package gobang

import (
	"encoding/json"
	"errors"
	"log/slog"
	"os"
	"strings"
	"time"

	"guuid"
)



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_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 := guuid.FromString(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 = guuid.FromString(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 = guuid.FromString(puuid)
		ErrorIf(err)
	})

	Testing("we can add groups to the default logger", func() {
		s := new(strings.Builder)
		SetLoggerOutput(s, slog.Group("one", "key", "value"))
		Info("", "")

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

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

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

	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 := guuid.FromString(puuid1)
		ErrorIf(err)
		uuid2, err := guuid.FromString(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_SetLevel() {
	TestStart("SetLevel()")

	savedValue := level

	Testing("the behaviour is a simple assignment", func() {
		levels := []LogLevel {
			LevelNone,
			LevelError,
			LevelWarning,
			LevelInfo,
			LevelDebug,
		}
		for _, l := range levels {
			SetLevel(l)
			AssertEqual(l, level)
		}
	})

	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 MainTest() {
	test_Random()
	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_SetLevel()
	test_setMetric()
	test_FatalIf()
	test_Assert()
	test_setHostname()
}