// ==UserScript==
// @name         Email Copy Button for All Sites
// @name:zh-CN   全站邮箱一键复制
// @namespace    http://tampermonkey.net/
// @version      2.7.1
// @description  Fixed: restored BTN_ATTR guard (was silently dropped in 2.7's stylesheet refactor, causing runaway button injection via aria-label re-match). Added BUTTON to SKIP_TAGS as a second guard.
// @description:zh-CN 修复：补回 BTN_ATTR 守卫属性（2.7 版单样式表重构时被误删，导致按钮通过 aria-label 被重新匹配从而无限追加）。SKIP_TAGS 增加 BUTTON 作为双重保险。
// @author       Nosy Swab (optimized, fixed)
// @match        *://*/*
// @exclude      https://apps.sfc.hk/*
// @noframes
// @run-at       document-end
// @grant        none
// @license      MIT
// ==/UserScript==

(function () {
  'use strict';

  // Subdomain-safe guard (covers apps.sfc.hk and *.apps.sfc.hk)
  if (location.hostname === 'apps.sfc.hk' || location.hostname.endsWith('.apps.sfc.hk')) return;

  var EMAIL_RE  = /[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}/;
  var EMAIL_RE_G = /[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}/g;

  var BTN_ATTR = 'data-ecb-btn';
  var DONE_ATTR = 'data-ecb-done';

  // FIX: added 'BUTTON' as a second guard against walking into our own
  // injected buttons (their aria-label contains the email and would
  // otherwise re-match and spawn another button — see BTN_ATTR fix below).
  var SKIP_TAGS = new Set([
    'SCRIPT','STYLE','NOSCRIPT','CODE','PRE','SVG','CANVAS',
    'HEAD','TEMPLATE','TEXTAREA','BUTTON'
  ]);

  // v2.7: strip leading <( and trailing .,;:'">[] so copies are clean
  function cleanEmail(raw) {
    return raw.replace(/^[<\s(]+/, '').replace(/[)\]}>;:'",.\s]+$/, '').trim();
  }

  function isInEditableRegion(node) {
    var el = node.nodeType === Node.ELEMENT_NODE ? node : node.parentElement;
    while (el) {
      if (el.isContentEditable) return true;
      el = el.parentElement;
    }
    return false;
  }

  // v2.7: modern async API first, legacy execCommand fallback; never false-success
  function legacyCopy(text) {
    try {
      var ta = document.createElement('textarea');
      ta.value = text;
      ta.style.cssText = 'position:fixed;opacity:0;top:0;left:0;width:1px;height:1px';
      document.body.appendChild(ta);
      ta.focus();
      ta.select();
      var ok = document.execCommand('copy');
      document.body.removeChild(ta);
      return ok;
    } catch (e) { return false; }
  }
  function copyToClipboard(text) {
    if (navigator.clipboard && window.isSecureContext) {
      return navigator.clipboard.writeText(text)
        .then(function () { return true; })
        .catch(function () { return legacyCopy(text); });
    }
    return Promise.resolve(legacyCopy(text));
  }

  // v2.7: single shared stylesheet (injected once) instead of per-button inline styles
  (function injectStyle() {
    var s = document.createElement('style');
    s.textContent =
      '.ecb-btn{display:inline-flex;align-items:center;justify-content:center;margin-left:4px;' +
      'padding:1px 5px;font-size:12px;line-height:1;border:1px solid #d9d9d9;border-radius:4px;' +
      'background:#fff;color:inherit;cursor:pointer;vertical-align:middle;transition:background .15s;flex-shrink:0}' +
      '.ecb-btn:hover{background:#f0f0f0}' +
      '.ecb-btn.ok{background:#52c41a;border-color:#52c41a;color:#fff}';
    (document.head || document.documentElement).appendChild(s);
  })();

  function makeBtn(email) {
    var btn = document.createElement('button');
    btn.type = 'button';
    btn.className = 'ecb-btn';
    // FIX (critical): this attribute was dropped in 2.7's refactor to
    // className-based styling. It is NOT a style artifact — it's the guard
    // that (a) makes TreeWalker's acceptNode FILTER_REJECT this button, and
    // (b) makes injectIntoMailto/injectIntoTextNode recognize "already ours".
    // Without it, the button's own aria-label (which contains the email)
    // gets re-matched by injectIntoAria on the next MutationObserver pass,
    // spawning a new button every ~200ms — runaway injection.
    btn.setAttribute(BTN_ATTR, '1');
    btn.textContent = '\uD83D\uDCCB';
    btn.title = 'Copy ' + email;
    btn.setAttribute('aria-label', 'Copy ' + email);
    btn.addEventListener('click', function (e) {
      e.preventDefault();
      e.stopPropagation();
      copyToClipboard(email).then(function (ok) {
        btn.classList.add('ok');
        btn.textContent = ok ? '\u2713' : '\u2716';
        setTimeout(function () {
          btn.classList.remove('ok');
          btn.textContent = '\uD83D\uDCCB';
        }, 1500);
      });
    });
    return btn;
  }

