/**
 * Deletes what has expired and seeds the first admin, each time connection.ts
 * opens the database.
 *
 * @module
 */

import type { DatabaseSync } from "node:sqlite";
import {
  ATTACHMENTS_DIR,
  ORPHANED_ATTACHMENTS_RETENTION_HOURS,
  UNUSED_INVITES_RETENTION_DAYS,
} from "../config.ts";
import { hashPassword } from "../lib/password.ts";

/** Returns the time `ms` ago as an ISO string, the format dates are stored in. */
function isoAgo(ms: number): string {
  return new Date(Date.now() - ms).toISOString();
}

/**
 * Runs after the migrations, each time the server starts. It deletes used or
 * expired reset tokens, invites past their validity, and attachments nothing
 * links to or whose resource is gone. On an instance with no users, it creates the user `admin` with the
 * password `admin`, which whoever installs it must change.
 */
export async function runStartupTasks(db: DatabaseSync): Promise<void> {
  // Dates are stored as ISO strings and compared as text, so the cutoffs are
  // ISO strings too. SQLite's datetime() has a space where ISO has a `T`.
  db.prepare(
    `DELETE FROM password_reset_tokens WHERE expires_at < ? OR used_at IS NOT NULL;`,
  ).run(isoAgo(0));

  db.prepare(
    `DELETE FROM invites WHERE used_at IS NULL AND created_at < ?;`,
  ).run(isoAgo(UNUSED_INVITES_RETENTION_DAYS * 86_400_000));

  // An image is uploaded as soon as it's pasted, and linked only when the text
  // it's pasted into is saved, so a fresh unlinked one is left alone. One whose
  // dump, comment, playlist, message or user is gone goes whatever its age.
  const attachmentCutoff = isoAgo(
    ORPHANED_ATTACHMENTS_RETENTION_HOURS * 3_600_000,
  );
  const ORPHANED = `
    (resource_id IS NULL AND created_at < ?)
    OR (resource_id IS NOT NULL AND NOT CASE resource_type
      WHEN 'dump'     THEN EXISTS (SELECT 1 FROM dumps WHERE id = resource_id)
      WHEN 'comment'  THEN EXISTS (SELECT 1 FROM comments WHERE id = resource_id AND deleted = 0)
      WHEN 'playlist' THEN EXISTS (SELECT 1 FROM playlists WHERE id = resource_id)
      WHEN 'chat'     THEN EXISTS (SELECT 1 FROM chat_messages WHERE id = resource_id)
      WHEN 'user'     THEN EXISTS (SELECT 1 FROM users WHERE id = resource_id)
      ELSE 0
    END)`;
  const orphanedAttachments = db.prepare(
    `SELECT id FROM attachments WHERE ${ORPHANED};`,
  ).all(attachmentCutoff) as { id: string }[];
  if (orphanedAttachments.length > 0) {
    for (const { id } of orphanedAttachments) {
      await Deno.remove(`${ATTACHMENTS_DIR}/${id}`).catch(() => {});
    }
    db.prepare(`DELETE FROM attachments WHERE ${ORPHANED};`)
      .run(attachmentCutoff);
  }

  // Registration needs an invite, so the first user can only come from here.
  const userCount = db.prepare(`SELECT COUNT(*) as count FROM users`).get() as {
    count: number;
  };
  if (userCount.count === 0) {
    db.prepare(
      `INSERT INTO users (id, username, password_hash, role, created_at, email) VALUES (?, 'admin', ?, 'admin', ?, 'admin@localhost')`,
    ).run(crypto.randomUUID(), await hashPassword("admin"), isoAgo(0));
    console.log(
      "Created default admin user (username: admin, password: admin)",
    );
  }
}