/*!
 * @license
 * Copyright 2016 Alfresco Software, Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { Component, Input, HostListener } from '@angular/core';

declare let PDFJS: any;
declare let __moduleName: string;

@Component({
    moduleId: __moduleName,
    selector: 'pdf-viewer',
    templateUrl: './pdfViewer.component.html',
    styleUrls: ['./pdfViewer.component.css']
})
export class PdfViewerComponent {

    @Input()
    urlFile: string;

    @Input()
    nameFile: string;

    currentPdfDocument: any;
    page: number;
    displayPage: number;
    totalPages: number;

    pdfViewer: any;

    currentScaleMode: string;
    currentScale: number;

    documentContainer: any;

    MAX_AUTO_SCALE: number = 1.25;

    ngOnChanges(changes) {
        if (!this.urlFile) {
            throw new Error('Attribute urlFile is required');
        }

        if (this.urlFile) {
            return new Promise((resolve, reject) => {
                this.getPDFJS().getDocument(this.urlFile, null, null).then((pdfDocument) => {
                    this.currentPdfDocument = pdfDocument;
                    this.totalPages = pdfDocument.numPages;
                    this.page = 1;
                    this.displayPage = 1;
                    this.initPDFViewer(this.currentPdfDocument);

                    this.currentPdfDocument.getPage(1).then(() => {
                        this.scalePage('auto');
                    });

                }, (error) => {
                    reject(error);
                });
                resolve();
            });
        }
    }

    /**
     * return the PDFJS global object (exist to facilitate the mock of PDFJS in the test)
     * @returns {PDFJS}
     */
    getPDFJS() {
        return PDFJS;
    }

    initPDFViewer(pdfDocument: any) {
        PDFJS.verbosity = 5;

        this.documentContainer = document.getElementById('viewer-pdf-container');
        let viewer: any = document.getElementById('viewer-viewerPdf');

        this.pdfViewer = new PDFJS.PDFViewer({
            container: this.documentContainer,
            viewer: viewer
        });

        this.pdfViewer.setDocument(pdfDocument);
    }


    /**
     * Method to scale the page current support implementation
     * @param {string} scaleMode - new scale mode
     */
    scalePage(scaleMode) {
        this.currentScaleMode = scaleMode;

        let currentPage = this.pdfViewer._pages[this.pdfViewer._currentPageNumber];

        let pageWidthScale = (this.documentContainer.clientWidth) /
            currentPage.width * currentPage.scale;
        let pageHeightScale = (this.documentContainer.clientHeight ) /
            currentPage.width * currentPage.scale;

        let scale;

        switch (this.currentScaleMode) {
            case 'page-actual':
                scale = 1;
                break;
            case 'page-width':
                scale = pageWidthScale;
                break;
            case 'page-height':
                scale = pageHeightScale;
                break;
            case 'page-fit':
                scale = Math.min(pageWidthScale, pageHeightScale);
                break;
            case 'auto':
                let horizontalScale;
                if (this.isLandscape) {
                    horizontalScale = Math.min(pageHeightScale, pageWidthScale);
                } else {
                    horizontalScale = pageWidthScale;
                }
                scale = Math.min(this.MAX_AUTO_SCALE, horizontalScale);

                break;
            default:
                console.error('pdfViewSetScale: \'' + scaleMode + '\' is an unknown zoom value.');
                return;
        }

        this.setScaleUpdatePages(scale);
    }

    /**
     * Update all the pages with the newScale scale
     * @param {number} newScale - new scale page
     */
    setScaleUpdatePages(newScale: number) {
        if (!this.isSameScale(this.currentScale, newScale)) {
            this.currentScale = newScale;

            this.pdfViewer._pages.forEach(function (currentPage) {
                currentPage.update(newScale);
            });
        }
    }

    /**
     * method to check if the request scale of the page is the same for avoid unuseful re-rendering
     *
     * @param {number} oldScale - old scale page
     * @param {number} newScale - new scale page
     */
    isSameScale(oldScale: number, newScale: number) {
        return (newScale === oldScale);
    }


    /**
     * method to check if is a land scape view
     *
     * @param {number} width
     * @param {number} height
     */
    isLandscape(width: number, height: number) {
        return (width > height);
    }

    /**
     * Method triggered when the page is resized
     */
    onResize() {
        this.scalePage('page-fit');
    }

    /**
     * load the previous page
     */
    previousPage() {
        if (this.pdfViewer && this.page > 1) {
            this.page--;
            this.displayPage = this.page;

            this.pdfViewer.currentPageNumber = this.page;
        }
    }

    /**
     * load the next page
     */
    nextPage() {
        if (this.pdfViewer && this.page < this.totalPages) {
            this.page++;
            this.displayPage = this.page;

            this.pdfViewer.currentPageNumber = this.page;
        }
    }

    /**
     * load the page in input
     *
     * @param {string} page - page to load
     */
    inputPage(page: string) {
        let pageInput = parseInt(page, 10);

        if (!isNaN(pageInput) && pageInput > 0 && pageInput <= this.totalPages) {
            this.page = pageInput;

            this.pdfViewer.currentPageNumber = this.page;
        } else {
            this.displayPage = this.page;
        }
    }

    /**
     * Litener Keyboard Event
     * @param {KeyboardEvent} event
     */
    @HostListener('document:keydown', ['$event'])
    handleKeyboardEvent(event: KeyboardEvent) {
        let key = event.keyCode;
        if (key === 39) { //right arrow
            this.nextPage();
        } else if (key === 37) {//left arrow
            this.previousPage();
        }
    }

}