package handler

import (
	"strconv"
	"strings"

	"github.com/gin-gonic/gin"

	"nl-game-api-gin/internal/database"
	"nl-game-api-gin/internal/middleware"
	"nl-game-api-gin/internal/model"
	"nl-game-api-gin/internal/room"
	"nl-game-api-gin/pkg/resp"
)

// ChatConversations 会话列表：每个聊过天的好友一条，带最后一条消息与未读数
func ChatConversations(c *gin.Context) {
	uid := middleware.UID(c)
	// 每个对端的最后一条消息ID
	type peerRow struct {
		Peer   int `gorm:"column:peer"`
		LastID int `gorm:"column:last_id"`
	}
	var peers []peerRow
	database.DB.Raw(`SELECT IF(from_id = ?, to_id, from_id) AS peer, MAX(id) AS last_id
		FROM chat_messages WHERE from_id = ? OR to_id = ?
		GROUP BY peer ORDER BY last_id DESC LIMIT 100`, uid, uid, uid).Scan(&peers)
	if len(peers) == 0 {
		resp.OK(c, gin.H{"list": []any{}, "total_unread": 0})
		return
	}
	lastIDs := make([]int, 0, len(peers))
	peerIDs := make([]int, 0, len(peers))
	for _, p := range peers {
		lastIDs = append(lastIDs, p.LastID)
		peerIDs = append(peerIDs, p.Peer)
	}
	// 最后一条消息内容
	var lastMsgs []model.ChatMessage
	database.DB.Where("id IN ?", lastIDs).Find(&lastMsgs)
	msgMap := map[int]model.ChatMessage{}
	for _, m := range lastMsgs {
		msgMap[m.ID] = m
	}
	// 各对端发给我的未读数
	type unreadRow struct {
		FromID int `gorm:"column:from_id"`
		Cnt    int `gorm:"column:cnt"`
	}
	var unreads []unreadRow
	database.DB.Raw(`SELECT from_id, COUNT(*) AS cnt FROM chat_messages
		WHERE to_id = ? AND is_read = 0 GROUP BY from_id`, uid).Scan(&unreads)
	unreadMap := map[int]int{}
	total := 0
	for _, u := range unreads {
		unreadMap[u.FromID] = u.Cnt
		total += u.Cnt
	}
	briefs := loadBriefs(peerIDs)
	type convItem struct {
		Peer    userBrief `json:"peer"`     // 对方信息
		LastMsg string    `json:"last_msg"` // 最后一条消息内容
		LastAt  int64     `json:"last_at"`  // 最后一条消息时间
		FromMe  bool      `json:"from_me"`  // 最后一条是否我发的
		Unread  int       `json:"unread"`   // 未读数
	}
	list := make([]convItem, 0, len(peers))
	for _, p := range peers {
		b, ok := briefs[p.Peer]
		if !ok {
			continue
		}
		m := msgMap[p.LastID]
		list = append(list, convItem{
			Peer: b, LastMsg: m.Content, LastAt: m.CreatedAt,
			FromMe: m.FromID == uid, Unread: unreadMap[p.Peer],
		})
	}
	resp.OK(c, gin.H{"list": list, "total_unread": total})
}

// ChatMessages 与某人的聊天记录（倒序分页，返回升序；拉取即把对方发来的标记已读）
func ChatMessages(c *gin.Context) {
	uid := middleware.UID(c)
	peer, _ := strconv.Atoi(c.Query("peer_id"))
	if peer <= 0 {
		resp.Fail(c, "参数有误")
		return
	}
	beforeID, _ := strconv.Atoi(c.Query("before_id"))
	size, _ := strconv.Atoi(c.Query("size"))
	if size <= 0 || size > 100 {
		size = 50
	}
	q := database.DB.Where("(from_id = ? AND to_id = ?) OR (from_id = ? AND to_id = ?)", uid, peer, peer, uid)
	if beforeID > 0 {
		q = q.Where("id < ?", beforeID)
	}
	var msgs []model.ChatMessage
	q.Order("id DESC").Limit(size + 1).Find(&msgs)
	hasMore := len(msgs) > size
	if hasMore {
		msgs = msgs[:size]
	}
	// 反转为时间升序（前端从上到下渲染）
	for i, j := 0, len(msgs)-1; i < j; i, j = i+1, j-1 {
		msgs[i], msgs[j] = msgs[j], msgs[i]
	}
	// 拉取历史即视为已读
	database.DB.Model(&model.ChatMessage{}).
		Where("from_id = ? AND to_id = ? AND is_read = 0", peer, uid).
		Update("is_read", 1)
	briefs := loadBriefs([]int{peer})
	resp.OK(c, gin.H{"list": msgs, "has_more": hasMore, "peer": briefs[peer]})
}

// chatSendBody 发送私聊请求体
type chatSendBody struct {
	ToID    int    `json:"to_id" binding:"required"`   // 接收方用户ID
	Content string `json:"content" binding:"required"` // 消息内容
}

// ChatSend 发送私聊：仅好友之间可发；对方在线时通过 WebSocket 实时推送
func ChatSend(c *gin.Context) {
	uid := middleware.UID(c)
	var req chatSendBody
	if err := c.ShouldBindJSON(&req); err != nil || req.ToID == uid {
		resp.Fail(c, "参数有误")
		return
	}
	content := strings.TrimSpace(req.Content)
	if content == "" {
		resp.Fail(c, "消息内容不能为空")
		return
	}
	if len([]rune(content)) > 500 {
		resp.Fail(c, "消息太长（最多 500 字）")
		return
	}
	if !isFriend(uid, req.ToID) {
		resp.Fail(c, "你们还不是好友，先添加对方为好友吧")
		return
	}
	msg := model.ChatMessage{FromID: uid, ToID: req.ToID, Content: content}
	if err := database.DB.Create(&msg).Error; err != nil {
		resp.Fail(c, "发送失败，请稍后重试")
		return
	}
	// 对方在线：实时推送消息（含发送者摘要，便于会话列表直接更新）
	var me model.User
	database.DB.First(&me, uid)
	room.PushToUser(req.ToID, "chat_msg", gin.H{"msg": msg, "from": briefOf(&me, true)})
	resp.OK(c, msg)
}

// chatReadBody 标记已读请求体
type chatReadBody struct {
	PeerID int `json:"peer_id" binding:"required"` // 对端用户ID
}

// ChatRead 把某人发给我的消息全部标记已读（聊天窗口打开时收到新消息调用）
func ChatRead(c *gin.Context) {
	uid := middleware.UID(c)
	var req chatReadBody
	if err := c.ShouldBindJSON(&req); err != nil {
		resp.Fail(c, "参数有误")
		return
	}
	database.DB.Model(&model.ChatMessage{}).
		Where("from_id = ? AND to_id = ? AND is_read = 0", req.PeerID, uid).
		Update("is_read", 1)
	resp.OK(c, nil)
}

// ChatUnread 我的未读私聊总数（导航角标）
func ChatUnread(c *gin.Context) {
	uid := middleware.UID(c)
	var cnt int64
	database.DB.Model(&model.ChatMessage{}).Where("to_id = ? AND is_read = 0", uid).Count(&cnt)
	resp.OK(c, gin.H{"unread": cnt})
}