package middleware

import (
	"bytes"
	"context"
	"io"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

// ComprehensiveLoggerMiddleware 全面日志中间件
type ComprehensiveLoggerMiddleware struct {
	logger *zap.Logger
	config *ComprehensiveLoggerConfig
}

// ComprehensiveLoggerConfig 全面日志配置
type ComprehensiveLoggerConfig struct {
	EnableRequestLogging    bool // 是否记录请求日志
	EnableResponseLogging   bool // 是否记录响应日志
	EnableRequestBodyLogging bool // 是否记录请求体
	EnableErrorLogging      bool // 是否记录错误日志
	EnableBusinessLogging   bool // 是否记录业务日志
	EnablePerformanceLogging bool // 是否记录性能日志
	MaxBodySize             int64 // 最大记录体大小
	ExcludePaths            []string // 排除的路径
	IncludePaths            []string // 包含的路径
}

// NewComprehensiveLoggerMiddleware 创建全面日志中间件
func NewComprehensiveLoggerMiddleware(logger *zap.Logger, config *ComprehensiveLoggerConfig) *ComprehensiveLoggerMiddleware {
	if config == nil {
		config = &ComprehensiveLoggerConfig{
			EnableRequestLogging:     true,
			EnableResponseLogging:    true,
			EnableRequestBodyLogging: false, // 生产环境默认关闭
			EnableErrorLogging:       true,
			EnableBusinessLogging:    true,
			EnablePerformanceLogging: true,
			MaxBodySize:              1024 * 10, // 10KB
			ExcludePaths:             []string{"/health", "/metrics", "/favicon.ico"},
		}
	}

	return &ComprehensiveLoggerMiddleware{
		logger: logger,
		config: config,
	}
}

// GetName 返回中间件名称
func (m *ComprehensiveLoggerMiddleware) GetName() string {
	return "comprehensive_logger"
}

// GetPriority 返回中间件优先级
func (m *ComprehensiveLoggerMiddleware) GetPriority() int {
	return 90 // 高优先级，在panic恢复之后
}

// Handle 返回中间件处理函数
func (m *ComprehensiveLoggerMiddleware) Handle() gin.HandlerFunc {
	return func(c *gin.Context) {
		// 检查是否应该记录此路径
		if !m.shouldLogPath(c.Request.URL.Path) {
			c.Next()
			return
		}

		startTime := time.Now()
		requestID := c.GetString("request_id")
		traceID := c.GetString("trace_id")
		userID := c.GetString("user_id")

		// 记录请求开始
		if m.config.EnableRequestLogging {
			m.logRequest(c, startTime, requestID, traceID, userID)
		}

		// 捕获请求体（如果需要）
		var requestBody []byte
		if m.config.EnableRequestBodyLogging && m.shouldLogRequestBody(c) {
			requestBody = m.captureRequestBody(c)
		}

		// 创建响应写入器包装器
		responseWriter := &responseWriterWrapper{
			ResponseWriter: c.Writer,
			logger:         m.logger,
			config:         m.config,
			requestID:      requestID,
			traceID:        traceID,
			userID:         userID,
			startTime:      startTime,
			path:           c.Request.URL.Path,
			method:         c.Request.Method,
		}
		c.Writer = responseWriter

		// 处理请求
		c.Next()

		// 记录响应
		if m.config.EnableResponseLogging {
			m.logResponse(c, responseWriter, startTime, requestID, traceID, userID, requestBody)
		}

		// 记录错误
		if m.config.EnableErrorLogging && len(c.Errors) > 0 {
			m.logErrors(c, requestID, traceID, userID)
		}

		// 记录性能指标
		if m.config.EnablePerformanceLogging {
			m.logPerformance(c, startTime, requestID, traceID, userID)
		}
	}
}

// IsGlobal 是否为全局中间件
func (m *ComprehensiveLoggerMiddleware) IsGlobal() bool {
	return true
}

// shouldLogPath 检查是否应该记录此路径
func (m *ComprehensiveLoggerMiddleware) shouldLogPath(path string) bool {
	// 检查排除路径
	for _, excludePath := range m.config.ExcludePaths {
		if strings.HasPrefix(path, excludePath) {
			return false
		}
	}

	// 检查包含路径（如果指定了）
	if len(m.config.IncludePaths) > 0 {
		for _, includePath := range m.config.IncludePaths {
			if strings.HasPrefix(path, includePath) {
				return true
			}
		}
		return false
	}

	return true
}

// shouldLogRequestBody 检查是否应该记录请求体
func (m *ComprehensiveLoggerMiddleware) shouldLogRequestBody(c *gin.Context) bool {
	contentType := c.GetHeader("Content-Type")
	return strings.Contains(contentType, "application/json") ||
		strings.Contains(contentType, "application/x-www-form-urlencoded")
}

