import { AlbumWithRefs, AlbumWithRefsWithId, ArtistWithRefs, ArtistWithRefsWithId, TagWithRefs, TagWithRefsWithId, TrackWithRefs, TrackWithRefsWithId } from "../../../client/src/api/api";
import { userEndpoints } from "../../endpoints/User";
import { createAlbum, createArtist, createTag, createTrack, deleteTrack, ReferenceDatabase } from "./DBReferenceModel";
import * as helpers from '../integration/helpers';
import { DBErrorKind, isDBError } from "../../endpoints/types";

export enum DBActionType {
    CreateTrack = "CreateTrack",
    CreateAlbum = "CreateAlbum",
    CreateTag = "CreateTag",
    CreateArtist = "CreateArtist",
    DeleteTrack = "DeleteTrack",
}

export interface DBAction {
    type: DBActionType,
    userId: number,
    payload: any,
}

export type Distribution<T> = Map<T, number>;

export interface RandomDBActionDistribution {
    type: Distribution<DBActionType>,
    userId: Distribution<number>,
    createTrackParams: RandomCreateTrackDistribution,
    createAlbumParams: RandomCreateAlbumDistribution,
    createArtistParams: RandomCreateArtistDistribution,
    createTagParams: RandomCreateTagDistribution,
    deleteTrackParams: RandomDeleteTrackDistribution,
}

export interface RandomCreateTrackDistribution {
    linkArtists: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
    linkTags: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
    linkAlbum: Distribution<boolean | 'nonexistent'>,
}

export interface RandomCreateAlbumDistribution {
    linkArtists: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
    linkTags: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
    linkTracks: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
}

export interface RandomCreateArtistDistribution {
    linkAlbums: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
    linkTags: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
    linkTracks: {
        numValid: Distribution<number>,
        numInvalid: Distribution<number>,
    }
}

export interface RandomCreateTagDistribution {
    linkParent: Distribution<boolean | 'nonexistent'>,
}

export interface RandomDeleteTrackDistribution {
    validTrack: Distribution<boolean>,
}

export function applyDistribution<T>(
    dist: Map<T, number>,
    randomNumGen: any,
): T {
    let n = randomNumGen();
    let r: T | undefined = undefined;
    dist.forEach((value: number, key: T) => {
        if (r) { return; }
        if (n <= value) { r = key; }
        else { n -= value; }
    })
    if (r === undefined) {
        throw new Error(`Invalid distribution: n=${n}, dist ${JSON.stringify(dist.entries())}`);
    }
    return r;
}

export function randomString(randomNumGen: any, length: number) {
    let chars = 'abcdefghijklmnopqrstuvwxyz';
    let retval = '';
    for (let i = 0; i < length; i++) {
        retval += chars[Math.floor(randomNumGen() * 26)];
    }
    return retval;
}

export function pickNFromArray<T>(
    array: T[],
    randomNumGen: any,
    N: number)
    : T[] {
    let r: T[] = [];
    for (let i = 0; i < N; i++) {
        let idx = Math.floor(randomNumGen() * array.length);
        r.push(array[idx]);
        array.splice(idx);
    }
    return r;
}

export function applyReferenceDBAction(
    action: DBAction,
    db: ReferenceDatabase
): {
    response: any,
    status: number,
} {
    let response: any = undefined;
    let status: number = 0;

    try {
        switch (action.type) {
            case DBActionType.CreateTrack: {
                response = createTrack(action.userId, action.payload, db);
                status = 200;
                break;
            }
            case DBActionType.CreateAlbum: {
                response = createAlbum(action.userId, action.payload, db);
                status = 200;
                break;
            }
            case DBActionType.CreateArtist: {
                response = createArtist(action.userId, action.payload, db);
                status = 200;
                break;
            }
            case DBActionType.CreateTag: {
                response = createTag(action.userId, action.payload, db);
                status = 200;
                break;
            }
            case DBActionType.DeleteTrack: {
                deleteTrack(action.userId, action.payload, db);
                response = {};
                status = 200;
                break;
            }
        }
    } catch (e) {
        if (isDBError(e)) {
            if (e.kind === DBErrorKind.ResourceNotFound) {
                status = 404;
                response = {};
            }
        } else {
            throw e;
        }
    }

    return { response: response, status: status };
}

export async function applyRealDBAction(
    action: DBAction,
    req: any,
): Promise<{
    response: any,
    status: number,
}> {
    let response: any = undefined;
    let status: number = 0;

