// ==UserScript==
// @name         dmm 换算人民币
// @namespace    http://94cat.com/
// @version      1.2
// @description  精确识别 FANZA 商品价格，将日元换算为人民币，保留折扣和原价样式
// @author       Melody
// @match        https://video.dmm.co.jp/*
// @match        https://www.dmm.co.jp/digital/*
// @match        https://www.dmm.co.jp/search/*
// @match        https://cashier.dmm.co.jp/choice/*
// @run-at       document-idle
// @grant        GM_xmlhttpRequest
// @grant        GM_setValue
// @grant        GM_getValue
// @connect      open.er-api.com
// @license      MIT
// ==/UserScript==

(function () {
    'use strict';

    const API_URL = 'https://open.er-api.com/v6/latest/JPY';
    const CACHE_KEY = 'dmm_cny_rate_v1';
    const RETRY_KEY = 'dmm_cny_rate_retry_after';
    const DAY = 24 * 60 * 60 * 1000;
    const MAX_CACHE_AGE = 7 * DAY;
    const IS_VIDEO = location.hostname === 'video.dmm.co.jp';

    // 列表有稳定的语义标记；首页目前没有，使用实际价格样式并校验商品卡片。
    // 不把通用红色文字、折扣、标题或所有含“円”的文字当作价格。
    const DETAIL_OPTION_SELECTOR = 'label .font-bold.text-right';
    const DETAIL_SPLIT_SELECTOR = 'span.text-red-900.items-baseline';
    const VIDEO_SELECTORS = [
        '[data-e2eid="content-price"]', 'div.font-bold.text-red-900',
        DETAIL_OPTION_SELECTOR, DETAIL_SPLIT_SELECTOR
    ].join(',');
    const LEGACY_SELECTORS = [
        '.price', '.tx-price', '.tx-lt', '#side-rank-tab .red',
        '.package-item_plice', '#tr_bmm_price', '.choice-totalAmount__txt'
    ].join(',');
    const SELECTORS = IS_VIDEO ? VIDEO_SELECTORS : LEGACY_SELECTORS;
    const EXCLUDED = [
        'script', 'style', 'noscript', 'template', 'textarea', 'input',
        'select', 'option', '[contenteditable]:not([contenteditable="false"])',
        '.salecount', '.tx-sale', '.tx-discount'
    ].join(',');

    const NUMBER = '(?:[0-9]{1,3}(?:,[0-9]{3})+|[0-9]+)(?:\\.[0-9]{1,2})?';
    // 一组相邻文本节点必须是一个金额；拒绝“300円以下”、销量、日期、百分比等。
    const PRICE_PATTERN = new RegExp(
        '^(\\s*(?:(?:通常価格|販売価格|税込価格|価格|合計)\\s*[:：]\\s*)?)' +
        '(?:[¥￥]\\s*(' + NUMBER + ')(?:\\s*円)?|(' + NUMBER + ')\\s*円)' +
        '(\\s*(?:(?:[〜～~]|から|より|税込|税抜|[（(](?:税込|税抜)[)）])\\s*)*)$'
    );

    // 保存每个文本节点的原始日元和输出，支持 React 复用节点、价格更新和汇率刷新。
    const converted = new WeakMap();
    const originalTitles = new WeakMap();
    let quote = readCache();
    let timer = null;
    let observer;

    function parsePrice(text) {
        const normalized = text
            .replace(/[０-９]/g, ch => String.fromCharCode(ch.charCodeAt(0) - 0xFEE0))
            .replace(/，/g, ',').replace(/．/g, '.');
        const match = PRICE_PATTERN.exec(normalized);
        if (!match) return null;
        const amount = Number((match[2] || match[3]).replace(/,/g, ''));
        if (!Number.isFinite(amount) || amount < 0) return null;
        return { amount, prefix: match[1], suffix: match[4] };
    }

    function isPositiveRate(rate) {
        return typeof rate === 'number' && Number.isFinite(rate) && rate > 0;
    }

    function readCache() {
        const cached = GM_getValue(CACHE_KEY, null);
        if (!cached || cached.base !== 'JPY' || !isPositiveRate(cached.rate) ||
            !Number.isFinite(cached.fetchedAt) || !Number.isFinite(cached.updatedAt)) return null;
        const age = Date.now() - cached.fetchedAt;
        return age >= 0 && age <= MAX_CACHE_AGE ? cached : null;
    }

    function isProductLink(link) {
        try {
            const url = new URL(link.getAttribute('href'), location.href);
            return url.hostname === 'video.dmm.co.jp' && /^\/[^/]+\/content\/$/.test(url.pathname);
        } catch (_) {
            return false;
        }
    }

    function isPriceContainer(element) {
        if (element.closest(EXCLUDED)) return false;
        if (!IS_VIDEO) return true;
        if (element.getAttribute('data-e2eid') === 'content-price') return true;

        if (/^\/[^/]+\/content\/$/.test(location.pathname)) {
            if (element.matches(DETAIL_OPTION_SELECTOR)) {
                const label = element.closest('label');
                return !!label.querySelector('input[type="radio"]') && hasPurchaseContext(element);
            }
            if (element.matches(DETAIL_SPLIT_SELECTOR)) return hasPurchaseContext(element);
        }

