Genarrative/apps/mobile-shell/src/host-bridge/protocol.ts

import {
  HOST_BRIDGE_PROTOCOL,
  HOST_BRIDGE_VERSION,
  type HostBridgeError,
  type HostBridgeMethod,
  type HostBridgeRequest,
  type HostBridgeResponse,
  isHostBridgeMethod,
  normalizeHostBridgeRequestId,
} from '../../../../packages/shared/src/contracts/hostBridge';
import type { MobileShellUrlOptions } from '../shell/url';

const HOST_BRIDGE_ERROR_CODES = new Set<HostBridgeError['code']>([
  'invalid_request',
  'unsupported_method',
  'unsupported_capability',
  'timeout',
  'cancelled',
  'host_error',
]);

export type MobileHostBridgeNavigation = {
  allowedOrigin: string;
  urlOptions: MobileShellUrlOptions;
  openWebViewUrl: (url: string) => void;
  reloadWebView: () => void;
};

export function unsupported(method: HostBridgeMethod): HostBridgeError {
  return {
    code: 'unsupported_method',
    message: `${method} unsupported in mobile shell`,
  };
}

export function invalidRequest(message: string): HostBridgeError {
  return {
    code: 'invalid_request',
    message,
  };
}

export function isHostBridgeRequest(value: unknown): value is HostBridgeRequest {
  if (!value || typeof value !== 'object') {
    return false;
  }

  const candidate = value as Partial<HostBridgeRequest>;
  const requestId = normalizeHostBridgeRequestId(candidate.id);
  return (
    candidate.bridge === HOST_BRIDGE_PROTOCOL &&
    candidate.version === HOST_BRIDGE_VERSION &&
    requestId !== null &&
    isHostBridgeMethod(candidate.method)
  );
}

export function parseRequest(raw: string) {
  try {
    return JSON.parse(raw) as unknown;
  } catch {
    return null;
  }
}

export function ok<Result>(
  request: HostBridgeRequest,
  result?: Result,
): HostBridgeResponse<Result> {
  return {
    bridge: HOST_BRIDGE_PROTOCOL,
    version: HOST_BRIDGE_VERSION,
    id: request.id,
    ok: true,
    result,
  };
}

export function failure(
  request: Pick<HostBridgeRequest, 'id'>,
  error: HostBridgeError,
): HostBridgeResponse {
  return {
    bridge: HOST_BRIDGE_PROTOCOL,
    version: HOST_BRIDGE_VERSION,
    id: request.id,
    ok: false,
    error,
  };
}

export function normalizeMobileHostBridgeError(error: unknown): HostBridgeError {
  if (
    error &&
    typeof error === 'object' &&
    'code' in error &&
    'message' in error &&
    typeof error.code === 'string' &&
    HOST_BRIDGE_ERROR_CODES.has(error.code as HostBridgeError['code']) &&
    typeof error.message === 'string'
  ) {
    return {
      code: error.code as HostBridgeError['code'],
      message: error.message,
    };
  }

  return {
    code: 'host_error',
    message:
      error instanceof Error
        ? error.message
        : 'mobile host bridge request failed',
  };
}