    switch (action.type) {
        case DBActionType.CreateTrack: {
            let res = await helpers.createTrack(req, action.payload);
            status = res.status;
            response = res.body;
            break;
        }
        case DBActionType.CreateAlbum: {
            let res = await helpers.createAlbum(req, action.payload);
            status = res.status;
            response = res.body;
            break;
        }
        case DBActionType.CreateArtist: {
            let res = await helpers.createArtist(req, action.payload);
            status = res.status;
            response = res.body;
            break;
        }
        case DBActionType.CreateTag: {
            let res = await helpers.createTag(req, action.payload);
            status = res.status;
            response = res.body;
            break;
        }
        case DBActionType.DeleteTrack: {
            let res = await helpers.deleteTrack(req, action.payload);
            status = res.status;
            response = res.body;
            break;
        }
    }

    return { response: response, status: status };
}

export function randomDBAction(
    db: ReferenceDatabase,
    randomNumGen: any,
    distribution: RandomDBActionDistribution,
): DBAction {
    let type = applyDistribution(
        distribution.type,
        randomNumGen
    );
    let userId = applyDistribution(
        distribution.userId,
        randomNumGen
    );

    switch (type) {
        case DBActionType.CreateTrack: {
            return {
                type: type,
                payload: createRandomTrack(
                    db,
                    userId,
                    distribution.createTrackParams,
                    randomNumGen
                ),
                userId: userId,
            };
        }
        case DBActionType.CreateArtist: {
            return {
                type: type,
                payload: createRandomArtist(
                    db,
                    userId,
                    distribution.createArtistParams,
                    randomNumGen
                ),
                userId: userId,
            };
        }
        case DBActionType.CreateAlbum: {
            return {
                type: type,
                payload: createRandomAlbum(
                    db,
                    userId,
                    distribution.createAlbumParams,
                    randomNumGen
                ),
                userId: userId,
            };
        }
        case DBActionType.CreateTag: {
            return {
                type: type,
                payload: createRandomTag(
                    db,
                    userId,
                    distribution.createTagParams,
                    randomNumGen
                ),
                userId: userId,
            };
        }
        case DBActionType.DeleteTrack: {
            return {
                type: type,
                payload: applyDistribution(distribution.deleteTrackParams.validTrack, randomNumGen) ?
                    Math.floor(randomNumGen() * db[userId].tracks.length) + 1 :
                    Math.floor(randomNumGen() * db[userId].tracks.length) + 1 + db[userId].tracks.length,
                userId: userId,
            }
        }
    }
}

function pickArtists(userId: number, nValid: number, nInvalid: number, rng: any, db: ReferenceDatabase) {
    let allValidArtistIds: number[] = db[userId] && db[userId].artists ?
        db[userId].artists.map((a: ArtistWithRefsWithId) => a.id) : [];
    let validArtists: number[] = pickNFromArray(allValidArtistIds, rng, nValid);
    let invalidArtists: number[] = [];
    for (let i = 0; i < nInvalid; i++) {
        invalidArtists.push(Math.round(rng() * 100) + allValidArtistIds.length);
    }
    return [...validArtists, ...invalidArtists];
}

function pickAlbums(userId: number, nValid: number, nInvalid: number, rng: any, db: ReferenceDatabase) {
    let allValidAlbumIds: number[] = db[userId] && db[userId].albums ?
        db[userId].albums.map((a: AlbumWithRefsWithId) => a.id) : [];
    let validAlbums: number[] = pickNFromArray(allValidAlbumIds, rng, nValid);
    let invalidAlbums: number[] = [];
    for (let i = 0; i < nInvalid; i++) {
        invalidAlbums.push(Math.round(rng() * 100) + allValidAlbumIds.length);
    }
    return [...validAlbums, ...invalidAlbums];
}

function pickTracks(userId: number, nValid: number, nInvalid: number, rng: any, db: ReferenceDatabase) {
    let allValidTrackIds: number[] = db[userId] && db[userId].tracks ?
        db[userId].tracks.map((a: TrackWithRefsWithId) => a.id) : [];
    let validTracks: number[] = pickNFromArray(allValidTrackIds, rng, nValid);
    let invalidTracks: number[] = [];
    for (let i = 0; i < nInvalid; i++) {
        invalidTracks.push(Math.round(rng() * 100) + allValidTrackIds.length);
    }
    return [...validTracks, ...invalidTracks];
}

