// ==UserScript==
// @name         Linux.do Credit Display
// @namespace    http://tampermonkey.net/
// @version      2.1
// @description  显示 linux.do 基础积分，支持手动计算差值
// @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';

    const TRANSACTIONS_API = 'https://credit.linux.do/api/v1/order/transactions';
    const LEADERBOARD_URL = 'https://linux.do/leaderboard';
    const STORAGE_KEY = 'linux_do_credit_cache';

    // 获取今天的时间范围
    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');

        return {
            startTime: `${y}-${m}-${d}T00:00:00+08:00`,
            endTime: `${y}-${m}-${d}T23:59:59+08:00`
        };
    }

    // 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+)/);
        return match ? parseInt(match[1], 10) : null;
    }

    // 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: 20, 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
            });
        });
    }

    // 检查缓存是否有效（当天有效）
    function getCachedScore() {
        const cache = GM_getValue(STORAGE_KEY, null);
        if (cache && cache.date === new Date().toDateString()) {
            return cache.score;
        }
        return null;
    }

    // 保存缓存
    function setCachedScore(score) {
        GM_setValue(STORAGE_KEY, { score, date: new Date().toDateString() });
    }

    // 创建 UI
    function createUI(baseScore) {
        const container = document.createElement('div');
        container.id = 'linux-do-credit';
        container.style.cssText = `
            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);
            display: flex;
            flex-direction: column;
            gap: 8px;
        `;

        container.innerHTML = `
            <div style="display: flex; align-items: center; gap: 8px; cursor: pointer;" id="credit-base">
                📊 历史积分: <span id="base-score">${baseScore}</span>
            </div>
            <div style="display: flex; align-items: center; gap: 6px;">
                <input id="current-input" type="number" placeholder="当前积分"
                    style="width: 80px; padding: 4px 6px; border: 1px solid #ddd; border-radius: 4px; font-size: 13px;">
                <span id="diff-result" style="font-weight: bold;">--</span>
            </div>
        `;

        document.body.appendChild(container);

        // 点击跳转排行榜（当前 tab）
        document.getElementById('credit-base').onclick = () => {
            window.location.href = LEADERBOARD_URL;
        };

        // 输入计算差值
        const input = document.getElementById('current-input');
        const diffResult = document.getElementById('diff-result');

        input.addEventListener('input', () => {
            const current = parseInt(input.value, 10);
            if (!isNaN(current)) {
                const diff = current - baseScore;
                const sign = diff >= 0 ? '+' : '';
                diffResult.textContent = `${sign}${diff}`;
                diffResult.style.color = diff >= 0 ? '#22c55e' : '#ef4444';
            } else {
                diffResult.textContent = '--';
                diffResult.style.color = '#999';
            }
        });
    }

    // 显示错误状态
    function showError() {
        const container = document.createElement('div');
        container.style.cssText = `
            position: fixed; bottom: 20px; right: 20px;
            background: #ef4444; color: white; padding: 10px 14px;
            border-radius: 8px; font-size: 14px; z-index: 9999;
        `;
        container.textContent = '📊 获取积分失败';
        document.body.appendChild(container);
    }

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

        // 尝试使用缓存
        const cached = getCachedScore();
        if (cached !== null) {
            createUI(cached);
            return;
        }

        // 请求新数据
        try {
            const score = await fetchBaseScore();
            setCachedScore(score);
            createUI(score);
        } catch (e) {
            console.error('获取积分失败:', e);
            showError();
        }
    }

    init();
})();