package gobang

import (
	"crypto/sha1"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"hash"
	"log/slog"
	"os"
	"strings"
	"time"
)



type pbkdfTestVector struct {
	password string
	salt     string
	iter     int
	output   []byte
}

// Test vectors from RFC 6070, http://tools.ietf.org/html/rfc6070
var sha1TestVectors = []pbkdfTestVector {
	{
		"password",
		"salt",
		1,
		[]byte {
			0x0c, 0x60, 0xc8, 0x0f, 0x96, 0x1f, 0x0e, 0x71,
			0xf3, 0xa9, 0xb5, 0x24, 0xaf, 0x60, 0x12, 0x06,
			0x2f, 0xe0, 0x37, 0xa6,
		},
	},
	{
		"password",
		"salt",
		2,
		[]byte{
			0xea, 0x6c, 0x01, 0x4d, 0xc7, 0x2d, 0x6f, 0x8c,
			0xcd, 0x1e, 0xd9, 0x2a, 0xce, 0x1d, 0x41, 0xf0,
			0xd8, 0xde, 0x89, 0x57,
		},
	},
	{
		"password",
		"salt",
		4096,
		[]byte{
			0x4b, 0x00, 0x79, 0x01, 0xb7, 0x65, 0x48, 0x9a,
			0xbe, 0xad, 0x49, 0xd9, 0x26, 0xf7, 0x21, 0xd0,
			0x65, 0xa4, 0x29, 0xc1,
		},
	},
	// // This one takes too long
	// {
	// 	"password",
	// 	"salt",
	// 	16777216,
	// 	[]byte {
	// 		0xee, 0xfe, 0x3d, 0x61, 0xcd, 0x4d, 0xa4, 0xe4,
	// 		0xe9, 0x94, 0x5b, 0x3d, 0x6b, 0xa2, 0x15, 0x8c,
	// 		0x26, 0x34, 0xe9, 0x84,
	// 	},
	// },
	{
		"passwordPASSWORDpassword",
		"saltSALTsaltSALTsaltSALTsaltSALTsalt",
		4096,
		[]byte{
			0x3d, 0x2e, 0xec, 0x4f, 0xe4, 0x1c, 0x84, 0x9b,
			0x80, 0xc8, 0xd8, 0x36, 0x62, 0xc0, 0xe4, 0x4a,
			0x8b, 0x29, 0x1a, 0x96, 0x4c, 0xf2, 0xf0, 0x70,
			0x38,
		},
	},
	{
		"pass\000word",
		"sa\000lt",
		4096,
		[]byte{
			0x56, 0xfa, 0x6a, 0xa7, 0x55, 0x48, 0x09, 0x9d,
			0xcc, 0x37, 0xd7, 0xf0, 0x34, 0x25, 0xe0, 0xc3,
		},
	},
}

// Test vectors from
// http://stackoverflow.com/questions/5130513/pbkdf2-hmac-sha2-test-vectors
var sha256TestVectors = []pbkdfTestVector {
	{
		"password",
		"salt",
		1,
		[]byte {
			0x12, 0x0f, 0xb6, 0xcf, 0xfc, 0xf8, 0xb3, 0x2c,
			0x43, 0xe7, 0x22, 0x52, 0x56, 0xc4, 0xf8, 0x37,
			0xa8, 0x65, 0x48, 0xc9,
		},
	},
	{
		"password",
		"salt",
		2,
		[]byte {
			0xae, 0x4d, 0x0c, 0x95, 0xaf, 0x6b, 0x46, 0xd3,
			0x2d, 0x0a, 0xdf, 0xf9, 0x28, 0xf0, 0x6d, 0xd0,
			0x2a, 0x30, 0x3f, 0x8e,
		},
	},
	{
		"password",
		"salt",
		4096,
		[]byte {
			0xc5, 0xe4, 0x78, 0xd5, 0x92, 0x88, 0xc8, 0x41,
			0xaa, 0x53, 0x0d, 0xb6, 0x84, 0x5c, 0x4c, 0x8d,
			0x96, 0x28, 0x93, 0xa0,
		},
	},
	{
		"passwordPASSWORDpassword",
		"saltSALTsaltSALTsaltSALTsaltSALTsalt",
		4096,
		[]byte {
			0x34, 0x8c, 0x89, 0xdb, 0xcb, 0xd3, 0x2b, 0x2f,
			0x32, 0xd8, 0x14, 0xb8, 0x11, 0x6e, 0x84, 0xcf,
			0x2b, 0x17, 0x34, 0x7e, 0xbc, 0x18, 0x00, 0x18,
			0x1c,
		},
	},
	{
		"pass\000word",
		"sa\000lt",
		4096,
		[]byte {
			0x89, 0xb6, 0x9d, 0x05, 0x16, 0xf8, 0x29, 0x89,
			0x3c, 0x69, 0x62, 0x26, 0x65, 0x0a, 0x86, 0x87,
		},
	},
}

func testHash(h func() hash.Hash, hashName string, vectors []pbkdfTestVector) {
	for i, v := range vectors {
		out := _PBKDF2Key(
			[]byte(v.password),
			[]byte(v.salt),
			v.iter,
			len(v.output),
			h,
		)
		AssertEqualI(i, out, v.output)
	}
}

func test__PBKDF() {
	TestStart("_PBKDF()")