        // 购买区候选不能走商品卡片的备用规则。
        if (!element.matches('div.font-bold.text-red-900')) return false;

        // 首页价格必须位于附近有商品详情链接的卡片里；不能仅凭红色+粗体判断。
        let card = element;
        for (let depth = 0; card && depth <= 4; depth++, card = card.parentElement) {
            if (card === document.body || card.matches('main, section, ul, nav, aside')) break;
            const links = card.querySelectorAll('a[href*="/content/"]');
            if (Array.from(links).some(isProductLink)) return true;
        }
        return false;
    }

    function hasPurchaseContext(element) {
        let panel = element;
        for (let depth = 0; panel && depth <= 7; depth++, panel = panel.parentElement) {
            if (panel === document.body || panel.matches('main, nav')) break;
            if (panel.querySelector('[data-e2eid="purchase-button"]')) return true;
        }
        return false;
    }

    function originalText(nodes) {
        return nodes.map(node => {
            const previous = converted.get(node);
            return previous && node.data === previous.output ? previous.source : node.data;
        });
    }

    function writeText(nodes, sources, output) {
        nodes.forEach((node, index) => {
            const part = index === 0 ? output : '';
            converted.set(node, { source: sources[index], output: part });
            if (node.data !== part) node.data = part;
        });
    }

    function convertGroup(nodes) {
        if (!nodes.length || nodes[0].parentElement.closest(EXCLUDED)) return;
        const sources = originalText(nodes);
        const source = sources.join('');
        const price = parsePrice(source);
        if (!price) return;
        const value = price.amount * quote.rate; // API 基准是 JPY：1 日元对应的人民币。
        if (!Number.isFinite(value)) return;
        const output = price.prefix + value.toFixed(2) + '元' + price.suffix;
        // React 会把“1,386”和“円”拆成相邻节点（有时中间有注释）。
        // 把显示文本放在第一个节点，其余节点置空但保留身份和原文记录。
        // 后续只更新数字节点时，仍可用原单位重新识别完整日元金额。
        writeText(nodes, sources, output);
        setPriceTitle(nodes[0].parentElement, source);
    }

    function convertSplitPrice(element) {
        // 优惠券金额的数字与单位使用不同字号的两个 span；仅接受这个明确结构。
        const children = Array.from(element.children);
        if (children.length !== 2 || children.some(child =>
            child.tagName !== 'SPAN' || child.childElementCount !== 0 || child.closest(EXCLUDED))) return;
        const amountNodes = Array.from(children[0].childNodes).filter(node => node.nodeType === 3);
        const unitNodes = Array.from(children[1].childNodes).filter(node => node.nodeType === 3);
        if (!amountNodes.length || !unitNodes.length) return;
        const amountSources = originalText(amountNodes);
        const unitSources = originalText(unitNodes);
        const unitSource = unitSources.join('');
        if (unitSource.trim() !== '円') return;
        const source = amountSources.join('') + unitSource;
        const price = parsePrice(source);
        if (!price) return;
        const value = price.amount * quote.rate;
        if (!Number.isFinite(value)) return;
        writeText(amountNodes, amountSources, price.prefix + value.toFixed(2));
        writeText(unitNodes, unitSources, unitSource.replace('円', '元'));
        setPriceTitle(element, source);
    }

    function setPriceTitle(parent, source) {
        if (!originalTitles.has(parent)) originalTitles.set(parent, parent.getAttribute('title') || '');
        const originalTitle = originalTitles.get(parent);
        const cached = Date.now() - quote.fetchedAt >= DAY ? '（缓存汇率）' : '';
        const date = new Date(quote.updatedAt).toISOString().slice(0, 10);
        parent.title = (originalTitle ? originalTitle + '\n' : '') +
            '原价：' + source.trim() + '\n1 JPY ≈ ' + quote.rate + ' CNY' + cached +
            '\n汇率日期：' + date + '；来源：ExchangeRate-API；仅供参考';
    }

