package logger

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/gofiber/fiber/v3"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
)

var Log *zap.Logger

const TraceIDKey = "request_id"

// ======================
// 配置结构
// ======================

type Config struct {
	Dir        string // 日志目录
	Level      string // debug info warn error
	MaxSize    int    // MB
	MaxBackups int
	MaxAge     int  // 天
	Compress   bool // 是否压缩
}

// ======================
// 初始化
// ======================

func Init(cfg Config) {
	if cfg.Dir == "" {
		cfg.Dir = "logs"
	}

	if cfg.Level == "" {
		cfg.Level = "info"
	}

	level := parseLevel(cfg.Level)

	// ======================
	// encoder 配置
	// ======================

	encoderConfig := zapcore.EncoderConfig{
		TimeKey:      "time",
		LevelKey:     "level",
		MessageKey:   "msg",
		CallerKey:    "caller",
		EncodeCaller: zapcore.ShortCallerEncoder,
	}

	// 👉 文件 JSON encoder
	jsonEncoder := zapcore.NewJSONEncoder(func() zapcore.EncoderConfig {
		cfg := encoderConfig
		cfg.EncodeLevel = zapcore.CapitalLevelEncoder
		cfg.EncodeTime = zapcore.TimeEncoderOfLayout("2006-01-02 15:04:05")
		return cfg
	}())

	// 👉 控制台 encoder（可读）
	consoleEncoder := zapcore.NewConsoleEncoder(func() zapcore.EncoderConfig {
		cfg := encoderConfig
		cfg.EncodeLevel = zapcore.CapitalColorLevelEncoder
		cfg.EncodeTime = zapcore.TimeEncoderOfLayout("2006-01-02 15:04:05")
		return cfg
	}())

	// ======================
	// writer
	// ======================

	consoleWriter := zapcore.AddSync(os.Stdout)
	infoWriter := getWriter(cfg, "info")
	errorWriter := getWriter(cfg, "error")

	// ======================
	// core
	// ======================

	// 控制台（所有级别）
	consoleCore := zapcore.NewCore(
		consoleEncoder,
		consoleWriter,
		level,
	)

	// info 文件
	infoCore := zapcore.NewCore(
		jsonEncoder,
		infoWriter,
		zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
			return lvl < zapcore.ErrorLevel && lvl >= level
		}),
	)

	// error 文件
	errorCore := zapcore.NewCore(
		jsonEncoder,
		errorWriter,
		zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
			return lvl >= zapcore.ErrorLevel
		}),
	)

	core := zapcore.NewTee(
		consoleCore,
		infoCore,
		errorCore,
	)

	Log = zap.New(
		core,
		zap.AddCaller(),      // 打印调用位置
		zap.AddCallerSkip(1), // 跳过封装层
	)
}

// ======================
// Daily Writer（按天切割）
// ======================

type DailyWriter struct {
	cfg   Config
	level string
	log   *lumberjack.Logger
	date  string
}

func newDailyWriter(cfg Config, level string) *DailyWriter {
	return &DailyWriter{
		cfg:   cfg,
		level: level,
	}
}

func (w *DailyWriter) Write(p []byte) (n int, err error) {
	today := time.Now().Format("2006-01-02")

	if w.log == nil || w.date != today {
		dir := filepath.Join(w.cfg.Dir, w.level)
		_ = os.MkdirAll(dir, os.ModePerm)

		filename := filepath.Join(dir, today+".log")

		w.log = &lumberjack.Logger{
			Filename:   filename,
			MaxSize:    w.cfg.MaxSize,
			MaxBackups: w.cfg.MaxBackups,
			MaxAge:     w.cfg.MaxAge,
			Compress:   w.cfg.Compress,
		}

		w.date = today
	}

	return w.log.Write(p)
}

func (w *DailyWriter) Sync() error {
	if w.log != nil {
		return w.log.Close()
	}
	return nil
}

// ======================
// writer 封装
// ======================

func getWriter(cfg Config, level string) zapcore.WriteSyncer {
	return zapcore.AddSync(newDailyWriter(cfg, level))
}

// ======================
// level 解析
// ======================

func parseLevel(lvl string) zapcore.Level {
	switch strings.ToLower(lvl) {
	case "debug":
		return zap.DebugLevel
	case "warn":
		return zap.WarnLevel
	case "error":
		return zap.ErrorLevel
	default:
		return zap.InfoLevel
	}
}

// ======================
// trace 支持
// ======================

func SetTraceID(c fiber.Ctx, traceID string) {
	if c == nil {
		return
	}

	ctx := context.WithValue(c.Context(), TraceIDKey, traceID)
	c.SetContext(ctx)
}

func FromCtx(ctx context.Context) *zap.Logger {
	if ctx == nil {
		return Log
	}

	traceID, _ := ctx.Value(TraceIDKey).(string)
	if traceID == "" {
		return Log
	}

	return Log.With(zap.String("trace_id", traceID))
}

// ======================
// 优雅退出
// ======================

func Sync() {
	if Log != nil {
		_ = Log.Sync()
	}
}