOnly = 1
			default:
				return nil, fmt.Errorf("Invalid _query_only: %v, expecting boolean value of '0 1 false true no yes off on'", val)
			}
		}

		// Recursive Triggers (_recursive_triggers)
		//
		// https://www.sqlite.org/pragma.html#pragma_recursive_triggers
		//
		pkey = "" // Reset pkey
		if _, ok := params["_recursive_triggers"]; ok {
			pkey = "_recursive_triggers"
		}
		if _, ok := params["_rt"]; ok {
			pkey = "_rt"
		}
		if val := params.Get(pkey); val != "" {
			switch strings.ToLower(val) {
			case "0", "no", "false", "off":
				recursiveTriggers = 0
			case "1", "yes", "true", "on":
				recursiveTriggers = 1
			default:
				return nil, fmt.Errorf("Invalid _recursive_triggers: %v, expecting boolean value of '0 1 false true no yes off on'", val)
			}
		}

		// Writable Schema (_writeable_schema)
		//
		// https://www.sqlite.org/pragma.html#pragma_writeable_schema
		//
		if val := params.Get("_writable_schema"); val != "" {
			switch strings.ToLower(val) {
			case "0", "no", "false", "off":
				writableSchema = 0
			case "1", "yes", "true", "on":
				writableSchema = 1
			default:
				return nil, fmt.Errorf("Invalid _writable_schema: %v, expecting boolean value of '0 1 false true no yes off on'", val)
			}
		}

		// Cache size (_cache_size)
		//
		// https://sqlite.org/pragma.html#pragma_cache_size
		//
		if val := params.Get("_cache_size"); val != "" {
			iv, err := strconv.ParseInt(val, 10, 64)
			if err != nil {
				return nil, fmt.Errorf("Invalid _cache_size: %v: %v", val, err)
			}
			cacheSize = &iv
		}

		if val := params.Get("vfs"); val != "" {
			vfsName = val
		}

		if !strings.HasPrefix(dsn, "file:") {
			dsn = dsn[:pos]
		}
	}

	var db *C.sqlite3
	name := C.CString(dsn)
	defer C.free(unsafe.Pointer(name))
	var vfs *C.char
	if vfsName != "" {
		vfs = C.CString(vfsName)
		defer C.free(unsafe.Pointer(vfs))
	}

	openFlags :=
		C.SQLITE_OPEN_READWRITE |
		C.SQLITE_OPEN_CREATE    |
		C.SQLITE_OPEN_URI       |
		mutex
	rv := C.sqlite3_open_v2(name, &db, openFlags, vfs)
	if rv != 0 {
		// Save off the error _before_ closing the database.
		// This is safe even if db is nil.
		err := lastError(db)
		if db != nil {
			C.sqlite3_close_v2(db)
		}
		return nil, err
	}
	if db == nil {
		return nil, errors.New("sqlite succeeded without returning a database")
	}

	exec := func(s string) error {
		cs := C.CString(s)
		rv := C.sqlite3_exec(db, cs, nil, nil, nil)
		C.free(unsafe.Pointer(cs))
		if rv != C.SQLITE_OK {
			return lastError(db)
		}
		return nil
	}

	// FIXME: these should be compiled into SQLite
	// Busy timeout
	if err := exec(fmt.Sprintf("PRAGMA busy_timeout = %d;", busyTimeout)); err != nil {
		C.sqlite3_close_v2(db)
		return nil, err
	}
	// Foreign Keys
	if err := exec("PRAGMA foreign_keys = ON;"); err != nil {
		C.sqlite3_close_v2(db)
		return nil, err
	}

	// Create connection to SQLite
	conn := &SQLiteConn{db: db, loc: loc, txlock: txlock}

	// Auto Vacuum
	// Moved auto_vacuum command, the user preference for auto_vacuum needs to be implemented directly after
	// the authentication and before the sqlite_user table gets created if the user
	// decides to activate User Authentication because
	// auto_vacuum needs to be set before any tables are created
	// and activating user authentication creates the internal table `sqlite_user`.
	if autoVacuum > -1 {
		if err := exec(fmt.Sprintf("PRAGMA auto_vacuum = %d;", autoVacuum)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	// Case Sensitive LIKE
	if caseSensitiveLike > -1 {
		if err := exec(fmt.Sprintf("PRAGMA case_sensitive_like = %d;", caseSensitiveLike)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	// Defer Foreign Keys
	if deferForeignKeys > -1 {
		if err := exec(fmt.Sprintf("PRAGMA defer_foreign_keys = %d;", deferForeignKeys)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	// Ignore CHECK Constraints
	if ignoreCheckConstraints > -1 {
		if err := exec(fmt.Sprintf("PRAGMA ignore_check_constraints = %d;", ignoreCheckConstraints)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	if err := exec("PRAGMA journal_mode = WAL;"); err != nil {
		C.sqlite3_close_v2(db)
		return nil, err
	}

