/**
 * Records the images pasted into Markdown bodies, and binds each one to the
 * resource whose body links it. `routes/attachments.ts` stores and serves the
 * files; the services that save a body call {@link linkAttachments}.
 *
 * @module
 */

import { db, transaction } from "../db/connection.ts";
import { APIErrorCode } from "../../shared/api.ts";
import { APIException } from "../lib/api-exception.ts";

/**
 * Records attachment `id` once `POST /api/attachments` has written its file.
 * Until a saved body links it, the startup purge deletes it after
 * `ORPHANED_ATTACHMENTS_RETENTION_HOURS`.
 */
export function createAttachment(id: string, mime: string): void {
  db.prepare(
    "INSERT INTO attachments (id, mime, created_at) VALUES (?, ?, ?)",
  ).run(id, mime, new Date().toISOString());
}

/**
 * Returns attachment `attachmentId`'s MIME type, for
 * `GET /api/attachments/:attachmentId` to serve its file with.
 *
 * @throws {APIException} 404 when there is no such attachment.
 */
export function getAttachment(attachmentId: string): { mime: string } {
  const row = db.prepare(
    "SELECT mime FROM attachments WHERE id = ?",
  ).get(attachmentId) as { mime: string } | undefined;

  if (!row) {
    throw new APIException(
      APIErrorCode.NOT_FOUND,
      404,
      "Attachment not found",
    );
  }

  return { mime: row.mime };
}

const ATTACHMENT_RE =
  /\/api\/attachments\/([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})/g;

/**
 * Binds the attachments whose URLs appear in `text` to `resourceId`, so the
 * startup purge keeps them. It is called whenever a dump, comment, chat
 * message, playlist or profile description is saved. An attachment already
 * bound stays with its resource, so pasting another's URL claims nothing, and
 * removing the link from a body never unbinds it.
 */
export function linkAttachments(text: string, resourceId: string): void {
  const ids = [...text.matchAll(ATTACHMENT_RE)].map((m) => m[1]);
  if (ids.length === 0) return;
  const update = db.prepare(
    "UPDATE attachments SET resource_id = ? WHERE id = ? AND resource_id IS NULL",
  );
  transaction(() => {
    for (const id of ids) update.run(resourceId, id);
  });
}