package logging

import (
	"context"
	"io"
	"log/slog"
	"strings"
)

type CtxKey int

const (
	_ CtxKey = iota
	CtxKeyLogger
	CtxKeyTraceID
)

func parseLogLevel(levelStr string) slog.Level {
	switch strings.ToUpper(levelStr) {
	case "DEBUG":
		return slog.LevelDebug
	case "INFO":
		return slog.LevelInfo
	case "WARN":
		return slog.LevelWarn
	case "ERROR":
		return slog.LevelError
	default:
		return slog.LevelInfo // Default level
	}
}

// InitLogggin initializes global structured logging for the entire application
func InitLogging(level string, w io.Writer, addSource bool) *slog.Logger {
	// Use os.Stderr
	//
	// Stderr is used for diagnostics and logging. Stdout is used for program
	// output. Stderr also have greater likely hood of being seen if a programs
	// output is being redirected.
	parsedLogLevel := parseLogLevel(level)
	loggerHandler := slog.NewJSONHandler(w, &slog.HandlerOptions{Level: parsedLogLevel, AddSource: addSource})
	logger := slog.New(loggerHandler)
	slog.SetDefault(logger)
	return logger
}

func LoggerFromCtx(ctx context.Context) *slog.Logger {
	// context doesn't enforce type when context.WithValue(ctx, ctxKeyLogger, logger) is used
	// it is stored as empty interface. So use type assertion .(*slog.Logger) to retrieve the
	// value
	if l, ok := ctx.Value(CtxKeyLogger).(*slog.Logger); ok && l != nil {
		return l
	}
	return slog.Default()
}