import Knex from "knex";
import { ArtistBaseWithRefs, ArtistWithDetails, ArtistWithRefs } 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 artist with details, or null if not found.
export async function getArtist(id: number, userId: number, knex: Knex):
    Promise<ArtistWithDetails> {
    // Start transfers for tags and albums.
    // Also request the artist itself.
    const tagsPromise: Promise<api.TagWithId[]> =
        knex.select('tagId')
            .from('artists_tags')
            .where({ 'artistId': id })
            .then((tags: any) => tags.map((tag: any) => tag['tagId']))
            .then((ids: number[]) =>
                knex.select(['id', 'name', 'parentId'])
                    .from('tags')
                    .whereIn('id', ids)
            );

    const albumsPromise: Promise<api.AlbumWithId[]> =
        knex.select('albumId')
            .from('artists_albums')
            .where({ 'artistId': id })
            .then((albums: any) => albums.map((album: any) => album['albumId']))
            .then((ids: number[]) =>
                knex.select(['id', 'name', 'storeLinks'])
                    .from('album')
                    .whereIn('id', ids)
            );

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

    // Wait for the requests to finish.
    const [artist, tags, albums] =
        await Promise.all([artistPromise, tagsPromise, albumsPromise]);

    if (artist) {
        return {
            mbApi_typename: 'artist',
            name: artist['name'],
            albums: albums as api.AlbumWithId[],
            tags: tags as api.TagWithId[],
            storeLinks: asJson(artist['storeLinks'] || []),
        };
    }

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

// Returns the id of the created artist.
export async function createArtist(userId: number, artist: ArtistWithRefs, knex: Knex): Promise<number> {
    return await knex.transaction(async (trx) => {
        try {
            // Start retrieving albums.
            const albumIdsPromise: Promise<number[]> =
                trx.select('id')
                    .from('albums')
                    .where({ 'user': userId })
                    .whereIn('id', artist.albumIds)
                    .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', artist.tagIds)
                    .then((as: any) => as.map((a: any) => a['id']));

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

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

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

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

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

            return artistId;

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

export async function modifyArtist(userId: number, artistId: number, artist: ArtistBaseWithRefs, knex: Knex): Promise<void> {
    await knex.transaction(async (trx) => {
        try {
            // Start retrieving the artist itself.
            const artistIdPromise: Promise<number | undefined> =
                trx.select('id')
                    .from('artists')
                    .where({ 'user': userId })
                    .where({ id: artistId })
                    .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined);

            // Start retrieving albums if we are modifying those.
            const albumIdsPromise: Promise<number[] | undefined> =
                artist.albumIds ?
                    trx.select('albumId')
                        .from('artists_albums')
                        .whereIn('id', artist.albumIds)
                        .then((as: any) => as.map((a: any) => a['albumId']))
                    : (async () => undefined)();

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

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

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

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

            const modifyArtistPromise = trx('artists')
                .where({ 'user': userId })
                .where({ 'id': artistId })
                .update(update)

            // Remove unlinked albums.
            const removeUnlinkedAlbums = albums ? trx('artists_albums')
                .where({ 'artistId': artistId })
                .whereNotIn('albumId', artist.albumIds || [])
                .delete() : undefined;

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

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

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

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

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

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

            return;

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

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

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

            // Start deleting artist associations with the artist.
            const deleteAlbumsPromise: Promise<any> =
                trx.delete()
                    .from('artists_albums')
                    .where({ 'artistId': artistId });

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

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

            // Start deleting the artist.
            const deleteArtistPromise: Promise<any> =
                trx.delete()
                    .from('artists')
                    .where({ id: artistId });

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