const { app, BrowserWindow, dialog, ipcMain } = require('electron');
const path = require('path');
const fs = require('fs');

let mainWindow = null;
let currentFilePath = null;
let pendingFilePath = null;
let fileWatcher = null;

function createWindow() {
  mainWindow = new BrowserWindow({
    width: 1200,
    height: 800,
    minWidth: 800,
    minHeight: 600,
    icon: path.join(__dirname, 'assets', 'icon.ico'),
    webPreferences: {
      preload: path.join(__dirname, 'preload.js'),
      contextIsolation: true,
      nodeIntegration: false
    },
    titleBarStyle: 'default',
    show: false
  });

  mainWindow.webContents.on('did-finish-load', () => {
    if (pendingFilePath) {
      openFile(pendingFilePath);
      pendingFilePath = null;
    }
  });

  mainWindow.loadFile(path.join(__dirname, 'renderer', 'index.html'));

  mainWindow.once('ready-to-show', () => {
    mainWindow.show();
  });

  mainWindow.setMenu(null);

  // Unsaved changes warning on close (with timeout fallback)
  mainWindow.on('close', (e) => {
    e.preventDefault();
    try {
      mainWindow.webContents.send('window:confirmClose');
    } catch (err) {
      // Renderer is gone, force close
      mainWindow.removeAllListeners('close');
      mainWindow.close();
      return;
    }
    // Safety: if renderer doesn't respond within 5s, force close
    setTimeout(() => {
      if (mainWindow && !mainWindow.isDestroyed()) {
        mainWindow.removeAllListeners('close');
        mainWindow.close();
      }
    }, 5000);
  });

  mainWindow.on('closed', () => {
    stopWatching();
    mainWindow = null;
  });
}

// File watcher - detect external modifications
function startWatching(filePath) {
  stopWatching();
  try {
    fileWatcher = fs.watch(filePath, (eventType) => {
      if (eventType === 'change' && mainWindow && !mainWindow.isDestroyed()) {
        mainWindow.webContents.send('file:externallyModified', filePath);
      }
    });
  } catch (err) {
    // Silently ignore watch errors
  }
}

function stopWatching() {
  if (fileWatcher) {
    fileWatcher.close();
    fileWatcher = null;
  }
}

async function showOpenDialog() {
  const result = await dialog.showOpenDialog(mainWindow, {
    properties: ['openFile'],
    filters: [
      { name: 'Markdown 文件', extensions: ['md', 'markdown', 'txt'] },
      { name: '所有文件', extensions: ['*'] }
    ]
  });
  if (!result.canceled && result.filePaths.length > 0) {
    return result.filePaths[0];
  }
  return null;
}

function openFile(filePath) {
  try {
    const content = fs.readFileSync(filePath, 'utf-8');
    currentFilePath = filePath;
    startWatching(filePath);
    mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
    mainWindow.webContents.send('file:opened', { filePath, content });
  } catch (err) {
    dialog.showErrorBox('错误', `无法读取文件: ${err.message}`);
  }
}

// IPC Handlers
ipcMain.handle('dialog:openFile', async () => {
  try {
    const filePath = await showOpenDialog();
    if (filePath) {
      const content = fs.readFileSync(filePath, 'utf-8');
      currentFilePath = filePath;
      startWatching(filePath);
      mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
      return { filePath, content };
    }
    return null;
  } catch (err) {
    return { error: err.message };
  }
});

ipcMain.handle('file:read', async (event, filePath) => {
  try {
    const content = fs.readFileSync(filePath, 'utf-8');
    return { success: true, content };
  } catch (err) {
    return { success: false, error: err.message };
  }
});

ipcMain.handle('file:save', async (event, { filePath, content }) => {
  try {
    if (filePath) {
      stopWatching();
      fs.writeFileSync(filePath, content, 'utf-8');
      currentFilePath = filePath;
      startWatching(filePath);
      mainWindow.setTitle(`MarkLite - ${path.basename(filePath)}`);
      return { success: true, filePath };
    } else {
      const result = await dialog.showSaveDialog(mainWindow, {
        filters: [
          { name: 'Markdown 文件', extensions: ['md'] },
          { name: '文本文件', extensions: ['txt'] }
        ]
      });
      if (!result.canceled) {
        stopWatching();
        fs.writeFileSync(result.filePath, content, 'utf-8');
        currentFilePath = result.filePath;
        startWatching(result.filePath);
        mainWindow.setTitle(`MarkLite - ${path.basename(result.filePath)}`);
        return { success: true, filePath: result.filePath };
      }
      return { success: false, canceled: true };
    }
  } catch (err) {
    return { success: false, error: err.message };
  }
});

ipcMain.handle('file:saveAs', async (event, { content }) => {
  try {
    const result = await dialog.showSaveDialog(mainWindow, {
      filters: [
        { name: 'Markdown 文件', extensions: ['md'] },
        { name: '文本文件', extensions: ['txt'] }
      ]
    });
    if (!result.canceled) {
      stopWatching();
      fs.writeFileSync(result.filePath, content, 'utf-8');
      currentFilePath = result.filePath;
      startWatching(result.filePath);
      mainWindow.setTitle(`MarkLite - ${path.basename(result.filePath)}`);
      return { success: true, filePath: result.filePath };
    }
    return { success: false, canceled: true };
  } catch (err) {
    return { success: false, error: err.message };
  }
});

ipcMain.handle('file:getCurrentPath', () => {
  return currentFilePath;
});

ipcMain.handle('file:stats', async (event, filePath) => {
  try {
    const stats = fs.statSync(filePath);
    return {
      success: true,
      size: stats.size,
      mtime: stats.mtime.toISOString()
    };
  } catch (err) {
    return { success: false, error: err.message };
  }
});

ipcMain.handle('file:reload', async () => {
  if (!currentFilePath) return { success: false, error: '没有打开的文件' };
  try {
    const content = fs.readFileSync(currentFilePath, 'utf-8');
    return { success: true, content, filePath: currentFilePath };
  } catch (err) {
    return { success: false, error: err.message };
  }
});

ipcMain.handle('window:forceClose', () => {
  stopWatching();
  mainWindow.removeAllListeners('close');
  mainWindow.close();
});

// Handle file open from command line or file association
function getCommandLineFile() {
  const args = process.argv.slice(1);
  if (args.length > 0 && !args[0].startsWith('--')) {
    const filePath = args[0];
    if (fs.existsSync(filePath)) {
      return filePath;
    }
  }
  return null;
}

// App lifecycle
app.whenReady().then(() => {
  app.on('open-file', (event, filePath) => {
    event.preventDefault();
    if (mainWindow && mainWindow.webContents.isLoading()) {
      pendingFilePath = filePath;
    } else if (mainWindow) {
      openFile(filePath);
    } else {
      pendingFilePath = filePath;
    }
  });

  createWindow();

  const fileToOpen = getCommandLineFile();
  if (fileToOpen) {
    pendingFilePath = fileToOpen;
  }
});

app.on('window-all-closed', () => {
  if (process.platform !== 'darwin') {
    app.quit();
  }
});

app.on('activate', () => {
  if (BrowserWindow.getAllWindows().length === 0) {
    createWindow();
  }
});