/**
 * Parsed AT-URI components
 */
export interface AtUri {
  protocol: string;
  did: string;
  collection: string;
  rkey: string;
  fragment?: string;
}

/**
 * Parse an AT-URI into its components
 * Format: at://did:method:identifier/collection/rkey#fragment
 */
export function parseAtUri(uri: string): AtUri {
  if (!uri.startsWith("at://")) {
    throw new Error(`Invalid AT-URI: must start with at:// - got ${uri}`);
  }

  const withoutProtocol = uri.slice(5); // Remove 'at://'
  const [didAndPath, fragment] = withoutProtocol.split("#");
  const parts = didAndPath.split("/");

  if (parts.length < 3) {
    throw new Error(`Invalid AT-URI: missing required parts - got ${uri}`);
  }

  const [did, collection, rkey, ...rest] = parts;

  if (rest.length > 0) {
    throw new Error(`Invalid AT-URI: too many path segments - got ${uri}`);
  }

  return {
    protocol: "at",
    did,
    collection,
    rkey,
    fragment,
  };
}

/**
 * Build an AT-URI from components
 */
export function buildAtUri(components: Omit<AtUri, "protocol">): string {
  const { did, collection, rkey, fragment } = components;
  let uri = `at://${did}/${collection}/${rkey}`;

  if (fragment) {
    uri += `#${fragment}`;
  }

  return uri;
}

/**
 * Extract just the record key from an AT-URI
 */
export function getRkeyFromUri(uri: string): string {
  return parseAtUri(uri).rkey;
}

/**
 * Extract the DID from an AT-URI
 */
export function getDidFromUri(uri: string): string {
  return parseAtUri(uri).did;
}

/**
 * Extract the collection from an AT-URI
 */
export function getCollectionFromUri(uri: string): string {
  return parseAtUri(uri).collection;
}

/**
 * Build a slice URI from DID and slice ID
 */
export function buildSliceUri(did: string, sliceId: string): string {
  return buildAtUri({ did, collection: "network.slices.slice", rkey: sliceId });
}