import {
    ChangeDetectorRef,
    Component,
    ElementRef,
    EventEmitter,
    HostListener,
    Output,
    QueryList,
    ViewChild
} from "@angular/core";
import {PhotoDTO} from "../../../../common/entities/PhotoDTO";
import {GalleryPhotoComponent} from "../grid/photo/photo.grid.gallery.component";
import {Dimension} from "../../model/IRenderable";
import {FullScreenService} from "../fullscreen.service";
import {OverlayService} from "../overlay.service";
import {Subscription} from "rxjs";

@Component({
    selector: 'gallery-lightbox',
    styleUrls: ['app/gallery/lightbox/lightbox.gallery.component.css'],
    templateUrl: 'app/gallery/lightbox/lightbox.gallery.component.html',
})
export class GalleryLightboxComponent {
    @Output('onLastElement') onLastElement = new EventEmitter();

    public navigation = {hasPrev: true, hasNext: true};
    public photoDimension: Dimension = <Dimension>{top: 0, left: 0, width: 0, height: 0};
    public lightboxDimension: Dimension = <Dimension>{top: 0, left: 0, width: 0, height: 0};
    private transition: string = "";
    public blackCanvasOpacity: any = 0;

    private activePhoto: GalleryPhotoComponent;
    private gridPhotoQL: QueryList<GalleryPhotoComponent>;

    private visible = false;
    private changeSubscription: Subscription = null;

    @ViewChild("root") elementRef: ElementRef;


    constructor(private fullScreenService: FullScreenService, private changeDetector: ChangeDetectorRef, private overlayService: OverlayService) {
    }


    //noinspection JSUnusedGlobalSymbols
    @HostListener('window:resize', ['$event'])
    onResize() {
        if (this.activePhoto) {
            this.disableAnimation();
            this.lightboxDimension.width = this.getScreenWidth();
            this.lightboxDimension.height = this.getScreenHeight();
            this.updateActivePhoto(this.activePhotoId);
        }
    }

    public nextImage() {
        this.disableAnimation();
        if (this.activePhotoId + 1 < this.gridPhotoQL.length) {
            this.showPhoto(this.activePhotoId + 1);
            if (this.activePhotoId + 3 >= this.gridPhotoQL.length) {
                this.onLastElement.emit({}); //trigger to render more photos if there are
            }
            return;
        }
        console.warn("can't find photo to show next");
    }

    public prevImage() {
        this.disableAnimation();
        if (this.activePhotoId > 0) {
            this.showPhoto(this.activePhotoId - 1);
            return;
        }
        console.warn("can't find photo to show prev");
    }


    activePhotoId: number = null;

    private showPhoto(photoIndex: number) {
        this.activePhoto = null;
        this.changeDetector.detectChanges();
        this.updateActivePhoto(photoIndex);
    }

    private updateActivePhoto(photoIndex: number) {
        let pcList = this.gridPhotoQL.toArray();


        if (photoIndex < 0 || photoIndex > this.gridPhotoQL.length) {
            throw new Error("Can't find the photo");
        }
        this.activePhotoId = photoIndex;
        this.activePhoto = pcList[photoIndex];

        this.photoDimension = this.calcLightBoxPhotoDimension(this.activePhoto.gridPhoto.photo);
        this.navigation.hasPrev = photoIndex > 0;
        this.navigation.hasNext = photoIndex + 1 < pcList.length;

        let to = this.activePhoto.getDimension();

        //if target image out of screen -> scroll to there
        if (this.getBodyScrollTop() > to.top || this.getBodyScrollTop() + this.getScreenHeight() < to.top) {
            this.setBodyScrollTop(to.top);
        }

    }

    public show(photo: PhotoDTO) {
        this.enableAnimation();
        this.visible = true;
        let selectedPhoto = this.findPhotoComponent(photo);
        if (selectedPhoto === null) {
            throw new Error("Can't find Photo");
        }

        this.lightboxDimension = selectedPhoto.getDimension();
        this.lightboxDimension.top -= this.getBodyScrollTop();
        this.blackCanvasOpacity = 0;
        this.photoDimension = selectedPhoto.getDimension();

        //disable scroll
        this.overlayService.showOverlay();
        setImmediate(() => {
            this.lightboxDimension = <Dimension>{
                top: 0,
                left: 0,
                width: this.getScreenWidth(),
                height: this.getScreenHeight()
            };
            this.blackCanvasOpacity = 1.0;
            this.showPhoto(this.gridPhotoQL.toArray().indexOf(selectedPhoto));
        });
    }

    public hide() {
        this.enableAnimation();
        this.fullScreenService.exitFullScreen();

        this.lightboxDimension = this.activePhoto.getDimension();
        this.lightboxDimension.top -= this.getBodyScrollTop();
        this.blackCanvasOpacity = 0;
        this.photoDimension = this.activePhoto.getDimension();
        setTimeout(() => {
            this.visible = false;
            this.activePhoto = null;
            this.overlayService.hideOverlay();
        }, 500);

    }


    setGridPhotoQL(value: QueryList<GalleryPhotoComponent>) {
        if (this.changeSubscription != null) {
            this.changeSubscription.unsubscribe();
        }
        this.gridPhotoQL = value;
        this.changeSubscription = this.gridPhotoQL.changes.subscribe(() => {
            if (this.activePhotoId != null && this.gridPhotoQL.length > this.activePhotoId) {
                this.updateActivePhoto(this.activePhotoId);
            }
        });
    }

    private findPhotoComponent(photo: any) {
        let galleryPhotoComponents = this.gridPhotoQL.toArray();
        for (let i = 0; i < galleryPhotoComponents.length; i++) {
            if (galleryPhotoComponents[i].gridPhoto.photo == photo) {
                return galleryPhotoComponents[i];
            }
        }
        return null;
    }

    //noinspection JSUnusedGlobalSymbols
    @HostListener('window:keydown', ['$event'])
    onKeyPress(e: KeyboardEvent) {
        if (this.visible != true) {
            return;
        }
        let event: KeyboardEvent = window.event ? <any>window.event : e;
        switch (event.keyCode) {
            case 37:
                if (this.activePhotoId > 0) {
                    this.prevImage();
                }
                break;
            case 39:
                if (this.activePhotoId < this.gridPhotoQL.length - 1) {
                    this.nextImage();
                }
                break;
            case 27: //escape
                this.hide();
                break;
        }
    }

    private enableAnimation() {
        this.transition = null;
    }

    private disableAnimation() {
        this.transition = "initial";
    }


    private getBodyScrollTop(): number {
        return window.scrollY;
    }

    private setBodyScrollTop(value: number) {
        window.scrollTo(window.scrollX, value);
    }

    private getScreenWidth() {
        return window.innerWidth;
    }

    private getScreenHeight() {
        return window.innerHeight;
    }


    private calcLightBoxPhotoDimension(photo: PhotoDTO): Dimension {
        let width = 0;
        let height = 0;
        if (photo.metadata.size.height > photo.metadata.size.width) {
            width = Math.round(photo.metadata.size.width * (this.getScreenHeight() / photo.metadata.size.height));
            height = this.getScreenHeight();
        } else {
            width = this.getScreenWidth();
            height = Math.round(photo.metadata.size.height * (this.getScreenWidth() / photo.metadata.size.width));
        }
        let top = (this.getScreenHeight() / 2 - height / 2);
        let left = (this.getScreenWidth() / 2 - width / 2);

        return <Dimension>{top: top, left: left, width: width, height: height};
    }
}