/**
 * Repairs the rows 0011 got wrong. 0011 took any path containing "favicon",
 * or ending in `.svg`, for an icon, so artwork such as
 * `/wp-content/uploads/2022/04/mir-logo-favicon.png` lost its `thumbnailUrl`,
 * and its dump showed as a pull-quote instead of an image in the journal
 * mosaic.
 *
 * This rule judges the file name and its folder instead. It spares
 * `mir-logo-favicon.png` and catches `icon_SEARCH.png`, which 0011 missed.
 *
 * @module
 */

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

/** 0011's rule, copied as it shipped, to tell which rows it moved. */
function wasIconUrl0011(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);
}

/**
 * Checks whether a URL is a site icon. It is one when the file ends in `.ico`,
 * sits in a `favicon(s)` or `icon(s)` folder, or is named `favicon`,
 * `apple-touch-icon` or `icon`, alone or followed by a digit, `-`, `_` or `.`.
 */
function isIconUrl(raw: string): boolean {
  let pathname: string;
  try {
    pathname = new URL(raw).pathname;
  } catch {
    return false;
  }
  const segments = pathname.split("/").filter(Boolean);
  const filename = segments.pop() ?? "";
  if (/\.ico$/i.test(filename)) return true;
  if (segments.some((s) => /^(favicons?|icons?)$/i.test(s))) return true;
  const basename = filename.replace(/\.[^.]+$/, "");
  return /^(favicon|apple-touch-icon|icon)(?=$|[-_.\d])/i.test(basename);
}

/**
 * Run once by `runMigrations`. It moves a `faviconUrl` back to `thumbnailUrl`
 * only when 0011's rule takes it for an icon and this one doesn't. That also
 * catches the ones a later fetch stored that this rule doesn't recognise, such
 * as a `logo.svg`. It then moves the icons 0011 missed.
 */
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 restored = 0;
  let reclassified = 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 &&
      wasIconUrl0011(rich.faviconUrl) && !isIconUrl(rich.faviconUrl)
    ) {
      const { faviconUrl: _dropped, ...rest } = rich;
      update.run(
        JSON.stringify({ ...rest, thumbnailUrl: rich.faviconUrl }),
        row.id,
      );
      restored++;
      continue;
    }

    if (
      rich.thumbnailUrl && !rich.faviconUrl && isIconUrl(rich.thumbnailUrl)
    ) {
      const { thumbnailUrl: _dropped, ...rest } = rich;
      update.run(
        JSON.stringify({ ...rest, faviconUrl: rich.thumbnailUrl }),
        row.id,
      );
      reclassified++;
    }
  }

  if (restored > 0 || reclassified > 0) {
    console.log(
      `[migrate] 0012: restored ${restored} thumbnail(s), reclassified ${reclassified} icon(s)`,
    );
  }
}