/**
 * Input validation for every user-supplied identifier that ends up on the
 * filesystem path. These two are the ONLY allowed shapes for module names
 * and versions on this registry; both must be enforced at every public
 * entry point in server.ts (publish, download, metadata, yank, unyank,
 * sparse index) because `storage.packagePath()` / `storage.indexPath()`
 * feed their inputs straight to `node:path.join`, which happily normalizes
 * `..` segments and escapes the data directory.
 *
 * Keep these as pure regex predicates so there is no way to accidentally
 * skip them — if the string passes, the path is guaranteed to contain
 * only safe chars (lowercase alphanum + `-` / digits + `.` / `+`). No
 * slashes, no `..`, no control chars.
 */

/** Module names: kebab-case lowercase, no leading/trailing hyphen. */
const NAME_REGEX = /^[a-z0-9]+(-[a-z0-9]+)*$/;

/**
 * Module versions: optional Debian-style epoch (`N:`), then semver
 * (major.minor.patch), then a literal `+`, then a numeric pkg revision.
 * Examples: `1.4.2+1`, `1.0.0+12`, `2:1.0.0+1` (epoch bump).
 * Rejects: `1.0.0+abc`, `1.0.0+1/../etc`, `1.0.0 +1`, empty, traversal.
 */
const VERSION_REGEX = /^(\d+:)?\d+\.\d+\.\d+\+\d+$/;

/** Max bytes we'll accept for either identifier — far beyond any real use. */
const MAX_IDENT_LENGTH = 128;

export function isValidName(name: string): boolean {
  return name.length > 0 && name.length <= MAX_IDENT_LENGTH && NAME_REGEX.test(name);
}

export function isValidVersion(vers: string): boolean {
  return vers.length > 0 && vers.length <= MAX_IDENT_LENGTH && VERSION_REGEX.test(vers);
}

/** Throw-style version for handler call sites — returns the offending field name. */
export function validateNameAndVersion(
  name: string,
  vers: string,
): { ok: true } | { ok: false; field: 'name' | 'vers'; message: string } {
  if (!isValidName(name)) {
    return {
      ok: false,
      field: 'name',
      message: 'Invalid module name — must be kebab-case lowercase, 1-128 chars (e.g. "my-module")',
    };
  }
  if (!isValidVersion(vers)) {
    return {
      ok: false,
      field: 'vers',
      message: 'Invalid version — must match "<major>.<minor>.<patch>+<pkgrev>" (e.g. "1.4.2+1")',
    };
  }
  return { ok: true };
}