// ==UserScript==
// @name         Linux.do Credit Display
// @namespace    http://tampermonkey.net/
// @version      2.3
// @description  显示 linux.do 今日积分变化，点击刷新，每半小时自动刷新
// @author       You
// @match        https://linux.do/*
// @grant        GM_xmlhttpRequest
// @grant        GM_setValue
// @grant        GM_getValue
// @connect      credit.linux.do
// @downloadURL none
// ==/UserScript==

(function() {
    'use strict';

    // API 和页面配置
    const TRANSACTIONS_API = 'https://credit.linux.do/api/v1/order/transactions';
    const LEADERBOARD_URL = 'https://linux.do/leaderboard';

    // 缓存 key
    const STORAGE_KEY = 'linux_do_credit_cache';
    const CURRENT_SCORE_KEY = 'linux_do_current_score_cache';

    // 请求配置
    const PAGE_SIZE = 20;
    const IFRAME_POLL_INTERVAL = 100;
    const IFRAME_MAX_ATTEMPTS = 50;
    const IFRAME_TIMEOUT = 10000;
    const ELEMENT_WAIT_TIMEOUT = 5000;
    const AUTO_REFRESH_INTERVAL = 30 * 60 * 1000; // 30分钟

    // 通用容器样式
    const CONTAINER_STYLE = `
        position: fixed;
        bottom: 20px;
        right: 20px;
        background: #fff;
        color: #333;
        padding: 10px 14px;
        border-radius: 8px;
        font-size: 14px;
        z-index: 9999;
        box-shadow: 0 2px 12px rgba(0,0,0,0.15);
    `;

    // 获取今天的时间范围（使用本地时区）
    function getTodayRange() {
        const now = new Date();
        const y = now.getFullYear();
        const m = String(now.getMonth() + 1).padStart(2, '0');
        const d = String(now.getDate()).padStart(2, '0');

        // 获取本地时区偏移，格式化为 +HH:MM 或 -HH:MM
        const offset = -now.getTimezoneOffset();
        const sign = offset >= 0 ? '+' : '-';
        const absOffset = Math.abs(offset);
        const hours = String(Math.floor(absOffset / 60)).padStart(2, '0');
        const minutes = String(absOffset % 60).padStart(2, '0');
        const tz = `${sign}${hours}:${minutes}`;

        return {
            startTime: `${y}-${m}-${d}T00:00:00${tz}`,
            endTime: `${y}-${m}-${d}T23:59:59${tz}`
        };
    }

    // 从 remark 解析积分: "社区积分从 1877 更新到 1938，变化 61" -> 1938
    function parseScore(remark) {
        const match = remark.match(/更新到\s*(\d+)/);
        if (!match) return null;
        const score = parseInt(match[1], 10);
        return isNaN(score) ? null : score;
    }

    // 安全解析数字文本（移除逗号，如 "2,003" -> 2003）
    function parseNumberText(text) {
        if (!text) return null;
        const num = parseInt(text.trim().replace(/,/g, ''), 10);
        return isNaN(num) ? null : num;
    }

    // 通用缓存读取（当天有效）
    function getCache(key) {
        const cache = GM_getValue(key, null);
        if (cache && cache.date === new Date().toDateString()) {
            return cache.score;
        }
        return null;
    }

    // 通用缓存写入
    function setCache(key, score) {
        GM_setValue(key, { score, date: new Date().toDateString() });
    }

    // 计算积分变化的显示信息
    function getDiffDisplay(currentScore, baseScore) {
        const diff = currentScore - baseScore;
        const sign = diff >= 0 ? '+' : '';
        const color = diff >= 0 ? '#22c55e' : '#ef4444';
        return { diff, sign, color };
    }

    // 获取今日基础积分
    function fetchBaseScore() {
        return new Promise((resolve, reject) => {
            const { startTime, endTime } = getTodayRange();

