import {
    of as observableOf,
    combineLatest as observableCombineLatest,
    concat as observableConcat,
    merge as observableMerge,
    empty as observableEmpty,
    Observable,
    Scheduler,
    Subject,
    Subscription,
} from "rxjs";

import {
    takeUntil,
    share,
    skip,
    withLatestFrom,
    map,
    switchMap,
    publishReplay,
    auditTime,
    distinctUntilChanged,
    startWith,
    retry,
    catchError,
    filter,
    publish,
    debounceTime,
    take,
    refCount,
} from "rxjs/operators";

import * as vd from "virtual-dom";

import {
    Component,
    ComponentService,
    ISequenceConfiguration,
    SequenceDOMRenderer,
} from "../../Component";
import { EdgeDirection } from "../../Edge";
import {
    IEdgeStatus,
    GraphMode,
    Node,
    Sequence,
} from "../../Graph";
import {
    ISize,
    IVNodeHash,
} from "../../Render";
import {
    Container,
    Navigator,
} from "../../Viewer";
import State from "../../state/State";

/**
 * @class SequenceComponent
 * @classdesc Component showing navigation arrows for sequence directions
 * as well as playing button. Exposes an API to start and stop play.
 */
export class SequenceComponent extends Component<ISequenceConfiguration> {
    /** @inheritdoc */
    public static componentName: string = "sequence";

    /**
     * Event fired when playing starts or stops.
     *
     * @event SequenceComponent#playingchanged
     * @type {boolean} Indicates whether the player is playing.
     */
    public static playingchanged: string = "playingchanged";

    /**
     * Event fired when the hovered key changes.
     *
     * @description Emits the key of the node for the direction
     * arrow that is being hovered. When the mouse leaves a
     * direction arrow null is emitted.
     *
     * @event SequenceComponent#hoveredkeychanged
     * @type {string} The hovered key, null if no key is hovered.
     */
    public static hoveredkeychanged: string = "hoveredkeychanged";

    private _sequenceDOMRenderer: SequenceDOMRenderer;
    private _scheduler: Scheduler;

    private _hoveredKeySubject$: Subject<string>;
    private _hoveredKey$: Observable<string>;
    private _containerWidth$: Subject<number>;

    private _emitHoveredKeySubscription: Subscription;
    private _renderSubscription: Subscription;
    private _playingSubscription: Subscription;
    private _containerWidthSubscription: Subscription;
    private _hoveredKeySubscription: Subscription;
    private _setSpeedSubscription: Subscription;
    private _setDirectionSubscription: Subscription;
    private _setSequenceGraphModeSubscription: Subscription;
    private _setSpatialGraphModeSubscription: Subscription;
    private _sequenceSubscription: Subscription;
    private _moveSubscription: Subscription;
    private _cacheSequenceNodesSubscription: Subscription;
    private _stopSubscription: Subscription;

    constructor(
        name: string,
        container: Container,
        navigator: Navigator,
        renderer?: SequenceDOMRenderer,
        scheduler?: Scheduler) {

        super(name, container, navigator);

        this._sequenceDOMRenderer = !!renderer ? renderer : new SequenceDOMRenderer(container);
        this._scheduler = scheduler;

        this._containerWidth$ = new Subject<number>();
        this._hoveredKeySubject$ = new Subject<string>();

        this._hoveredKey$ = this._hoveredKeySubject$.pipe(share());

        this._navigator.playService.playing$.pipe(
            skip(1),
            withLatestFrom(this._configuration$))
            .subscribe(
                ([playing, configuration]: [boolean, ISequenceConfiguration]): void => {
                    this.fire(SequenceComponent.playingchanged, playing);

                    if (playing === configuration.playing) {
                        return;
                    }

                    if (playing) {
                        this.play();
                    } else {
                        this.stop();
                    }
                });

        this._navigator.playService.direction$.pipe(
            skip(1),
            withLatestFrom(this._configuration$))
            .subscribe(
                ([direction, configuration]: [EdgeDirection, ISequenceConfiguration]): void => {
                    if (direction !== configuration.direction) {
                        this.setDirection(direction);
                    }
                });
    }

