package log

import (
	"context"
	"errors"
	"log/slog"
	"os"
	"regexp"
	"strings"
)

func New(c Customization) {
	// check configuration values and set defaults for missing items
	setDefaults(&c)

	slogOptions := &slog.HandlerOptions{
		Level: &L.SLogLevel,
		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
			if a.Key == slog.TimeKey {
				// set time key
				a.Value = slog.StringValue(c.TimeStamp.Key)
				// set time format
				a.Value = slog.StringValue(a.Value.Time().Format(c.TimeStamp.Format))
			}
			if a.Key == slog.LevelKey {
				level := a.Value.Any().(slog.Level)
				levelLabel, exists := LevelNames[level]
				if !exists {
					levelLabel = level.String()
				}

				a.Value = slog.StringValue(levelLabel)
			}

			return a
		},
	}

	// Initialize SLog and translate new logging levels
	switch c.Format {
	case "json":
		L.Log = slog.New(slog.NewJSONHandler(os.Stdout, slogOptions))
	default:
		L.Log = slog.New(slog.NewTextHandler(os.Stdout, slogOptions))
	}

	// create context
	L.Ctx = context.Background()
}

// SetNumericLevel will set the log level based on a number from 1-100.
// The larger the number the more verbose the logs.
//
// 1-20 = Fatal, 21-40 = Error, 41-60 = Warn, 61-80 = Info, 81-99 = Debug,
// and 100 = Trace.
func SetNumericLevel(level int) {
	var llu string = "Log Level Updated"

	switch {
	// fatal
	case level <= 20:
		L.SLogLevel.Set(LevelFatal)
		Info(llu, "level", LevelFatal)
	// error
	case level > 20 && level <= 40:
		L.SLogLevel.Set(slog.LevelError)
		Info(llu, "level", slog.LevelError)
	// warning
	case level > 40 && level <= 60:
		L.SLogLevel.Set(slog.LevelWarn)
		Info(llu, "level", slog.LevelWarn)
	// info
	case level > 60 && level <= 80:
		L.SLogLevel.Set(slog.LevelInfo)
		Info(llu, "level", slog.LevelInfo)
	// debug
	case level > 80 && level <= 99:
		L.SLogLevel.Set(slog.LevelDebug)
		Info(llu, "level", slog.LevelDebug)
	// trace
	case level > 99:
		L.SLogLevel.Set(LevelTrace)
		Info(llu, "level", LevelTrace)
	}

	// set default logger
	slog.SetDefault(L.Log)
}

func setDefaults(c *Customization) error {
	// \/ \/ \/ REQUIRED FIELDS \/ \/ \/ //

	// format, can be one of "json" or "text"
	switch {
	case len(c.Format) == 0:
		c.Format = "json"
	case c.Format == "json" || c.Format == "text":
		break
	default:
		return errors.New("Invalid format requested.")
	}

	// set default timestamp identifier
	if len(c.TimeStamp.Key) == 0 {
		c.TimeStamp.Key = "ts"
	}

	// set default timestamp format
	if len(c.TimeStamp.Format) == 0 {
		c.TimeStamp.Format = "2006-01-02T15:04:05.000-0700"
	}

	// set default for type of event
	switch {
	case len(c.Type) == 0:
		c.Type = "Business"
	case c.Type == "Business" || c.Type == "Performance" || c.Type == "Security":
		break
	default:
		return errors.New("Invalid type of event, must be one of \"Business\", \"Performance\", or \"Security\".")
	}

	// set default for application
	if !regexp.MustCompile(`^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$`).MatchString(string(c.Application)) {
		return errors.New("Invalid application id, must be a valid uuid string.")
	}

	// /\ /\ /\ REQUIRED FIELDS /\ /\ /\ //

	return nil
}

func Fatal(operation, correlationID, msg string, attrs ...interface{}) {
	L.Log.Log(
		L.Ctx,
		LevelFatal,
		msg,
		attrs...,
	)
}

func Error(operation, correlationID, msg string, attrs ...interface{}) {
	L.Log.Log(
		L.Ctx,
		slog.LevelError,
		msg,
		attrs...,
	)
}

func Warn(operation, correlationID, msg string, attrs ...interface{}) {
	L.Log.Log(
		L.Ctx,
		slog.LevelWarn,
		msg,
		attrs...,
	)
}

func Info(operation, correlationID, msg string, attrs ...interface{}) {
	L.Log.Log(
		L.Ctx,
		slog.LevelInfo,
		msg,
		attrs...,
	)
}

func Debug(operation, correlationID, msg string, attrs ...interface{}) {
	L.Log.Log(
		L.Ctx,
		slog.LevelDebug,
		msg,
		attrs...,
	)
}

func Trace(operation, correlationID, msg string, attrs ...interface{}) {
	L.Log.Log(
		L.Ctx,
		LevelTrace,
		msg,
		attrs...,
	)
}