export type Result<T, E> =
  | { ok: true; value: T }
  | { ok: false; error: E };

export function formatTimestamp(date: Date): string {
  const year = date.getFullYear();
  const month = String(date.getMonth() + 1).padStart(2, "0");
  const day = String(date.getDate()).padStart(2, "0");
  const hours = String(date.getHours()).padStart(2, "0");
  const minutes = String(date.getMinutes()).padStart(2, "0");
  const seconds = String(date.getSeconds()).padStart(2, "0");

  return `${year}-${month}-${day} at ${hours}.${minutes}.${seconds}`;
}

export type FilenameValidationError =
  | "empty"
  | "too_long"
  | "path_traversal"
  | "invalid_chars";

export function validateFilename(
  filename: string
): Result<string, FilenameValidationError> {
  if (!filename || filename.trim() === "") {
    return { ok: false, error: "empty" };
  }

  if (filename.length > 255) {
    return { ok: false, error: "too_long" };
  }

  // Check for path traversal attempts
  if (
    filename.includes("..") ||
    filename.includes("/") ||
    filename.includes("\\")
  ) {
    return { ok: false, error: "path_traversal" };
  }

  // Check for null bytes and control characters
  if (/[\x00-\x1f\x7f-\x9f]/.test(filename)) {
    return { ok: false, error: "invalid_chars" };
  }

  return { ok: true, value: filename.trim() };
}