	Testing("HMAC with SHA1", func() {
		testHash(sha1.New, "SHA1", sha1TestVectors)
	})

	Testing("HMAC with SHA256", func() {
		testHash(sha256.New, "SHA256", sha256TestVectors)
	})
}

type scryptTestVector struct {
	password string
	salt     string
	N, r, p  int
	output   []byte
}

var good = []scryptTestVector {
	{
		"password",
		"salt",
		2, 10, 10,
		[]byte {
			0x48, 0x2c, 0x85, 0x8e, 0x22, 0x90, 0x55, 0xe6, 0x2f,
			0x41, 0xe0, 0xec, 0x81, 0x9a, 0x5e, 0xe1, 0x8b, 0xdb,
			0x87, 0x25, 0x1a, 0x53, 0x4f, 0x75, 0xac, 0xd9, 0x5a,
			0xc5, 0xe5, 0xa, 0xa1, 0x5f,
		},
	},
	{
		"password",
		"salt",
		16, 100, 100,
		[]byte {
			0x88, 0xbd, 0x5e, 0xdb, 0x52, 0xd1, 0xdd, 0x0, 0x18,
			0x87, 0x72, 0xad, 0x36, 0x17, 0x12, 0x90, 0x22, 0x4e,
			0x74, 0x82, 0x95, 0x25, 0xb1, 0x8d, 0x73, 0x23, 0xa5,
			0x7f, 0x91, 0x96, 0x3c, 0x37,
		},
	},
	{
		"this is a long \000 password",
		"and this is a long \000 salt",
		16384, 8, 1,
		[]byte {
			0xc3, 0xf1, 0x82, 0xee, 0x2d, 0xec, 0x84, 0x6e, 0x70,
			0xa6, 0x94, 0x2f, 0xb5, 0x29, 0x98, 0x5a, 0x3a, 0x09,
			0x76, 0x5e, 0xf0, 0x4c, 0x61, 0x29, 0x23, 0xb1, 0x7f,
			0x18, 0x55, 0x5a, 0x37, 0x07, 0x6d, 0xeb, 0x2b, 0x98,
			0x30, 0xd6, 0x9d, 0xe5, 0x49, 0x26, 0x51, 0xe4, 0x50,
			0x6a, 0xe5, 0x77, 0x6d, 0x96, 0xd4, 0x0f, 0x67, 0xaa,
			0xee, 0x37, 0xe1, 0x77, 0x7b, 0x8a, 0xd5, 0xc3, 0x11,
			0x14, 0x32, 0xbb, 0x3b, 0x6f, 0x7e, 0x12, 0x64, 0x40,
			0x18, 0x79, 0xe6, 0x41, 0xae,
		},
	},
	{
		"p",
		"s",
		2, 1, 1,
		[]byte {
			0x48, 0xb0, 0xd2, 0xa8, 0xa3, 0x27, 0x26, 0x11, 0x98,
			0x4c, 0x50, 0xeb, 0xd6, 0x30, 0xaf, 0x52,
		},
	},

