import { ref, computed, onMounted, onUnmounted } from 'vue'
import { useStore } from 'vuex'
import { listActivityMessagesApi, createActivityMessageApi } from '@/utils/api.js'
import { getActivitySocket } from '@/utils/socket/ActivitySocket.js'
import { formatRelativeTime } from '@/utils/format.js'

const MAX_MESSAGES = 50

/**
 * 活动留言实时推送 composable
 * @param {import('vue').Ref<string|number>} activityId
 */
export function useMessageRealtime(activityId) {
    const store = useStore()
    const messages = ref([])
    const loading = ref(false)
    const error = ref(null)
    const currentUserId = computed(() => store.state.user?.userInfo?.uid)
    const socket = getActivitySocket()

    // 字段映射：后端 → MessageBoard props
    function toComponentShape(m) {
        return {
            id: m.id,
            user: m.nickname || '',
            avatar: m.avatar_url || '',
            content: m.content,
            time: formatRelativeTime(m.created_at),
            isSelf: m.user_id === currentUserId.value,
        }
    }

    async function loadHistory() {
        if (!activityId.value) return
        loading.value = true
        error.value = null
        try {
            const res = await listActivityMessagesApi(activityId.value, 1, 20)
            if (res.code === 0) {
                messages.value = (res.data.messages || []).map(toComponentShape)
            } else {
                error.value = res.message || '加载留言失败'
            }
        } catch (e) {
            error.value = e.message || '网络错误'
            console.error('[useMessageRealtime] loadHistory error:', e)
        } finally {
            loading.value = false
        }
    }

    function onWsMessage(payload) {
        if (!payload || Number(payload.activity_id) !== Number(activityId.value)) return
        if (!payload.message) return
        messages.value.push(toComponentShape(payload.message))
        if (messages.value.length > MAX_MESSAGES) {
            messages.value.splice(0, messages.value.length - MAX_MESSAGES)
        }
    }

    async function sendMessage(content) {
        if (!content || !content.trim()) return
        const trimmed = content.trim()
        try {
            const res = await createActivityMessageApi(activityId.value, trimmed)
            if (res.code === 0) {
                // WS 推回时会再次触发 onMessage → 列表会出现该留言
                // 断线时本地 fallback 插入
                if (!socket.isConnected && res.data?.message) {
                    messages.value.push(toComponentShape(res.data.message))
                    if (messages.value.length > MAX_MESSAGES) {
                        messages.value.splice(0, messages.value.length - MAX_MESSAGES)
                    }
                }
                // 无论 WS 还是 fallback，都弹一个轻量 toast 提示
                // uni.showToast({ title: '留言成功', icon: 'success', duration: 1200 })
            } else {
                uni.showToast({ title: res.message || '留言失败', icon: 'none' })
            }
        } catch (e) {
            console.error('[useMessageRealtime] sendMessage error:', e)
            uni.showToast({ title: '网络错误', icon: 'none' })
        }
    }

    onMounted(() => {
        loadHistory()
        // 总是调用 connect():SocketManager.connect() 内部会判断 token 是否变化。
        // - 同 token + 已连接 → _doConnect 空跑,无副作用
        // - 异 token(用户切换登录) → _hardReset 关闭旧连接、强制重连
        // 这样即使旧用户 WS 还活着但 token 已变,也能拿到新用户自己的连接,
        // 解决"另一个账户没有接收到实时推送"的问题。
        const token = uni.getStorageSync('access_token')
        if (token) {
            // 连接统一由页面 onShow 管理
			// socket.connect(token).catch(err => console.warn('[useMessageRealtime] connect error:', err))
        }
        // 同步分支：如果 WS 已连接（单例复用，另一个 composable 可能先连上了），
        // subscribe 会直接发送；否则缓存到 _topics，等待 connect 事件触发 resubscribeAll
        socket.subscribe(activityId.value, ['messages'])
        socket.onMessagesResponse(onWsMessage)

        // 如果后端 pub/sub 被禁用，WS 订阅无效，需要手动刷新才能看到新消息
        if (!socket.isPubSubEnabled()) {
            console.warn('[useMessageRealtime] Pub/Sub disabled, real-time messages unavailable. Pull-to-refresh to see new messages.')
        }
    })

    // 后端 pub/sub 状态变化：禁用时提醒用户
    function onPubsubDisabled() {
        console.warn('[useMessageRealtime] Pub/Sub became disabled, new messages will not arrive in real-time')
    }
    socket.on('pubsub_disabled', onPubsubDisabled)

    onUnmounted(() => {
        socket.unsubscribe(activityId.value, ['messages'])
        socket.offMessagesResponse(onWsMessage)
        socket.off('pubsub_disabled', onPubsubDisabled)
    })

    return {
        messages,
        loading,
        error,
        sendMessage,
        refresh: loadHistory,
    }
}