import { ensureAtpDocument, IdResolver } from '@atproto/identity';

/**
 * Resolve a handle to a DID using AT Protocol identity resolution.
 * Uses @atproto/identity directly rather than routing through the authenticated
 * agent, so the result is independent of which PDS the caller is logged into.
 *
 * @param handle - Handle string (e.g., "mark.bsky.social" or "@mark.bsky.social")
 * @returns DID string (e.g., "did:plc:abc123")
 * @throws Error if handle cannot be resolved
 */
export async function resolveHandleToDid(handle: string): Promise<string> {
  // Strip leading @ if present
  const cleanHandle = handle.startsWith('@') ? handle.slice(1) : handle;

  try {
    const resolver = new IdResolver();
    const did = await resolver.handle.resolve(cleanHandle);

    if (!did) {
      throw new Error(`No DID found for handle: ${cleanHandle}`);
    }

    return did;
  } catch (error) {
    if (error instanceof Error && error.message.startsWith('No DID found')) {
      throw error;
    }
    if (error instanceof Error) {
      throw new Error(`Failed to resolve handle '${cleanHandle}': ${error.message}`);
    }
    throw new Error(`Failed to resolve handle '${cleanHandle}': Unknown error`);
  }
}

export async function resolvePdsFromIdentifier(identifier: string): Promise<string> {
  const resolver = new IdResolver();

  let did: string;
  if (identifier.startsWith('did:')) {
    did = identifier;
  } else {
    const resolved = await resolver.handle.resolve(identifier);
    if (!resolved) {
      throw new Error(`Could not resolve handle "${identifier}" to a DID`);
    }
    did = resolved;
  }

  // resolveNoCheck fetches the DID document without verifying its signature.
  // Acceptable for a CLI that trusts the DNS/HTTPS infrastructure used for
  // handle resolution; avoids the overhead of full cryptographic verification.
  const didDoc = await resolver.did.resolveNoCheck(did);
  // Cast needed because resolveNoCheck returns a broader type than ensureAtpDocument expects.
  const atpData = ensureAtpDocument(didDoc as Parameters<typeof ensureAtpDocument>[0]);
  return atpData.pds;
}