	{
		"",
		"",
		16, 1, 1,
		[]byte {
			0x77, 0xd6, 0x57, 0x62, 0x38, 0x65, 0x7b, 0x20, 0x3b,
			0x19, 0xca, 0x42, 0xc1, 0x8a, 0x04, 0x97, 0xf1, 0x6b,
			0x48, 0x44, 0xe3, 0x07, 0x4a, 0xe8, 0xdf, 0xdf, 0xfa,
			0x3f, 0xed, 0xe2, 0x14, 0x42, 0xfc, 0xd0, 0x06, 0x9d,
			0xed, 0x09, 0x48, 0xf8, 0x32, 0x6a, 0x75, 0x3a, 0x0f,
			0xc8, 0x1f, 0x17, 0xe8, 0xd3, 0xe0, 0xfb, 0x2e, 0x0d,
			0x36, 0x28, 0xcf, 0x35, 0xe2, 0x0c, 0x38, 0xd1, 0x89,
			0x06,
		},
	},
	{
		"password",
		"NaCl",
		1024, 8, 16,
		[]byte {
			0xfd, 0xba, 0xbe, 0x1c, 0x9d, 0x34, 0x72, 0x00, 0x78,
			0x56, 0xe7, 0x19, 0x0d, 0x01, 0xe9, 0xfe, 0x7c, 0x6a,
			0xd7, 0xcb, 0xc8, 0x23, 0x78, 0x30, 0xe7, 0x73, 0x76,
			0x63, 0x4b, 0x37, 0x31, 0x62, 0x2e, 0xaf, 0x30, 0xd9,
			0x2e, 0x22, 0xa3, 0x88, 0x6f, 0xf1, 0x09, 0x27, 0x9d,
			0x98, 0x30, 0xda, 0xc7, 0x27, 0xaf, 0xb9, 0x4a, 0x83,
			0xee, 0x6d, 0x83, 0x60, 0xcb, 0xdf, 0xa2, 0xcc, 0x06,
			0x40,
		},
	},
	{
		"pleaseletmein", "SodiumChloride",
		16384, 8, 1,
		[]byte {
			0x70, 0x23, 0xbd, 0xcb, 0x3a, 0xfd, 0x73, 0x48, 0x46,
			0x1c, 0x06, 0xcd, 0x81, 0xfd, 0x38, 0xeb, 0xfd, 0xa8,
			0xfb, 0xba, 0x90, 0x4f, 0x8e, 0x3e, 0xa9, 0xb5, 0x43,
			0xf6, 0x54, 0x5d, 0xa1, 0xf2, 0xd5, 0x43, 0x29, 0x55,
			0x61, 0x3f, 0x0f, 0xcf, 0x62, 0xd4, 0x97, 0x05, 0x24,
			0x2a, 0x9a, 0xf9, 0xe6, 0x1e, 0x85, 0xdc, 0x0d, 0x65,
			0x1e, 0x40, 0xdf, 0xcf, 0x01, 0x7b, 0x45, 0x57, 0x58,
			0x87,
		},
	},
	// // Disabled: needs 1 GiB RAM and takes too long for a simple test.
	// {
	// 	"pleaseletmein", "SodiumChloride",
	// 	1048576, 8, 1,
	// 	[]byte{
	// 		0x21, 0x01, 0xcb, 0x9b, 0x6a, 0x51, 0x1a, 0xae, 0xad,
	// 		0xdb, 0xbe, 0x09, 0xcf, 0x70, 0xf8, 0x81, 0xec, 0x56,
	// 		0x8d, 0x57, 0x4a, 0x2f, 0xfd, 0x4d, 0xab, 0xe5, 0xee,
	// 		0x98, 0x20, 0xad, 0xaa, 0x47, 0x8e, 0x56, 0xfd, 0x8f,
	// 		0x4b, 0xa5, 0xd0, 0x9f, 0xfa, 0x1c, 0x6d, 0x92, 0x7c,
	// 		0x40, 0xf4, 0xc3, 0x37, 0x30, 0x40, 0x49, 0xe8, 0xa9,
	// 		0x52, 0xfb, 0xcb, 0xf4, 0x5c, 0x6f, 0xa7, 0x7a, 0x41,
	// 		0xa4,
	// 	},
	// },
}

const halfMax = maxInt / 2
var bad = []scryptTestVector {
	{"p", "s", 0, 1, 1, nil},                    // N == 0
	{"p", "s", 1, 1, 1, nil},                    // N == 1
	{"p", "s", 7, 8, 1, nil},                    // N is not power of 2
	{"p", "s", 16, halfMax, halfMax, nil},       // p * r too large
}

func test_scrypt() {
	TestStart("scrypt()")

	Testing("good hashes", func() {
		for i, v := range good {
			k, err := scrypt(
				[]byte(v.password),
				[]byte(v.salt),
				v.N,
				v.r,
				v.p,
				len(v.output),
			)
			ErrorIf(err)
			AssertEqualI(i, k, v.output)
		}
	})

	Testing("bad hashes", func() {
		for _, v := range bad {
			_, err := scrypt(
				[]byte(v.password),
				[]byte(v.salt),
				v.N,
				v.r,
				v.p,
				32,
			)
			ErrorNil(err)
		}
	})

	Testing("example value", func() {
		const expected = "lGnMz8io0AUkfzn6Pls1qX20Vs7PGN6sbYQ2TQgY12M="
		// DO NOT use this salt value; generate your own random salt.
		// 8 bytes is a good length.
		salt := []byte{0xc8, 0x28, 0xf2, 0x58, 0xa7, 0x6a, 0xad, 0x7b}

		dk, err := scrypt(
			[]byte("some password"),
			salt,
			1<<15,
			8,
			1,
			32,
		)
		ErrorIf(err)

		given := base64.StdEncoding.EncodeToString(dk)
		AssertEqual(given, expected)
	})
}

func test_Random() {
	TestStart("Random()")

