package logger

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

	"github.com/spf13/viper"
	"go.opentelemetry.io/contrib/bridges/otelslog"
	"go.opentelemetry.io/otel/trace"
)

type multiHandler struct {
	handlers []slog.Handler
}

func (m *multiHandler) Enabled(ctx context.Context, l slog.Level) bool {
	for _, h := range m.handlers {
		if h.Enabled(ctx, l) {
			return true
		}
	}
	return false
}

func (m *multiHandler) 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()),
		)
	}

	for _, h := range m.handlers {
		_ = h.Handle(ctx, r)
	}
	return nil
}

func (m *multiHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
	newHandlers := make([]slog.Handler, len(m.handlers))
	for i, h := range m.handlers {
		newHandlers[i] = h.WithAttrs(attrs)
	}
	return &multiHandler{handlers: newHandlers}
}

func (m *multiHandler) WithGroup(name string) slog.Handler {
	newHandlers := make([]slog.Handler, len(m.handlers))
	for i, h := range m.handlers {
		newHandlers[i] = h.WithGroup(name)
	}
	return &multiHandler{handlers: newHandlers}
}

func Init() {
	levelStr := strings.ToLower(viper.GetString("server.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)
	}

	localHandler := slog.NewJSONHandler(writer, &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
		},
	})

	otelHandler := otelslog.NewHandler(viper.GetString("server.service_name"))

	combinedHandler := &multiHandler{
		handlers: []slog.Handler{localHandler, otelHandler},
	}

	slog.SetDefault(slog.New(combinedHandler))
}