import {
    Inject,
    Injectable,
    Optional,
    SkipSelf,
    Renderer2,
} from '@angular/core';
import { DOCUMENT } from '@angular/common';
import { WINDOW } from '../ngx-window-token/window-token';

@Injectable()
export class ClipboardService {
    private tempTextArea: HTMLTextAreaElement;
    private _currentCopiedText: string;
    constructor(
        @Inject(DOCUMENT) private document: any,
        @Inject(WINDOW) private window: any
    ) {}
    public get isSupported(): boolean {
        return (
            !!this.document.queryCommandSupported &&
            !!this.document.queryCommandSupported('copy')
        );
    }

    getCurrentCopiedText(): string {
        return this._currentCopiedText;
    }

    public isTargetValid(
        element: HTMLInputElement | HTMLTextAreaElement
    ): boolean {
        if (
            element instanceof HTMLInputElement ||
            element instanceof HTMLTextAreaElement
        ) {
            if (element.hasAttribute('disabled')) {
                throw new Error(
                    'Invalid "target" attribute. Please use "readonly" instead of "disabled" attribute'
                );
            }
            return true;
        }
        throw new Error('Target should be input or textarea');
    }

    /**
     * copyFromInputElement
     */
    public copyFromInputElement(
        targetElm: HTMLInputElement | HTMLTextAreaElement,
        renderer: Renderer2
    ): boolean {
        try {
            this.selectTarget(targetElm, renderer);
            const re = this.copyText();
            this.clearSelection(targetElm, this.window);
            this._currentCopiedText = targetElm?.value;
            return re;
        } catch (error) {
            return false;
        }
    }

    /**
     * Creates a fake textarea element, sets its value from `text` property,
     * and makes a selection on it.
     */
    public copyFromContent(content: string, renderer: Renderer2) {
        if (!this.tempTextArea) {
            this.tempTextArea = this.createTempTextArea(
                this.document,
                this.window
            );
            this.document.body.appendChild(this.tempTextArea);
        }
        this.tempTextArea.value = content;
        this._currentCopiedText = content;
        return this.copyFromInputElement(this.tempTextArea, renderer);
    }

    // remove temporary textarea if any
    public destroy() {
        if (this.tempTextArea) {
            this.document.body.removeChild(this.tempTextArea);
            this.tempTextArea = undefined;
        }
    }

    // select the target html input element
    private selectTarget(
        inputElement: HTMLInputElement | HTMLTextAreaElement,
        renderer: Renderer2
    ): number | undefined {
        inputElement.select();
        inputElement.setSelectionRange(0, inputElement.value.length);
        return inputElement.value.length;
    }

    private copyText(): boolean {
        return this.document.execCommand('copy');
    }
    // Removes current selection and focus from `target` element.
    private clearSelection(
        inputElement: HTMLInputElement | HTMLTextAreaElement,
        window: Window
    ) {
        if (inputElement) {
            inputElement.blur();
        }
        window.getSelection().removeAllRanges();
    }

    // create a fake textarea for copy command
    private createTempTextArea(
        doc: Document,
        window: Window
    ): HTMLTextAreaElement {
        const isRTL = doc.documentElement.getAttribute('dir') === 'rtl';
        let ta: HTMLTextAreaElement;
        ta = doc.createElement('textarea');
        // Prevent zooming on iOS
        ta.style.fontSize = '12pt';
        // Reset box model
        ta.style.border = '0';
        ta.style.padding = '0';
        ta.style.margin = '0';
        // Move element out of screen horizontally
        ta.style.position = 'absolute';
        ta.style[isRTL ? 'right' : 'left'] = '-9999px';
        // Move element to the same position vertically
        let yPosition = window.pageYOffset || doc.documentElement.scrollTop;
        ta.style.top = yPosition + 'px';
        ta.setAttribute('readonly', '');
        return ta;
    }
}
// this pattern is mentioned in https://github.com/angular/angular/issues/13854 in #43
export function CLIPBOARD_SERVICE_PROVIDER_FACTORY(
    doc: Document,
    win: Window,
    parentDispatcher: ClipboardService
) {
    return parentDispatcher || new ClipboardService(doc, win);
}

export const CLIPBOARD_SERVICE_PROVIDER = {
    provide: ClipboardService,
    deps: [
        DOCUMENT,
        WINDOW,
        [new Optional(), new SkipSelf(), ClipboardService],
    ],
    useFactory: CLIPBOARD_SERVICE_PROVIDER_FACTORY,
};