	// Locking Mode
	// Because the default is NORMAL and this is not changed in this package
	// by using the compile time SQLITE_DEFAULT_LOCKING_MODE this PRAGMA can always be executed
	if err := exec(fmt.Sprintf("PRAGMA locking_mode = %s;", lockingMode)); err != nil {
		C.sqlite3_close_v2(db)
		return nil, err
	}

	// Query Only
	if queryOnly > -1 {
		if err := exec(fmt.Sprintf("PRAGMA query_only = %d;", queryOnly)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	// Recursive Triggers
	if recursiveTriggers > -1 {
		if err := exec(fmt.Sprintf("PRAGMA recursive_triggers = %d;", recursiveTriggers)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	// FIXME: see ~/dev/papo/STUFF/napiqlite/src/napiqlite.c
	if err := exec("PRAGMA synchronous = EXTRA;"); err != nil {
		conn.Close()
		return nil, err
	}

	// Writable Schema
	if writableSchema > -1 {
		if err := exec(fmt.Sprintf("PRAGMA writable_schema = %d;", writableSchema)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	// Cache Size
	if cacheSize != nil {
		if err := exec(fmt.Sprintf("PRAGMA cache_size = %d;", *cacheSize)); err != nil {
			C.sqlite3_close_v2(db)
			return nil, err
		}
	}

	if d.ConnectHook != nil {
		if err := d.ConnectHook(conn); err != nil {
			conn.Close()
			return nil, err
		}
	}
	runtime.SetFinalizer(conn, (*SQLiteConn).Close)
	return conn, nil
}

// Close the connection.
func (c *SQLiteConn) Close() error {
	rv := C.sqlite3_close_v2(c.db)
	if rv != C.SQLITE_OK {
		return c.lastError()
	}
	deleteHandles(c)
	c.mu.Lock()
	c.db = nil
	c.mu.Unlock()
	runtime.SetFinalizer(c, nil)
	return nil
}

func (c *SQLiteConn) dbConnOpen() bool {
	if c == nil {
		return false
	}
	c.mu.Lock()
	defer c.mu.Unlock()
	return c.db != nil
}

// Prepare the query string. Return a new statement.
func (c *SQLiteConn) Prepare(query string) (driver.Stmt, error) {
	return c.prepare(context.Background(), query)
}

func (c *SQLiteConn) prepare(ctx context.Context, query string) (driver.Stmt, error) {
	pquery := C.CString(query)
	defer C.free(unsafe.Pointer(pquery))
	var s *C.sqlite3_stmt
	var tail *C.char
	rv := C.sqlite3_prepare_v2(c.db, pquery, C.int(-1), &s, &tail)
	if rv != C.SQLITE_OK {
		return nil, c.lastError()
	}
	var t string
	if tail != nil && *tail != '\000' {
		t = strings.TrimSpace(C.GoString(tail))
	}
	ss := &SQLiteStmt{c: c, s: s, t: t}
	runtime.SetFinalizer(ss, (*SQLiteStmt).Close)
	return ss, nil
}

// Run-Time Limit Categories.
// See: http://www.sqlite.org/c3ref/c_limit_attached.html
const (
	SQLITE_LIMIT_LENGTH              = C.SQLITE_LIMIT_LENGTH
	SQLITE_LIMIT_SQL_LENGTH          = C.SQLITE_LIMIT_SQL_LENGTH
	SQLITE_LIMIT_COLUMN              = C.SQLITE_LIMIT_COLUMN
	SQLITE_LIMIT_EXPR_DEPTH          = C.SQLITE_LIMIT_EXPR_DEPTH
	SQLITE_LIMIT_COMPOUND_SELECT     = C.SQLITE_LIMIT_COMPOUND_SELECT
	SQLITE_LIMIT_VDBE_OP             = C.SQLITE_LIMIT_VDBE_OP
	SQLITE_LIMIT_FUNCTION_ARG        = C.SQLITE_LIMIT_FUNCTION_ARG
	SQLITE_LIMIT_ATTACHED            = C.SQLITE_LIMIT_ATTACHED
	SQLITE_LIMIT_LIKE_PATTERN_LENGTH = C.SQLITE_LIMIT_LIKE_PATTERN_LENGTH
	SQLITE_LIMIT_VARIABLE_NUMBER     = C.SQLITE_LIMIT_VARIABLE_NUMBER
	SQLITE_LIMIT_TRIGGER_DEPTH       = C.SQLITE_LIMIT_TRIGGER_DEPTH
	SQLITE_LIMIT_WORKER_THREADS      = C.SQLITE_LIMIT_WORKER_THREADS
)