	Testing("we get the desired output size", func() {
		for i := 0; i < 100; i++ {
			buffer := Random(i)
			AssertEqual(len(buffer), i)
		}
	})
}

func test_Salt() {
	TestStart("Salt()")

	Testing("we generate a random salt of a fixed size", func() {
		salt := Salt()
		AssertEqual(len(salt), scryptSaltMinLength)

		var buffer [scryptSaltMinLength * 2]byte
		hex.Encode(buffer[:], salt)
		fmt.Fprintf(os.Stderr, "%s ", string(buffer[:]))
	})
}

func test_Hash() {
	TestStart("Hash()")

	Testing("same input, same output", func() {
		password := Random(16)
		salt := Salt()
		hash1 := Hash(password, salt)
		hash2 := Hash(password, salt)
		AssertEqual(hash1, hash2)
	})
}

func test_getV7Time() {
	// FIXME
}

func test_newUUIDFrom() {
	TestStart("newUUIDFrom()")

	Testing("same UUID from same input", func() {
		for i := 0; i < 100; i++ {
			var b [uuidByteCount]byte
			buffer := Random(uuidByteCount)
			now := time.Now().UnixNano()

			lastV7Time = now + 1
			copy(b[:], buffer)
			uuid1 := newUUIDFrom(b, now)

			lastV7Time = now + 1
			copy(b[:], buffer)
			uuid2 := newUUIDFrom(b, now)

			AssertEqual(uuid1, uuid2)
		}
	})
}

func test_NewUUID() {
	TestStart("NewUUID()")

	Testing("we can generate UUID values", func() {
		var uuid UUID = NewUUID()
		AssertEqual(len(uuid.bytes), uuidByteCount)
	})
}

func test_UUIDString() {
	TestStart("UUID.String()")

	Testing("simple example values", func() {
		uuids := []UUID {
			UUID {
				bytes: [uuidByteCount]byte {
					0, 0, 0, 0, 0, 0, 0, 0,
					0, 0, 0, 0, 0, 0, 0, 0,
				},
			},
			UUID {
				bytes: [uuidByteCount]byte {
					0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
					10, 11, 12, 13, 14, 15,
				},
			},
			UUID {
				bytes: [uuidByteCount]byte {
					222, 222, 222, 222, 222, 222, 222, 222,
					222, 222, 222, 222, 222, 222, 222, 222,
				},
			},
			UUID {
				bytes: [uuidByteCount]byte {
					255, 255, 255, 255, 255, 255, 255, 255,
					255, 255, 255, 255, 255, 255, 255, 255,
				},
			},
		}

		strs := []string {
			"00000000-0000-0000-0000-000000000000",
			"00010203-0405-0607-0809-0a0b0c0d0e0f",
			"dededede-dede-dede-dede-dededededede",
			"ffffffff-ffff-ffff-ffff-ffffffffffff",
		}

		for i := range uuids {
			AssertEqual(uuids[i].String(), strs[i])
		}
	})
}

func test_ParseUUID() {
	TestStart("ParseUUID()")

	Testing("UUID -> string -> UUID round trip", func() {
		for i := 0; i < 100; i++ {
			uuid0 := NewUUID()
			uuid1, err := ParseUUID(uuid0.String())
			ErrorIf(err)
			AssertEqual(uuid1, uuid0)
		}
	})

	Testing("errors we detect", func() {
		var err error

		_, err = ParseUUID("")
		AssertEqual(err, badUUIDLengthError)

		_, err = ParseUUID("---000000000000000000000000000000000")
		AssertEqual(err, badUUIDDashCountError)

		_, err = ParseUUID("----00000000000000000000000000000000")
		AssertEqual(err, badUUIDDashPositionError)

		_, err = ParseUUID("00000000-0000-0000-0000-00000000000g")
		AssertEqual(err, hex.InvalidByteError('g'))

		_, err = ParseUUID("00000000-0000-0000-0000-000000000000")
		ErrorIf(err)
	})
}

func test_sourceInfo() {
	TestStart("sourceInfo()")

	Testing("sourceInfo() is defined at...", func() {
		const FILENAME = "src/gobang.go"
		info := sourceInfo(1)
		AssertEqual(info.Key, "src")
		AssertEqual(len(info.Value.Group()), 3)

		AssertEqual(info.Value.Group()[0].Key, "file")
		file := info.Value.Group()[0].Value.String()
		AssertEqual(file[len(file) - len(FILENAME):], FILENAME)

		AssertEqual(info.Value.Group()[1].Key, "function")
		AssertEqual(
			info.Value.Group()[1].Value.String(),
			"gobang.sourceInfo",
		)

		AssertEqual(info.Value.Group()[2].Key, "line")
		AssertEqual(info.Value.Group()[2].Value.Kind(), slog.KindInt64)
	})