            GM_xmlhttpRequest({
                method: 'POST',
                url: TRANSACTIONS_API,
                headers: { 'Content-Type': 'application/json' },
                data: JSON.stringify({ page: 1, page_size: PAGE_SIZE, startTime, endTime }),
                onload: (res) => {
                    try {
                        const data = JSON.parse(res.responseText);
                        const orders = data.data?.orders || [];
                        for (const item of orders) {
                            if (item.remark?.includes('社区积分')) {
                                const score = parseScore(item.remark);
                                if (score !== null) {
                                    resolve(score);
                                    return;
                                }
                            }
                        }
                        reject(new Error('未找到积分记录'));
                    } catch (e) {
                        reject(e);
                    }
                },
                onerror: reject
            });
        });
    }

    // 等待元素出现
    function waitForElement(selector, timeout = ELEMENT_WAIT_TIMEOUT) {
        return new Promise((resolve) => {
            const el = document.querySelector(selector);
            if (el) {
                resolve(el);
                return;
            }

            let resolved = false;
            const observer = new MutationObserver(() => {
                if (resolved) return;
                const el = document.querySelector(selector);
                if (el) {
                    resolved = true;
                    observer.disconnect();
                    resolve(el);
                }
            });

            observer.observe(document.body, { childList: true, subtree: true });

            setTimeout(() => {
                if (!resolved) {
                    resolved = true;
                    observer.disconnect();
                    resolve(null);
                }
            }, timeout);
        });
    }

    // 从排行榜页面 DOM 获取当前积分
    function parseScoreFromElement(userEl) {
        if (!userEl) return null;
        return parseNumberText(userEl.textContent);
    }

    // 判断是否在排行榜页面
    function isLeaderboardPage() {
        return location.pathname === '/leaderboard' || location.pathname === '/leaderboard/';
    }

    // 创建基础容器
    function createContainer() {
        const container = document.createElement('div');
        container.id = 'linux-do-credit';
        container.style.cssText = CONTAINER_STYLE;
        return container;
    }

    // 创建积分变化显示元素
    function createDiffElement(currentScore, baseScore) {
        const { sign, diff, color } = getDiffDisplay(currentScore, baseScore);
        const span = document.createElement('span');
        span.style.cssText = `font-weight: bold; color: ${color};`;
        span.textContent = `${sign}${diff}`;
        return span;
    }

    // 创建 UI（排行榜页面专用）
    async function createLeaderboardUI(baseScore) {
        const container = createContainer();
        container.textContent = '计算中...';
        document.body.appendChild(container);

        const userEl = await waitForElement('.user.-self .user__score');
        const currentScore = parseScoreFromElement(userEl);

        container.textContent = '';
        if (currentScore !== null) {
            const textNode = document.createTextNode('今日变化: ');
            container.appendChild(textNode);
            container.appendChild(createDiffElement(currentScore, baseScore));
        } else {
            container.style.color = '#f59e0b';
            container.textContent = '无法获取积分';
        }
    }

    // 通过隐藏 iframe 获取排行榜积分
    function fetchScoreViaIframe() {
        return new Promise((resolve, reject) => {
            const iframe = document.createElement('iframe');
            iframe.style.cssText = 'position: absolute; width: 1px; height: 1px; opacity: 0; pointer-events: none;';
            iframe.src = LEADERBOARD_URL;

            let resolved = false;

            const cleanup = () => {
                if (iframe.parentNode) {
                    document.body.removeChild(iframe);
                }
            };

            const finish = (success, value) => {
                if (resolved) return;
                resolved = true;
                cleanup();
                success ? resolve(value) : reject(value);
            };

            iframe.onload = () => {
                let iframeDoc;
                try {
                    iframeDoc = iframe.contentDocument || iframe.contentWindow.document;
                } catch (e) {
                    finish(false, new Error('无法访问 iframe 内容（跨域限制）'));
                    return;
                }

