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

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

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

    await knex.transaction(async (trx) => {
        try {
            // Retrieve the song to be modified itself.
            const song = await trx.select('id')
                .from('songs')
                .where({ id: req.params.id })
                .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined)

            // Construct the new object from the original plus the
            // changes included in the PUT.
            const newSong = {
                ...song,
                ...reqObject,
            };

            // Start retrieving artists.
            const artistIdsPromise = newSong.artistIds ?
                trx.select('artistId')
                    .from('songs_artists')
                    .whereIn('id', newSong.artistIds)
                    .then((as: any) => as.map((a: any) => a['artistId'])) :
                (async () => { return undefined })();

            // Start retrieving tags.
            const tagIdsPromise = newSong.tagIds ?
                trx.select('id')
                    .from('songs_tags')
                    .whereIn('id', newSong.tagIds)
                    .then((ts: any) => ts.map((t: any) => t['tagId'])) :
                (async () => { return undefined })();

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

            // 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 ((newSong.artistIds && artists.length !== newSong.artistIds.length) ||
                (newSong.tagIds && tags.length !== newSong.tagIds.length) ||
                (newSong.albumIds && albums.length !== newSong.albumIds.length) ||
                !song) {
                const e: EndpointError = {
                    internalMessage: 'Not all albums and/or artists and/or tags exist for ModifySong request: ' + JSON.stringify(req.body),
                    httpStatus: 400
                };
                throw e;
            }

            // Modify the song.
            const modifySongPromise = trx('songs')
                .where({ 'id': req.params.id })
                .update({
                    title: newSong.title,
                    storeLinks: JSON.stringify(newSong.storeLinks || []),
                })

            // Remove unlinked artists.
            // TODO: test this!
            const removeUnlinkedArtists = artists ? trx('songs_artists')
                .where({ 'songId': req.params.id })
                .whereNotIn('artistId', newSong.artistIds || [])
                .delete() : undefined;

            // Remove unlinked tags.
            // TODO: test this!
            const removeUnlinkedTags = tags ? trx('songs_tags')
                .where({ 'songId': req.params.id })
                .whereNotIn('tagId', newSong.tagIds || [])
                .delete() : undefined;

            // Remove unlinked albums.
            // TODO: test this!
            const removeUnlinkedAlbums = albums ? trx('songs_albums')
                .where({ 'songId': req.params.id })
                .whereNotIn('albumId', newSong.albumIds || [])
                .delete() : undefined;

            // Link new artists.
            // TODO: test this!
            const addArtists = artists ? trx('songs_artists')
                .where({ 'songId': req.params.id })
                .then((as: any) => as.map((a: any) => a['artistId']))
                .then((doneArtistIds: number[]) => {
                    // Get the set of artists that are not yet linked
                    const toLink = artists.filter((id: number) => {
                        return !doneArtistIds.includes(id);
                    });
                    const insertObjects = toLink.map((artistId: number) => {
                        return {
                            artistId: artistId,
                            songId: req.params.id,
                        }
                    })

                    // Link them
                    return Promise.all(
                        insertObjects.map((obj: any) =>
                            trx('songs_artists').insert(obj)
                        )
                    );
                }) : undefined;

            // Link new tags.
            // TODO: test this!
            const addTags = tags ? trx('songs_tags')
                .where({ 'songId': req.params.id })
                .then((ts: any) => ts.map((t: any) => t['tagId']))
                .then((doneTagIds: number[]) => {
                    // Get the set of tags that are not yet linked
                    const toLink = tags.filter((id: number) => {
                        return !doneTagIds.includes(id);
                    });
                    const insertObjects = toLink.map((tagId: number) => {
                        return {
                            tagId: tagId,
                            songId: req.params.id,
                        }
                    })

                    // Link them
                    return Promise.all(
                        insertObjects.map((obj: any) =>
                            trx('songs_tags').insert(obj)
                        )
                    );
                }) : undefined;

            // Link new albums.
            // TODO: test this!
            const addAlbums = albums ? trx('songs_albums')
                .where({ 'albumId': req.params.id })
                .then((as: any) => as.map((a: any) => a['albumId']))
                .then((doneAlbumIds: number[]) => {
                    // Get the set of albums that are not yet linked
                    const toLink = albums.filter((id: number) => {
                        return !doneAlbumIds.includes(id);
                    });
                    const insertObjects = toLink.map((albumId: number) => {
                        return {
                            albumId: albumId,
                            songId: req.params.id,
                        }
                    })

                    // Link them
                    return Promise.all(
                        insertObjects.map((obj: any) =>
                            trx('songs_albums').insert(obj)
                        )
                    );
                }) : undefined;

            // Wait for all operations to finish.
            await Promise.all([
                modifySongPromise,
                removeUnlinkedArtists,
                removeUnlinkedTags,
                removeUnlinkedAlbums,
                addArtists,
                addTags,
                addAlbums,
            ]);

            // Respond to the request.
            res.status(200).send();

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