package adtracking

import (
	"crypto/rand"
	"encoding/hex"
	"errors"
	"net/http"
	"strconv"
	"strings"

	"hfb_sys/backend/internal/middleware"
	"hfb_sys/backend/pkg/response"

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

type Handler struct {
	service *Service
}

func NewHandler(service *Service) *Handler {
	return &Handler{service: service}
}

// Redirect 公开短链 302 智能重定向
func (h *Handler) Redirect(c *gin.Context) {
	code := strings.TrimSpace(c.Param("code"))
	if code == "" {
		c.Redirect(http.StatusFound, "https://hao858.com/")
		return
	}

	visitorID, err := c.Cookie("hfb_v_id")
	if err != nil || visitorID == "" {
		visitorID = generateVisitorID()
		isSecure := c.Request.TLS != nil || c.Request.Header.Get("X-Forwarded-Proto") == "https"
		c.SetSameSite(http.SameSiteLaxMode)
		c.SetCookie("hfb_v_id", visitorID, 31536000, "/", "", isSecure, true)
	}

	ip := c.ClientIP()
	ua := c.Request.UserAgent()
	referer := c.Request.Referer()

	targetURL, err := h.service.ResolveRedirect(c.Request.Context(), code, ip, ua, referer, visitorID)
	if err != nil {
		// 链接不存在或已停用时，优雅兜底跳转至官网首页，附带失效短码参数以备提示
		c.Redirect(http.StatusFound, "https://hao858.com/?ref_invalid="+urlEscape(code))
		return
	}

	c.Redirect(http.StatusFound, targetURL)
}

// List 推广链接列表查询（带多维度汇总数据）
func (h *Handler) List(c *gin.Context) {
	var query ListTrackingLinksQuery
	if err := c.ShouldBindQuery(&query); err != nil {
		response.BadRequest(c, "查询参数有误")
		return
	}

	baseURL := getRequestBaseURL(c)
	items, total, err := h.service.ListLinks(c.Request.Context(), query, baseURL)
	if err != nil {
		response.InternalServerError(c, "获取推广链接列表失败")
		return
	}

	response.OK(c, gin.H{
		"items": items,
		"total": total,
	})
}

// Overview 推广大盘统计汇总
func (h *Handler) Overview(c *gin.Context) {
	stats, err := h.service.GetOverview(c.Request.Context())
	if err != nil {
		response.InternalServerError(c, "获取推广统计数据失败")
		return
	}
	response.OK(c, stats)
}

// Create 创建推广链接
func (h *Handler) Create(c *gin.Context) {
	var req CreateTrackingLinkRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, "请求参数不正确: "+err.Error())
		return
	}

	adminID, _ := currentAdminID(c)
	item, err := h.service.CreateLink(c.Request.Context(), adminID, req)
	if err != nil {
		writeAdTrackingError(c, err)
		return
	}

	response.Created(c, item)
}

// Update 更新推广链接
func (h *Handler) Update(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}

	var req UpdateTrackingLinkRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, "请求参数不正确: "+err.Error())
		return
	}

	if err := h.service.UpdateLink(c.Request.Context(), id, req); err != nil {
		writeAdTrackingError(c, err)
		return
	}

	response.OK(c, gin.H{"updated": true})
}

// UpdateStatus 启停推广链接
func (h *Handler) UpdateStatus(c *gin.Context) {
	id, ok := parseID(c)
	if !ok {
		return
	}

	var req UpdateLinkStatusRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, "状态参数不合法")
		return
	}

	if err := h.service.UpdateStatus(c.Request.Context(), id, req.Status); err != nil {
		writeAdTrackingError(c, err)
		return
	}

	response.OK(c, gin.H{"updated": true})
}

func parseID(c *gin.Context) (uint64, bool) {
	val := c.Param("id")
	id, err := strconv.ParseUint(val, 10, 64)
	if err != nil || id == 0 {
		response.BadRequest(c, "无效的ID")
		return 0, false
	}
	return id, true
}

func currentAdminID(c *gin.Context) (uint64, bool) {
	val, exists := c.Get(middleware.ContextAdminID)
	if !exists {
		return 0, false
	}
	id, ok := val.(uint64)
	if !ok {
		return 0, false
	}
	return id, true
}

func generateVisitorID() string {
	b := make([]byte, 16)
	_, _ = rand.Read(b)
	return hex.EncodeToString(b)
}

func urlEscape(s string) string {
	return strings.ReplaceAll(s, " ", "%20")
}

func getRequestBaseURL(c *gin.Context) string {
	scheme := "https"
	if proto := c.Request.Header.Get("X-Forwarded-Proto"); proto != "" {
		scheme = proto
	} else if c.Request.TLS == nil {
		scheme = "http"
	}
	host := c.Request.Host
	if host == "" {
		return "https://hao858.com"
	}
	// 如果是本地开发环境端口，保留域名
	return scheme + "://" + host
}

func writeAdTrackingError(c *gin.Context, err error) {
	response.RecordError(c, err)
	switch {
	case errors.Is(err, ErrLinkNotFound):
		response.Error(c, http.StatusNotFound, "not_found", err.Error())
	case errors.Is(err, ErrCodeAlreadyExists):
		response.Error(c, http.StatusConflict, "already_exists", err.Error())
	case errors.Is(err, ErrInvalidCodeFormat), errors.Is(err, ErrReservedCode), errors.Is(err, ErrLinkDisabled), errors.Is(err, ErrDisallowedTargetDomain):
		response.BadRequest(c, err.Error())
	default:
		response.InternalServerError(c, err.Error())
	}
}