// (C) Copyright 2015 Martin Dougiamas
//
// 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 { Injectable } from '@angular/core';
import { Platform } from 'ionic-angular';
import { CoreFileProvider } from '../file';
import { CoreLoggerProvider } from '../logger';
import { CoreSitesProvider } from '../sites';
import { CoreDomUtilsProvider } from './dom';
import { CoreTextUtilsProvider } from './text';
import { CoreUrlUtilsProvider } from './url';
import { CoreUtilsProvider } from './utils';

/*
 * "Utils" service with helper functions for iframes, embed and similar.
 */
@Injectable()
export class CoreIframeUtilsProvider {
    static FRAME_TAGS = ['iframe', 'frame', 'object', 'embed'];

    protected logger;

    constructor(logger: CoreLoggerProvider, private fileProvider: CoreFileProvider, private sitesProvider: CoreSitesProvider,
            private urlUtils: CoreUrlUtilsProvider, private textUtils: CoreTextUtilsProvider, private utils: CoreUtilsProvider,
            private domUtils: CoreDomUtilsProvider, private platform: Platform) {
        this.logger = logger.getInstance('CoreUtilsProvider');
    }

    /**
     * Given an element, return the content window and document.
     * Please notice that the element should be an iframe, embed or similar.
     *
     * @param {any} element Element to treat (iframe, embed, ...).
     * @return {{ window: Window, document: Document }} Window and Document.
     */
    getContentWindowAndDocument(element: any): { window: Window, document: Document } {
        let contentWindow: Window = element.contentWindow,
            contentDocument: Document;

        try {
            contentDocument = element.contentDocument || (contentWindow && contentWindow.document);
        } catch (ex) {
            // Ignore errors.
        }

        if (!contentWindow && contentDocument) {
            // It's probably an <object>. Try to get the window.
            contentWindow = contentDocument.defaultView;
        }

        if (!contentWindow && element.getSVGDocument) {
            // It's probably an <embed>. Try to get the window and the document.
            try {
                contentDocument = element.getSVGDocument();
            } catch (ex) {
                // Ignore errors.
            }

            if (contentDocument && contentDocument.defaultView) {
                contentWindow = contentDocument.defaultView;
            } else if (element.window) {
                contentWindow = element.window;
            } else if (element.getWindow) {
                contentWindow = element.getWindow();
            }
        }

        return { window: contentWindow, document: contentDocument };
    }

    /**
     * Redefine the open method in the contentWindow of an element and the sub frames.
     * Please notice that the element should be an iframe, embed or similar.
     *
     * @param {any} element Element to treat (iframe, embed, ...).
     * @param {Window} contentWindow The window of the element contents.
     * @param {Document} contentDocument The document of the element contents.
     */
    redefineWindowOpen(element: any, contentWindow: Window, contentDocument: Document): void {
        if (contentWindow) {
            // Intercept window.open.
            contentWindow.open = (url: string): Window => {
                const scheme = this.urlUtils.getUrlScheme(url);
                if (!scheme) {
                    // It's a relative URL, use the frame src to create the full URL.
                    const src = element.src || element.data;
                    if (src) {
                        const dirAndFile = this.fileProvider.getFileAndDirectoryFromPath(src);
                        if (dirAndFile.directory) {
                            url = this.textUtils.concatenatePaths(dirAndFile.directory, url);
                        } else {
                            this.logger.warn('Cannot get iframe dir path to open relative url', url, element);

                            return new Window(); // Return new Window object.
                        }
                    } else {
                        this.logger.warn('Cannot get iframe src to open relative url', url, element);

