import { deserialise as deserialiseTrack, type TrackInitOptions, isValidTimeSigRange, Track } from "@/Track";
import { greatestCommonDivisor, isPosInt, EffectScoped } from "@/utils";
import { watch, computed, ref, shallowRef, triggerRef, type WritableComputedRef, type Ref, type ShallowRef, nextTick } from "vue";
import { z } from "zod";

export interface BeatManager {
    notifyChange(): void;
}

type BeatGroupInitOptions = {
    barCount: number;
    isLooping: boolean;
    timeSigUp: number;
    tracks?: TrackInitOptions[],
    loopLength?: number,
    useAutoBeatLength?: boolean,
    name?: string,
};

const BeatSerialSchema = z.object({
    tracks: z.array(z.unknown()),
    barCount: z.number(),
    timeSigUp: z.number(),
    globalLoopLength: z.number(),
    globalIsLooping: z.boolean(),
    useAutoBeatLength: z.boolean(),
    barSettingsLocked: z.boolean(),
    name: z.string(),
});
export type BeatSerial = z.infer<typeof BeatSerialSchema>;

export class Beat extends EffectScoped {
    private static count = 0;
    private barCountInternal: Ref<number>;
    private globalLoopLengthInternal: Ref<number>;
    readonly id = Beat.count++;

    tracks: ShallowRef<Track[]>;
    barCount: WritableComputedRef<number>;
    timeSigUp: Ref<number>;
    globalLoopLength: WritableComputedRef<number>;
    globalIsLooping: Ref<boolean>;
    useAutoBeatLength: Ref<boolean>;
    barSettingsLocked: Ref<boolean>;
    name: Ref<string>;
    saveDirty = ref(false);

    constructor(opts: BeatGroupInitOptions) {
        super();
        this.tracks = shallowRef<Track[]>([]);
        this.barCountInternal = ref<number>(opts.barCount ?? 4);
        this.barCount = computed({
            get: () => {
                if (this.useAutoBeatLength.value) {
                    const loopLengths = [this.timeSigUp.value];
                    for (const track of this.tracks.value) {
                        if (track.looping.value) {
                            const loopLength = track.loopLength.value;
                            if (loopLengths.indexOf(loopLength) === -1) {
                                loopLengths.push(loopLength);
                            }
                        }
                    }
                    const smallestLoopLength = loopLengths.reduce((prev, curr) => (prev * curr) / greatestCommonDivisor(prev, curr), 1);
                    return smallestLoopLength / this.timeSigUp.value;
                }
                return this.barCountInternal.value;
            },
            set: (val) => {
                if (this.barSettingsLocked.value || !isPosInt(val)) {
                    return;
                }
                this.barCountInternal.value = val;
            },
        });
        this.timeSigUp = ref<number>(opts.timeSigUp ?? 4);
        this.globalLoopLengthInternal = ref<number>(opts.loopLength ?? this.timeSigUp.value);
        this.globalLoopLength = computed({
            get: () => {
                return this.globalLoopLengthInternal.value;
            },
            set: (val) => {
                if (!isPosInt(val)) {
                    return;
                }
                this.globalLoopLengthInternal.value = val;
            },
        });
        this.globalIsLooping = ref<boolean>(opts.isLooping ?? false);
        this.useAutoBeatLength = ref(opts.useAutoBeatLength ?? false);
        this.barSettingsLocked = computed(() => this.useAutoBeatLength.value);
        this.name = ref(opts.name ?? `Beat-${ this.id }`);

        watch([this.barCount, this.timeSigUp, this.name], ([newBarCount, newTimeSigUp]) => {
            for (const track of this.tracks.value) {
                track.barCount.value = newBarCount;
                track.timeSigUp.value = newTimeSigUp;
            }
            this.saveDirty.value = true;
        }, { immediate: true });

        nextTick(() => this.saveDirty.value = false);
    }

    setTimeSigUp(timeSigVal: number): void {
        if (!isValidTimeSigRange(timeSigVal)) {
            timeSigVal = this.timeSigUp.value;
        }
        this.timeSigUp.value = timeSigVal;
        for (const track of this.tracks.value) {
            track.timeSigUp.value = timeSigVal;
        }
    }

    getTrackByIndex(trackIndex: number) {
        const track = this.tracks.value[trackIndex];
        if (!track) {
            throw new Error(`Could not find the track with index: ${trackIndex}`);
        }
        return track;
    }

    insertAt(trackIndex: number, newIndex: number): void {
        const track = this.getTrackByIndex(trackIndex);
        this.tracks.value.splice(trackIndex, 1);
        this.tracks.value = this.tracks.value.slice(0, newIndex).concat([track]).concat(this.tracks.value.slice(newIndex));
        triggerRef(this.tracks);
    }

    notifyChange() {
        this.saveDirty.value = true;
    }

    addTrack(options?: Omit<TrackInitOptions, 'manager'>): Track | null {
        const optionsResolved = {
            manager: this,
            barCount: this.barCount.value,
            isLooping: this.globalIsLooping.value,
            loopLength: this.globalLoopLength.value,
            ...options,
            timeSig: {
                up: this.timeSigUp.value,
                down: 4,
                ...options?.timeSig ?? {},
            },
        } satisfies TrackInitOptions;
        const newTrack = Track.asScoped(optionsResolved) ?? null;
        if (newTrack) {
            this.tracks.value.push(newTrack);
            triggerRef(this.tracks);
        }
        return newTrack;
    }

    removeTrack(index: number): void {
        const track = this.getTrackByIndex(index);
        this.tracks.value.splice(index, 1);
        track.destroy();
        triggerRef(this.tracks);
    }

    bakeLoops(): void {
        const barCountLooped = this.barCount.value;
        this.useAutoBeatLength.value = false;
        this.barCount.value = barCountLooped;
        this.tracks.value.forEach(track => track.bakeLoops());
    }

    serialise(): Readonly<BeatSerial> {
        return {
            tracks: this.tracks.value.map(track => track.serialise()),
            barCount: this.barCount.value,
            timeSigUp: this.timeSigUp.value,
            globalLoopLength: this.globalLoopLength.value,
            globalIsLooping: this.globalIsLooping.value,
            useAutoBeatLength: this.useAutoBeatLength.value,
            barSettingsLocked: this.barSettingsLocked.value,
            name: this.name.value,
        } as const;
    }
}

export function deserialise(serial: unknown): Beat | null {
    const parse = BeatSerialSchema.safeParse(serial);
    if (!parse.success) {
        console.error('Encountered invalid beat serial:', parse.error, serial);
        return null;
    }
    const beat = parse.data;
    const newBeat = Beat.asScoped({
        loopLength: beat.globalLoopLength,
        barCount: beat.barCount,
        isLooping: beat.globalIsLooping,
        name: beat.name,
        timeSigUp: beat.timeSigUp,
        useAutoBeatLength: beat.useAutoBeatLength,
    });
    beat.tracks.forEach(trackSerial => {
        const track = deserialiseTrack(trackSerial, newBeat);
        if (track) newBeat.tracks.value.push(track);
    });
    return newBeat;
}