import * as api from '../../client/src/api';
import { EndpointError, EndpointHandler, catchUnhandledErrors } from './types';
import Knex from 'knex';

export const CreateSongEndpointHandler: EndpointHandler = async (req: any, res: any, knex: Knex) => {
  if (!api.checkCreateSongRequest(req)) {
    const e: EndpointError = {
      internalMessage: 'Invalid CreateSong request: ' + JSON.stringify(req.body),
      httpStatus: 400
    };
    throw e;
  }
  const reqObject: api.CreateSongRequest = req.body;

  console.log("Create Song:", reqObject);

  await knex.transaction(async (trx) => {
    try {
      // Start retrieving artists.
      const artistIdsPromise = reqObject.artistIds ?
        trx.select('id')
          .from('artists')
          .whereIn('id', reqObject.artistIds)
          .then((as: any) => as.map((a: any) => a['id'])) :
        (async () => { return [] })();

      // Start retrieving tags.
      const tagIdsPromise = reqObject.tagIds ?
        trx.select('id')
          .from('tags')
          .whereIn('id', reqObject.tagIds)
          .then((as: any) => as.map((a: any) => a['id'])) :
        (async () => { return [] })();

      // Start retrieving albums.
      const albumIdsPromise = reqObject.albumIds ?
        trx.select('id')
          .from('albums')
          .whereIn('id', reqObject.albumIds)
          .then((as: any) => as.map((a: any) => a['id'])) :
        (async () => { return [] })();

      // Wait for the requests to finish.
      var [artists, tags, albums] = await Promise.all([artistIdsPromise, tagIdsPromise, albumIdsPromise]);;

      // Check that we found all objects we need.
      if ((reqObject.artistIds && artists.length !== reqObject.artistIds.length) ||
        (reqObject.tagIds && tags.length !== reqObject.tagIds.length) ||
        (reqObject.albumIds && albums.length !== reqObject.albumIds.length)) {
        const e: EndpointError = {
          internalMessage: 'Not all albums and/or artists and/or tags exist for CreateSong request: ' + JSON.stringify(req.body),
          httpStatus: 400
        };
        throw e;
      }

      // Create the song.
      const songId = (await trx('songs')
        .insert({
          title: reqObject.title,
          storeLinks: JSON.stringify(reqObject.storeLinks || []),
        })
      )[0];

      // Link the artists via the linking table.
      if (artists && artists.length) {
        await Promise.all(
          artists.map((artistId: number) => {
            return trx('songs_artists').insert({
              artistId: artistId,
              songId: songId,
            })
          })
        )
      }

      // Link the tags via the linking table.
      if (tags && tags.length) {
        await Promise.all(
          tags.map((tagId: number) => {
            return trx('songs_tags').insert({
              songId: songId,
              tagId: tagId,
            })
          })
        )
      }

      // Link the albums via the linking table.
      if (albums && albums.length) {
        await Promise.all(
          albums.map((albumId: number) => {
            return trx('songs_albums').insert({
              songId: songId,
              albumId: albumId,
            })
          })
        )
      }

      // Respond to the request.
      const responseObject: api.CreateSongResponse = {
        id: songId
      };
      res.status(200).send(responseObject);

    } catch (e) {
      catchUnhandledErrors(e);
      trx.rollback();
    }
  })
}