import {
  app,
  BrowserWindow,
  clipboard,
  ipcMain,
  Menu,
  shell,
  type MenuItemConstructorOptions,
} from 'electron';

const MAX_LINK_LENGTH = 4_096;
const LOCAL_WEB_FILE_PATTERN = /\.(?:html?|xhtml)$/i;

export type ConversationLinkContextMenuRequest =
  | { kind: 'external'; target: string }
  | { kind: 'local-web'; target: string };

export interface ConversationLinkMenuActions {
  platform: NodeJS.Platform;
  homePath: string;
  openExternal: (url: string) => Promise<void>;
  openPath: (path: string) => Promise<string>;
  showItemInFolder: (path: string) => void;
  writeText: (value: string) => void;
}

function isBoundedSingleLine(value: string): boolean {
  return value.length > 0
    && value.length <= MAX_LINK_LENGTH
    && !/[\0\r\n]/.test(value);
}

function safeExternalTarget(value: unknown): string | null {
  const candidate = typeof value === 'string' ? value.trim() : '';
  if (!isBoundedSingleLine(candidate)) return null;

  try {
    const url = new URL(candidate);
    if ((url.protocol !== 'https:' && url.protocol !== 'http:')
      || url.username
      || url.password) {
      return null;
    }
    return url.toString();
  } catch {
    return null;
  }
}

function resolveHomeRelativePath(value: string, homePath: string): string {
  if (value === '~') return homePath;
  const separator = homePath.includes('\\') ? '\\' : '/';
  const suffix = value.slice(2).replace(/[\\/]/g, separator);
  return `${homePath.replace(/[\\/]$/, '')}${separator}${suffix}`;
}

function safeLocalWebTarget(value: unknown, homePath: string): string | null {
  const candidate = typeof value === 'string' ? value.trim() : '';
  if (!isBoundedSingleLine(candidate) || !LOCAL_WEB_FILE_PATTERN.test(candidate)) return null;

  if (candidate === '~' || /^~[\\/]/.test(candidate)) {
    return resolveHomeRelativePath(candidate, homePath);
  }

  const absolute = candidate.startsWith('/')
    || /^[A-Za-z]:[\\/]/.test(candidate)
    || /^\\\\[^\\]+\\[^\\]+/.test(candidate);
  return absolute ? candidate : null;
}

function ignoreRejectedAction(action: Promise<unknown>): void {
  void action.catch(() => undefined);
}

export function createConversationLinkMenuTemplate(
  request: ConversationLinkContextMenuRequest,
  actions: ConversationLinkMenuActions,
): MenuItemConstructorOptions[] {
  if (request?.kind === 'external') {
    const target = safeExternalTarget(request.target);
    if (!target) throw new Error('Unsupported external URL');

    return [
      {
        label: '用默认浏览器打开',
        click: () => ignoreRejectedAction(actions.openExternal(target)),
      },
      { type: 'separator' },
      {
        label: '复制链接地址',
        click: () => actions.writeText(target),
      },
    ];
  }

  if (request?.kind === 'local-web') {
    const target = safeLocalWebTarget(request.target, actions.homePath);
    if (!target) throw new Error('Unsupported local web file');

    return [
      {
        label: '用默认浏览器打开',
        click: () => ignoreRejectedAction(actions.openPath(target)),
      },
      {
        label: actions.platform === 'darwin' ? '在访达中显示' : '在文件夹中显示',
        click: () => actions.showItemInFolder(target),
      },
      { type: 'separator' },
      {
        label: '复制地址',
        click: () => actions.writeText(target),
      },
    ];
  }

  throw new Error('Unsupported link context menu request');
}

export function registerConversationLinkContextMenuHandler(mainWindow: BrowserWindow): void {
  ipcMain.handle('shell:showLinkContextMenu', (event, request: ConversationLinkContextMenuRequest) => {
    const template = createConversationLinkMenuTemplate(request, {
      platform: process.platform,
      homePath: app.getPath('home'),
      openExternal: (url) => shell.openExternal(url),
      openPath: (path) => shell.openPath(path),
      showItemInFolder: (path) => shell.showItemInFolder(path),
      writeText: (value) => clipboard.writeText(value),
    });
    const menu = Menu.buildFromTemplate(template);
    const ownerWindow = BrowserWindow.fromWebContents(event.sender) ?? mainWindow;
    menu.popup({ window: ownerWindow });
  });
}