// 阅读器独立窗口的生命周期管理。
// 全局只保留一个阅读器窗口，书籍通过窗口内标签切换，避免同一 PDF 出现两个并发编辑器。

const path = require('path');
const { pathToFileURL } = require('url');
const { BrowserWindow } = require('electron');

let readerWindow = null;
let rendererReady = false;
let pendingMessages = [];
let closeAllowed = false;
let closePending = false;
let closeTimer = null;

function alive(win) {
  return !!win && !win.isDestroyed();
}

function get() {
  if (alive(readerWindow)) return readerWindow;
  readerWindow = null;
  return null;
}

function sendEntry(win, channel, payload) {
  if (!rendererReady) {
    pendingMessages.push([channel, payload]);
    return;
  }
  win.webContents.send(channel, payload);
}

function markReady(webContents) {
  const win = get();
  if (!win || win.webContents.id !== webContents.id) return false;
  rendererReady = true;
  const messages = pendingMessages;
  pendingMessages = [];
  for (const [channel, payload] of messages) {
    if (alive(win)) win.webContents.send(channel, payload);
  }
  return true;
}

function isReady(win) {
  return alive(win) && win === get() && rendererReady;
}

function open(entryId, rootDir, fileIndex, locator, uiTheme = 'dark') {
  const existing = get();
  if (existing) {
    if (existing.isMinimized()) existing.restore();
    const payload = {
      entryId: String(entryId),
      fileIndex: Number.isInteger(fileIndex) ? fileIndex : null
    };
    if (locator && typeof locator === 'object') payload.locator = locator;
    sendEntry(existing, 'reader:openEntry', payload);
    existing.focus();
    return existing;
  }

  readerWindow = new BrowserWindow({
    width: 1180,
    height: 900,
    minWidth: 760,
    minHeight: 540,
    frame: false,
    backgroundColor: '#141414',
    icon: path.join(
      rootDir,
      'icons',
      'dist',
      uiTheme === 'light' ? 'book-ai-light.ico' : 'book-ai-dark.ico'
    ),
    title: 'PeopleLib',
    webPreferences: {
      preload: path.join(rootDir, 'preload.js'),
      contextIsolation: true,
      nodeIntegration: false,
      // 重排图书正文来自不可信来源，即使已净化也不给它任何 Node 能力
      sandbox: false,
      spellcheck: false
    }
  });
  rendererReady = false;
  pendingMessages = [];
  closeAllowed = false;
  closePending = false;
  if (closeTimer) clearTimeout(closeTimer);
  closeTimer = null;

  readerWindow.webContents.setWindowOpenHandler(() => ({ action: 'deny' }));
  readerWindow.webContents.on('will-navigate', (event, url) => {
    const expected = pathToFileURL(path.join(rootDir, 'src', 'ui', 'reader.html')).href;
    if (!String(url).startsWith(expected)) event.preventDefault();
  });

  const query = { entryId: String(entryId) };
  if (Number.isInteger(fileIndex)) query.fileIndex = String(fileIndex);
  if (locator && typeof locator === 'object') query.locator = JSON.stringify(locator);
  readerWindow.loadFile(path.join(rootDir, 'src', 'ui', 'reader.html'), { query });

  readerWindow.on('close', (event) => {
    if (closeAllowed || !alive(readerWindow)) return;
    event.preventDefault();
    if (closePending) return;
    closePending = true;
    sendEntry(readerWindow, 'reader:prepareClose', null);
    closeTimer = setTimeout(() => {
      const win = get();
      if (win) win.destroy();
    }, 10000);
  });
  readerWindow.on('closed', () => {
    readerWindow = null;
    rendererReady = false;
    pendingMessages = [];
    closeAllowed = false;
    closePending = false;
    if (closeTimer) clearTimeout(closeTimer);
    closeTimer = null;
  });
  return readerWindow;
}

function closeFor(entryId) {
  const win = get();
  if (win) sendEntry(win, 'reader:closeEntry', String(entryId));
}

function purgeFor(entryId, requestId) {
  const win = get();
  if (win) {
    sendEntry(win, 'reader:purgeEntry', {
      entryId: String(entryId),
      requestId: String(requestId)
    });
  }
  return !!win;
}

function shutdownReady(webContents) {
  const win = get();
  if (!win || win.webContents.id !== webContents.id || !closePending) return false;
  if (closeTimer) clearTimeout(closeTimer);
  closeTimer = null;
  closeAllowed = true;
  closePending = false;
  win.close();
  return true;
}

function fromWebContents(wc) {
  const win = get();
  return win && win.webContents.id === wc.id ? 'reader' : null;
}

function all() {
  const win = get();
  return win ? [win] : [];
}

module.exports = {
  open, get, closeFor, purgeFor, fromWebContents, all,
  markReady, isReady, shutdownReady
};