	Testing("we're calling it from...", func() {
		const FILENAME = "tests/gobang.go"
		info := sourceInfo(2)
		AssertEqual(info.Key, "src")
		AssertEqual(len(info.Value.Group()), 3)

		AssertEqual(info.Value.Group()[0].Key, "file")
		file := info.Value.Group()[0].Value.String()
		AssertEqual(file[len(file) - len(FILENAME):], FILENAME)

		AssertEqual(info.Value.Group()[1].Key, "function")
		AssertEqual(
			info.Value.Group()[1].Value.String(),
			"gobang.test_sourceInfo.func2",
		)

		AssertEqual(info.Value.Group()[2].Key, "line")
		AssertEqual(info.Value.Group()[2].Value.Kind(), slog.KindInt64)
	})
}

func test_logArgs() {
	TestStart("logArgs()")

	Testing("direct string array return", func() {
		args := logArgs("the-type")
		AssertEqual(len(args), 6)
		AssertEqual(args[0], "id")

		_, err := ParseUUID(args[1])
		ErrorIf(err)

		expected := []string { "kind", "log", "type", "the-type" }
		AssertEqual(args[2:], expected)
	})
}

func test_anyArr() {
	TestStart("anyArr()")

	Testing("we can turn []string into []any", func() {
		var input []string = []string { "one", "two", "three" }
		var given []any    = anyArr(input)
		var expected []any = []any { "one", "two", "three" }

		AssertEqual(given, expected)
	})
}

func testLog(
	levelName string,
	filterLevel logLevel,
	fn func(string, string, ...any),
) {
	savedLogger := slog.Default()
	savedLevel  := level

	s := new(strings.Builder)
	setLoggerOutput(s)
	level = filterLevel

	fn("a-message", "a-type", "a-key", "a-value")

	{
		var data map[string]interface{}
		err := json.Unmarshal([]byte(s.String()), &data)
		ErrorIf(err)

		timeRaw, ok := data["time"]
		AssertEqual(ok, true)
		timeStr, ok := timeRaw.(string)
		AssertEqual(ok, true)
		_, err = time.Parse(time.RFC3339, timeStr)
		ErrorIf(err)

		levelRaw, ok := data["level"]
		AssertEqual(ok, true)
		level, ok := levelRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(level, levelName)

		kindRaw, ok := data["kind"]
		AssertEqual(ok, true)
		kind, ok := kindRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(kind, "log")

		msgRaw, ok := data["msg"]
		AssertEqual(ok, true)
		msg, ok := msgRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(msg, "a-message")

		typeRaw, ok := data["type"]
		AssertEqual(ok, true)
		type_, ok := typeRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(type_, "a-type")

		keyRaw, ok := data["a-key"]
		AssertEqual(ok, true)
		key, ok := keyRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(key, "a-value")
	}

	slog.SetDefault(savedLogger)
	level = savedLevel
}

func testNoLog(filterLevel logLevel, fn func(string, string, ...any)) {
	savedLogger := slog.Default()
	savedLevel  := level

	s := new(strings.Builder)
	setLoggerOutput(s)
	level = filterLevel
	fn("a-message", "a-type", "a-key", "a-value")

	AssertEqual(s.String(), "")

	slog.SetDefault(savedLogger)
	level = savedLevel
}

func test_Debug() {
	TestStart("Debug()")

	Testing("exists in LevelDebug", func() {
		testLog("DEBUG", LevelDebug, Debug)
	})

	Testing("doesn't in lower levels", func() {
		testNoLog(LevelInfo, Debug)
	})
}

func test_Info() {
	TestStart("Info()")

	Testing("exists in LevelInfo", func() {
		testLog("INFO", LevelInfo, Info)
	})

	Testing("doesn't in lower levels", func() {
		testNoLog(LevelWarning, Info)
	})
}

func test_Warning() {
	TestStart("Warning()")

	Testing("exists in LevelWarning", func() {
		testLog("WARN" /* WARNING */, LevelWarning, Warning)
	})

	Testing("doesn't in lower levels", func() {
		testNoLog(LevelError, Warning)
	})
}

func test_Error() {
	TestStart("Error()")

	Testing("exists in LevelError", func() {
		testLog("ERROR", LevelError, Error)
	})

	Testing("doesn't in lower levels", func() {
		testNoLog(LevelNone, Error)
	})
}

func test_metric() {
	TestStart("metric()")

	Testing("noop when emitMetric is false", func() {
		savedLogger := slog.Default()
		savedFlag   := emitMetric

		s := new(strings.Builder)
		setLoggerOutput(s)
		emitMetric = false

		metric("", "")
		AssertEqual(s.String(), "")

		slog.SetDefault(savedLogger)
		emitMetric = savedFlag
	})

