// ==UserScript==
// @name         请不要污染我的剪贴板
// @namespace    Violentmonkey Scripts
// @version      0.6
// @description  保护用户剪贴板内容，允许或禁止网站污染剪贴板。
// @license      MIT
// @match        *://*/*
// @grant        none
// @downloadURL none
// ==/UserScript==
/* jshint esversion: 8 */

(function () {
    'use strict';

    let clipboardPermission = null;
    let rejectCount = 0;
    const maxRejectCount = 3;

    function requestPermission(message) {
        if (clipboardPermission === true) return true;
        if (rejectCount >= maxRejectCount) return false;

        const permission = confirm(message);

        if (permission) {
            clipboardPermission = true;
            return true;
        } else {
            rejectCount++;
            if (rejectCount >= maxRejectCount) clipboardPermission = false;
            return false;
        }
    }

    // 处理 copy/cut 事件
    const handleClipboardEvent = (e, action) => {
        const selection = window.getSelection().toString();
        const message = `此网站试图修改${action === 'copy' ? '复制' : '剪切'}到剪贴板的内容，是否允许？`;

        if (!requestPermission(message)) {
            e.stopImmediatePropagation();
            e.preventDefault();
            e.clipboardData.setData('text/plain', selection);

            if (action === 'cut') {
                const range = window.getSelection().getRangeAt(0);
                range.deleteContents();
            }
        }
    };

    document.addEventListener('copy', (e) => handleClipboardEvent(e, 'copy'), true);
    document.addEventListener('cut', (e) => handleClipboardEvent(e, 'cut'), true);

    // 劫持 clipboard.writeText
    const originalWriteText = navigator.clipboard.writeText.bind(navigator.clipboard);
    navigator.clipboard.writeText = async function (text) {
        if (requestPermission('此网站试图写入内容到剪贴板，是否允许？')) {
            return originalWriteText(text);
        } else {
            throw new Error('用户拒绝写入剪贴板');
        }
    };
})();