  // v2.7: process ALL direct text children of the parent at once, so a parent
  // with emails split across multiple text nodes is fully handled (no skips)
  function injectIntoTextNode(node) {
    var text = node.nodeValue;
    if (!text || !EMAIL_RE.test(text)) return;
    var parent = node.parentNode;
    if (!parent || !parent.tagName) return;
    if (SKIP_TAGS.has(parent.tagName)) return;
    if (parent.getAttribute(BTN_ATTR)) return;
    if (parent.getAttribute(DONE_ATTR)) return;
    if (isInEditableRegion(parent)) return;

    var targets = [];
    for (var c = parent.firstChild; c; c = c.nextSibling) {
      if (c.nodeType === Node.TEXT_NODE && EMAIL_RE.test(c.nodeValue)) targets.push(c);
    }
    if (!targets.length) return;

    parent.setAttribute(DONE_ATTR, '1');
    targets.forEach(function (tn) {
      var parts = tn.nodeValue.split(EMAIL_RE_G);
      var matches = tn.nodeValue.match(EMAIL_RE_G);
      var frag = document.createDocumentFragment();
      parts.forEach(function (part, i) {
        frag.appendChild(document.createTextNode(part));
        if (i < matches.length) {
          var email = cleanEmail(matches[i]);
          if (email) frag.appendChild(makeBtn(email));
        }
      });
      parent.replaceChild(frag, tn);
    });
  }

  function injectIntoMailto(a) {
    if (a.getAttribute(DONE_ATTR)) return;
    if (isInEditableRegion(a)) return;
    var href  = a.getAttribute('href') || '';
    var match = href.match(/^mailto:([^?]+)/);
    if (!match) return;
    var email = cleanEmail(match[1]);
    if (!email) return;

    a.setAttribute(DONE_ATTR, '1');

    var existingBtn = a.querySelector('button, [role="button"]');
    if (existingBtn && !existingBtn.getAttribute(BTN_ATTR)) {
      existingBtn.addEventListener('click', function (e) {
        e.stopPropagation();
        copyToClipboard(email);
      });
      return;
    }
    a.insertAdjacentElement('afterend', makeBtn(email));
  }

  function injectIntoInput(el) {
    if (el.getAttribute(DONE_ATTR)) return;
    if (el.type === 'hidden' || el.type === 'password') return;
    if (isInEditableRegion(el)) return;
    var val = el.value || '';
    var m   = val.match(EMAIL_RE);
    if (!m) return;
    var email = cleanEmail(m[0]);
    if (!email) return;
    el.setAttribute(DONE_ATTR, '1');
    el.insertAdjacentElement('afterend', makeBtn(email));
  }

  function injectIntoAria(el) {
    if (el.getAttribute(DONE_ATTR)) return;
    if (isInEditableRegion(el)) return;
    if (el.closest && el.closest('a[' + DONE_ATTR + ']')) return;
    var label = el.getAttribute('aria-label') || el.getAttribute('aria-description') || '';
    var m = label.match(EMAIL_RE);
    if (!m) return;
    var email = cleanEmail(m[0]);
    if (!email) return;
    el.setAttribute(DONE_ATTR, '1');
    el.insertAdjacentElement('afterend', makeBtn(email));
  }

  function walkNode(root) {
    if (isInEditableRegion(root)) return;

    var fields = [];
    if (root.nodeType === Node.ELEMENT_NODE) {
      if (root.tagName === 'INPUT' || root.tagName === 'TEXTAREA') fields.push(root);
      if (root.querySelectorAll) {
        fields = fields.concat(Array.prototype.slice.call(root.querySelectorAll('input, textarea')));
      }
    }
    fields.forEach(injectIntoInput);

    var walker = document.createTreeWalker(
      root,
      NodeFilter.SHOW_TEXT | NodeFilter.SHOW_ELEMENT,
      {
        acceptNode: function (node) {
          if (node.nodeType === Node.ELEMENT_NODE) {
            if (SKIP_TAGS.has(node.tagName)) return NodeFilter.FILTER_REJECT;
            if (node.getAttribute(BTN_ATTR)) return NodeFilter.FILTER_REJECT;
            if (node.isContentEditable) return NodeFilter.FILTER_REJECT;
            if (node.tagName === 'A' && node.getAttribute('href') &&
                node.getAttribute('href').indexOf('mailto:') === 0 &&
                node.getAttribute(DONE_ATTR)) return NodeFilter.FILTER_REJECT;
          }
          return NodeFilter.FILTER_ACCEPT;
        }
      },
      false
    );

    var textNodes = [];
    var node;
    while ((node = walker.nextNode())) {
      if (node.nodeType === Node.TEXT_NODE) {
        textNodes.push(node);
      } else if (node.nodeType === Node.ELEMENT_NODE) {
        if (node.tagName === 'A') injectIntoMailto(node);
        injectIntoAria(node);
      }
    }
    textNodes.forEach(injectIntoTextNode);
  }

  walkNode(document.body);

  // v2.7 FIX: trailing debounce + accumulated roots. The earlier build did
  // `if (_timer) return`, which dropped every mutation batch arriving inside
  // the 200ms window (only the first batch's addedRoots were ever walked, so
  // sibling nodes added in later batches could stay unscanned). Here we push
  // every batch's roots into a persistent Set and reset the timer on each
  // batch, so we drain ALL roots once, 200ms after the last activity.
  var _scanning = false, _timer = null;
  var pendingRoots = new Set();

  function drain() {
    if (_scanning) return;
    _scanning = true;
    try {
      var roots = pendingRoots;
      pendingRoots = new Set();
      roots.forEach(function (root) {
        if (document.body && document.body.contains(root)) walkNode(root);
      });
    } finally {
      _scanning = false;
    }
  }

  var observer = new MutationObserver(function (mutations) {
    mutations.forEach(function (m) {
      m.addedNodes.forEach(function (n) {
        if (n.nodeType === Node.ELEMENT_NODE || n.nodeType === Node.TEXT_NODE) {
          var root = n.nodeType === Node.ELEMENT_NODE ? n : n.parentElement;
          if (root && !root.getAttribute(BTN_ATTR) && !root.getAttribute(DONE_ATTR)) {
            pendingRoots.add(root);
          }
        }
      });
    });
    // reset timer on every batch -> trailing debounce
    clearTimeout(_timer);
    _timer = setTimeout(drain, 200);
  });

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

})();