    function showAttribution() {
        // 此免费接口要求显示来源链接：https://www.exchangerate-api.com/docs/free
        let link = document.getElementById('dmm-cny-rate-source');
        if (!link) {
            link = document.createElement('a');
            link.id = 'dmm-cny-rate-source';
            link.href = 'https://www.exchangerate-api.com';
            link.target = '_blank';
            link.rel = 'noopener noreferrer';
            link.style.cssText = 'position:fixed;right:8px;bottom:4px;font:10px/1.4 sans-serif;' +
                'color:#666;background:rgba(255,255,255,.9);padding:2px 4px;z-index:10;';
            document.body.appendChild(link);
        }
        const stale = Date.now() - quote.fetchedAt >= DAY;
        link.textContent = '汇率：ExchangeRate-API' + (stale ? '（缓存）' : '');
        link.title = 'Rates By Exchange Rate API；1 JPY ≈ ' + quote.rate + ' CNY；仅供参考';
    }

    function scan() {
        timer = null;
        if (!quote || !document.body) return;
        observer.disconnect();
        try {
            const elements = new Set();
            const splitPrices = new Set();
            for (const container of document.querySelectorAll(SELECTORS)) {
                if (!isPriceContainer(container)) continue;
                if (IS_VIDEO && container.matches(DETAIL_SPLIT_SELECTOR)) {
                    splitPrices.add(container);
                    continue;
                }
                elements.add(container);
                for (const child of container.querySelectorAll('*')) elements.add(child);
            }
            for (const element of elements) {
                if (element.closest(EXCLUDED)) continue;
                let group = [];
                for (const child of element.childNodes) {
                    if (child.nodeType === 3) group.push(child);
                    else if (child.nodeType !== 8) {
                        // 跨元素不拼接，避免把划线原价和折后价串成一个数字。
                        convertGroup(group);
                        group = [];
                    }
                }
                convertGroup(group);
            }
            for (const element of splitPrices) convertSplitPrice(element);
            showAttribution();
        } finally {
            // 新站没有 #mu；body 同时覆盖旧站、结算页和动态加载列表。
            observer.observe(document.body, {
                childList: true, subtree: true, characterData: true,
                attributes: true, attributeFilter: ['class', 'data-e2eid']
            });
        }
    }

    function scheduleScan() {
        // 页面连续更新时合并扫描；自身写入时暂停 observer，避免无限循环。
        if (timer === null) timer = setTimeout(scan, 150);
    }

    function refreshRate() {
        if (quote && Date.now() - quote.fetchedAt < DAY) return;
        const retryAfter = GM_getValue(RETRY_KEY, 0);
        if (Number.isFinite(retryAfter) && Date.now() < retryAfter) return;

        function failed(reason) {
            GM_setValue(RETRY_KEY, Date.now() + 60 * 60 * 1000);
            console.warn('[DMM 人民币] 汇率获取失败，' +
                (quote ? '暂用最近缓存。' : '保留日元原价。'), reason);
        }

        try {
            GM_xmlhttpRequest({
                method: 'GET', url: API_URL, responseType: 'json', timeout: 12000,
                onload(response) {
                    try {
                        if (response.status !== 200) throw new Error('HTTP ' + response.status);
                        const data = response.response && typeof response.response === 'object'
                            ? response.response : JSON.parse(response.responseText);
                        if (data.result !== 'success' || data.base_code !== 'JPY' ||
                            !data.rates || !isPositiveRate(data.rates.CNY) ||
                            !Number.isFinite(data.time_last_update_unix) || data.time_last_update_unix <= 0) {
                            throw new Error('无效的 JPY/CNY 汇率响应');
                        }
                        quote = {
                            base: 'JPY', rate: data.rates.CNY,
                            fetchedAt: Date.now(), updatedAt: data.time_last_update_unix * 1000
                        };
                        GM_setValue(CACHE_KEY, quote);
                        GM_setValue(RETRY_KEY, 0);
                        scheduleScan();
                    } catch (error) {
                        failed(error.message);
                    }
                },
                onerror() { failed('网络错误'); },
                ontimeout() { failed('请求超时'); },
                onabort() { failed('请求中止'); }
            });
        } catch (error) {
            failed(error.message);
        }
    }

    function start() {
        observer = new MutationObserver(scheduleScan);
        // 即使暂时没有汇率，也监听页面；首次获取成功后会开始转换。
        observer.observe(document.body, { childList: true, subtree: true, characterData: true });
        scan();
        refreshRate();
    }

    if (document.body) start();
    else document.addEventListener('DOMContentLoaded', start, { once: true });
})();