package web

import (
	"log"
	"net/http"

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

// CtxRequestID Gin Context 中存放 request_id 的键（由 middleware.RequestID 写入）。
const CtxRequestID = "req_id"

// RequestIDOf 从 Gin Context 读取本次请求的 request_id（无则返回空串）。
func RequestIDOf(c *gin.Context) string {
	if v, ok := c.Get(CtxRequestID); ok {
		if s, ok := v.(string); ok {
			return s
		}
	}
	return ""
}

// OK 成功响应信封 {"code":0,"message":"success","data":...,"error":null}
func OK(c *gin.Context, data any) {
	c.JSON(http.StatusOK, gin.H{
		"code":    CodeOK,
		"message": "success",
		"data":    data,
		"error":   nil,
	})
}

// Fail 错误响应信封，统一输出四层模型：
//
//	{"code": 稳定业务错误码, "message": 用户主提示, "data": null,
//	  "error": {"category":分类, "status":HTTP状态码, "hint":下一步建议, "request_id":追踪编号, "details":开发上下文}}
//
// 并回写 X-Request-ID 响应头，便于前后端与日志联查。
func Fail(c *gin.Context, e *AppError) {
	requestID := RequestIDOf(c)
	e.RequestID = requestID
	c.Header("X-Request-ID", requestID)

	errorObj := gin.H{
		"category":   e.Category,
		"status":     e.StatusCode,
		"hint":       e.Hint,
		"request_id": requestID,
	}
	if e.Details != nil {
		errorObj["details"] = e.Details
	}

	logFail(c, e)

	c.JSON(e.StatusCode, gin.H{
		"code":    e.Code,
		"message": e.Message,
		"data":    nil,
		"error":   errorObj,
	})
}

// logFail 记录结构化错误日志，满足可定位要求：request_id / method / path / status / code / category。
func logFail(c *gin.Context, e *AppError) {
	if e == nil {
		return
	}
	req := c.Request
	method := ""
	path := ""
	if req != nil {
		method = req.Method
		path = req.URL.Path
	}
	log.Printf("HTTP ERROR [%s] status=%d code=%d %s %s -> %s request_id=%s",
		e.Category, e.StatusCode, e.Code, method, path, e.Message, e.RequestID)
}