import { AgentBrowserFault } from './fault';

const BLOCKED_METHODS = new Set([
  'DOM.getFileInfo',
  'DOM.setFileInputFiles',
  'Page.crash',
  'Page.setDownloadBehavior',
  'Security.handleCertificateError',
  'Security.setDisableNetworkAccessForOrigins',
  'Security.setIgnoreCertificateErrors',
  'Security.setOverrideCertificateErrors',
]);

const BLOCKED_DOMAINS = [
  'Cast.',
  'DeviceAccess.',
  'Extensions.',
  'Tethering.',
] as const;

const URL_FIELDS_BY_METHOD = new Map<string, string[]>([
  ['Fetch.continueRequest', ['url']],
  ['Network.continueInterceptedRequest', ['url']],
  ['Network.loadNetworkResource', ['url']],
  ['Page.navigate', ['url']],
]);

function hasExternalTargetReference(params: Record<string, unknown> | undefined): boolean {
  return Boolean(params && (
    typeof params.targetId === 'string'
    || typeof params.browserContextId === 'string'
  ));
}

function isAllowedPageUrl(value: string): boolean {
  try {
    const url = new URL(value);
    return url.protocol === 'http:' || url.protocol === 'https:';
  } catch {
    return false;
  }
}

export class AgentBrowserCdpGuard {
  assertAllowed(
    method: string,
    params: Record<string, unknown> | undefined,
    sessionRef: string | undefined,
    childSessions: ReadonlySet<string>,
    ioHandles: ReadonlySet<string>,
  ): void {
    const blockedHostDomain = (
      (method.startsWith('Browser.') && method !== 'Browser.getVersion')
      || method.startsWith('SystemInfo.')
      || method.startsWith('Memory.')
      || method.startsWith('Tracing.')
      || BLOCKED_DOMAINS.some((domain) => method.startsWith(domain))
    );
    if (BLOCKED_METHODS.has(method) || blockedHostDomain) {
      throw new AgentBrowserFault(
        'CDP_METHOD_BLOCKED',
        `CDP method ${method} 可能影响 Makelore 宿主，已阻止。`,
        false,
      );
    }
    if (method.startsWith('Target.')) {
      throw new AgentBrowserFault(
        'TARGET_DENIED',
        'Target 域由开发浏览器托管，不能直接操作其他 Electron 页面。',
        false,
      );
    }
    if (hasExternalTargetReference(params)) {
      throw new AgentBrowserFault(
        'TARGET_DENIED',
        '不能指定开发浏览器之外的 CDP target。',
        false,
      );
    }
    for (const field of URL_FIELDS_BY_METHOD.get(method) ?? []) {
      const value = params?.[field];
      if (typeof value === 'string' && !isAllowedPageUrl(value)) {
        throw new AgentBrowserFault(
          'CDP_METHOD_BLOCKED',
          `${method} 只允许访问 HTTP 或 HTTPS 地址。`,
          false,
        );
      }
    }
    if (sessionRef && !childSessions.has(sessionRef)) {
      throw new AgentBrowserFault(
        'TARGET_DENIED',
        'CDP session 不属于当前开发浏览器。',
        false,
      );
    }
    if (method.startsWith('IO.')) {
      const handle = params?.handle;
      if (typeof handle !== 'string' || !ioHandles.has(handle)) {
        throw new AgentBrowserFault(
          'TARGET_DENIED',
          'IO handle 不属于当前开发浏览器会话。',
          false,
        );
      }
    }
  }
}