package logger

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

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
)

// LevelLoggerConfig 按级别分文件的日志配置
type LevelLoggerConfig struct {
	BaseConfig Config
	// 是否启用按级别分文件
	EnableLevelSeparation bool
	// 各级别日志文件配置
	LevelConfigs map[zapcore.Level]LevelFileConfig
}

// LevelFileConfig 单个级别文件配置
type LevelFileConfig struct {
	MaxSize    int  // 单个文件最大大小(MB)
	MaxBackups int  // 最大备份文件数
	MaxAge     int  // 最大保留天数
	Compress   bool // 是否压缩
}

// LevelLogger 按级别分文件的日志器
type LevelLogger struct {
	loggers map[zapcore.Level]*zap.Logger
	config  LevelLoggerConfig
}

// NewLevelLogger 创建按级别分文件的日志器
func NewLevelLogger(config LevelLoggerConfig) (*LevelLogger, error) {
	if !config.EnableLevelSeparation {
		// 如果不启用按级别分文件，使用普通日志器
		normalLogger, err := NewLogger(config.BaseConfig)
		if err != nil {
			return nil, err
		}
		
		// 转换为LevelLogger格式
		zapLogger := normalLogger.(*ZapLogger).GetZapLogger()
		return &LevelLogger{
			loggers: map[zapcore.Level]*zap.Logger{
				zapcore.DebugLevel: zapLogger,
				zapcore.InfoLevel:  zapLogger,
				zapcore.WarnLevel:  zapLogger,
				zapcore.ErrorLevel: zapLogger,
				zapcore.FatalLevel: zapLogger,
				zapcore.PanicLevel: zapLogger,
			},
			config: config,
		}, nil
	}

	// 设置默认级别配置
	if config.LevelConfigs == nil {
		config.LevelConfigs = getDefaultLevelConfigs()
	}

	// 确保日志目录存在
	if err := os.MkdirAll(config.BaseConfig.LogDir, 0755); err != nil {
		return nil, fmt.Errorf("创建日志目录失败: %w", err)
	}

	// 为每个级别创建独立的日志器
	loggers := make(map[zapcore.Level]*zap.Logger)
	
	for level := range config.LevelConfigs {
		logger, err := createLevelLogger(level, config)
		if err != nil {
			return nil, fmt.Errorf("创建级别日志器失败 [%s]: %w", level.String(), err)
		}
		loggers[level] = logger
	}

	return &LevelLogger{
		loggers: loggers,
		config:  config,
	}, nil
}

// getDefaultLevelConfigs 获取默认级别配置
func getDefaultLevelConfigs() map[zapcore.Level]LevelFileConfig {
	return map[zapcore.Level]LevelFileConfig{
		zapcore.DebugLevel: {
			MaxSize:    50,  // 50MB
			MaxBackups: 3,
			MaxAge:     7,   // 7天
			Compress:   true,
		},
		zapcore.InfoLevel: {
			MaxSize:    100, // 100MB
			MaxBackups: 5,
			MaxAge:     30,  // 30天
			Compress:   true,
		},
		zapcore.WarnLevel: {
			MaxSize:    100, // 100MB
			MaxBackups: 5,
			MaxAge:     30,  // 30天
			Compress:   true,
		},
		zapcore.ErrorLevel: {
			MaxSize:    200, // 200MB
			MaxBackups: 10,
			MaxAge:     90,  // 90天
			Compress:   true,
		},
		zapcore.FatalLevel: {
			MaxSize:    100, // 100MB
			MaxBackups: 10,
			MaxAge:     365, // 1年
			Compress:   true,
		},
		zapcore.PanicLevel: {
			MaxSize:    100, // 100MB
			MaxBackups: 10,
			MaxAge:     365, // 1年
			Compress:   true,
		},
	}
}

// createLevelLogger 为单个级别创建日志器
func createLevelLogger(level zapcore.Level, config LevelLoggerConfig) (*zap.Logger, error) {
	levelConfig := config.LevelConfigs[level]
	
	// 创建编码器
	encoderConfig := getEncoderConfig()
	var encoder zapcore.Encoder
	if config.BaseConfig.Format == "json" {
		encoder = zapcore.NewJSONEncoder(encoderConfig)
	} else {
		encoder = zapcore.NewConsoleEncoder(encoderConfig)
	}

	// 创建文件输出
	writeSyncer, err := createLevelFileWriteSyncer(level, config.BaseConfig, levelConfig)
	if err != nil {
		return nil, err
	}

	// 创建核心
	core := zapcore.NewCore(encoder, writeSyncer, level)