	Testing("JSON entry of kind \"metric\"", func() {
		savedLogger := slog.Default()
		savedFlag   := emitMetric

		s := new(strings.Builder)
		setLoggerOutput(s)
		emitMetric = true

		metric("a-type", "a-label", "count-something", 123)

		var data map[string]interface{}
		err := json.Unmarshal([]byte(s.String()), &data)
		ErrorIf(err)

		timeRaw, ok := data["time"]
		AssertEqual(ok, true)
		timeStr, ok := timeRaw.(string)
		AssertEqual(ok, true)
		_, err = time.Parse(time.RFC3339, timeStr)
		ErrorIf(err)

		levelRaw, ok := data["level"]
		AssertEqual(ok, true)
		level, ok := levelRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(level, "INFO")

		msgRaw, ok := data["msg"]
		AssertEqual(ok, true)
		msg, ok := msgRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(msg, "_")

		idRaw, ok := data["id"]
		AssertEqual(ok, true)
		id, ok := idRaw.(string)
		AssertEqual(ok, true)
		_, err = ParseUUID(id)
		ErrorIf(err)

		kindRaw, ok := data["kind"]
		AssertEqual(ok, true)
		kind, ok := kindRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(kind, "metric")

		typeRaw, ok := data["type"]
		AssertEqual(ok, true)
		type_, ok := typeRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(type_, "a-type")

		labelRaw, ok := data["label"]
		AssertEqual(ok, true)
		label, ok := labelRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(label, "a-label")

		keyRaw, ok := data["count-something"]
		AssertEqual(ok, true)
		key, ok := keyRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(key), 123)

		slog.SetDefault(savedLogger)
		emitMetric = savedFlag
	})
}

func test_MakeCounter() {
	TestStart("MakeCounter()")

	Testing("\"value\" is always 1", func() {
		savedLogger := slog.Default()
		savedFlag   := emitMetric

		s := new(strings.Builder)
		setLoggerOutput(s)
		emitMetric = true

		emitTCPError := MakeCounter("emit-tcp-error")
		emitTCPError("more-data", 555)

		var data map[string]interface{}
		err := json.Unmarshal([]byte(s.String()), &data)
		ErrorIf(err)

		typeRaw, ok := data["type"]
		AssertEqual(ok, true)
		type_, ok := typeRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(type_, "counter")

		labelRaw, ok := data["label"]
		AssertEqual(ok, true)
		label, ok := labelRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(label, "emit-tcp-error")

		valueRaw, ok := data["value"]
		AssertEqual(ok, true)
		value, ok := valueRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(value), 1)

		keyRaw, ok := data["more-data"]
		AssertEqual(ok, true)
		key, ok := keyRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(key), 555)

		slog.SetDefault(savedLogger)
		emitMetric = savedFlag
	})
}

func test_MakeGauge() {
	TestStart("MakeGauge()")

	Testing("errors on underflow", func() {
		savedLogger := slog.Default()
		savedLevel  := level

		s := new(strings.Builder)
		setLoggerOutput(s)
		level = LevelError

		activeTCPConnections := MakeGauge("active-tcp-connections")
		activeTCPConnections.Dec()

		{
			var data map[string]interface{}
			err := json.Unmarshal([]byte(s.String()), &data)
			ErrorIf(err)

			levelRaw, ok := data["level"]
			AssertEqual(ok, true)
			level, ok := levelRaw.(string)
			AssertEqual(ok, true)
			AssertEqual(level, "ERROR")

			msgRaw, ok := data["msg"]
			AssertEqual(ok, true)
			msg, ok := msgRaw.(string)
			AssertEqual(ok, true)
			AssertEqual(msg, "Gauge went negative")

			kindRaw, ok := data["kind"]
			AssertEqual(ok, true)
			kind, ok := kindRaw.(string)
			AssertEqual(ok, true)
			AssertEqual(kind, "log")

			typeRaw, ok := data["type"]
			AssertEqual(ok, true)
			type_, ok := typeRaw.(string)
			AssertEqual(ok, true)
			AssertEqual(type_, "process-metric")

			valueRaw, ok := data["value"]
			AssertEqual(ok, true)
			value, ok := valueRaw.(float64)
			AssertEqual(ok, true)
			AssertEqual(int(value), -1)
		}

		slog.SetDefault(savedLogger)
		level = savedLevel
	})

