import type {
  DomainRuntimeHandoffCandidate,
  DomainRuntimeHandoffSource,
} from './domain-access-orchestrator.js';
import type { DomainNodeType } from './domain-access.js';

const IDENTIFIER_PATTERN = /^[A-Z0-9][A-Z0-9._:-]{1,159}$/;

export interface DomainRuntimeHandoffRequest {
  domainId: string;
  nodeId: string;
  nodeType: DomainNodeType;
}

export interface DomainRuntimeHandoffTransport {
  request(input: Readonly<DomainRuntimeHandoffRequest>): Promise<unknown>;
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null && !Array.isArray(value);
}

function hasExactKeys(value: Record<string, unknown>, expected: readonly string[]): boolean {
  const actual = Object.keys(value).sort();
  const keys = [...expected].sort();
  return actual.length === keys.length && actual.every((key, index) => key === keys[index]);
}

function parseResponse(input: unknown): Readonly<DomainRuntimeHandoffCandidate> | null {
  if (!isRecord(input)
    || !hasExactKeys(input, ['handoff', 'schema', 'signer_lookup'])
    || input.schema !== 'gh-aios.domain-runtime-handoff-response/v1'
    || !isRecord(input.handoff)
    || !isRecord(input.signer_lookup)
    || !hasExactKeys(input.signer_lookup, ['repository_id', 'signer_id'])
    || typeof input.signer_lookup.repository_id !== 'string'
    || !IDENTIFIER_PATTERN.test(input.signer_lookup.repository_id)
    || typeof input.signer_lookup.signer_id !== 'string'
    || !IDENTIFIER_PATTERN.test(input.signer_lookup.signer_id)) {
    return null;
  }
  return Object.freeze({
    handoff: input.handoff,
    signerLookup: Object.freeze({
      repositoryId: input.signer_lookup.repository_id,
      signerId: input.signer_lookup.signer_id,
    }),
  });
}

export class StrictDomainRuntimeHandoffSource implements DomainRuntimeHandoffSource {
  constructor(private readonly transport: DomainRuntimeHandoffTransport) {}

  async read(domainId: string, nodeId: string, nodeType: DomainNodeType): Promise<Readonly<DomainRuntimeHandoffCandidate> | null> {
    if (!IDENTIFIER_PATTERN.test(domainId) || !IDENTIFIER_PATTERN.test(nodeId)) return null;
    if (nodeType !== 'local-terminal' && nodeType !== 'cloud-resident') return null;
    try {
      return parseResponse(await this.transport.request(Object.freeze({ domainId, nodeId, nodeType })));
    } catch {
      return null;
    }
  }
}