// captureRequestBody 捕获请求体
func (m *ComprehensiveLoggerMiddleware) captureRequestBody(c *gin.Context) []byte {
	if c.Request.Body == nil {
		return nil
	}

	body, err := io.ReadAll(c.Request.Body)
	if err != nil {
		return nil
	}

	// 重新设置body
	c.Request.Body = io.NopCloser(bytes.NewBuffer(body))

	// 限制大小
	if int64(len(body)) > m.config.MaxBodySize {
		return body[:m.config.MaxBodySize]
	}

	return body
}

// logRequest 记录请求日志
func (m *ComprehensiveLoggerMiddleware) logRequest(c *gin.Context, startTime time.Time, requestID, traceID, userID string) {
	logFields := []zap.Field{
		zap.String("log_type", "request"),
		zap.String("request_id", requestID),
		zap.String("trace_id", traceID),
		zap.String("user_id", userID),
		zap.String("method", c.Request.Method),
		zap.String("path", c.Request.URL.Path),
		zap.String("query", c.Request.URL.RawQuery),
		zap.String("client_ip", c.ClientIP()),
		zap.String("user_agent", c.Request.UserAgent()),
		zap.String("referer", c.Request.Referer()),
		zap.Int64("content_length", c.Request.ContentLength),
		zap.String("content_type", c.GetHeader("Content-Type")),
		zap.Time("timestamp", startTime),
	}

	m.logger.Info("收到HTTP请求", logFields...)
}

// logResponse 记录响应日志
func (m *ComprehensiveLoggerMiddleware) logResponse(c *gin.Context, responseWriter *responseWriterWrapper, startTime time.Time, requestID, traceID, userID string, requestBody []byte) {
	duration := time.Since(startTime)
	statusCode := responseWriter.Status()

	logFields := []zap.Field{
		zap.String("log_type", "response"),
		zap.String("request_id", requestID),
		zap.String("trace_id", traceID),
		zap.String("user_id", userID),
		zap.String("method", c.Request.Method),
		zap.String("path", c.Request.URL.Path),
		zap.Int("status_code", statusCode),
		zap.Duration("duration", duration),
		zap.Int("response_size", responseWriter.Size()),
		zap.Time("timestamp", time.Now()),
	}

	// 添加请求体（如果记录了）
	if len(requestBody) > 0 {
		logFields = append(logFields, zap.String("request_body", string(requestBody)))
	}

	// 根据状态码选择日志级别
	if statusCode >= 500 {
		m.logger.Error("HTTP响应错误", logFields...)
	} else if statusCode >= 400 {
		m.logger.Warn("HTTP响应警告", logFields...)
	} else {
		m.logger.Info("HTTP响应成功", logFields...)
	}
}

// logErrors 记录错误日志
func (m *ComprehensiveLoggerMiddleware) logErrors(c *gin.Context, requestID, traceID, userID string) {
	for _, ginErr := range c.Errors {
		logFields := []zap.Field{
			zap.String("log_type", "error"),
			zap.String("request_id", requestID),
			zap.String("trace_id", traceID),
			zap.String("user_id", userID),
			zap.String("method", c.Request.Method),
			zap.String("path", c.Request.URL.Path),
			zap.String("error_type", string(ginErr.Type)),
			zap.Error(ginErr.Err),
			zap.Time("timestamp", time.Now()),
		}

		m.logger.Error("请求处理错误", logFields...)
	}
}

// logPerformance 记录性能日志
func (m *ComprehensiveLoggerMiddleware) logPerformance(c *gin.Context, startTime time.Time, requestID, traceID, userID string) {
	duration := time.Since(startTime)

	// 记录慢请求
	if duration > 1*time.Second {
		logFields := []zap.Field{
			zap.String("log_type", "performance"),
			zap.String("performance_type", "slow_request"),
			zap.String("request_id", requestID),
			zap.String("trace_id", traceID),
			zap.String("user_id", userID),
			zap.String("method", c.Request.Method),
			zap.String("path", c.Request.URL.Path),
			zap.Duration("duration", duration),
			zap.Time("timestamp", time.Now()),
		}

		m.logger.Warn("检测到慢请求", logFields...)
	}

	// 记录性能指标
	logFields := []zap.Field{
		zap.String("log_type", "performance"),
		zap.String("performance_type", "request_metrics"),
		zap.String("request_id", requestID),
		zap.String("trace_id", traceID),
		zap.String("user_id", userID),
		zap.String("method", c.Request.Method),
		zap.String("path", c.Request.URL.Path),
		zap.Duration("duration", duration),
		zap.Time("timestamp", time.Now()),
	}

	m.logger.Debug("请求性能指标", logFields...)
}

// responseWriterWrapper 响应写入器包装器
type responseWriterWrapper struct {
	gin.ResponseWriter
	logger    *zap.Logger
	config    *ComprehensiveLoggerConfig
	requestID string
	traceID   string
	userID    string
	startTime time.Time
	path      string
	method    string
	status    int
	size      int
}