	// 创建日志器
	logger := zap.New(core, zap.AddCaller(), zap.AddStacktrace(zapcore.ErrorLevel))

	return logger, nil
}

// createLevelFileWriteSyncer 创建级别文件输出同步器
func createLevelFileWriteSyncer(level zapcore.Level, baseConfig Config, levelConfig LevelFileConfig) (zapcore.WriteSyncer, error) {
	// 构建日志文件路径
	var logFilePath string
	if baseConfig.UseDaily {
		// 按日分包：logs/2024-01-01/error.log
		today := time.Now().Format("2006-01-02")
		dailyDir := filepath.Join(baseConfig.LogDir, today)
		if err := os.MkdirAll(dailyDir, 0755); err != nil {
			return nil, fmt.Errorf("创建日期目录失败: %w", err)
		}
		logFilePath = filepath.Join(dailyDir, fmt.Sprintf("%s.log", level.String()))
	} else {
		// 传统方式：logs/error.log
		logFilePath = filepath.Join(baseConfig.LogDir, fmt.Sprintf("%s.log", level.String()))
	}

	// 创建lumberjack日志轮转器
	lumberJackLogger := &lumberjack.Logger{
		Filename:   logFilePath,
		MaxSize:    levelConfig.MaxSize,
		MaxBackups: levelConfig.MaxBackups,
		MaxAge:     levelConfig.MaxAge,
		Compress:   levelConfig.Compress,
	}

	return zapcore.AddSync(lumberJackLogger), nil
}

// Debug 调试日志
func (l *LevelLogger) Debug(msg string, fields ...zapcore.Field) {
	if logger, exists := l.loggers[zapcore.DebugLevel]; exists {
		logger.Debug(msg, fields...)
	}
}

// Info 信息日志
func (l *LevelLogger) Info(msg string, fields ...zapcore.Field) {
	if logger, exists := l.loggers[zapcore.InfoLevel]; exists {
		logger.Info(msg, fields...)
	}
}

// Warn 警告日志
func (l *LevelLogger) Warn(msg string, fields ...zapcore.Field) {
	if logger, exists := l.loggers[zapcore.WarnLevel]; exists {
		logger.Warn(msg, fields...)
	}
}

// Error 错误日志
func (l *LevelLogger) Error(msg string, fields ...zapcore.Field) {
	if logger, exists := l.loggers[zapcore.ErrorLevel]; exists {
		logger.Error(msg, fields...)
	}
}

// Fatal 致命错误日志
func (l *LevelLogger) Fatal(msg string, fields ...zapcore.Field) {
	if logger, exists := l.loggers[zapcore.FatalLevel]; exists {
		logger.Fatal(msg, fields...)
	}
}

// Panic 恐慌日志
func (l *LevelLogger) Panic(msg string, fields ...zapcore.Field) {
	if logger, exists := l.loggers[zapcore.PanicLevel]; exists {
		logger.Panic(msg, fields...)
	}
}

// With 添加字段
func (l *LevelLogger) With(fields ...zapcore.Field) Logger {
	// 为每个级别创建带字段的日志器
	newLoggers := make(map[zapcore.Level]*zap.Logger)
	for level, logger := range l.loggers {
		newLoggers[level] = logger.With(fields...)
	}
	
	return &LevelLogger{
		loggers: newLoggers,
		config:  l.config,
	}
}

// WithContext 从上下文添加字段
func (l *LevelLogger) WithContext(ctx context.Context) Logger {
	// 从上下文中提取常用字段
	fields := []zapcore.Field{}

	if traceID := getTraceIDFromContextLevel(ctx); traceID != "" {
		fields = append(fields, zap.String("trace_id", traceID))
	}

	if userID := getUserIDFromContextLevel(ctx); userID != "" {
		fields = append(fields, zap.String("user_id", userID))
	}

	if requestID := getRequestIDFromContextLevel(ctx); requestID != "" {
		fields = append(fields, zap.String("request_id", requestID))
	}

	return l.With(fields...)
}

// Sync 同步日志
func (l *LevelLogger) Sync() error {
	var lastErr error
	for _, logger := range l.loggers {
		if err := logger.Sync(); err != nil {
			lastErr = err
		}
	}
	return lastErr
}

// GetLevelLogger 获取指定级别的日志器
func (l *LevelLogger) GetLevelLogger(level zapcore.Level) *zap.Logger {
	if logger, exists := l.loggers[level]; exists {
		return logger
	}
	return nil
}

// GetLoggers 获取所有级别的日志器
func (l *LevelLogger) GetLoggers() map[zapcore.Level]*zap.Logger {
	return l.loggers
}

// 辅助函数（从logger.go复制）
func getTraceIDFromContextLevel(ctx context.Context) string {
	if traceID := ctx.Value("trace_id"); traceID != nil {
		if id, ok := traceID.(string); ok {
			return id
		}
	}
	return ""
}

func getUserIDFromContextLevel(ctx context.Context) string {
	if userID := ctx.Value("user_id"); userID != nil {
		if id, ok := userID.(string); ok {
			return id
		}
	}
	return ""
}

func getRequestIDFromContextLevel(ctx context.Context) string {
	if requestID := ctx.Value("request_id"); requestID != nil {
		if id, ok := requestID.(string); ok {
			return id
		}
	}
	return ""
}