                let attempts = 0;
                const checkElement = () => {
                    if (resolved) return;

                    const userEl = iframeDoc.querySelector('.user.-self .user__score');
                    if (userEl) {
                        const score = parseNumberText(userEl.textContent);
                        if (score !== null) {
                            finish(true, score);
                        } else {
                            finish(false, new Error('积分解析失败'));
                        }
                    } else if (attempts < IFRAME_MAX_ATTEMPTS) {
                        attempts++;
                        setTimeout(checkElement, IFRAME_POLL_INTERVAL);
                    } else {
                        finish(false, new Error('无法找到积分元素'));
                    }
                };

                setTimeout(checkElement, 500);
            };

            iframe.onerror = () => {
                finish(false, new Error('iframe 加载失败'));
            };

            setTimeout(() => {
                finish(false, new Error('获取积分超时'));
            }, IFRAME_TIMEOUT);

            document.body.appendChild(iframe);
        });
    }

    // 创建 UI（普通页面）
    function createUI(baseScore) {
        const container = createContainer();
        container.style.cssText += 'cursor: pointer;';

        let isLoading = false;

        // 更新显示
        const updateDisplay = (currentScore) => {
            container.textContent = '';
            container.appendChild(document.createTextNode('今日: '));
            container.appendChild(createDiffElement(currentScore, baseScore));
        };

        // 显示加载状态
        const showLoading = () => {
            container.textContent = '获取中...';
            container.style.color = '#999';
        };

        // 显示错误
        const showError = (msg) => {
            container.textContent = msg;
            container.style.color = '#ef4444';
        };

        // 恢复正常样式
        const resetStyle = () => {
            container.style.color = '#333';
        };

        // 获取积分
        const doFetch = async () => {
            if (isLoading) return;
            isLoading = true;
            showLoading();

            try {
                const currentScore = await fetchScoreViaIframe();
                setCache(CURRENT_SCORE_KEY, currentScore);
                resetStyle();
                updateDisplay(currentScore);
            } catch (e) {
                console.error('获取积分失败:', e);
                showErrorWithLogin(container);
            }

            isLoading = false;
        };

        document.body.appendChild(container);

        // 点击刷新
        container.onclick = doFetch;

        // 初始显示
        const cachedCurrentScore = getCache(CURRENT_SCORE_KEY);
        if (cachedCurrentScore !== null) {
            updateDisplay(cachedCurrentScore);
        } else {
            container.textContent = '点击获取今日积分';
        }

        // 定时自动刷新
        setInterval(doFetch, AUTO_REFRESH_INTERVAL);
    }

    // 显示错误状态（带登录链接）
    function showErrorWithLogin(container) {
        container.innerHTML = '';
        container.style.color = '#333';
        container.appendChild(document.createTextNode('请登录 '));
        const link = document.createElement('a');
        link.href = 'https://credit.linux.do/';
        link.target = '_blank';
        link.style.cssText = 'color: #3b82f6; text-decoration: underline;';
        link.textContent = 'LINUX DO Credit';
        container.appendChild(link);
    }

    // 显示错误状态
    function showError() {
        const container = createContainer();
        showErrorWithLogin(container);
        document.body.appendChild(container);
    }

    // 初始化
    async function init() {
        if (document.readyState === 'loading') {
            document.addEventListener('DOMContentLoaded', init);
            return;
        }

        // 获取基础积分（优先缓存）
        let baseScore = getCache(STORAGE_KEY);

        if (baseScore === null) {
            try {
                baseScore = await fetchBaseScore();
                setCache(STORAGE_KEY, baseScore);
            } catch (e) {
                console.error('获取积分失败:', e);
                showError();
                return;
            }
        }

        // 根据页面类型显示不同 UI
        if (isLeaderboardPage()) {
            createLeaderboardUI(baseScore);
        } else {
            createUI(baseScore);
        }
    }

    init();
})();