package logger

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

	"go.opentelemetry.io/otel/trace"
)

type otlpHandler struct {
	slog.Handler
}

func Init() {
	levelStr := strings.ToLower(os.Getenv("LOG_LEVEL"))
	var level slog.Level
	switch levelStr {
	case "debug":
		level = slog.LevelDebug
	case "warn":
		level = slog.LevelWarn
	case "error":
		level = slog.LevelError
	default:
		level = slog.LevelInfo
	}

	var writer io.Writer = os.Stdout
	if level == slog.LevelDebug {
		file, _ := os.OpenFile("app.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666)
		writer = io.MultiWriter(os.Stdout, file)
	}

	opts := &slog.HandlerOptions{
		Level:     level,
		AddSource: true,
		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
			if a.Key == slog.TimeKey {
				return slog.String(a.Key, a.Value.Time().Format("2006-01-02 15:04:05"))
			}
			return a
		},
	}

	baseHandler := slog.NewJSONHandler(writer, opts)
	handler := &otlpHandler{baseHandler}
	logger := slog.New(handler)
	slog.SetDefault(logger)
}

func (h *otlpHandler) Handle(ctx context.Context, r slog.Record) error {
	span := trace.SpanFromContext(ctx)
	if span.SpanContext().HasTraceID() {
		r.AddAttrs(
			slog.String("trace_id", span.SpanContext().TraceID().String()),
			slog.String("span_id", span.SpanContext().SpanID().String()),
		)
	}
	return h.Handler.Handle(ctx, r)
}