import { defineStore } from "pinia";
import { messagesDb } from "@/utils/db/messageDB";
import { messageService } from "@/services/message";

export const useChatStore = defineStore('chat', {
    state: () => ({
        activeSessionId: null,
        activeConversationId: null,
        messages: [],
        pageSize: 20
    }),
    actions: {
        async addMessage(msg, sessionId) {
            await messagesDb.save({ ...msg, sessionId });
            this.messages.push({ ...msg, sessionId })
        },
        /**
         * 切换会话加载当前会话消息列表
         * @param {*} sessionId 
         */
        async swtichSession(sessionId, conversationId) {
            this.activeSessionId = sessionId;
            this.activeConversationId = conversationId;
            this.messages = [];
            //先从浏览器缓存加载一部分消息列表
            const localHistory = await messagesDb.getPageMessages(sessionId, new Date().toISOString(), this.pageSize);
            if (localHistory.length > 0) {
                this.messages = localHistory;
            } else {
                //如果本地没有消息数据则从后端拉取数据
                const conversation = (await messageService.getConversationById(this.activeConversationId)).data;
                const serverHistoryMsg = await this.fetchHistoryFromServer(this.activeConversationId, conversation.lastReadMessageId);
                //对消息进行过滤，防止重复消息
                const filterMsg = serverHistoryMsg.filter(m => !this.messages.find(exist => exist.msgId === m.msgId));
                this.messages = [...filterMsg, ...this.messages]
            }
            //拉取新消息
            this.fetchNewMsgFromServier(this.activeConversationId).then((newMsg) => {
                //去重
                const filterNewMsg = newMsg.filter(m => !this.messages.find(exist => exist.msgId === m.msgId));
                this.messages = [...filterNewMsg, ...this.messages]
            });
        },
        /**
         * 从服务器加载新消息
         * @param {*} sessionId 
         * @returns 
         */
        async fetchNewMsgFromServier(conversationId) {
            const newMsg = (await messageService.getMessages(conversationId)).data;
            if (newMsg.length > 0) {
                const sessionId = this.activeSessionId;
                await Promise.all(newMsg.map(msg =>
                    messagesDb.save({ ...msg, sessionId })
                ));
                return newMsg;
            } else {
                return [];
            }
        },
        /**
         * 从服务器加载历史消息
         * @param {*} sessionId 
         * @param {*} msgId 
         * @returns 
         */
        async fetchHistoryFromServer(conversationId, msgId) {
            const res = (await messageService.getHistoryMessages(conversationId, msgId, this.pageSize)).data;

            if (res.length > 0) {
                const sessionId = this.activeSessionId;
                await Promise.all(res.map(msg =>
                    messagesDb.save({ ...msg, sessionId })
                ));
                return res;
            } else {
                return [];
            }
        },
        /**
         * 加载更多历史消息
         */
        async loadMoreMessages() {
            const lastTimeStamp = this.messages.length > 0 ? this.messages[0].timeStamp : new Date().toISOString();
            const history = await messagesDb.getPageMessages(this.activeSessionId, lastTimeStamp, this.pageSize);
            if (history.length > 0) {
                this.messages = [...history, ...this.messages]
            } else {
                const fetchMsg = await this.fetchHistoryFromServer(this.conversationId, this.messages[0].msgId);
                const newMsgs = fetchMsg.filter(m => !this.messages.find(exist => exist.msgId === m.msgId));
                this.messages = [...newMsgs, ...this.messages]
            }
        }
    }
})