// GetFilename returns the absolute path to the file containing
// the requested schema. When passed an empty string, it will
// instead use the database's default schema: "main".
// See: sqlite3_db_filename, https://www.sqlite.org/c3ref/db_filename.html
func (c *SQLiteConn) GetFilename(schemaName string) string {
	if schemaName == "" {
		schemaName = "main"
	}
	return C.GoString(C.sqlite3_db_filename(c.db, C.CString(schemaName)))
}

func (c *SQLiteConn) GetLimit(id int) int {
	return int(C.sqlite3_limit(c.db, C.int(id), C.int(-1)))
}

func (c *SQLiteConn) SetLimit(id int, newVal int) int {
	return int(C.sqlite3_limit(c.db, C.int(id), C.int(newVal)))
}

// SetFileControlInt invokes the xFileControl method on a given database. The
// dbName is the name of the database. It will default to "main" if left blank.
// The op is one of the opcodes prefixed by "SQLITE_FCNTL_". The arg argument
// and return code are both opcode-specific. Please see the SQLite documentation.
//
// This method is not thread-safe as the returned error code can be changed by
// another call if invoked concurrently.
//
// See: sqlite3_file_control, https://www.sqlite.org/c3ref/file_control.html
func (c *SQLiteConn) SetFileControlInt(dbName string, op int, arg int) error {
	if dbName == "" {
		dbName = "main"
	}

	cDBName := C.CString(dbName)
	defer C.free(unsafe.Pointer(cDBName))

	cArg := C.int(arg)
	rv := C.sqlite3_file_control(c.db, cDBName, C.int(op), unsafe.Pointer(&cArg))
	if rv != C.SQLITE_OK {
		return c.lastError()
	}
	return nil
}

func (s *SQLiteStmt) Close() error {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.closed {
		return nil
	}
	s.closed = true
	if !s.c.dbConnOpen() {
		return errors.New("sqlite statement with already closed database connection")
	}
	rv := C.sqlite3_finalize(s.s)
	s.s = nil
	if rv != C.SQLITE_OK {
		return s.c.lastError()
	}
	s.c = nil
	runtime.SetFinalizer(s, nil)
	return nil
}

func (s *SQLiteStmt) NumInput() int {
	return int(C.sqlite3_bind_parameter_count(s.s))
}

var placeHolder = []byte{0}

func (s *SQLiteStmt) bind(args []driver.NamedValue) error {
	rv := C.sqlite3_reset(s.s)
	if rv != C.SQLITE_ROW && rv != C.SQLITE_OK && rv != C.SQLITE_DONE {
		return s.c.lastError()
	}

	bindIndices := make([][3]int, len(args))
	prefixes := []string{":", "@", "$"}
	for i, v := range args {
		bindIndices[i][0] = args[i].Ordinal
		if v.Name != "" {
			for j := range prefixes {
				cname := C.CString(prefixes[j] + v.Name)
				bindIndices[i][j] = int(C.sqlite3_bind_parameter_index(s.s, cname))
				C.free(unsafe.Pointer(cname))
			}
			args[i].Ordinal = bindIndices[i][0]
		}
	}