    /**
     * Get hovered key observable.
     *
     * @description An observable emitting the key of the node for the direction
     * arrow that is being hovered. When the mouse leaves a direction arrow null
     * is emitted.
     *
     * @returns {Observable<string>}
     */
    public get hoveredKey$(): Observable<string> {
        return this._hoveredKey$;
    }

    /**
     * Start playing.
     *
     * @fires PlayerComponent#playingchanged
     */
    public play(): void {
        this.configure({ playing: true });
    }

    /**
     * Stop playing.
     *
     * @fires PlayerComponent#playingchanged
     */
    public stop(): void {
        this.configure({ playing: false });
    }

    /**
     * Set the direction to follow when playing.
     *
     * @param {EdgeDirection} direction - The direction that will be followed when playing.
     */
    public setDirection(direction: EdgeDirection): void {
        this.configure({ direction: direction });
    }

    /**
     * Set highlight key.
     *
     * @description The arrow pointing towards the node corresponding to the
     * highlight key will be highlighted.
     *
     * @param {string} highlightKey Key of node to be highlighted if existing.
     */
    public setHighlightKey(highlightKey: string): void {
        this.configure({ highlightKey: highlightKey });
    }

    /**
     * Set max width of container element.
     *
     * @description Set max width of the container element holding
     * the sequence navigation elements. If the min width is larger than the
     * max width the min width value will be used.
     *
     * The container element is automatically resized when the resize
     * method on the Viewer class is called.
     *
     * @param {number} minWidth
     */
    public setMaxWidth(maxWidth: number): void {
        this.configure({ maxWidth: maxWidth });
    }

    /**
     * Set min width of container element.
     *
     * @description Set min width of the container element holding
     * the sequence navigation elements. If the min width is larger than the
     * max width the min width value will be used.
     *
     * The container element is automatically resized when the resize
     * method on the Viewer class is called.
     *
     * @param {number} minWidth
     */
    public setMinWidth(minWidth: number): void {
        this.configure({ minWidth: minWidth });
    }

    /**
     * Set the value indicating whether the sequence UI elements should be visible.
     *
     * @param {boolean} visible
     */
    public setVisible(visible: boolean): void {
        this.configure({ visible: visible });
    }

    protected _activate(): void {
        this._sequenceDOMRenderer.activate();

        const edgeStatus$: Observable<IEdgeStatus> = this._navigator.stateService.currentNode$.pipe(
            switchMap(
                (node: Node): Observable<IEdgeStatus> => {
                    return node.sequenceEdges$;
                }),
            publishReplay(1),
            refCount());

        const sequence$: Observable<Sequence> = this._navigator.stateService.currentNode$.pipe(
            distinctUntilChanged(
                undefined,
                (node: Node): string => {
                    return node.sequenceKey;
                }),
            switchMap(
                (node: Node): Observable<Sequence> => {
                    return observableConcat(
                        observableOf(null),
                        this._navigator.graphService.cacheSequence$(node.sequenceKey).pipe(
                            retry(3),
                            catchError(
                                (e: Error): Observable<Sequence> => {
                                    console.error("Failed to cache sequence", e);

                                    return observableOf(null);
                                })));
                }),
            startWith(null),
            publishReplay(1),
            refCount());

        this._sequenceSubscription = sequence$.subscribe();

        const rendererKey$: Observable<string> = this._sequenceDOMRenderer.index$.pipe(
            withLatestFrom(sequence$),
            map(
                ([index, sequence]: [number, Sequence]): string => {
                    return sequence != null ? sequence.keys[index] : null;
                }),
            filter(
                (key: string): boolean => {
                    return !!key;
                }),
            distinctUntilChanged(),
            publish(),
            refCount());

        this._moveSubscription = observableMerge(
            rendererKey$.pipe(debounceTime(100, this._scheduler)),
            rendererKey$.pipe(auditTime(400, this._scheduler))).pipe(
                distinctUntilChanged(),
                switchMap(
                    (key: string): Observable<Node> => {
                        return this._navigator.moveToKey$(key).pipe(
                            catchError(
                                (e: Error): Observable<Node> => {
                                    return observableEmpty();
                                }));
                    }))
            .subscribe();

