/**
 * Stops older dumps from showing a site's icon as their thumbnail. The metadata
 * fetch used to fall back on the page's icon, and then on a guessed
 * `/favicon.ico`, so most thumbnails were a 16×16 icon, or a 404, that the UI
 * stretched over a 128×72 box. It now stops at real artwork, and a missing
 * `thumbnailUrl` means none, which the frontend draws a placeholder for. This
 * gives the older rows that meaning, by moving their icons out of
 * `rich_content.thumbnailUrl` into the new `faviconUrl`.
 *
 * It judges the stored URL alone and fetches nothing, so it doesn't fill
 * `accentColor`. The frontend derives a hue from the hostname when it is
 * missing, and refreshing a dump's metadata fetches the real one.
 *
 * @module
 */

import type { DatabaseSync } from "node:sqlite";

/**
 * Checks whether a stored thumbnail URL is a site icon. It is loose on
 * purpose, since artwork taken for an icon still shows whole on a tinted field,
 * only not cropped to fill the box. 0012 fixes the rows it got wrong.
 */
function isIconUrl(raw: string): boolean {
  let pathname: string;
  try {
    pathname = new URL(raw).pathname;
  } catch {
    return false;
  }
  return /favicon|apple-touch-icon|\/icons?\//i.test(pathname) ||
    /\.(ico|svg)$/i.test(pathname);
}

/**
 * Run once by `runMigrations`. It leaves alone a row that already has a
 * `faviconUrl`, and one whose `rich_content` doesn't parse. 0012 undoes its
 * mistakes.
 */
export function up(db: DatabaseSync): void {
  const rows = db.prepare(
    `SELECT id, rich_content FROM dumps
      WHERE kind = 'url' AND rich_content IS NOT NULL;`,
  ).all() as { id: string; rich_content: string }[];

  const update = db.prepare(
    `UPDATE dumps SET rich_content = ? WHERE id = ?;`,
  );

  let patched = 0;
  for (const row of rows) {
    let rich: { thumbnailUrl?: string; faviconUrl?: string };
    try {
      rich = JSON.parse(row.rich_content);
    } catch {
      continue;
    }
    if (rich.faviconUrl || !rich.thumbnailUrl) continue;
    if (!isIconUrl(rich.thumbnailUrl)) continue;

    const { thumbnailUrl: _dropped, ...rest } = rich;
    update.run(
      JSON.stringify({ ...rest, faviconUrl: rich.thumbnailUrl }),
      row.id,
    );
    patched++;
  }

  if (patched > 0) {
    console.log(
      `[migrate] 0011: reclassified ${patched} favicon thumbnail(s)`,
    );
  }
}