// The size a client declares before a direct upload starts.
//
// Shared because the R2 and Bunny paths have to agree on it: both hand the
// number to the storage quota before a single byte moves, so a value one of them
// would accept and the other would not is a hole in whichever is laxer.

export type DeclaredUploadSize = { sizeBytes: bigint } | { error: string };

/**
 * Reads a declared upload size, refusing anything that is not a whole positive
 * number of bytes within the host's per-file ceiling.
 *
 * The number is the client's word and is treated as such. Overstating it only
 * spends the caller's own quota, and understating it is caught where the bytes
 * land: R2 compares the object against the declaration and deletes it on a
 * mismatch, and Bunny's own storage reporting replaces the estimate once the
 * upload settles. What is not tolerated is an absent or nonsense value, which is
 * what asking for zero bytes effectively was.
 */
export function parseDeclaredUploadSize(raw: unknown, maxBytes: bigint): DeclaredUploadSize {
  if (typeof raw !== 'number' && typeof raw !== 'string' && typeof raw !== 'bigint') {
    return { error: 'sizeBytes must be a positive integer' };
  }

  let sizeBytes: bigint;
  try {
    sizeBytes = BigInt(raw);
  } catch {
    return { error: 'sizeBytes must be a positive integer' };
  }

  if (sizeBytes <= BigInt(0)) {
    return { error: 'sizeBytes must be a positive integer' };
  }

  if (sizeBytes > maxBytes) {
    return { error: 'File exceeds the maximum allowed upload size' };
  }

  return { sizeBytes };
}