import { Beat, deserialise as deserialiseBeat } from "@/Beat";
import { inject, computed, type InjectionKey, onScopeDispose, ref, shallowRef, triggerRef, watch, nextTick, getCurrentInstance } from "vue";
import { z } from "zod";
import { Bound } from "./utils";

export const DrumSlayerSaveSchema = z.object({
    orientation: z.union([z.literal("horizontal"), z.literal("vertical")]),
    activeBeatIndex: z.number(),
    beats: z.array(z.unknown()),
});
export type DrumSlayerSave = z.infer<typeof DrumSlayerSaveSchema>;

function createDefaultMainBeatGroup(): Beat {
    const defaultSettings = {
        barCount: 2,
        isLooping: false,
        timeSigUp: 8,
    };
    const mainBeatGroup = Beat.asScoped(defaultSettings);
    mainBeatGroup.addTrack({ name: "Crash" });
    mainBeatGroup.addTrack({ name: "Hi-Hat" });
    mainBeatGroup.addTrack({ name: "Snare" });
    mainBeatGroup.addTrack({ name: "Kick" });
    return mainBeatGroup;
}

export class BeatStore extends Bound {
    private saveDirtyGlobal = ref(false);
    beats = shallowRef<Beat[]>([ createDefaultMainBeatGroup() ]);
    saveDirty = computed(() => this.saveDirtyGlobal.value || this.beats.value.reduce((last, beat) => beat.saveDirty.value || last, false));
    activeBeatIndex = ref(0);
    activeBeat = computed<Beat | null>(() => this.beats.value[this.activeBeatIndex.value] ?? null);
    orientation = ref<"horizontal" | "vertical">("horizontal");

    constructor() {
        super();
        watch([this.activeBeatIndex, this.orientation, this.beats], () => {
            this.saveDirtyGlobal.value = true;
        });

        const saveInterval = setInterval(() => this.saveDirtyGlobal.value && this.save("localStorage"), 5 * 60 * 1000);

        onScopeDispose(() => clearInterval(saveInterval));

        window.addEventListener("beforeunload", (e) => {
            if (this.saveDirty.value) {
                e.preventDefault();
                e.returnValue = true;
            } 
        });

        const savedItem = localStorage.getItem("drum-slayer-save");
        if (savedItem) {
            const serial = JSON.parse(savedItem);
            this.beats.value = [createDefaultMainBeatGroup()];
            this.loadFromSave(serial);
        }
    }

    resetActiveBeat(): void {
        const current = this.activeBeat.value;
        this.beats.value[this.activeBeatIndex.value] = createDefaultMainBeatGroup();
        current?.destroy();
        triggerRef(this.beats);
    }

    removeBeat(index: number): void {
        const beat = this.beats.value[index];
        this.beats.value.splice(index, 1);
        if (this.activeBeatIndex.value === index) {
            this.activeBeatIndex.value = 0;
        }
        if (this.beats.value.length === 0) {
            this.addNewBeat();
            this.activeBeatIndex.value = 0;
        }
        triggerRef(this.beats);
        nextTick(() => {
            beat?.destroy();
        });
    }

    addNewBeat(config?: unknown): number {
        let newBeat: Beat | null = null;
        if (config) {
            newBeat = deserialiseBeat(config);
            if (!newBeat) {
                return -1;
            }
        } else {
            newBeat = createDefaultMainBeatGroup();
        }
        const newIndex = this.beats.value.push(newBeat);
        triggerRef(this.beats);
        this.activeBeatIndex.value = newIndex - 1;
        return newIndex - 1;
    }

    save(destination: "localStorage"): void {
        if (destination === "localStorage") {
            const serials = this.beats.value.map(beat => beat.serialise());
            localStorage.setItem("drum-slayer-save", JSON.stringify({
                beats: serials,
                activeBeatIndex: this.activeBeatIndex.value,
                orientation: this.orientation.value ?? "horizontal",
            } satisfies DrumSlayerSave));
            for (const beat of this.beats.value) {
                beat.saveDirty.value = false;
            }
            this.saveDirtyGlobal.value = false;
        }
    }

    loadFromSave(source: unknown): void {
        this.beats.value.length = 0;
        const parse = DrumSlayerSaveSchema.safeParse(source);
        if (parse.success) {
            parse.data.beats.forEach((beat: unknown) => {
                const deserialisedBeat = deserialiseBeat(beat);
                if (deserialisedBeat) {
                    this.beats.value.push(deserialisedBeat);
                }
            });
            this.activeBeatIndex.value = parse.data.activeBeatIndex;
            this.orientation.value = parse.data.orientation;
        } 
        if (this.beats.value.length === 0) {
            this.resetActiveBeat();
        }
        nextTick(() => this.saveDirtyGlobal.value = false);
    }
    
    bakeAll(): void {
        this.activeBeat.value?.bakeLoops();
    }
}

const BeatStoreKey = Symbol("BeatStore") as InjectionKey<BeatStore>;

export function useBeatStore(): BeatStore {
    return inject(BeatStoreKey, () => {
        const store = new BeatStore();
        getCurrentInstance()?.appContext?.app.provide(BeatStoreKey, store);
        return store;
    }, true);
}