import Knex from "knex";
import { AlbumBaseWithRefs, AlbumWithDetails, AlbumWithRefs } from "../../client/src/api/api";
import * as api from '../../client/src/api/api';
import asJson from "../lib/asJson";
import { DBError, DBErrorKind } from "../endpoints/types";
import { makeNotFoundError } from "./common";
var _ = require('lodash');

// Returns an album with details, or null if not found.
export async function getAlbum(id: number, userId: number, knex: Knex):
    Promise<AlbumWithDetails> {


    // Start transfers for tracks, tags and artists.
    // Also request the album itself.
    const tagsPromise: Promise<api.TagWithId[]> =
        knex.select('tagId')
            .from('albums_tags')
            .where({ 'albumId': id })
            .then((tags: any) => tags.map((tag: any) => tag['tagId']))
            .then((ids: number[]) =>
                knex.select(['id', 'name', 'parentId'])
                    .from('tags')
                    .whereIn('id', ids)
            );

    const tracksPromise: Promise<api.TrackWithId[]> =
        knex.select('trackId')
            .from('tracks_albums')
            .where({ 'albumId': id })
            .then((tracks: any) => tracks.map((track: any) => track['trackId']))
            .then((ids: number[]) =>
                knex.select(['id', 'name', 'storeLinks'])
                    .from('tracks')
                    .whereIn('id', ids)
            );

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

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

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

    if (album) {
        return {
            mbApi_typename: 'album',
            name: album['name'],
            artists: artists as api.ArtistWithId[],
            tags: tags as api.TagWithId[],
            tracks: tracks as api.TrackWithId[],
            storeLinks: asJson(album['storeLinks'] || []),
        };
    }

    throw makeNotFoundError();
}

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

        // Start retrieving tracks.
        const trackIdsPromise: Promise<number[]> =
            trx.select('id')
                .from('tracks')
                .where({ 'user': userId })
                .whereIn('id', album.trackIds || [])
                .then((as: any) => as.map((a: any) => a['id']));

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

        // Check that we found all artists and tags we need.
        if ((!_.isEqual(artists.sort(), (album.artistIds || []).sort())) ||
            (!_.isEqual(tags.sort(), (album.tagIds || []).sort())) ||
            (!_.isEqual(tracks.sort(), (album.trackIds || []).sort()))) {
            throw makeNotFoundError();
        }

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

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

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

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

        console.log('created album', album, ', ID ', albumId);
        return albumId;
    })
}

export async function modifyAlbum(userId: number, albumId: number, album: AlbumBaseWithRefs, knex: Knex): Promise<void> {
    await knex.transaction(async (trx) => {
        // Start retrieving the album itself.
        const albumIdPromise: Promise<number | undefined> =
            trx.select('id')
                .from('albums')
                .where({ 'user': userId })
                .where({ id: albumId })
                .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined);

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

        // Start retrieving tracks if we are modifying those.
        const trackIdsPromise: Promise<number[] | undefined> =
            album.trackIds ?
                trx.select('artistId')
                    .from('tracks_albums')
                    .whereIn('albumId', album.trackIds)
                    .then((as: any) => as.map((a: any) => a['trackId']))
                : (async () => undefined)();

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

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

        // Check that we found all objects we need.
        if ((!artists || !_.isEqual(artists.sort(), (album.artistIds || []).sort())) ||
            (!tags || !_.isEqual(tags.sort(), (album.tagIds || []).sort())) ||
            (!tracks || !_.isEqual(tracks.sort(), (album.trackIds || []).sort())) ||
            !oldAlbum) {
            throw makeNotFoundError();
        }

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

        const modifyAlbumPromise = trx('albums')
            .where({ 'user': userId })
            .where({ 'id': albumId })
            .update(update)

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

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

        // Remove unlinked tracks.
        const removeUnlinkedTracks = tracks ? trx('tracks_albums')
            .where({ 'albumId': albumId })
            .whereNotIn('trackId', album.trackIds || [])
            .delete() : undefined;

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

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

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

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

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

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

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

        return;
    })

    const e: DBError = {
        kind: DBErrorKind.Unknown,
        message: "Reached the unreachable.",
        name: "DBError"
    }
    throw e;
}

export async function deleteAlbum(userId: number, albumId: number, knex: Knex): Promise<void> {
    await knex.transaction(async (trx) => {

        // Start by retrieving the album itself for sanity.
        const confirmAlbumId: number | undefined =
            await trx.select('id')
                .from('albums')
                .where({ 'user': userId })
                .where({ id: albumId })
                .then((r: any) => (r && r[0]) ? r[0]['id'] : undefined);

        if (!confirmAlbumId) {
            throw makeNotFoundError();
        }

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

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

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

        // Start deleting the album.
        const deleteAlbumPromise: Promise<any> =
            trx.delete()
                .from('albums')
                .where({ id: albumId });

        // Wait for the requests to finish.
        await Promise.all([deleteArtistsPromise, deleteTagsPromise, deleteTracksPromise, deleteAlbumPromise]);
    })
}