        this._setSequenceGraphModeSubscription = this._sequenceDOMRenderer.changingPositionChanged$.pipe(
            filter(
                (changing: boolean): boolean => {
                    return changing;
                }))
            .subscribe(
                (): void => {
                    this._navigator.graphService.setGraphMode(GraphMode.Sequence);
                });

        this._setSpatialGraphModeSubscription = this._sequenceDOMRenderer.changingPositionChanged$.pipe(
            filter(
                (changing: boolean): boolean => {
                    return !changing;
                }))
            .subscribe(
                (): void => {
                    this._navigator.graphService.setGraphMode(GraphMode.Spatial);
                });

        this._navigator.graphService.graphMode$.pipe(
            switchMap(
                (mode: GraphMode): Observable<Node> => {
                    return mode === GraphMode.Spatial ?
                        this._navigator.stateService.currentNode$.pipe(
                            take(2)) :
                        observableEmpty();
                }),
            filter(
                (node: Node): boolean => {
                    return !node.spatialEdges.cached;
                }),
            switchMap(
                (node: Node): Observable<Node> => {
                    return this._navigator.graphService.cacheNode$(node.key).pipe(
                        catchError(
                            (e: Error): Observable<Node> => {
                                return observableEmpty();
                            }));
                }))
            .subscribe();

        this._stopSubscription = this._sequenceDOMRenderer.changingPositionChanged$.pipe(
            filter(
                (changing: boolean): boolean => {
                    return changing;
                }))
            .subscribe(
                (): void => {
                    this._navigator.playService.stop();
                });

        this._cacheSequenceNodesSubscription = observableCombineLatest(
            this._navigator.graphService.graphMode$,
            this._sequenceDOMRenderer.changingPositionChanged$.pipe(
                startWith(false),
                distinctUntilChanged())).pipe(
                    withLatestFrom(this._navigator.stateService.currentNode$),
                    switchMap(
                        ([[mode, changing], node]: [[GraphMode, boolean], Node]): Observable<Sequence> => {
                            return changing && mode === GraphMode.Sequence ?
                                this._navigator.graphService.cacheSequenceNodes$(node.sequenceKey, node.key).pipe(
                                    retry(3),
                                    catchError(
                                        (error: Error): Observable<Sequence> => {
                                            console.error("Failed to cache sequence nodes.", error);

                                            return observableEmpty();
                                        })) :
                                observableEmpty();
                        }))
            .subscribe();

        const position$: Observable<{ index: number, max: number }> = sequence$.pipe(
            switchMap(
                (sequence: Sequence): Observable<{ index: number, max: number }> => {
                    if (!sequence) {
                        return observableOf({ index: null, max: null });
                    }

                    let firstCurrentKey: boolean = true;

                    return this._sequenceDOMRenderer.changingPositionChanged$.pipe(
                        startWith(false),
                        distinctUntilChanged(),
                        switchMap(
                            (changingPosition: boolean): Observable<string> => {
                                const skipCount: number = !changingPosition && firstCurrentKey ? 0 : 1;
                                firstCurrentKey = false;

                                return changingPosition ?
                                    rendererKey$ :
                                    this._navigator.stateService.currentNode$.pipe(
                                        map(
                                            (node: Node): string => {
                                                return node.key;
                                            }),
                                        distinctUntilChanged(),
                                        skip(skipCount));
                            }),
                        map(
                            (key: string): { index: number, max: number } => {
                                const index: number = sequence.keys.indexOf(key);

                                if (index === -1) {
                                    return { index: null, max: null };
                                }

                                return { index: index, max: sequence.keys.length - 1 };
                            }));
                }));

        const earth$ = this._navigator.stateService.state$.pipe(
            map(
                (state: State): boolean => {
                    return state === State.Earth;
                }),
            distinctUntilChanged());

        this._renderSubscription = observableCombineLatest(
            edgeStatus$,
            this._configuration$,
            this._containerWidth$,
            this._sequenceDOMRenderer.changed$.pipe(startWith(this._sequenceDOMRenderer)),
            this._navigator.playService.speed$,
            position$,
            earth$).pipe(
                map(
                    (
                        [edgeStatus, configuration, containerWidth, renderer, speed, position, earth]:
                            [
                                IEdgeStatus,
                                ISequenceConfiguration,
                                number,
                                SequenceDOMRenderer,
                                number,
                                { index: number, max: number },
                                boolean,
                            ]): IVNodeHash => {

