// MarkLite — Tabs Module
(function () {
  'use strict';
  var ML = window.MarkLite;

  // ===== Tab State =====
  ML.tabs = [];
  ML.activeTabId = null;
  var tabIdCounter = 0;
  ML.mruTabStack = [];

  ML.createTab = function (filePath, content) {
    var id = ++tabIdCounter;
    return { id: id, filePath: filePath || null, content: content || '', isModified: false, scrollTop: 0, scrollLeft: 0, selectionStart: 0, selectionEnd: 0, previewScrollTop: 0 };
  };

  ML.getActiveTab = function () { return ML.tabs.find(function (t) { return t.id === ML.activeTabId; }) || null; };
  ML.getTabIndex = function (tabId) { return ML.tabs.findIndex(function (t) { return t.id === tabId; }); };

  ML.saveCurrentTabState = function () {
    var tab = ML.getActiveTab();
    if (!tab) return;
    tab.content = ML.editor.value;
    tab.scrollTop = ML.editor.scrollTop;
    tab.scrollLeft = ML.editor.scrollLeft;
    tab.selectionStart = ML.editor.selectionStart;
    tab.selectionEnd = ML.editor.selectionEnd;
    tab.previewScrollTop = ML.previewPanel.scrollTop;
  };

  ML.loadTabState = function (tab) {
    ML.editor.focus(); ML.editor.select();
    var inserted = document.execCommand('insertText', false, tab.content);
    if (!inserted) ML.editor.value = tab.content;
    ML.lineCountCache = 0;
    ML.updateLineNumbers();
    ML.renderMarkdown(tab.content);
    ML.updateFileSize();
    ML.cachePreviewPositions();
    requestAnimationFrame(function () {
      ML.editor.scrollTop = tab.scrollTop;
      ML.editor.scrollLeft = tab.scrollLeft;
      ML.lineNumbers.scrollTop = tab.scrollTop;
      ML.editor.setSelectionRange(tab.selectionStart, tab.selectionEnd);
      ML.previewPanel.scrollTop = tab.previewScrollTop;
      ML.updateCursorPosition();
    });
    ML.setModified(tab.isModified);
    if (typeof window.electronAPI !== 'undefined') window.electronAPI.tabSwitched(tab.filePath);
  };

  ML.setModified = function (modified) {
    var tab = ML.getActiveTab();
    if (tab) {
      tab.isModified = modified;
      var tabEl = ML.tabList.querySelector('.tab-item[data-tab-id="' + tab.id + '"]');
      if (tabEl) tabEl.classList.toggle('modified', modified);
    }
    ML.updateTitle();
  };

  ML.createNewTab = function (filePath, content) {
    if (filePath) {
      var existing = ML.tabs.find(function (t) { return t.filePath === filePath; });
      if (existing) { ML.switchToTab(existing.id); return existing; }
    }
    var tab = ML.createTab(filePath, content);
    ML.tabs.push(tab);
    ML.switchToTab(tab.id);
    return tab;
  };

  ML.switchToTab = function (tabId) {
    if (tabId === ML.activeTabId) return;
    ML.saveCurrentTabState();
    if (ML.activeTabId) {
      ML.mruTabStack = ML.mruTabStack.filter(function (id) { return id !== ML.activeTabId; });
      ML.mruTabStack.unshift(ML.activeTabId);
    }
    ML.activeTabId = tabId;
    var tab = ML.getActiveTab();
    if (!tab) return;
    ML.loadTabState(tab);
    ML.renderTabBar();
    ML.updateTitle();
    ML.updateSidebarHighlight();
    ML.welcomeScreen.classList.add('hidden');
  };

  ML.closeTab = function (tabId) {
    var index = ML.getTabIndex(tabId);
    if (index === -1) return;
    var tab = ML.tabs[index];
    if (tab.isModified) {
      var name = tab.filePath ? ML.getFileName(tab.filePath) : '未命名';
      if (!confirm('"' + name + '" 尚未保存，确定要关闭吗？')) return;
    }
    ML.tabs.splice(index, 1);
    ML.mruTabStack = ML.mruTabStack.filter(function (id) { return id !== tabId; });
    if (tabId === ML.activeTabId) {
      if (ML.tabs.length === 0) {
        ML.activeTabId = null;
        ML.editor.value = '';
        ML.preview.innerHTML = '';
        ML.lineNumbers.innerHTML = '';
        ML.lineCountCache = 0;
        ML.statusSize.textContent = '';
        ML.statusSizeDivider.classList.remove('visible');
        ML.welcomeScreen.classList.remove('hidden');
        document.title = 'MarkLite';
        ML.statusText.textContent = '就绪';
        if (typeof window.electronAPI !== 'undefined') window.electronAPI.tabSwitched(null);
      } else {
        var newIndex = Math.min(index, ML.tabs.length - 1);
        ML.activeTabId = ML.tabs[newIndex].id;
        ML.loadTabState(ML.tabs[newIndex]);
      }
    }
    ML.renderTabBar();
    ML.updateTitle();
    ML.updateSidebarHighlight();
  };

  ML.renderTabBar = function () {
    ML.tabList.innerHTML = '';
    ML.tabs.forEach(function (tab) {
      var el = document.createElement('div');
      el.className = 'tab-item' + (tab.id === ML.activeTabId ? ' active' : '') + (tab.isModified ? ' modified' : '');
      el.dataset.tabId = tab.id;
      var name = document.createElement('span');
      name.className = 'tab-name';
      name.textContent = tab.filePath ? ML.getFileName(tab.filePath) : '未命名';
      el.appendChild(name);
      var close = document.createElement('button');
      close.className = 'tab-close';
      close.innerHTML = '<svg width="10" height="10" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg>';
      close.addEventListener('click', function (e) { e.stopPropagation(); ML.closeTab(tab.id); });
      el.appendChild(close);
      el.addEventListener('click', function () { ML.switchToTab(tab.id); });
      ML.tabList.appendChild(el);
    });
  };

  ML.updateTitle = function () {
    var tab = ML.getActiveTab();
    if (tab) {
      var name = tab.filePath ? ML.getFileName(tab.filePath) : '未命名';
      var mod = tab.isModified ? ' *' : '';
      document.title = 'MarkLite - ' + name + mod;
      ML.statusText.textContent = name;
    } else {
      document.title = 'MarkLite';
      ML.statusText.textContent = '就绪';
    }
  };
})();