	for i, arg := range args {
		for j := range bindIndices[i] {
			if bindIndices[i][j] == 0 {
				continue
			}
			n := C.int(bindIndices[i][j])
			switch v := arg.Value.(type) {
			case nil:
				rv = C.sqlite3_bind_null(s.s, n)
			case string:
				if len(v) == 0 {
					rv = C.sqlite3_bind_text(
						s.s,
						n,
						(*C.char)(unsafe.Pointer(&placeHolder[0])),
						C.int(0),
						C.SQLITE_TRANSIENT,
					)
				} else {
					b := []byte(v)
					rv = C.sqlite3_bind_text(
						s.s,
						n,
						(*C.char)(unsafe.Pointer(&b[0])),
						C.int(len(b)),
						C.SQLITE_TRANSIENT,
					)
				}
			case int64:
				rv = C.sqlite3_bind_int64(s.s, n, C.sqlite3_int64(v))
			case bool:
				if v {
					rv = C.sqlite3_bind_int(s.s, n, 1)
				} else {
					rv = C.sqlite3_bind_int(s.s, n, 0)
				}
			case float64:
				rv = C.sqlite3_bind_double(s.s, n, C.double(v))
			case []byte:
				if v == nil {
					rv = C.sqlite3_bind_null(s.s, n)
				} else {
					ln := len(v)
					if ln == 0 {
						v = placeHolder
					}
					rv = C.sqlite3_bind_blob(
						s.s,
						n,
						unsafe.Pointer(&v[0]),
						C.int(ln),
						C.SQLITE_TRANSIENT,
					)
				}
			case time.Time:
				b := []byte(v.Format(SQLiteTimestampFormats[0]))
				rv = C.sqlite3_bind_text(
					s.s,
					n,
					(*C.char)(unsafe.Pointer(&b[0])),
					C.int(len(b)),
					C.SQLITE_TRANSIENT,
				)
			}
			if rv != C.SQLITE_OK {
				return s.c.lastError()
			}
		}
	}
	return nil
}

// Query the statement with arguments. Return records.
func (s *SQLiteStmt) Query(args []driver.Value) (driver.Rows, error) {
	list := make([]driver.NamedValue, len(args))
	for i, v := range args {
		list[i] = driver.NamedValue{
			Ordinal: i + 1,
			Value:   v,
		}
	}
	return s.query(context.Background(), list)
}

func (s *SQLiteStmt) query(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
	if err := s.bind(args); err != nil {
		return nil, err
	}

	rows := &SQLiteRows{
		s:        s,
		nc:       int(C.sqlite3_column_count(s.s)),
		cols:     nil,
		decltype: nil,
		cls:      s.cls,
		closed:   false,
		ctx:      ctx,
	}
	runtime.SetFinalizer(rows, (*SQLiteRows).Close)

	return rows, nil
}

// LastInsertId return last inserted ID.
func (r *SQLiteResult) LastInsertId() (int64, error) {
	return r.id, nil
}

// RowsAffected return how many rows affected.
func (r *SQLiteResult) RowsAffected() (int64, error) {
	return r.changes, nil
}

// Exec execute the statement with arguments. Return result object.
func (s *SQLiteStmt) Exec(args []driver.Value) (driver.Result, error) {
	list := make([]driver.NamedValue, len(args))
	for i, v := range args {
		list[i] = driver.NamedValue{
			Ordinal: i + 1,
			Value:   v,
		}
	}
	return s.exec(context.Background(), list)
}

func isInterruptErr(err error) bool {
	sqliteErr, ok := err.(Error)
	if ok {
		return sqliteErr.Code == ErrInterrupt
	}
	return false
}

// exec executes a query that doesn't return rows. Attempts to honor context timeout.
func (s *SQLiteStmt) exec(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
	if ctx.Done() == nil {
		return s.execSync(args)
	}

	type result struct {
		r   driver.Result
		err error
	}
	resultCh := make(chan result)
	defer close(resultCh)
	go func() {
		r, err := s.execSync(args)
		resultCh <- result{r, err}
	}()
	var rv result
	select {
	case rv = <-resultCh:
	case <-ctx.Done():
		select {
		case rv = <-resultCh: // no need to interrupt, operation completed in db
		default:
			// this is still racy and can be no-op if executed between sqlite3_* calls in execSync.
			C.sqlite3_interrupt(s.c.db)
			rv = <-resultCh // wait for goroutine completed
			if isInterruptErr(rv.err) {
				return nil, ctx.Err()
			}
		}
	}
	return rv.r, rv.err
}

func (s *SQLiteStmt) execSync(args []driver.NamedValue) (driver.Result, error) {
	if err := s.bind(args); err != nil {
		C.sqlite3_reset(s.s)
		C.sqlite3_clear_bindings(s.s)
		return nil, err
	}

	rv := C.sqlite3_step(s.s)
	if rv != C.SQLITE_ROW && rv != C.SQLITE_OK && rv != C.SQLITE_DONE {
		err := s.c.lastError()
		C.sqlite3_reset(s.s)
		C.sqlite3_clear_bindings(s.s)
		return nil, err
	}

