import Knex from "knex";
import { TrackBaseWithRefs, TrackWithDetails, TrackWithRefs } from "../../client/src/api/api";
import * as api from '../../client/src/api/api';
import asJson from "../lib/asJson";
import { DBError, DBErrorKind } from "../endpoints/types";

// Returns an track with details, or null if not found.
export async function getTrack(id: number, userId: number, knex: Knex):
    Promise<TrackWithDetails> {
    // Start transfers for tracks, tags and artists.
    // Also request the track itself.
    const tagsPromise: Promise<api.TagWithId[]> =
        knex.select('tagId')
            .from('tracks_tags')
            .where({ 'trackId': id })
            .then((tags: any) => tags.map((tag: any) => tag['tagId']))
            .then((ids: number[]) =>
                knex.select(['id', 'name', 'parentId'])
                    .from('tags')
                    .whereIn('id', ids)
            );

    const artistsPromise: Promise<api.ArtistWithId[]> =
        knex.select('artistId')
            .from('artists_tracks')
            .where({ 'trackId': id })
            .then((artists: any) => artists.map((artist: any) => artist['artistId']))
            .then((ids: number[]) =>
                knex.select(['id', 'name', 'storeLinks'])
                    .from('artists')
                    .whereIn('id', ids)
            );

    const trackPromise: Promise<api.Track | undefined> =
        knex.select('name', 'storeLinks')
            .from('tracks')
            .where({ 'user': userId })
            .where({ id: id })
            .then((tracks: any) => tracks[0]);


    const albumPromise: Promise<api.AlbumWithId | null> =
        trackPromise
            .then((t: api.Track | undefined) =>
                t ? knex.select('id', 'name', 'storeLinks')
                    .from('albums')
                    .where({ 'user': userId })
                    .where({ id: t.albumId })
                    .then((albums: any) => albums.length > 0 ? albums[0] : null)
                    : (() => null)()
            )

    // Wait for the requests to finish.
    const [track, tags, album, artists] =
        await Promise.all([trackPromise, tagsPromise, albumPromise, artistsPromise]);

    if (track) {
        return {
            mbApi_typename: 'track',
            name: track['name'],
            artists: artists as api.ArtistWithId[],
            tags: tags as api.TagWithId[],
            album: album as api.AlbumWithId | null,
            storeLinks: asJson(track['storeLinks'] || []),
        };
    } else {
        const e: DBError = {
            name: "DBError",
            kind: DBErrorKind.ResourceNotFound,
            message: 'Not all resources were found.',
        };
        throw e;
    }
}

// Returns the id of the created track.
export async function createTrack(userId: number, track: TrackWithRefs, knex: Knex): Promise<number> {
    return await knex.transaction(async (trx) => {
        try {
            // Start retrieving artists.
            const artistIdsPromise: Promise<number[]> =
                trx.select('id')
                    .from('artists')
                    .where({ 'user': userId })
                    .whereIn('id', track.artistIds)
                    .then((as: any) => as.map((a: any) => a['id']));

            // Start retrieving tags.
            const tagIdsPromise: Promise<number[]> =
                trx.select('id')
                    .from('tags')
                    .where({ 'user': userId })
                    .whereIn('id', track.tagIds)
                    .then((as: any) => as.map((a: any) => a['id']));

            // Start retrieving album.
            const albumIdPromise: Promise<number | null> =
                knex.select('id')
                    .from('albums')
                    .where({ 'user': userId, 'albumId': track.albumId })
                    .then((albums: any) => albums.map((album: any) => album['albumId']))
                    .then((ids: number[]) =>
                        ids.length > 0 ? ids[0] : (() => null)()
                    );

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

            // Check that we found all artists and tags we need.
            if ((new Set((artists as number[]).map((a: any) => a['id'])) !== new Set(track.artistIds)) ||
                (new Set((tags as number[]).map((a: any) => a['id'])) !== new Set(track.tagIds)) ||
                (album === null)) {
                const e: DBError = {
                    name: "DBError",
                    kind: DBErrorKind.ResourceNotFound,
                    message: 'Not all to-be-linked resources were found.',
                };
                throw e;
            }

            // Create the track.
            const trackId = (await trx('tracks')
                .insert({
                    name: track.name,
                    storeLinks: JSON.stringify(track.storeLinks || []),
                    user: userId,
                    albumId: album,
                })
                .returning('id') // Needed for Postgres
            )[0];

