import { and, count, eq } from "drizzle-orm";

import type { Env } from "~/types/env";
import { WatchStatusValues } from "~/types/title/watchStatus";

import { getDb } from "./db";
import { watchStatusTable } from "./schema";

/** If watch status is "CURRENT", the title will be added to the watch status table. Otherwise, it will be removed.
 *
 * @returns an object with the following properties:
 * - wasAdded: whether the title was set as watching for the first time
 * - wasDeleted: whether any users are still watching the title
 */
export function setWatchStatus(
  env: Env,
  deviceId: string,
  titleId: number,
  watchStatus: (typeof WatchStatusValues)[number] | null,
) {
  let dbAction;
  const isSavingTitle = watchStatus === "CURRENT";
  if (isSavingTitle) {
    dbAction = saveTitle(env, deviceId, titleId);
  } else {
    dbAction = removeTitle(env, deviceId, titleId);
  }

  return dbAction
    .then(() =>
      getDb(env)
        .select({ count: count(watchStatusTable.titleId) })
        .from(watchStatusTable)
        .where(eq(watchStatusTable.titleId, titleId))
        .get(),
    )
    .then((result) => ({
      wasAdded: isSavingTitle && result?.count === 1,
      wasDeleted: !isSavingTitle && result?.count === 0,
    }));
}

function saveTitle(env: Env, deviceId: string, titleId: number) {
  return getDb(env)
    .insert(watchStatusTable)
    .values({ deviceId, titleId })
    .onConflictDoNothing();
}

function removeTitle(env: Env, deviceId: string, titleId: number) {
  return getDb(env)
    .delete(watchStatusTable)
    .where(
      and(
        eq(watchStatusTable.deviceId, deviceId),
        eq(watchStatusTable.titleId, titleId),
      ),
    );
}