	db      := C.sqlite3_db_handle(s.s)
	id      := int64(C.sqlite3_last_insert_rowid(db))
	changes := int64(C.sqlite3_changes(db))

	return &SQLiteResult{
		id:      id,
		changes: changes,
	}, nil
}

// Readonly reports if this statement is considered readonly by SQLite.
//
// See: https://sqlite.org/c3ref/stmt_readonly.html
func (s *SQLiteStmt) Readonly() bool {
	return C.sqlite3_stmt_readonly(s.s) == 1
}

func (rc *SQLiteRows) Close() error {
	rc.s.mu.Lock()
	if rc.s.closed || rc.closed {
		rc.s.mu.Unlock()
		return nil
	}
	rc.closed = true
	if rc.cls {
		rc.s.mu.Unlock()
		return rc.s.Close()
	}
	rv := C.sqlite3_reset(rc.s.s)
	if rv != C.SQLITE_OK {
		rc.s.mu.Unlock()
		return rc.s.c.lastError()
	}
	rc.s.mu.Unlock()
	rc.s = nil
	runtime.SetFinalizer(rc, nil)
	return nil
}

func (rc *SQLiteRows) Columns() []string {
	rc.s.mu.Lock()
	defer rc.s.mu.Unlock()
	if rc.s.s != nil && rc.nc != len(rc.cols) {
		rc.cols = make([]string, rc.nc)
		for i := 0; i < rc.nc; i++ {
			rc.cols[i] = C.GoString(C.sqlite3_column_name(rc.s.s, C.int(i)))
		}
	}
	return rc.cols
}

func (rc *SQLiteRows) declTypes() []string {
	if rc.s.s != nil && rc.decltype == nil {
		rc.decltype = make([]string, rc.nc)
		for i := 0; i < rc.nc; i++ {
			rc.decltype[i] = strings.ToLower(C.GoString(C.sqlite3_column_decltype(rc.s.s, C.int(i))))
		}
	}
	return rc.decltype
}

// DeclTypes return column types.
func (rc *SQLiteRows) DeclTypes() []string {
	rc.s.mu.Lock()
	defer rc.s.mu.Unlock()
	return rc.declTypes()
}

// Next move cursor to next. Attempts to honor context timeout from QueryContext call.
func (rc *SQLiteRows) Next(dest []driver.Value) error {
	rc.s.mu.Lock()
	defer rc.s.mu.Unlock()

	if rc.s.closed {
		return io.EOF
	}

	if rc.ctx.Done() == nil {
		return rc.nextSyncLocked(dest)
	}
	resultCh := make(chan error)
	defer close(resultCh)
	go func() {
		resultCh <- rc.nextSyncLocked(dest)
	}()
	select {
	case err := <-resultCh:
		return err
	case <-rc.ctx.Done():
		select {
		case <-resultCh: // no need to interrupt
		default:
			// this is still racy and can be no-op if executed between sqlite3_* calls in nextSyncLocked.
			C.sqlite3_interrupt(rc.s.c.db)
			<-resultCh // ensure goroutine completed
		}
		return rc.ctx.Err()
	}
}

// nextSyncLocked moves cursor to next; must be called with locked mutex.
func (rc *SQLiteRows) nextSyncLocked(dest []driver.Value) error {
	rv := C.sqlite3_step(rc.s.s)
	if rv == C.SQLITE_DONE {
		return io.EOF
	}
	if rv != C.SQLITE_ROW {
		rv = C.sqlite3_reset(rc.s.s)
		if rv != C.SQLITE_OK {
			return rc.s.c.lastError()
		}
		return nil
	}

	rc.declTypes()

	for i := range dest {
		switch C.sqlite3_column_type(rc.s.s, C.int(i)) {
		case C.SQLITE_INTEGER:
			val := int64(C.sqlite3_column_int64(rc.s.s, C.int(i)))
			switch rc.decltype[i] {
			case columnTimestamp, columnDatetime, columnDate:
				var t time.Time
				// Assume a millisecond unix timestamp if it's 13 digits -- too
				// large to be a reasonable timestamp in seconds.
				if val > 1e12 || val < -1e12 {
					val *= int64(time.Millisecond) // convert ms to nsec
					t = time.Unix(0, val)
				} else {
					t = time.Unix(val, 0)
				}
				t = t.UTC()
				if rc.s.c.loc != nil {
					t = t.In(rc.s.c.loc)
				}
				dest[i] = t
			case "boolean":
				dest[i] = val > 0
			default:
				dest[i] = val
			}
		case C.SQLITE_FLOAT:
			dest[i] = float64(C.sqlite3_column_double(rc.s.s, C.int(i)))
		case C.SQLITE_BLOB:
			p := C.sqlite3_column_blob(rc.s.s, C.int(i))
			if p == nil {
				dest[i] = []byte{}
				continue
			}
			n := C.sqlite3_column_bytes(rc.s.s, C.int(i))
			dest[i] = C.GoBytes(p, n)
		case C.SQLITE_NULL:
			dest[i] = nil
		case C.SQLITE_TEXT:
			var err error
			var timeVal time.Time