// Write 实现Write方法
func (w *responseWriterWrapper) Write(b []byte) (int, error) {
	size, err := w.ResponseWriter.Write(b)
	w.size += size
	return size, err
}

// WriteHeader 实现WriteHeader方法
func (w *responseWriterWrapper) WriteHeader(code int) {
	w.status = code
	w.ResponseWriter.WriteHeader(code)
}

// WriteString 实现WriteString方法
func (w *responseWriterWrapper) WriteString(s string) (int, error) {
	size, err := w.ResponseWriter.WriteString(s)
	w.size += size
	return size, err
}

// Status 获取状态码
func (w *responseWriterWrapper) Status() int {
	return w.status
}

// Size 获取响应大小
func (w *responseWriterWrapper) Size() int {
	return w.size
}

// BusinessLogger 业务日志记录器
type BusinessLogger struct {
	logger *zap.Logger
}

// NewBusinessLogger 创建业务日志记录器
func NewBusinessLogger(logger *zap.Logger) *BusinessLogger {
	return &BusinessLogger{
		logger: logger,
	}
}

// LogUserAction 记录用户操作
func (bl *BusinessLogger) LogUserAction(ctx context.Context, action string, details map[string]interface{}) {
	requestID := bl.getRequestIDFromContext(ctx)
	traceID := bl.getTraceIDFromContext(ctx)
	userID := bl.getUserIDFromContext(ctx)

	logFields := []zap.Field{
		zap.String("log_type", "business"),
		zap.String("business_type", "user_action"),
		zap.String("action", action),
		zap.String("request_id", requestID),
		zap.String("trace_id", traceID),
		zap.String("user_id", userID),
		zap.Time("timestamp", time.Now()),
	}

	// 添加详细信息
	for key, value := range details {
		logFields = append(logFields, zap.Any(key, value))
	}

	bl.logger.Info("用户操作记录", logFields...)
}

// LogBusinessEvent 记录业务事件
func (bl *BusinessLogger) LogBusinessEvent(ctx context.Context, event string, details map[string]interface{}) {
	requestID := bl.getRequestIDFromContext(ctx)
	traceID := bl.getTraceIDFromContext(ctx)
	userID := bl.getUserIDFromContext(ctx)

	logFields := []zap.Field{
		zap.String("log_type", "business"),
		zap.String("business_type", "business_event"),
		zap.String("event", event),
		zap.String("request_id", requestID),
		zap.String("trace_id", traceID),
		zap.String("user_id", userID),
		zap.Time("timestamp", time.Now()),
	}

	// 添加详细信息
	for key, value := range details {
		logFields = append(logFields, zap.Any(key, value))
	}

	bl.logger.Info("业务事件记录", logFields...)
}

// LogSystemEvent 记录系统事件
func (bl *BusinessLogger) LogSystemEvent(ctx context.Context, event string, details map[string]interface{}) {
	requestID := bl.getRequestIDFromContext(ctx)
	traceID := bl.getTraceIDFromContext(ctx)

	logFields := []zap.Field{
		zap.String("log_type", "business"),
		zap.String("business_type", "system_event"),
		zap.String("event", event),
		zap.String("request_id", requestID),
		zap.String("trace_id", traceID),
		zap.Time("timestamp", time.Now()),
	}

	// 添加详细信息
	for key, value := range details {
		logFields = append(logFields, zap.Any(key, value))
	}

	bl.logger.Info("系统事件记录", logFields...)
}

// 辅助方法
func (bl *BusinessLogger) getRequestIDFromContext(ctx context.Context) string {
	if requestID := ctx.Value("request_id"); requestID != nil {
		if id, ok := requestID.(string); ok {
			return id
		}
	}
	return ""
}

func (bl *BusinessLogger) getTraceIDFromContext(ctx context.Context) string {
	if traceID := ctx.Value("trace_id"); traceID != nil {
		if id, ok := traceID.(string); ok {
			return id
		}
	}
	return ""
}

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