package logger

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

var L *slog.Logger

const (
	reset  = "\033[0m"
	red    = "\033[31m"
	yellow = "\033[33m"
	green  = "\033[32m"
	blue   = "\033[36m"
	gray   = "\033[90m"
)

type consoleHandler struct {
	w        io.Writer
	colorize bool
}

func (h *consoleHandler) Enabled(ctx context.Context, level slog.Level) bool {
	return true
}

func (h *consoleHandler) Handle(ctx context.Context, r slog.Record) error {
	level := r.Level.String()
	color := reset

	switch r.Level {
	case slog.LevelError:
		color = red
	case slog.LevelWarn:
		color = yellow
	case slog.LevelInfo:
		color = green
	case slog.LevelDebug:
		color = gray
	}

	var msg string
	if h.colorize {
		msg = fmt.Sprintf("%s%s%s %s%s%s %s%s%s",
			gray, r.Time.Format("15:04:05"), reset,
			color, level, reset,
			blue, r.Message, reset)
	} else {
		msg = fmt.Sprintf("%s %s %s", r.Time.Format("15:04:05"), level, r.Message)
	}

	var pairs []string
	r.Attrs(func(attr slog.Attr) bool {
		if h.colorize {
			pairs = append(pairs, fmt.Sprintf("%s=%v%s", blue, attr.Value, reset))
		} else {
			pairs = append(pairs, fmt.Sprintf("%s=%v", attr.Key, attr.Value))
		}
		return true
	})

	if len(pairs) > 0 {
		msg += " " + strings.Join(pairs, " ")
	}

	fmt.Fprintln(h.w, msg)
	return nil
}

func (h *consoleHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
	return &consoleHandler{w: h.w, colorize: h.colorize}
}

func (h *consoleHandler) WithGroup(name string) slog.Handler {
	return &consoleHandler{w: h.w, colorize: h.colorize}
}

func Init(service string, output io.Writer, level string, colorize bool) {
	if output == nil {
		output = os.Stderr
	}

	var lvl slog.Level
	switch level {
	case "debug":
		lvl = slog.LevelDebug
	case "warn":
		lvl = slog.LevelWarn
	case "error":
		lvl = slog.LevelError
	default:
		lvl = slog.LevelInfo
	}

	if colorize {
		L = slog.New(&consoleHandler{w: output, colorize: true}).With("service", service, "level", lvl.String())
	} else {
		L = slog.New(slog.NewJSONHandler(output, &slog.HandlerOptions{
			Level:     lvl,
			AddSource: false,
			ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
				if a.Key == slog.TimeKey && groups == nil {
					a.Key = "timestamp"
				}
				if a.Key == slog.LevelKey {
					a.Key = "level"
				}
				if a.Key == slog.MessageKey {
					a.Key = "message"
				}
				return a
			},
		})).With("service", service)
	}
}

func Info(msg string, args ...any) {
	if L != nil {
		L.Info(msg, args...)
	}
}

func Warn(msg string, args ...any) {
	if L != nil {
		L.Warn(msg, args...)
	}
}

func Error(msg string, args ...any) {
	if L != nil {
		L.Error(msg, args...)
	}
}

func Debug(msg string, args ...any) {
	if L != nil {
		L.Debug(msg, args...)
	}
}

func With(args ...any) *slog.Logger {
	if L == nil {
		return nil
	}
	return L.With(args...)
}