import { Inject, Injectable, Renderer2, RendererFactory2 } from '@angular/core';
import { MatDialog, MatDialogRef } from '@angular/material/dialog';
import { TranslateService } from '@ngx-translate/core';
import { BehaviorSubject, firstValueFrom } from 'rxjs';
import { HelpModeDialogComponent } from './help-mode-dialog/help-mode-dialog.component';
import { HELP_DOCS, MANUAL_BASE_URL } from './tokens';

const VIRTUAL_SCROLL_ID = 'virtual-scroll';
const ANNOTATIONS_LIST_ID = 'annotations-list';
const SCROLL_BUTTONS_IDS = ['scroll-up', 'scroll-down'];

export const ScrollableParentViews = {
    VIRTUAL_SCROLL: 'VIRTUAL_SCROLL',
    ANNOTATIONS_LIST: 'ANNOTATIONS_LIST',
} as const;

export type ScrollableParentView = keyof typeof ScrollableParentViews;

interface Helper {
    readonly element: HTMLElement;
    readonly helperElement: HTMLElement;
    readonly scrollableParentView: ScrollableParentView;
    readonly dialogElement: boolean;
}

@Injectable({
    providedIn: 'root',
})
export class HelpModeService {
    private readonly _isHelpModeActive$ = new BehaviorSubject(false);
    readonly isHelpModeActive$ = this._isHelpModeActive$.asObservable();
    private readonly _helpModeDialogIsOpened$ = new BehaviorSubject(false);
    readonly helpModeDialogIsOpened$ = this._helpModeDialogIsOpened$.asObservable();

    private readonly _helperElements: Record<string, Helper> = {};
    private readonly _renderer: Renderer2;

    private _dialogMode = false;

    constructor(
        @Inject(HELP_DOCS) private readonly _docs: Record<string, Record<string, string>>,
        @Inject(MANUAL_BASE_URL) private readonly _manualBaseURL: string,
        private readonly _dialog: MatDialog,
        private readonly _rendererFactory: RendererFactory2,
        private readonly _translateService: TranslateService,
    ) {
        this._renderer = this._rendererFactory.createRenderer(null, null);
    }

    get isHelpModeActive(): boolean {
        return this._isHelpModeActive$.getValue();
    }

    get helpModeDialogIsOpened(): boolean {
        return this._helpModeDialogIsOpened$.getValue();
    }

    openHelpModeDialog(): MatDialogRef<HelpModeDialogComponent> {
        this._helpModeDialogIsOpened$.next(true);

        const ref = this._dialog.open(HelpModeDialogComponent, {
            width: '600px',
        });

        firstValueFrom(ref.afterClosed()).then(() => {
            this._helpModeDialogIsOpened$.next(false);
        });
        return ref;
    }

    getDocsLink(elementName: string): string {
        return this._docs[elementName] ? `${this._manualBaseURL}${this._docs[elementName][this._translateService.currentLang]}` : '';
    }

    activateHelpMode(dialogMode: boolean = false): void {
        if (!this.isHelpModeActive) {
            document.body.style.setProperty('overflow', 'hidden');
            this._isHelpModeActive$.next(true);
            this.openHelpModeDialog();
            this._dialogMode = dialogMode;
            setTimeout(() => {
                this._enableHelperElements();
            });
        }
    }

    deactivateHelpMode(): void {
        if (this.isHelpModeActive) {
            document.body.style.removeProperty('overflow');
            this._isHelpModeActive$.next(false);
            this._disableHelperElements();
        }
    }

    highlightHelperElements(): void {
        Object.values(this._helperElements).forEach(({ element, helperElement }) => {
            this._renderer.addClass(helperElement, 'help-highlight');
            setTimeout(() => {
                this._renderer.removeClass(helperElement, 'help-highlight');
            }, 500);
        });
    }

    addElement(
        helperElementName: string,
        element: HTMLElement,
        helperElement: HTMLElement,
        scrollableParentView: ScrollableParentView,
        dialogElement: boolean,
    ): void {
        this._helperElements[helperElementName] = { element, helperElement, scrollableParentView, dialogElement };
    }

    updateHelperElements() {
        Object.values(this._helperElements).forEach(({ element, helperElement, scrollableParentView }) => {
            this._updateHelperElement(element, helperElement, scrollableParentView);
        });
    }

    private _isElementVisible(element: HTMLElement, scrollableParentView: ScrollableParentView): boolean {

        let elementRect: DOMRect = element.getBoundingClientRect();
        if (elementRect.top === 0 && elementRect.left === 0 && elementRect.bottom === 0 && elementRect.bottom === 0) {
            return false;
        }

        if (scrollableParentView) {
            const scrollableElementId = scrollableParentView === ScrollableParentViews.VIRTUAL_SCROLL ? VIRTUAL_SCROLL_ID : ANNOTATIONS_LIST_ID;
            const scrollableElement: HTMLElement = <HTMLElement>document.getElementById(scrollableElementId);

            if (!scrollableElement) {
                return false;
            }

            const scrollableElementRect = scrollableElement.getBoundingClientRect();

            if (!(elementRect.top > scrollableElementRect.top
                && elementRect.left > scrollableElementRect.left
                && elementRect.bottom < scrollableElementRect.bottom
                && elementRect.right < scrollableElementRect.right)) {
                return false;
            }

            if (scrollableParentView === ScrollableParentViews.VIRTUAL_SCROLL) {
                for (const id of SCROLL_BUTTONS_IDS) {
                    const scroll: HTMLElement = <HTMLElement>document.getElementById(id);

                    elementRect = element.getBoundingClientRect();
                    const scrollRect = scroll?.getBoundingClientRect();

                    if (elementRect.top + elementRect.height > scrollRect.top
                        && elementRect.left + elementRect.width > scrollRect.left
                        && elementRect.bottom - elementRect.height < scrollRect.bottom
                        && elementRect.right - elementRect.width < scrollRect.right) {
                        return false;
                    }
                }
            }
        }

        return true;
    }

    private _updateHelperElement(element: HTMLElement, helperElement: HTMLElement, scrollableParentView: ScrollableParentView) {
        if (this._isElementVisible(element, scrollableParentView)) {
            const dimensions = this._getElementDimensions(element);
            helperElement.style.cssText = `
                top:${dimensions.y}px;
                left:${dimensions.x}px;
                width:${dimensions.width}px;
                height:${dimensions.height}px;
            `;
            helperElement.classList.add('help-mode');
        } else {
            helperElement.classList.remove('help-mode');
        }

    }

    private _enableHelperElements() {
        Object.values(this._helperElements).forEach(({ element, helperElement, scrollableParentView, dialogElement }) => {
            if (this._dialogMode === dialogElement ) {
                document.body.appendChild(helperElement);
                this._updateHelperElement(element, helperElement, scrollableParentView);
            }
        });
    }

    private _disableHelperElements() {
        Object.values(this._helperElements).forEach(({ helperElement }) => {
            if (document.body.contains(helperElement)) {
                document.body.removeChild(helperElement);
            }
        });
    }

    private _getElementDimensions(element: HTMLElement) {
        const rect = element.getBoundingClientRect();
        return {
            y: rect.top,
            x: rect.left,
            height: rect.height,
            width: rect.width,
        };
    }
}