			n := int(C.sqlite3_column_bytes(rc.s.s, C.int(i)))
			s := C.GoStringN((*C.char)(unsafe.Pointer(C.sqlite3_column_text(rc.s.s, C.int(i)))), C.int(n))

			switch rc.decltype[i] {
			case columnTimestamp, columnDatetime, columnDate:
				var t time.Time
				s = strings.TrimSuffix(s, "Z")
				for _, format := range SQLiteTimestampFormats {
					if timeVal, err = time.ParseInLocation(format, s, time.UTC); err == nil {
						t = timeVal
						break
					}
				}
				if err != nil {
					// The column is a time value, so return the zero time on parse failure.
					t = time.Time{}
				}
				if rc.s.c.loc != nil {
					t = t.In(rc.s.c.loc)
				}
				dest[i] = t
			default:
				dest[i] = s
			}
		}
	}
	return nil
}

const i64 = unsafe.Sizeof(int(0)) > 4

// SQLiteContext behave sqlite3_context
type SQLiteContext C.sqlite3_context

// ResultBool sets the result of an SQL function.
func (c *SQLiteContext) ResultBool(b bool) {
	if b {
		c.ResultInt(1)
	} else {
		c.ResultInt(0)
	}
}

// ResultBlob sets the result of an SQL function.
// See: sqlite3_result_blob, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultBlob(b []byte) {
	if i64 && len(b) > math.MaxInt32 {
		C.sqlite3_result_error_toobig((*C.sqlite3_context)(c))
		return
	}
	var p *byte
	if len(b) > 0 {
		p = &b[0]
	}
	C.sqlite3_result_blob(
		(*C.sqlite3_context)(c),
		unsafe.Pointer(p),
		C.int(len(b)),
		C.SQLITE_TRANSIENT,
	)
}

// ResultDouble sets the result of an SQL function.
// See: sqlite3_result_double, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultDouble(d float64) {
	C.sqlite3_result_double((*C.sqlite3_context)(c), C.double(d))
}

// ResultInt sets the result of an SQL function.
// See: sqlite3_result_int, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultInt(i int) {
	if i64 && (i > math.MaxInt32 || i < math.MinInt32) {
		C.sqlite3_result_int64((*C.sqlite3_context)(c), C.sqlite3_int64(i))
	} else {
		C.sqlite3_result_int((*C.sqlite3_context)(c), C.int(i))
	}
}

// ResultInt64 sets the result of an SQL function.
// See: sqlite3_result_int64, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultInt64(i int64) {
	C.sqlite3_result_int64((*C.sqlite3_context)(c), C.sqlite3_int64(i))
}

// ResultNull sets the result of an SQL function.
// See: sqlite3_result_null, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultNull() {
	C.sqlite3_result_null((*C.sqlite3_context)(c))
}

// ResultText sets the result of an SQL function.
// See: sqlite3_result_text, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultText(s string) {
	h := (*reflect.StringHeader)(unsafe.Pointer(&s))
	cs, l := (*C.char)(unsafe.Pointer(h.Data)), C.int(h.Len)
	C.sqlite3_result_text(
		(*C.sqlite3_context)(c),
		cs,
		l,
		C.SQLITE_TRANSIENT,
	)
}

// ResultZeroblob sets the result of an SQL function.
// See: sqlite3_result_zeroblob, http://sqlite.org/c3ref/result_blob.html
func (c *SQLiteContext) ResultZeroblob(n int) {
	C.sqlite3_result_zeroblob((*C.sqlite3_context)(c), C.int(n))
}

// Ping implement Pinger.
func (c *SQLiteConn) Ping(ctx context.Context) error {
	if c.db == nil {
		// must be ErrBadConn for sql to close the database
		return driver.ErrBadConn
	}
	return nil
}

// QueryContext implement QueryerContext.
func (c *SQLiteConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
	return c.query(ctx, query, args)
}

