/**
 * Checks the JSON bodies that `routes/dumps.ts` takes to post a link and to
 * edit a dump. A file dump arrives as a multipart form instead, and
 * `dump-service.ts` checks its title and comment.
 *
 * @module
 */

import type {
  CreateUrlDumpRequest,
  UpdateDumpRequest,
} from "../../shared/dump.ts";
import { VALIDATION } from "../../shared/validation.ts";

function isStringArray(value: unknown): value is string[] {
  return Array.isArray(value) && value.every((v) => typeof v === "string");
}

/**
 * Checks whether `obj` is a {@link CreateUrlDumpRequest} whose title and
 * comment fit the `VALIDATION` limits. It leaves the URL to `createUrlDump`,
 * which rejects anything but a public http(s) URL.
 */
export function isCreateUrlDumpRequest(
  obj: unknown,
): obj is CreateUrlDumpRequest {
  if (
    !obj || typeof obj !== "object" ||
    !("url" in obj) || typeof obj.url !== "string"
  ) return false;
  const o = obj as Record<string, unknown>;
  if ("comment" in o && typeof o.comment !== "string") return false;
  if (
    typeof o.comment === "string" &&
    (o.comment as string).length > VALIDATION.DUMP_COMMENT_MAX
  ) return false;
  if ("title" in o && typeof o.title !== "string") return false;
  if (
    typeof o.title === "string" &&
    (o.title as string).length > VALIDATION.DUMP_TITLE_MAX
  ) return false;
  if ("isPrivate" in o && typeof o.isPrivate !== "boolean") return false;
  if ("categoryIds" in o && !isStringArray(o.categoryIds)) return false;
  return true;
}

/**
 * Checks whether `obj` is an {@link UpdateDumpRequest} whose title and comment
 * fit the `VALIDATION` limits. Unlike on creation, a title that is given must
 * not be blank.
 */
export function isUpdateDumpRequest(obj: unknown): obj is UpdateDumpRequest {
  if (!obj || typeof obj !== "object") return false;
  const o = obj as Record<string, unknown>;
  if ("url" in o && typeof o.url !== "string") return false;
  // Its format is changeSlug's check, which says what is wrong.
  if ("slug" in o && typeof o.slug !== "string") return false;
  if ("title" in o) {
    if (typeof o.title !== "string") return false;
    const trimmed = (o.title as string).trim();
    if (!trimmed || trimmed.length > VALIDATION.DUMP_TITLE_MAX) return false;
  }
  if (
    "comment" in o && typeof o.comment !== "string" && o.comment !== null
  ) return false;
  if (
    typeof o.comment === "string" &&
    (o.comment as string).length > VALIDATION.DUMP_COMMENT_MAX
  ) return false;
  if ("isPrivate" in o && typeof o.isPrivate !== "boolean") return false;
  if ("categoryIds" in o && !isStringArray(o.categoryIds)) return false;
  return true;
}

/**
 * Parses a multipart form's `categoryIds`, a JSON array sent as a string. A
 * missing or malformed value counts as no category. The dumps and files
 * routes read the forms that post and replace a file with it.
 */
export function parseCategoryIds(value: FormDataEntryValue | null): string[] {
  if (typeof value !== "string" || !value) return [];
  try {
    const parsed: unknown = JSON.parse(value);
    return Array.isArray(parsed)
      ? parsed.filter((v): v is string => typeof v === "string")
      : [];
  } catch {
    return [];
  }
}