import { createBackendClient, resolveSyncContext, timeoutFetch, type BackendClient } from '@henkaku-center/chi-sync';
import { identityFromOwnerId, type HumanIdentity } from './protocol.js';

export type ParticipantDirectory = { actor: HumanIdentity; participants: HumanIdentity[] };

export async function discoverParticipants(cwd: string, options: {
  home?: string;
  clientFactory?: (headers: Record<string, string>) => Pick<BackendClient, 'listParticipants'>;
} = {}): Promise<ParticipantDirectory | null> {
  const context = resolveSyncContext(cwd, options.home);
  if (!context.ok) return null;
  const headers = { authorization: `Bearer ${context.sessionToken}`, 'x-chi-repo': context.repoSlug };
  const client = (options.clientFactory ?? ((requestHeaders) => createBackendClient({ headers: requestHeaders, fetchImpl: timeoutFetch() })))(headers);
  const response = await client.listParticipants();
  const actorRecord = response.participants.find((participant) => participant.ownerId.toLowerCase() === response.self.toLowerCase());
  const actor = identityFromOwnerId(actorRecord ? `github:${actorRecord.handle}` : response.self);
  if (!actor) throw new Error('authenticated Chi identity is not a GitHub handle');

  const byId = new Map<string, HumanIdentity>();
  for (const record of response.participants) {
    const participant = identityFromOwnerId(`github:${record.handle}`);
    if (participant && participant.id === record.ownerId.toLowerCase() && participant.id !== actor.id && !byId.has(participant.id)) byId.set(participant.id, participant);
  }
  return { actor, participants: [...byId.values()].sort((left, right) => left.handle.localeCompare(right.handle)) };
}