// ==============================================================================
// <品类名> · VOC 数据分析模块（模板）
// ==============================================================================
// 职责：
//   - 加载 _merged.json
//   - 提供 getEvidence() 主查询 API
//   - 提供 filterByPlatform/Hypothesis/Product 等辅助筛选
//   - 判断 "substantive" 内容（过滤纯表情/水字）
// ==============================================================================

const fs = require('fs');
const path = require('path');

const CATEGORY = '<品类>';  // TODO: 改为实际目录名

// ==========================================================
// 1. 常量
// ==========================================================
const HYPOTHESES = {
    H1: '<H1 主题>',  // TODO: 按 2.VOC深度思路 填写
    H2: '<H2 主题>',
    H3: '<H3 主题>',
    H4: '<H4 主题>',
    H5: '<H5 主题>',
    H6: '<H6 主题>',
    H7: '<H7 主题>',
    H8: '<H8 主题>',
};

const PLATFORMS = ['xhs', 'douyin', 'weibo', 'jd', 'tmall', 'amazon'];

// ==========================================================
// 2. 数据加载
// ==========================================================
function loadMerged() {
    const fp = path.resolve(__dirname, '..', '..', 'docs', CATEGORY, 'raw', '_merged.json');
    if (!fs.existsSync(fp)) {
        throw new Error(`_merged.json 不存在。请先跑 collect --merge。路径：${fp}`);
    }
    const data = JSON.parse(fs.readFileSync(fp, 'utf8'));
    if (!data.items || !Array.isArray(data.items)) {
        throw new Error(`_merged.json 格式错误：缺少 items 数组`);
    }
    return data;
}

// ==========================================================
// 3. 内容实质性判断
// ==========================================================
function isSubstantive(content, minChars = 10) {
    const s = String(content || '').trim();
    if (s.length < minChars) return false;
    // 剥离 [表情] 标记和 unicode 表情
    const stripped = s
        .replace(/\[[^\]]+\]/g, '')
        .replace(/[\s\p{P}\p{Emoji_Presentation}\p{Extended_Pictographic}]/gu, '');
    return stripped.length >= Math.max(4, Math.floor(minChars / 2));
}

// ==========================================================
// 4. 基础筛选
// ==========================================================
const filterByPlatform = (items, p) => items.filter((it) => it.platform === p);
const filterByHypothesis = (items, h) => items.filter((it) => (it.hypotheses || []).includes(h));
const filterByProduct = (items, prod) => items.filter((it) => it.product === prod);
const filterByKeyword = (items, kw) => items.filter((it) => it.keyword === kw);
const filterBySentiment = (items, s) => items.filter((it) => it.sentiment === s);

// ==========================================================
// 5. 内容匹配
// ==========================================================
function filterByContentMatch(items, regex) {
    if (!regex) return items;
    const re = regex instanceof RegExp ? regex : new RegExp(regex);
    return items.filter((it) => re.test(it.content || ''));
}

// ==========================================================
// 6. 核心 API · getEvidence
// ==========================================================
/**
 * 从 items 池里取出证据卡
 * @param {Array<Item>} items
 * @param {Object} opts
 * @param {string}        [opts.keyword]
 * @param {string}        [opts.product]
 * @param {string}        [opts.platform]
 * @param {RegExp|string} [opts.contentMatch]
 * @param {Array<string>} [opts.hypotheses]   - 必含的 H 标签（AND 关系）
 * @param {string}        [opts.sentiment]    - positive / negative / neutral
 * @param {number}        [opts.minChars=10]
 * @param {number}        [opts.minLikes=0]
 * @param {number}        [opts.top=5]
 * @param {number}        [opts.seed=0]       - 乱序种子（避免章节重复）
 * @returns {Array<Item>}
 */
function getEvidence(items, opts = {}) {
    let pool = items;

    if (opts.keyword) pool = filterByKeyword(pool, opts.keyword);
    if (opts.product) pool = filterByProduct(pool, opts.product);
    if (opts.platform) pool = filterByPlatform(pool, opts.platform);
    if (opts.sentiment) pool = filterBySentiment(pool, opts.sentiment);
    if (opts.contentMatch) pool = filterByContentMatch(pool, opts.contentMatch);
    if (opts.hypotheses?.length) {
        pool = pool.filter((it) => opts.hypotheses.every((h) => (it.hypotheses || []).includes(h)));
    }

    const minChars = opts.minChars ?? 10;
    pool = pool.filter((it) => isSubstantive(it.content, minChars));
    if (opts.minLikes) pool = pool.filter((it) => (it.likes || 0) >= opts.minLikes);

    // 去重：前 40 字相同视为同内容
    const seen = new Set();
    pool = pool.filter((it) => {
        const key = String(it.content || '').slice(0, 40);
        if (seen.has(key)) return false;
        seen.add(key);
        return true;
    });

    // 按 likes 降序
    pool.sort((a, b) => (b.likes || 0) - (a.likes || 0));

    const top = opts.top || 5;
    // 取前 top*2 再按 seed 乱序选 top（避免每章都抽到同几条）
    const top2 = pool.slice(0, top * 2);
    if (opts.seed) return shuffleWithSeed(top2, opts.seed).slice(0, top);
    return top2.slice(0, top);
}

// ==========================================================
// 7. 工具
// ==========================================================
function shuffleWithSeed(arr, seed) {
    const result = arr.slice();
    let rnd = seed || 1;
    for (let i = result.length - 1; i > 0; i--) {
        rnd = (rnd * 9301 + 49297) % 233280;
        const j = Math.floor((rnd / 233280) * (i + 1));
        [result[i], result[j]] = [result[j], result[i]];
    }
    return result;
}

function fmtLikes(n) {
    if (!n) return '0';
    if (n >= 10000) return (n / 10000).toFixed(1) + 'w';
    if (n >= 1000) return (n / 1000).toFixed(1) + 'k';
    return String(n);
}

// ==========================================================
// 8. 聚合统计
// ==========================================================
function statsByPlatform(items) {
    const map = {};
    for (const it of items) map[it.platform] = (map[it.platform] || 0) + 1;
    return map;
}

function statsByHypothesis(items) {
    const map = {};
    for (const it of items) {
        for (const h of it.hypotheses || []) map[h] = (map[h] || 0) + 1;
    }
    return map;
}

function statsByProduct(items) {
    const map = {};
    for (const it of items) map[it.product] = (map[it.product] || 0) + 1;
    return map;
}

function statsBySentiment(items) {
    const map = { positive: 0, negative: 0, neutral: 0 };
    for (const it of items) map[it.sentiment || 'neutral']++;
    return map;
}

// ==========================================================
// 9. 导出
// ==========================================================
module.exports = {
    loadMerged,
    getEvidence,
    isSubstantive,
    filterByPlatform,
    filterByHypothesis,
    filterByProduct,
    filterByKeyword,
    filterBySentiment,
    filterByContentMatch,
    shuffleWithSeed,
    fmtLikes,
    statsByPlatform,
    statsByHypothesis,
    statsByProduct,
    statsBySentiment,
    HYPOTHESES,
    PLATFORMS,
};