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

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

            return trackId;

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

export async function modifyTrack(userId: number, trackId: number, track: TrackBaseWithRefs, knex: Knex): Promise<void> {
    await knex.transaction(async (trx) => {
        try {
            // Start retrieving the track itself.
            const trackIdPromise: Promise<number | undefined> =
                trx.select('id')
                    .from('tracks')
                    .where({ 'user': userId })
                    .where({ id: trackId })
                    .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined);

            // Start retrieving artists if we are modifying those.
            const artistIdsPromise: Promise<number[] | undefined> =
                track.artistIds ?
                    trx.select('artistId')
                        .from('artists_tracks')
                        .whereIn('artistId', track.artistIds)
                        .then((as: any) => as.map((a: any) => a['artistId']))
                    : (async () => undefined)();

            // Start retrieving tags if we are modifying those.
            const tagIdsPromise =
                track.tagIds ?
                    trx.select('id')
                        .from('tracks_tags')
                        .whereIn('tagId', track.tagIds)
                        .then((ts: any) => ts.map((t: any) => t['tagId'])) :
                    (async () => undefined)();

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

            // Check that we found all objects we need.
            if ((!artists || new Set(artists.map((a: any) => a['id'])) !== new Set(track.artistIds)) ||
                (!tags || new Set(tags.map((a: any) => a['id'])) !== new Set(track.tagIds)) ||
                !oldTrack) {
                const e: DBError = {
                    name: "DBError",
                    kind: DBErrorKind.ResourceNotFound,
                    message: 'Not all to-be-linked resources were found.',
                };
                throw e;
            }

            // Modify the track.
            var update: any = {};
            if ("name" in track) { update["name"] = track.name; }
            if ("storeLinks" in track) { update["storeLinks"] = JSON.stringify(track.storeLinks || []); }
            if ("albumId" in track) { update["albumId"] = track.albumId; }

            const modifyTrackPromise = trx('tracks')
                .where({ 'user': userId })
                .where({ 'id': trackId })
                .update(update)

            // Remove unlinked artists.
            const removeUnlinkedArtists = artists ? trx('artists_tracks')
                .where({ 'trackId': trackId })
                .whereNotIn('artistId', track.artistIds || [])
                .delete() : undefined;

            // Remove unlinked tags.
            const removeUnlinkedTags = tags ? trx('tracks_tags')
                .where({ 'trackId': trackId })
                .whereNotIn('tagId', track.tagIds || [])
                .delete() : undefined;

            // Link new artists.
            const addArtists = artists ? trx('artists_tracks')
                .where({ 'trackId': trackId })
                .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,
                            trackId: trackId,
                        }
                    })

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

            // Link new tags.
            const addTags = tags ? trx('tracks_tags')
                .where({ 'trackId': trackId })
                .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,
                            trackId: trackId,
                        }
                    })

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

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

            return;

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

export async function deleteTrack(userId: number, trackId: number, knex: Knex): Promise<void> {
    await knex.transaction(async (trx) => {
        try {
            // Start by retrieving the track itself for sanity.
            const confirmTrackId: number | undefined =
                await trx.select('id')
                    .from('tracks')
                    .where({ 'user': userId })
                    .where({ id: trackId })
                    .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined);

            if (!confirmTrackId) {
                const e: DBError = {
                    name: "DBError",
                    kind: DBErrorKind.ResourceNotFound,
                    message: 'Not all resources were found.',
                };
                throw e;
            }

            // Start deleting artist associations with the track.
            const deleteArtistsPromise: Promise<any> =
                trx.delete()
                    .from('artists_tracks')
                    .where({ 'trackId': trackId });

            // Start deleting tag associations with the track.
            const deleteTagsPromise: Promise<any> =
                trx.delete()
                    .from('tracks_tags')
                    .where({ 'trackId': trackId });

            // Start deleting the track.
            const deleteTrackPromise: Promise<any> =
                trx.delete()
                    .from('tracks')
                    .where({ id: trackId });

            // Wait for the requests to finish.
            await Promise.all([deleteArtistsPromise, deleteTagsPromise, deleteTrackPromise]);
        } catch (e) {
            trx.rollback();
            throw e;
        }
    })
}