package handler

import (
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"net/http"
	"regexp"
	"strings"

	"github.com/gin-gonic/gin"
	"kefu-cloud/server/internal/middleware"
	"kefu-cloud/server/internal/model"
)

type ChannelHandler struct{}

func NewChannelHandler() *ChannelHandler { return &ChannelHandler{} }

var scriptIDPattern = regexp.MustCompile(`data-id="([A-Za-z0-9_-]+)"`)

type channelView struct {
	ID         uint   `json:"id"`
	TenantID   uint   `json:"tenant_id"`
	Type       string `json:"type"`
	Name       string `json:"name"`
	Status     string `json:"status"`
	Config     string `json:"config"`
	ScriptCode string `json:"script_code"`
	ChannelKey string `json:"channel_key"`
}

func extractChannelKey(script string) string {
	m := scriptIDPattern.FindStringSubmatch(script)
	if len(m) == 2 {
		return m[1]
	}
	return ""
}

func buildWebScript(channelKey string) string {
	return fmt.Sprintf(`<script src="/widget.js" data-id="%s"></script>`, channelKey)
}

func newChannelKey(prefix string) (string, error) {
	buf := make([]byte, 4)
	if _, err := rand.Read(buf); err != nil {
		return "", err
	}
	return fmt.Sprintf("%s_%s", prefix, hex.EncodeToString(buf)), nil
}

func toChannelView(ch model.Channel) channelView {
	return channelView{
		ID: ch.ID, TenantID: ch.TenantID, Type: ch.Type, Name: ch.Name,
		Status: ch.Status, Config: ch.Config, ScriptCode: ch.ScriptCode,
		ChannelKey: extractChannelKey(ch.ScriptCode),
	}
}

func requireTenantAdmin(c *gin.Context) bool {
	if middleware.HasAnyRole(c, "admin") {
		return true
	}
	c.JSON(http.StatusForbidden, gin.H{"code": 403, "message": "仅租户管理员可操作"})
	return false
}

func (h *ChannelHandler) List(c *gin.Context) {
	tenantID := middleware.GetTenantID(c)
	var channels []model.Channel
	if err := model.DB.Where("tenant_id = ?", tenantID).Order("id asc").Find(&channels).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "查询渠道失败"})
		return
	}
	views := make([]channelView, 0, len(channels))
	for _, ch := range channels {
		views = append(views, toChannelView(ch))
	}
	middleware.JSON(c, views)
}

type updateChannelReq struct {
	Name   *string `json:"name"`
	Status *string `json:"status"`
}

func (h *ChannelHandler) Update(c *gin.Context) {
	if !requireTenantAdmin(c) {
		return
	}
	tenantID := middleware.GetTenantID(c)
	id := c.Param("id")

	var channel model.Channel
	if err := model.DB.Where("id = ? AND tenant_id = ?", id, tenantID).First(&channel).Error; err != nil {
		c.JSON(http.StatusNotFound, gin.H{"code": 404, "message": "渠道不存在"})
		return
	}

	var req updateChannelReq
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "参数错误"})
		return
	}

	updates := map[string]interface{}{}
	if req.Name != nil {
		name := strings.TrimSpace(*req.Name)
		if name == "" || len([]rune(name)) > 50 {
			c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "渠道名称无效"})
			return
		}
		updates["name"] = name
	}
	if req.Status != nil {
		status := strings.TrimSpace(*req.Status)
		if status != "enabled" && status != "disabled" {
			c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "状态仅支持 enabled/disabled"})
			return
		}
		updates["status"] = status
	}
	if len(updates) == 0 {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "没有可更新字段"})
		return
	}

	if err := model.DB.Model(&channel).Updates(updates).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "更新失败"})
		return
	}
	model.DB.First(&channel, channel.ID)
	middleware.JSON(c, toChannelView(channel))
}

type createChannelReq struct {
	Type string `json:"type" binding:"required"`
	Name string `json:"name"`
}

func (h *ChannelHandler) Create(c *gin.Context) {
	if !requireTenantAdmin(c) {
		return
	}
	var req createChannelReq
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "参数错误"})
		return
	}
	channelType := strings.TrimSpace(req.Type)
	allowed := map[string]string{
		"web": "网页聊天", "wechat": "微信公众号", "app": "APP 内嵌",
		"phone": "电话客服", "email": "邮件工单",
	}
	defaultName, ok := allowed[channelType]
	if !ok {
		c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "不支持的渠道类型"})
		return
	}
	tenantID := middleware.GetTenantID(c)
	var exists int64
	model.DB.Model(&model.Channel{}).Where("tenant_id = ? AND type = ?", tenantID, channelType).Count(&exists)
	if exists > 0 {
		c.JSON(http.StatusConflict, gin.H{"code": 409, "message": "该类型渠道已存在"})
		return
	}

	name := strings.TrimSpace(req.Name)
	if name == "" {
		name = defaultName
	}
	prefix := map[string]string{"web": "WK", "wechat": "WX", "app": "AP", "phone": "PH", "email": "EM"}[channelType]
	key, err := newChannelKey(prefix)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "生成渠道标识失败"})
		return
	}

	channel := model.Channel{
		TenantID: tenantID,
		Type:     channelType,
		Name:     name,
		Status:   "disabled",
	}
	if channelType == "web" {
		channel.Status = "enabled"
		channel.ScriptCode = buildWebScript(key)
	} else {
		channel.ScriptCode = fmt.Sprintf(`data-id="%s"`, key)
	}
	if err := model.DB.Create(&channel).Error; err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"code": 500, "message": "创建失败"})
		return
	}
	middleware.JSON(c, toChannelView(channel))
}