package middleware

import (
	"bytes"
	"errors"
	"io"
	"log/slog"
	"net/http"
	"strings"
	"time"

	"kra/internal/biz"
	"kra/internal/conf"

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

const defaultRequestBodyLimit int64 = 8 << 20

// AccessLog is the single global request/response capture point, matching
// the reference middleware ordering and making every HTTP request observable.
func AccessLog(runtime *conf.Runtime, logger *slog.Logger, version string) gin.HandlerFunc {
	return func(c *gin.Context) {
		started := time.Now()
		var requestBody []byte
		multipart := strings.Contains(c.GetHeader("Content-Type"), "multipart/form-data")
		mediaUpload := multipart && isMediaUploadRoute(c.FullPath())
		config := runtime.Admin()
		bodyLimit := defaultRequestBodyLimit
		if mediaUpload {
			bodyLimit = biz.DefaultMaxMediaFileSize + (1 << 20)
			if config != nil && config.Media != nil && config.Media.MaxFileSize > 0 {
				bodyLimit = config.Media.MaxFileSize + (1 << 20)
			}
		}
		bytesIn := c.Request.ContentLength
		maxBytes := 1 << 20
		writer := &captureWriter{ResponseWriter: c.Writer, maxBytes: maxBytes}
		c.Writer = writer
		c.Header("X-Kra-Version", version)
		requestReadFailed := c.Request.ContentLength > bodyLimit
		if requestReadFailed {
			c.AbortWithStatusJSON(http.StatusRequestEntityTooLarge, gin.H{"code": CodeError, "msg": "请求体超过大小上限"})
		} else if c.Request.Body != nil && !mediaUpload {
			limited := http.MaxBytesReader(c.Writer, c.Request.Body, bodyLimit)
			var err error
			requestBody, err = io.ReadAll(limited)
			if err != nil {
				requestReadFailed = true
				var tooLarge *http.MaxBytesError
				if errors.As(err, &tooLarge) {
					c.AbortWithStatusJSON(http.StatusRequestEntityTooLarge, gin.H{"code": CodeError, "msg": "请求体超过大小上限"})
				} else {
					c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"code": CodeError, "msg": "请求体读取失败"})
				}
			} else {
				c.Request.Body = io.NopCloser(bytes.NewReader(requestBody))
				bytesIn = int64(len(requestBody))
			}
		} else if c.Request.Body != nil {
			c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, bodyLimit)
		}
		if bytesIn < 0 {
			bytesIn = 0
		}
		logLimit := 1024
		if config != nil && config.Zap != nil && config.Zap.AccessLogMaxBytes > 0 {
			logLimit = int(config.Zap.AccessLogMaxBytes)
		}
		requestText := ""
		if multipart {
			requestText = "[文件]"
		} else {
			requestText = redactJSON(requestBody, c.GetHeader("Content-Type"), logLimit)
		}
		c.Set(ctxReqBodyKey, requestText)
		c.Set(ctxRespBufferKey, &writer.body)
		if !requestReadFailed {
			c.Next()
		}
		if logger == nil {
			return
		}
		responseText := redactJSON(writer.body.Bytes(), c.Writer.Header().Get("Content-Type"), logLimit)
		userID, authorityID := uint(0), uint(0)
		if claims := Claims(c); claims != nil {
			userID, authorityID = claims.ID, claims.AuthorityID
		}
		route := c.FullPath()
		if route == "" {
			route = "unmatched"
		}
		bytesOut := int64(c.Writer.Size())
		if bytesOut < 0 {
			bytesOut = 0
		}
		privateErrors := strings.TrimRight(c.Errors.ByType(gin.ErrorTypePrivate).String(), "\n")
		attributes := []any{
			"mod", "http", "ip", c.ClientIP(), "method", c.Request.Method, "http_path", c.Request.URL.Path, "http_route", route,
			"http_status", c.Writer.Status(), "latency_ms", time.Since(started).Milliseconds(),
			"request_id", stringValueFromContext(c, "request_id"), "trace_id", stringValueFromContext(c, "trace_id"),
			"bytes_in", bytesIn, "bytes_out", bytesOut, "user_id", userID, "authority_id", authorityID,
			"error", c.Writer.Status() >= http.StatusInternalServerError || privateErrors != "", "ua", c.Request.UserAgent(), "req_query", c.Request.URL.RawQuery}
		if config != nil && config.Zap != nil && config.Zap.AccessReqHeaders {
			attributes = append(attributes, "req_headers", redactHeaders(c.Request.Header))
		}
		if config != nil && config.Zap != nil && config.Zap.AccessReqBody {
			attributes = append(attributes, "req_body", requestText)
		}
		if config != nil && config.Zap != nil && config.Zap.AccessRespData {
			attributes = append(attributes, "resp_data", responseText)
		}
		if privateErrors != "" {
			attributes = append(attributes, "error_msg", privateErrors)
		}
		logger.InfoContext(c.Request.Context(), "请求完成", attributes...)
	}
}

func isMediaUploadRoute(route string) bool {
	return strings.HasSuffix(route, "/fileUploadAndDownload/upload") ||
		strings.HasSuffix(route, "/mediaUpload/chunk")
}

func redactHeaders(headers map[string][]string) map[string]string {
	out := make(map[string]string, len(headers))
	for key, values := range headers {
		lower := strings.ToLower(key)
		if lower == "authorization" || lower == "cookie" || lower == "set-cookie" || lower == "x-token" {
			out[key] = "***"
		} else {
			out[key] = strings.Join(values, ",")
		}
	}
	return out
}

func stringValueFromContext(c *gin.Context, key string) string {
	value, _ := c.Get(key)
	return stringValue(value)
}