                        const vNode: vd.VNode = this._sequenceDOMRenderer
                            .render(
                                edgeStatus,
                                configuration,
                                containerWidth,
                                speed,
                                position.index,
                                position.max,
                                !earth,
                                this,
                                this._navigator);

                        return { name: this._name, vnode: vNode };
                    }))
            .subscribe(this._container.domRenderer.render$);

        this._setSpeedSubscription = this._sequenceDOMRenderer.speed$
            .subscribe(
                (speed: number): void => {
                    this._navigator.playService.setSpeed(speed);
                });

        this._setDirectionSubscription = this._configuration$.pipe(
            map(
                (configuration: ISequenceConfiguration): EdgeDirection => {
                    return configuration.direction;
                }),
            distinctUntilChanged())
            .subscribe(
                (direction: EdgeDirection): void => {
                    this._navigator.playService.setDirection(direction);
                });

        this._containerWidthSubscription = observableCombineLatest(
            this._container.renderService.size$,
            this._configuration$.pipe(
                distinctUntilChanged(
                    (value1: [number, number], value2: [number, number]): boolean => {
                        return value1[0] === value2[0] && value1[1] === value2[1];
                    },
                    (configuration: ISequenceConfiguration) => {
                        return [configuration.minWidth, configuration.maxWidth];
                    }))).pipe(
                        map(
                            ([size, configuration]: [ISize, ISequenceConfiguration]): number => {
                                return this._sequenceDOMRenderer.getContainerWidth(
                                    size,
                                    configuration);
                            }))
            .subscribe(this._containerWidth$);

        this._playingSubscription = this._configuration$.pipe(
            map(
                (configuration: ISequenceConfiguration): boolean => {
                    return configuration.playing;
                }),
            distinctUntilChanged())
            .subscribe(
                (playing: boolean) => {
                    if (playing) {
                        this._navigator.playService.play();
                    } else {
                        this._navigator.playService.stop();
                    }
                });

        this._hoveredKeySubscription = this._sequenceDOMRenderer.mouseEnterDirection$.pipe(
            switchMap(
                (direction: EdgeDirection): Observable<string> => {
                    const edgeTo$: Observable<string> = edgeStatus$.pipe(
                        map(
                            (edgeStatus: IEdgeStatus): string => {
                                for (let edge of edgeStatus.edges) {
                                    if (edge.data.direction === direction) {
                                        return edge.to;
                                    }
                                }

                                return null;
                            }),
                        takeUntil(this._sequenceDOMRenderer.mouseLeaveDirection$));

                    return observableConcat(edgeTo$, observableOf<string>(null));
                }),
            distinctUntilChanged())
            .subscribe(this._hoveredKeySubject$);

        this._emitHoveredKeySubscription = this._hoveredKey$
            .subscribe(
                (key: string): void => {
                    this.fire(SequenceComponent.hoveredkeychanged, key);
                });
    }

    protected _deactivate(): void {
        this._emitHoveredKeySubscription.unsubscribe();
        this._renderSubscription.unsubscribe();
        this._playingSubscription.unsubscribe();
        this._containerWidthSubscription.unsubscribe();
        this._hoveredKeySubscription.unsubscribe();
        this._setSpeedSubscription.unsubscribe();
        this._setDirectionSubscription.unsubscribe();
        this._setSequenceGraphModeSubscription.unsubscribe();
        this._setSpatialGraphModeSubscription.unsubscribe();
        this._sequenceSubscription.unsubscribe();
        this._moveSubscription.unsubscribe();
        this._cacheSequenceNodesSubscription.unsubscribe();
        this._stopSubscription.unsubscribe();

        this._sequenceDOMRenderer.deactivate();
    }

    protected _getDefaultConfiguration(): ISequenceConfiguration {
        return {
            direction: EdgeDirection.Next,
            maxWidth: 108,
            minWidth: 70,
            playing: false,
            visible: true,
        };
    }
}

ComponentService.register(SequenceComponent);
export default SequenceComponent;