// pages/wiki/index.js
import { MOCK_WIKI } from '../../utils/mockData';

Page({
    data: {
        // Data Source (effectively the backend result)
        filteredSourceList: [],

        // Display Data (rendered list)
        displayedList: [],

        // Filter State
        searchQuery: '',
        activeCategory: '全部',

        // Pagination State
        page: 1,
        pageSize: 5,
        isLoading: false,
        hasMore: true,

        // Modal State
        showIdentifyModal: false
    },

    onLoad() {
        // Initial Load
        this.filterList();
    },

    onShow() {
        if (typeof this.getTabBar === 'function' &&
            this.getTabBar()) {
            this.getTabBar().setData({ selected: 3 });
        }
    },

    // Search Input Handler
    onSearchInput(e) {
        this.setData({ searchQuery: e.detail.value }, () => {
            this.filterList();
        });
    },

    // Category Filter Handler
    setCategory(e) {
        this.setData({ activeCategory: e.currentTarget.dataset.cat }, () => {
            this.filterList();
        });
    },

    /**
     * Simulates "Backend" Search & Filtering
     * Resets pagination and prepares the filtered data source.
     */
    filterList() {
        const { searchQuery, activeCategory } = this.data;
        let result = MOCK_WIKI;

        // Filter by Search Query
        if (searchQuery) {
            const q = searchQuery.toLowerCase();
            result = result.filter(item =>
                item.name.toLowerCase().includes(q) ||
                item.scientificName.toLowerCase().includes(q)
            );
        }

        // Filter by Category
        if (activeCategory !== '全部') {
            result = result.filter(item => item.category.includes(activeCategory));
        }

        this.setData({
            filteredSourceList: result,
            displayedList: [],
            page: 1,
            hasMore: true
        }, () => {
            this.loadMoreData();
        });
    },

    /**
     * Simulates "Backend" Pagination
     * Appends the next page of data from filteredSourceList to displayedList.
     * key-value data path update is used for performance optimization.
     */
    loadMoreData() {
        const { isLoading, hasMore, page, pageSize, filteredSourceList, displayedList } = this.data;

        if (isLoading || !hasMore) return;

        this.setData({ isLoading: true });

        // Simulate Network Delay
        setTimeout(() => {
            const startIndex = (page - 1) * pageSize;
            const endIndex = startIndex + pageSize;
            const newItems = filteredSourceList.slice(startIndex, endIndex);

            const isLastPage = endIndex >= filteredSourceList.length;

            if (newItems.length > 0) {
                // Performance Optimization: Use data path to append items
                // Instead of setData({ displayedList: [...old, ...new] })
                const updateData = {};
                const currentLen = displayedList.length;
                newItems.forEach((item, index) => {
                    updateData[`displayedList[${currentLen + index}]`] = item;
                });

                updateData['page'] = page + 1;
                updateData['hasMore'] = !isLastPage;
                updateData['isLoading'] = false;

                this.setData(updateData);
            } else {
                this.setData({
                    hasMore: false,
                    isLoading: false
                });
            }
        }, 500);
    },

    // Infinite Scroll Handler
    onReachBottom() {
        this.loadMoreData();
    },

    goToDetail(e) {
        const item = e.currentTarget.dataset.item;
        wx.navigateTo({
            url: `/pages/wiki/detail/index?id=${item.id}`
        });
    },

    openIdentifyModal() { this.setData({ showIdentifyModal: true }); },

    onPopupVisibleChange(e) {
        this.setData({
            showIdentifyModal: e.detail.visible
        });
    },

    closeIdentifyModal() { this.setData({ showIdentifyModal: false }); }
})