// ==UserScript==
// @name 防止未经授权的自动复制
// @version 5
// @description 在将内容复制到剪贴板之前提示用户以防止未经授权的自动复制。
// @grant GM_setClipboard
// @run-at document-start
// @match *://*/*
// @namespace https://greasyfork.org/users/452911
// @downloadURL none
// ==/UserScript==

(function() {
  'use strict';

  let hasCopied = false;
  let allowCopy = true;

  const handleCopy = function(event) {
    if (!allowCopy) return;

    event.preventDefault();

    const selection = window.getSelection().toString();

    const shouldCopy = hasCopied ? true : confirm('是否复制?\n' + selection);

    if (shouldCopy) {
      hasCopied = true;
      GM_setClipboard(selection);
    } else {
      document.execCommand = function() {
        return true;
      };
    }
  };

  const handleSelectionChange = function() {
    allowCopy = false;

    setTimeout(() => {
      allowCopy = true;
    }, 300);

    const selection = window.getSelection().toString();

    if (selection.length > 0) {
      document.removeEventListener('copy', handleCopy);
    } else {
      document.addEventListener('copy', handleCopy);
    }
  };

  document.addEventListener('selectionchange', handleSelectionChange);
  document.addEventListener('copy', handleCopy);
})();