                        return new Window(); // Return new Window object.
                    }
                }

                if (url.indexOf('cdvfile://') === 0 || url.indexOf('file://') === 0) {
                    // It's a local file.
                    this.utils.openFile(url).catch((error) => {
                        this.domUtils.showErrorModal(error);
                    });
                } else {
                    // It's an external link, we will open with browser. Check if we need to auto-login.
                    if (!this.sitesProvider.isLoggedIn()) {
                        // Not logged in, cannot auto-login.
                        this.utils.openInBrowser(url);
                    } else {
                        this.sitesProvider.getCurrentSite().openInBrowserWithAutoLoginIfSameSite(url);
                    }
                }

                return new Window(); // Return new Window object.
            };
        }

        if (contentDocument) {
            // Search sub frames.
            CoreIframeUtilsProvider.FRAME_TAGS.forEach((tag) => {
                const elements = Array.from(contentDocument.querySelectorAll(tag));
                elements.forEach((subElement) => {
                    this.treatFrame(subElement);
                });
            });
        }
    }

    /**
     * Intercept window.open in a frame and its subframes, shows an error modal instead.
     * Search links (<a>) and open them in browser or InAppBrowser if needed.
     *
     * @param {any} element Element to treat (iframe, embed, ...).
     */
    treatFrame(element: any): void {
        if (element) {
            let winAndDoc = this.getContentWindowAndDocument(element);
            // Redefine window.open in this element and sub frames, it might have been loaded already.
            this.redefineWindowOpen(element, winAndDoc.window, winAndDoc.document);
            // Treat links.
            this.treatFrameLinks(element, winAndDoc.document);

            element.addEventListener('load', () => {
                // Element loaded, redefine window.open and treat links again.
                winAndDoc = this.getContentWindowAndDocument(element);
                this.redefineWindowOpen(element, winAndDoc.window, winAndDoc.document);
                this.treatFrameLinks(element, winAndDoc.document);

                if (winAndDoc.window) {
                    // Send a resize events to the iframe so it calculates the right size if needed.
                    setTimeout(() => {
                        winAndDoc.window.dispatchEvent(new Event('resize'));
                    }, 1000);
                }
            });
        }
    }

    /**
     * Search links (<a>) in a frame and open them in browser or InAppBrowser if needed.
     * Only links that haven't been treated by the frame's Javascript will be treated.
     *
     * @param {any} element Element to treat (iframe, embed, ...).
     * @param {Document} contentDocument The document of the element contents.
     */
    treatFrameLinks(element: any, contentDocument: Document): void {
        if (!contentDocument) {
            return;
        }

        contentDocument.addEventListener('click', (event) => {
            if (event.defaultPrevented) {
                // Event already prevented by some other code.
                return;
            }

            // Find the link being clicked.
            let el = <Element> event.target;
            while (el && el.tagName !== 'A') {
                el = el.parentElement;
            }
            if (!el || el.tagName !== 'A') {
                return;
            }
            const link = <HTMLAnchorElement> el;

            const scheme = this.urlUtils.getUrlScheme(link.href);
            if (!link.href || (scheme && scheme == 'javascript')) {
                // Links with no URL and Javascript links are ignored.
                return;
            }

            if (scheme && scheme != 'file' && scheme != 'filesystem') {
                // Scheme suggests it's an external resource, open it in browser.
                event.preventDefault();
                if (!this.sitesProvider.isLoggedIn()) {
                    this.utils.openInBrowser(link.href);
                } else {
                    this.sitesProvider.getCurrentSite().openInBrowserWithAutoLoginIfSameSite(link.href);
                }
            } else if (link.target == '_parent' || link.target == '_top' || link.target == '_blank') {
                // Opening links with _parent, _top or _blank can break the app. We'll open it in InAppBrowser.
                event.preventDefault();
                this.utils.openFile(link.href).catch((error) => {
                    this.domUtils.showErrorModal(error);
                });
            } else if (this.platform.is('ios') && (!link.target || link.target == '_self')) {
                // In cordova ios 4.1.0 links inside iframes stopped working. We'll manually treat them.
                event.preventDefault();
                if (element.tagName.toLowerCase() == 'object') {
                    element.setAttribute('data', link.href);
                } else {
                    element.setAttribute('src', link.href);
                }
            }
        });
    }
}