package logger

import (
	"os"
	"path/filepath"
	"sync"
	"time"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

var Log *zap.Logger

var (
	currentDate string
	mu          sync.Mutex
	envMode     string
)

// ======================
// 初始化
// ======================
func Init(env string) error {
	envMode = env
	logger := buildLogger()

	Log = logger
	return nil
}

// ======================
// 构建 logger
// ======================
func buildLogger() *zap.Logger {
	currentDate = getToday()

	level := zap.InfoLevel
	if envMode == "dev" {
		level = zap.DebugLevel
	}

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

	encoder := zapcore.NewJSONEncoder(encoderConfig)

	consoleWriter := zapcore.AddSync(os.Stdout)

	infoWriter := zapcore.AddSync(&dailyWriter{
		level: "info",
	})

	errorWriter := zapcore.AddSync(&dailyWriter{
		level: "error",
	})

	infoCore := zapcore.NewCore(
		encoder,
		zapcore.NewMultiWriteSyncer(consoleWriter, infoWriter),
		zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
			return lvl < zapcore.ErrorLevel && lvl >= level
		}),
	)

	errorCore := zapcore.NewCore(
		encoder,
		zapcore.NewMultiWriteSyncer(consoleWriter, errorWriter),
		zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
			return lvl >= zapcore.ErrorLevel
		}),
	)

	core := zapcore.NewTee(infoCore, errorCore)

	return zap.New(core, zap.AddCaller(), zap.AddCallerSkip(1))
}

// ======================
// 自定义 Writer（核心）
// ======================
type dailyWriter struct {
	level string
	file  *os.File
}

func (w *dailyWriter) Write(p []byte) (n int, err error) {
	mu.Lock()
	defer mu.Unlock()

	today := getToday()

	// 跨天切换
	if w.file == nil || today != currentDate {
		if w.file != nil {
			_ = w.file.Close()
		}

		currentDate = today

		filename := getLogFilePath(w.level, today)

		file, err := os.OpenFile(filename, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
		if err != nil {
			return 0, err
		}

		w.file = file
	}

	return w.file.Write(p)
}

func (w *dailyWriter) Sync() error {
	return nil
}

// ======================
// 工具函数
// ======================

// 获取当天
func getToday() string {
	return time.Now().Format("2006-01-02")
}

// 获取日志路径
func getLogFilePath(level, date string) string {
	dir := filepath.Join("logs", level)

	// 自动创建目录
	_ = os.MkdirAll(dir, os.ModePerm)

	return filepath.Join(dir, date+".log")
}

// 时间格式
func timeEncoder(t time.Time, enc zapcore.PrimitiveArrayEncoder) {
	enc.AppendString(t.Format("2006-01-02 15:04:05"))
}