function pickTags(userId: number, nValid: number, nInvalid: number, rng: any, db: ReferenceDatabase) {
    let allValidTagIds: number[] = db[userId] && db[userId].tags ?
        db[userId].tags.map((a: TagWithRefsWithId) => a.id) : [];
    let validTags: number[] = pickNFromArray(allValidTagIds, rng, nValid);
    let invalidTags: number[] = [];
    for (let i = 0; i < nInvalid; i++) {
        invalidTags.push(Math.round(rng() * 100) + allValidTagIds.length);
    }
    return [...validTags, ...invalidTags];
}

export function createRandomTrack(
    db: ReferenceDatabase,
    userId: number,
    dist: RandomCreateTrackDistribution,
    randomNumGen: any,
): TrackWithRefs {
    let artists: number[] = pickArtists(userId,
        applyDistribution(dist.linkArtists.numValid, randomNumGen),
        applyDistribution(dist.linkArtists.numInvalid, randomNumGen),
        randomNumGen,
        db);

    let tags: number[] = pickTags(userId,
        applyDistribution(dist.linkTags.numValid, randomNumGen),
        applyDistribution(dist.linkTags.numInvalid, randomNumGen),
        randomNumGen,
        db);

    let maybeAlbum: number | null = (() => {
        let r: boolean | null | 'nonexistent' = applyDistribution(dist.linkAlbum, randomNumGen);
        let albums = pickAlbums(userId, r === true ? 1 : 0, r === 'nonexistent' ? 1 : 0, randomNumGen, db);
        return albums.length ? albums[0] : null;
    })();

    return {
        mbApi_typename: 'track',
        albumId: maybeAlbum,
        artistIds: artists,
        tagIds: tags,
        name: randomString(randomNumGen, 20),
        storeLinks: [], // TODO
    }
}

export function createRandomArtist(
    db: ReferenceDatabase,
    userId: number,
    dist: RandomCreateArtistDistribution,
    randomNumGen: any,
): ArtistWithRefs {
    let tracks: number[] = pickTracks(userId,
        applyDistribution(dist.linkTracks.numValid, randomNumGen),
        applyDistribution(dist.linkTracks.numInvalid, randomNumGen),
        randomNumGen,
        db);

    let tags: number[] = pickTags(userId,
        applyDistribution(dist.linkTags.numValid, randomNumGen),
        applyDistribution(dist.linkTags.numInvalid, randomNumGen),
        randomNumGen,
        db);

    let albums: number[] = pickAlbums(userId,
        applyDistribution(dist.linkAlbums.numValid, randomNumGen),
        applyDistribution(dist.linkAlbums.numInvalid, randomNumGen),
        randomNumGen,
        db);

    return {
        mbApi_typename: 'artist',
        albumIds: albums,
        trackIds: tracks,
        tagIds: tags,
        name: randomString(randomNumGen, 20),
        storeLinks: [], // TODO
    }
}

export function createRandomAlbum(
    db: ReferenceDatabase,
    userId: number,
    dist: RandomCreateAlbumDistribution,
    randomNumGen: any,
): AlbumWithRefs {
    let tracks: number[] = pickTracks(userId,
        applyDistribution(dist.linkTracks.numValid, randomNumGen),
        applyDistribution(dist.linkTracks.numInvalid, randomNumGen),
        randomNumGen,
        db);

    let tags: number[] = pickTags(userId,
        applyDistribution(dist.linkTags.numValid, randomNumGen),
        applyDistribution(dist.linkTags.numInvalid, randomNumGen),
        randomNumGen,
        db);

    let artists: number[] = pickArtists(userId,
        applyDistribution(dist.linkArtists.numValid, randomNumGen),
        applyDistribution(dist.linkArtists.numInvalid, randomNumGen),
        randomNumGen,
        db);

    return {
        mbApi_typename: 'album',
        artistIds: artists,
        trackIds: tracks,
        tagIds: tags,
        name: randomString(randomNumGen, 20),
        storeLinks: [], // TODO
    }
}

export function createRandomTag(
    db: ReferenceDatabase,
    userId: number,
    dist: RandomCreateTagDistribution,
    randomNumGen: any,
): TagWithRefs {
    let maybeParent: number | null = (() => {
        let r: boolean | null | 'nonexistent' = applyDistribution(dist.linkParent, randomNumGen);
        let tags = pickTags(userId, r === true ? 1 : 0, r === 'nonexistent' ? 1 : 0, randomNumGen, db);
        return tags.length ? tags[0] : null;
    })();

    return {
        mbApi_typename: 'tag',
        name: randomString(randomNumGen, 20),
        parentId: maybeParent,
    }
}