// ExecContext implement ExecerContext.
func (c *SQLiteConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
	return c.exec(ctx, query, args)
}

// PrepareContext implement ConnPrepareContext.
func (c *SQLiteConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
	return c.prepare(ctx, query)
}

// BeginTx implement ConnBeginTx.
func (c *SQLiteConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
	return c.begin(ctx)
}

// QueryContext implement QueryerContext.
func (s *SQLiteStmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
	return s.query(ctx, args)
}

// ExecContext implement ExecerContext.
func (s *SQLiteStmt) ExecContext(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
	return s.exec(ctx, args)
}

// ColumnTableName returns the table that is the origin of a particular result
// column in a SELECT statement.
//
// See https://www.sqlite.org/c3ref/column_database_name.html
func (s *SQLiteStmt) ColumnTableName(n int) string {
	return C.GoString(C.sqlite3_column_table_name(s.s, C.int(n)))
}

// Serialize returns a byte slice that is a serialization of the database.
//
// See https://www.sqlite.org/c3ref/serialize.html
func (c *SQLiteConn) Serialize(schema string) ([]byte, error) {
	if schema == "" {
		schema = "main"
	}
	var zSchema *C.char
	zSchema = C.CString(schema)
	defer C.free(unsafe.Pointer(zSchema))

	var sz C.sqlite3_int64
	ptr := C.sqlite3_serialize(c.db, zSchema, &sz, 0)
	if ptr == nil {
		return nil, fmt.Errorf("serialize failed")
	}
	defer C.sqlite3_free(unsafe.Pointer(ptr))

	if sz > C.sqlite3_int64(math.MaxInt) {
		return nil, fmt.Errorf("serialized database is too large (%d bytes)", sz)
	}

	cBuf := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
		Data: uintptr(unsafe.Pointer(ptr)),
		Len:  int(sz),
		Cap:  int(sz),
	}))

	res := make([]byte, int(sz))
	copy(res, cBuf)
	return res, nil
}

// Deserialize causes the connection to disconnect from the current database and
// then re-open as an in-memory database based on the contents of the byte slice.
//
// See https://www.sqlite.org/c3ref/deserialize.html
func (c *SQLiteConn) Deserialize(b []byte, schema string) error {
	if schema == "" {
		schema = "main"
	}
	var zSchema *C.char
	zSchema = C.CString(schema)
	defer C.free(unsafe.Pointer(zSchema))

	tmpBuf := (*C.uchar)(C.sqlite3_malloc64(C.sqlite3_uint64(len(b))))
	cBuf := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
		Data: uintptr(unsafe.Pointer(tmpBuf)),
		Len:  len(b),
		Cap:  len(b),
	}))
	copy(cBuf, b)

	rc := C.sqlite3_deserialize(c.db, zSchema, tmpBuf, C.sqlite3_int64(len(b)),
		C.sqlite3_int64(len(b)), C.SQLITE_DESERIALIZE_FREEONCLOSE)
	if rc != C.SQLITE_OK {
		return fmt.Errorf("deserialize failed with return %v", rc)
	}
	return nil
}

// Op is type of operations.
type Op uint8

// Op mean identity of operations.
const (
	OpEQ         Op = 2
	OpGT            = 4
	OpLE            = 8
	OpLT            = 16
	OpGE            = 32
	OpMATCH         = 64
	OpLIKE          = 65 /* 3.10.0 and later only */
	OpGLOB          = 66 /* 3.10.0 and later only */
	OpREGEXP        = 67 /* 3.10.0 and later only */
	OpScanUnique    = 1  /* Scan visits at most 1 row */
)

// InfoConstraint give information of constraint.
type InfoConstraint struct {
	Column int
	Op     Op
	Usable bool
}

// InfoOrderBy give information of order-by.
type InfoOrderBy struct {
	Column int
	Desc   bool
}

func constraints(info *C.sqlite3_index_info) []InfoConstraint {
	slice := *(*[]C.struct_sqlite3_index_constraint)(unsafe.Pointer(&reflect.SliceHeader{
		Data: uintptr(unsafe.Pointer(info.aConstraint)),
		Len:  int(info.nConstraint),
		Cap:  int(info.nConstraint),
	}))

	cst := make([]InfoConstraint, 0, len(slice))
	for _, c := range slice {
		var usable bool
		if c.usable > 0 {
			usable = true
		}
		cst = append(cst, InfoConstraint{
			Column: int(c.iColumn),
			Op:     Op(c.op),
			Usable: usable,
		})
	}
	return cst
}