	Testing("\"value\" grows monotonically", func() {
		savedLogger := slog.Default()
		savedFlag   := emitMetric

		s := new(strings.Builder)
		setLoggerOutput(s)
		emitMetric = true

		activeTCPConnections := MakeGauge("active-tcp-connections")
		activeTCPConnections.Inc()
		activeTCPConnections.Inc()
		activeTCPConnections.Dec()
		activeTCPConnections.Inc()
		activeTCPConnections.Inc("more-data", 999)

		strs := strings.Split(s.String(), "\n")
		AssertEqual(len(strs), 6)
		AssertEqual(strs[5], "")

		var data map[string]interface{}
		err := json.Unmarshal([]byte(strs[len(strs) - 2]), &data)
		ErrorIf(err)

		typeRaw, ok := data["type"]
		AssertEqual(ok, true)
		type_, ok := typeRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(type_, "gauge")

		labelRaw, ok := data["label"]
		AssertEqual(ok, true)
		label, ok := labelRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(label, "active-tcp-connections")

		valueRaw, ok := data["value"]
		AssertEqual(ok, true)
		value, ok := valueRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(value), 3)

		keyRaw, ok := data["more-data"]
		AssertEqual(ok, true)
		key, ok := keyRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(key), 999)

		slog.SetDefault(savedLogger)
		emitMetric = savedFlag
	})
}

func test_ErrorIf() {
	TestStart("ErrorIf()")

	Testing("noop on nil value", func() {
		ErrorIf(nil)
	})
}

func test_ErrorNil() {
	TestStart("ErrorNil()")

	Testing("noop on thruthy value", func() {
		ErrorNil(errors.New("some error"))
	})
}

func test_showColour() {
	TestStart("showColour()")

	const NAME = "NO_COLOUR"
	savedEnvvar := os.Getenv(NAME)

	Testing("true when envvar is unset", func() {
		ErrorIf(os.Unsetenv(NAME))
		AssertEqual(showColour(), true)
	})

	Testing("true when envvar is empty", func() {
		ErrorIf(os.Setenv(NAME, ""))
		AssertEqual(showColour(), true)
	})

	Testing("false otherwise", func() {
		ErrorIf(os.Setenv(NAME, "1"))
		AssertEqual(showColour(), false)
	})

	ErrorIf(os.Setenv(NAME, savedEnvvar))
}

func test_setLoggerOutput() {
	TestStart("setLoggerOutput()")

	savedLogger := slog.Default()

	Testing("the output JSON has data under \"src\"", func() {
		s := new(strings.Builder)
		setLoggerOutput(s)
		Info("", "")

		var data map[string]interface{}
		err := json.Unmarshal([]byte(s.String()), &data)
		ErrorIf(err)

		srcRaw, ok := data["src"]
		AssertEqual(ok, true)
		src, ok := srcRaw.(map[string]interface{})
		AssertEqual(ok, true)

		fileRaw, ok := src["file"]
		AssertEqual(ok, true)
		file, ok := fileRaw.(string)
		AssertEqual(ok, true)
		const FILENAME = "tests/gobang.go"
		AssertEqual(file[len(file) - len(FILENAME):], FILENAME)

		functionRaw, ok := src["function"]
		AssertEqual(ok, true)
		function, ok := functionRaw.(string)
		AssertEqual(ok, true)
		AssertEqual(function, "gobang.test_setLoggerOutput.func1")

		lineRaw, ok := src["line"]
		AssertEqual(ok, true)
		_, ok = lineRaw.(float64)
		AssertEqual(ok, true)
	})

	Testing("the output JSON has data under \"info\"", func() {
		s := new(strings.Builder)
		setLoggerOutput(s)
		Info("", "")

		var data map[string]interface{}
		err := json.Unmarshal([]byte(s.String()), &data)
		ErrorIf(err)

		infoRaw, ok := data["info"]
		AssertEqual(ok, true)
		info, ok := infoRaw.(map[string]interface{})
		AssertEqual(ok, true)

		pidRaw, ok := info["pid"]
		AssertEqual(ok, true)
		pid, ok := pidRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(pid), os.Getpid())

		ppidRaw, ok := info["ppid"]
		AssertEqual(ok, true)
		ppid, ok := ppidRaw.(float64)
		AssertEqual(ok, true)
		AssertEqual(int(ppid), os.Getppid())

		puuidRaw, ok := info["puuid"]
		AssertEqual(ok, true)
		puuid, ok := puuidRaw.(string)
		AssertEqual(ok, true)
		_, err = ParseUUID(puuid)
		ErrorIf(err)
	})

