/**
 * 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"
	"fmt"
	"io"
	"strings"
	"time"
	"xk-websocket-v2/internal/model"
	"xk-websocket-v2/internal/utils"

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

// 二进制 Content-Type 前缀列表
var binaryContentTypes = []string{
	"image/",
	"audio/",
	"video/",
	"application/octet-stream",
	"application/pdf",
	"application/zip",
	"application/x-rar",
	"application/x-7z",
	"application/gzip",
	"application/x-tar",
	"font/",
}

// 不需要记录响应体的路由前缀
var skipResponseBodyRoutes = []string{
	"/uploads/",
	"/static/",
}

// 需要完全跳过中间件的路由（如 WebSocket）
var skipMiddlewareRoutes = []string{
	"/ws",
	"/api/call/ws-push",
}

// isBinaryContentType 检测是否为二进制 Content-Type
func isBinaryContentType(contentType string) bool {
	contentType = strings.ToLower(contentType)
	for _, prefix := range binaryContentTypes {
		if strings.HasPrefix(contentType, prefix) {
			return true
		}
	}
	return false
}

// isBinaryData 检测数据是否为二进制（通过检查是否包含非 UTF-8 字符）
func isBinaryData(data []byte) bool {
	if len(data) == 0 {
		return false
	}
	// 检查前 512 字节是否包含二进制特征
	checkLen := len(data)
	if checkLen > 512 {
		checkLen = 512
	}
	for i := 0; i < checkLen; i++ {
		// 检测常见的二进制文件头
		if data[i] == 0 {
			return true
		}
	}
	// 检查是否以常见的二进制文件头开始
	if len(data) >= 2 {
		// JPEG: FF D8
		if data[0] == 0xFF && data[1] == 0xD8 {
			return true
		}
		// PNG: 89 50
		if data[0] == 0x89 && data[1] == 0x50 {
			return true
		}
		// GIF: 47 49
		if data[0] == 0x47 && data[1] == 0x49 {
			return true
		}
		// PDF: 25 50
		if data[0] == 0x25 && data[1] == 0x50 {
			return true
		}
		// ZIP/DOCX/XLSX: 50 4B
		if data[0] == 0x50 && data[1] == 0x4B {
			return true
		}
	}
	return false
}

// shouldSkipResponseBody 检测是否应该跳过响应体记录
func shouldSkipResponseBody(path string) bool {
	for _, prefix := range skipResponseBodyRoutes {
		if strings.HasPrefix(path, prefix) {
			return true
		}
	}
	return false
}

// 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}
}

// shouldSkipMiddleware 检测是否应该完全跳过中间件
func shouldSkipMiddleware(path string) bool {
	for _, route := range skipMiddlewareRoutes {
		if strings.HasPrefix(path, route) {
			return true
		}
	}
	return false
}

// 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
		}

		// 跳过 WebSocket 路由（包装 Writer 会干扰 WebSocket 升级）
		if shouldSkipMiddleware(c.Request.URL.Path) {
			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 && !isBinaryData(responseBody) {
		// 尝试解析响应体获取code（仅对非二进制数据）
		var resp model.ApiResponse
		if err := json.Unmarshal(responseBody, &resp); err == nil {
			responseCode = resp.Code
		}
	}

	// 处理请求参数
	var requestParams string
	requestContentType := c.GetHeader("Content-Type")
	if isBinaryContentType(requestContentType) || isBinaryData(requestBody) {
		// 二进制请求体，只记录大小
		requestParams = fmt.Sprintf("[binary data: %d bytes]", len(requestBody))
	} else {
		requestParams = string(requestBody)
		if len(requestParams) > 5000 {
			requestParams = requestParams[:5000] + "...(truncated)"
		}
	}

	// 处理响应参数
	var responseParams string
	responseContentType := c.Writer.Header().Get("Content-Type")
	requestPath := c.Request.URL.Path

	if shouldSkipResponseBody(requestPath) {
		// 静态文件路由，跳过响应体记录
		responseParams = fmt.Sprintf("[static file: %d bytes]", len(responseBody))
	} else if isBinaryContentType(responseContentType) || isBinaryData(responseBody) {
		// 二进制响应体，只记录大小
		responseParams = fmt.Sprintf("[binary data: %d bytes]", len(responseBody))
	} else {
		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)
}