func orderBys(info *C.sqlite3_index_info) []InfoOrderBy {
	slice := *(*[]C.struct_sqlite3_index_orderby)(unsafe.Pointer(&reflect.SliceHeader{
		Data: uintptr(unsafe.Pointer(info.aOrderBy)),
		Len:  int(info.nOrderBy),
		Cap:  int(info.nOrderBy),
	}))

	ob := make([]InfoOrderBy, 0, len(slice))
	for _, c := range slice {
		var desc bool
		if c.desc > 0 {
			desc = true
		}
		ob = append(ob, InfoOrderBy{
			Column: int(c.iColumn),
			Desc:   desc,
		})
	}
	return ob
}

// IndexResult is a Go struct representation of what eventually ends up in the
// output fields for `sqlite3_index_info`
// See: https://www.sqlite.org/c3ref/index_info.html
type IndexResult struct {
	Used           []bool // aConstraintUsage
	IdxNum         int
	IdxStr         string
	AlreadyOrdered bool // orderByConsumed
	EstimatedCost  float64
	EstimatedRows  float64
}

func fillDBError(dbErr *Error, db *C.sqlite3) {
	// See SQLiteConn.lastError(), in file 'sqlite3.go' at the time of writing (Sept 5, 2016)
	dbErr.Code = ErrNo(C.sqlite3_errcode(db))
	dbErr.ExtendedCode = ErrNoExtended(C.sqlite3_extended_errcode(db))
	dbErr.err = C.GoString(C.sqlite3_errmsg(db))
}

// ColumnTypeDatabaseTypeName implement RowsColumnTypeDatabaseTypeName.
func (rc *SQLiteRows) ColumnTypeDatabaseTypeName(i int) string {
	return C.GoString(C.sqlite3_column_decltype(rc.s.s, C.int(i)))
}

// ColumnTypeNullable implement RowsColumnTypeNullable.
func (rc *SQLiteRows) ColumnTypeNullable(i int) (nullable, ok bool) {
	return true, true
}

// ColumnTypeScanType implement RowsColumnTypeScanType.
func (rc *SQLiteRows) ColumnTypeScanType(i int) reflect.Type {
	//ct := C.sqlite3_column_type(rc.s.s, C.int(i))  // Always returns 5
	return scanType(C.GoString(C.sqlite3_column_decltype(rc.s.s, C.int(i))))
}

const (
	SQLITE_INTEGER = iota
	SQLITE_TEXT
	SQLITE_BLOB
	SQLITE_REAL
	SQLITE_NUMERIC
	SQLITE_TIME
	SQLITE_BOOL
	SQLITE_NULL
)

func scanType(cdt string) reflect.Type {
	t := strings.ToUpper(cdt)
	i := databaseTypeConvSqlite(t)
	switch i {
	case SQLITE_INTEGER:
		return reflect.TypeOf(sql.NullInt64{})
	case SQLITE_TEXT:
		return reflect.TypeOf(sql.NullString{})
	case SQLITE_BLOB:
		return reflect.TypeOf(sql.RawBytes{})
	case SQLITE_REAL:
		return reflect.TypeOf(sql.NullFloat64{})
	case SQLITE_NUMERIC:
		return reflect.TypeOf(sql.NullFloat64{})
	case SQLITE_BOOL:
		return reflect.TypeOf(sql.NullBool{})
	case SQLITE_TIME:
		return reflect.TypeOf(sql.NullTime{})
	}
	return reflect.TypeOf(new(any))
}

func databaseTypeConvSqlite(t string) int {
	if strings.Contains(t, "INT") {
		return SQLITE_INTEGER
	}
	if t == "CLOB" || t == "TEXT" ||
		strings.Contains(t, "CHAR") {
		return SQLITE_TEXT
	}
	if t == "BLOB" {
		return SQLITE_BLOB
	}
	if t == "REAL" || t == "FLOAT" ||
		strings.Contains(t, "DOUBLE") {
		return SQLITE_REAL
	}
	if t == "DATE" || t == "DATETIME" ||
		t == "TIMESTAMP" {
		return SQLITE_TIME
	}
	if t == "NUMERIC" ||
		strings.Contains(t, "DECIMAL") {
		return SQLITE_NUMERIC
	}
	if t == "BOOLEAN" {
		return SQLITE_BOOL
	}

	return SQLITE_NULL
}