/**
 * package middleware
 * 作用：接口请求日志中间件
 * 说明：记录所有API请求信息，异步写入数据库
 */
package middleware

import (
	"bytes"
	"encoding/json"
	"io"
	"strings"
	"time"
	"xk-websocket-v2/internal/model"
	"xk-websocket-v2/internal/utils"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

// RequestLogMiddleware 请求日志中间件
type RequestLogMiddleware struct {
	DB *gorm.DB
}

// NewRequestLogMiddleware 创建请求日志中间件
func NewRequestLogMiddleware(db *gorm.DB) *RequestLogMiddleware {
	return &RequestLogMiddleware{DB: db}
}

// Handler 中间件处理函数
func (m *RequestLogMiddleware) Handler() gin.HandlerFunc {
	return func(c *gin.Context) {
		// 跳过OPTIONS请求
		if c.Request.Method == "OPTIONS" {
			c.Next()
			return
		}

		// 获取请求IP
		ip := getClientIP(c)
		
		// 本地IP不记录
		if utils.GetIPLocation(ip) == "本地" {
			c.Next()
			return
		}

		// 获取请求参数
		var requestBody []byte
		if c.Request.Body != nil {
			requestBody, _ = io.ReadAll(c.Request.Body)
			c.Request.Body = io.NopCloser(bytes.NewBuffer(requestBody))
		}

		// 获取用户ID（从Context中获取，未登录为"0"）
		userID := "0"
		if uid, exists := c.Get("user_id"); exists {
			if uidStr, ok := uid.(string); ok {
				userID = uidStr
			}
		}

		// 记录开始时间
		startTime := time.Now()

		// 创建响应写入器
		writer := &responseWriter{
			ResponseWriter: c.Writer,
			body:          &bytes.Buffer{},
		}
		c.Writer = writer

		// 处理请求
		c.Next()

		// 计算请求时间
		duration := time.Since(startTime)

		// 异步记录日志（避免影响性能）
		go m.logRequest(c, ip, userID, requestBody, writer.body.Bytes(), writer.status, duration)
	}
}

// logRequest 记录请求日志
func (m *RequestLogMiddleware) logRequest(c *gin.Context, ip, userID string, requestBody, responseBody []byte, httpStatus int, duration time.Duration) {
	// 获取IP归属地
	location := utils.GetIPLocation(ip)

	// 获取响应code（从响应体中解析）
	responseCode := 0
	if len(responseBody) > 0 {
		// 尝试解析响应体获取code
		var resp model.ApiResponse
		if err := json.Unmarshal(responseBody, &resp); err == nil {
			responseCode = resp.Code
		}
	}

	// 限制请求参数长度（避免存储过大）
	requestParams := string(requestBody)
	if len(requestParams) > 5000 {
		requestParams = requestParams[:5000] + "...(truncated)"
	}

	// 限制返回参数长度
	responseParams := string(responseBody)
	if len(responseParams) > 5000 {
		responseParams = responseParams[:5000] + "...(truncated)"
	}

	// 创建日志记录
	log := model.ApiRequestLog{
		Route:          c.FullPath(),
		IP:             ip,
		IPLocation:     location,
		UserID:         userID,
		Method:         c.Request.Method,
		RequestParams:  requestParams,
		ResponseParams: responseParams,
		ResponseCode:   responseCode,
		HTTPStatus:     httpStatus,
		RequestTime:    time.Now(),
	}

	// 异步写入数据库
	m.DB.Create(&log)
}

// getClientIP 获取客户端IP
func getClientIP(c *gin.Context) string {
	// 优先从X-Forwarded-For获取
	ip := c.GetHeader("X-Forwarded-For")
	if ip != "" {
		// X-Forwarded-For可能包含多个IP，取第一个
		ips := strings.Split(ip, ",")
		if len(ips) > 0 {
			return strings.TrimSpace(ips[0])
		}
	}

	// 从X-Real-IP获取
	ip = c.GetHeader("X-Real-IP")
	if ip != "" {
		return ip
	}

	// 从RemoteAddr获取
	return c.ClientIP()
}

// responseWriter 响应写入器（用于捕获响应内容）
type responseWriter struct {
	gin.ResponseWriter
	body   *bytes.Buffer
	status int
}

func (w *responseWriter) Write(b []byte) (int, error) {
	w.body.Write(b)
	return w.ResponseWriter.Write(b)
}

func (w *responseWriter) WriteString(s string) (int, error) {
	w.body.WriteString(s)
	return w.ResponseWriter.WriteString(s)
}

func (w *responseWriter) WriteHeader(statusCode int) {
	w.status = statusCode
	w.ResponseWriter.WriteHeader(statusCode)
}