	Testing("the puuid is the same across calls to the logger", func() {
		s := new(strings.Builder)
		setLoggerOutput(s)
		Info("", "first")
		Info("", "second")

		strs := strings.Split(s.String(), "\n")
		AssertEqual(len(strs), 3)
		AssertEqual(strs[2], "")

		log1 := strs[0]
		log2 := strs[1]

		var puuidFromString = func(str string) string {
			var data map[string]interface{}
			err := json.Unmarshal([]byte(str), &data)
			ErrorIf(err)

			infoRaw, ok := data["info"]
			AssertEqual(ok, true)
			info, ok := infoRaw.(map[string]interface{})
			AssertEqual(ok, true)

			puuidRaw, ok := info["puuid"]
			AssertEqual(ok, true)
			puuid, ok := puuidRaw.(string)
			AssertEqual(ok, true)

			return puuid
		}

		puuid1 := puuidFromString(log1)
		puuid2 := puuidFromString(log2)
		AssertEqual(puuid1, puuid2)

		uuid1, err := ParseUUID(puuid1)
		ErrorIf(err)
		uuid2, err := ParseUUID(puuid2)
		ErrorIf(err)
		AssertEqual(uuid1, uuid2)
	})

	slog.SetDefault(savedLogger)
}

func test_levelFromString() {
	TestStart("levelFromString()")

	values := []string { "NONE", "ERROR", "WARNING", "INFO", "DEBUG" }
	Testing("ok for expected values", func() {
		for _, s := range values {
			var fallback logLevel = 123
			theLevel := levelFromString(s, fallback)
			notFallback :=
				theLevel >= LevelNone &&
				theLevel <= LevelDebug &&
				theLevel != fallback
			AssertEqual(notFallback, true)
		}
	})

	Testing("fallback for unexpected values", func() {
		var fallback logLevel = 123
		theLevel := levelFromString(string(Random(10)), fallback)
		AssertEqual(theLevel, fallback)
	})
}

func test_setLogLevel() {
	TestStart("setLogLevel()")

	const NAME = "LOG_LEVEL"
	savedEnvvar := os.Getenv(NAME)
	savedValue  := level
	var fallbackValue logLevel = 123

	Testing("noop when envvar is unset", func() {
		ErrorIf(os.Unsetenv(NAME))
		level = fallbackValue

		setLogLevel()

		AssertEqual(level, fallbackValue)
	})

	Testing("noop when envvar is empty", func() {
		ErrorIf(os.Setenv(NAME, ""))
		level = fallbackValue

		setLogLevel()

		AssertEqual(level, fallbackValue)
	})

	Testing("update variable otherwise", func() {
		ErrorIf(os.Setenv(NAME, "DEBUG"))
		level = fallbackValue

		setLogLevel()

		AssertEqual(level, LevelDebug)
	})

	ErrorIf(os.Setenv(NAME, savedEnvvar))
	level = savedValue
}

func test_setMetric() {
	TestStart("setMetric()")

	const NAME = "NO_METRIC"
	savedEnvvar := os.Getenv(NAME)
	savedValue  := emitMetric

	Testing("noop when envvar is unset", func() {
		ErrorIf(os.Unsetenv(NAME))
		emitMetric = true

		setMetric()

		AssertEqual(emitMetric, true)
	})

	Testing("noop when envvar is empty", func() {
		ErrorIf(os.Setenv(NAME, ""))
		emitMetric = true

		setMetric()

		AssertEqual(emitMetric, true)
	})

	Testing("make variable false otherwise", func() {
		ErrorIf(os.Setenv(NAME, "1"))
		emitMetric = true

		setMetric()

		AssertEqual(emitMetric, false)
	})

	ErrorIf(os.Setenv(NAME, savedEnvvar))
	emitMetric = savedValue
}

func test_FatalIf() {
	TestStart("FatalIf()")

	Testing("noop on nil value", func() {
		FatalIf(nil)
	})
}

func test_Assert() {
	TestStart("Assert()")

	Testing("noop on true value", func() {
		Assert(true, "")
	})
}

func test_setHostname() {
	TestStart("setHostname()")

	Testing("it assigns the value to the global variable", func() {
		name, _ := os.Hostname()
		hostname = ""
		setHostname()
		AssertEqual(hostname, name)
	})
}


func t1() {
	test__PBKDF()
}

func t2() {
	test_scrypt()
}

func t3() {
	test_Hash()
}

func t4() {
	test_Random()
	test_Salt()
	test_getV7Time()
	test_newUUIDFrom()
	test_NewUUID()
	test_UUIDString()
	test_ParseUUID()
	test_sourceInfo()
	test_logArgs()
	test_anyArr()
	test_Debug()
	test_Info()
	test_Warning()
	test_Error()
	test_metric()
	test_MakeCounter()
	test_MakeGauge()
	test_ErrorIf()
	test_ErrorNil()
	test_showColour()
	test_setLoggerOutput()
	test_levelFromString()
	test_setLogLevel()
	test_setMetric()
	test_FatalIf()
	test_Assert()
	test_setHostname()
}

func MainTest() {
	arg := ""
	if len(os.Args) > 1 {
		arg = os.Args[1]
	}

	switch arg {
		case "1":
			t1()
		case "2":
			t2()
		case "3":
			t3()
		case "4":
			t4()
		default:
			t1()
			t2()
			t3()
			t4()
	}
}