// (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 {
    Component, OnInit, Input, Output, EventEmitter, Optional, DoCheck, KeyValueDiffers, ViewChild, ElementRef
} from '@angular/core';
import { NavController } from 'ionic-angular';
import { CoreDomUtilsProvider } from '@providers/utils/dom';
import { CoreSitePluginsProvider } from '../../providers/siteplugins';
import { Subject } from 'rxjs';

/**
 * Component to render a site plugin content.
 */
@Component({
    selector: 'core-site-plugins-plugin-content',
    templateUrl: 'core-siteplugins-plugin-content.html',
})
export class CoreSitePluginsPluginContentComponent implements OnInit, DoCheck {
    // Get the compile element. Don't set the right type to prevent circular dependencies.
    @ViewChild('compile') compileComponent: ElementRef;

    @Input() component: string;
    @Input() method: string;
    @Input() args: any;
    @Input() initResult: any; // Result of the init WS call of the handler.
    @Input() data: any; // Data to pass to the component.
    @Input() preSets: any; // The preSets for the WS call.
    @Output() onContentLoaded?: EventEmitter<boolean>; // Emits an event when the content is loaded.
    @Output() onLoadingContent?: EventEmitter<boolean>; // Emits an event when starts to load the content.

    content: string; // Content.
    javascript: string; // Javascript to execute.
    otherData: any; // Other data of the content.
    dataLoaded: boolean;
    invalidateObservable: Subject<void>; // An observable to notify observers when to invalidate data.
    jsData: any; // Data to pass to the component.
    forceCompile: boolean; // Force compilation on PTR.

    protected differ: any; // To detect changes in the data input.

    constructor(protected domUtils: CoreDomUtilsProvider, protected sitePluginsProvider: CoreSitePluginsProvider,
            @Optional() protected navCtrl: NavController, differs: KeyValueDiffers) {
        this.onContentLoaded = new EventEmitter();
        this.onLoadingContent = new EventEmitter();
        this.invalidateObservable = new Subject<void>();
        this.differ = differs.find([]).create();
    }

    /**
     * Component being initialized.
     */
    ngOnInit(): void {
        this.fetchContent();
    }

    /**
     * Detect and act upon changes that Angular can’t or won’t detect on its own (objects and arrays).
     */
    ngDoCheck(): void {
        if (!this.data || !this.jsData) {
            return;
        }

        // Check if there's any change in the data object.
        const changes = this.differ.diff(this.data);
        if (changes) {
            this.jsData = Object.assign(this.jsData, this.data);
        }
    }

    /**
     * Fetches the content to render.
     *
     * @param refresh Whether the user is refreshing.
     * @return Promise resolved when done.
     */
    fetchContent(refresh?: boolean): Promise<any> {
        this.onLoadingContent.emit(refresh);

        this.forceCompile = false;

        return this.sitePluginsProvider.getContent(this.component, this.method, this.args, this.preSets).then((result) => {
            this.content = result.templates.length ? result.templates[0].html : ''; // Load first template.
            this.javascript = result.javascript;
            this.otherData = result.otherdata;
            this.data = this.data || {};
            this.forceCompile = true;

            this.jsData = Object.assign(this.data, this.sitePluginsProvider.createDataForJS(this.initResult, result));

            // Pass some methods as jsData so they can be called from the template too.
            this.jsData.openContent = this.openContent.bind(this);
            this.jsData.refreshContent = this.refreshContent.bind(this);
            this.jsData.updateContent = this.updateContent.bind(this);

            this.onContentLoaded.emit(refresh);
        }).catch((error) => {
            // Make it think it's loaded - otherwise it sticks on 'loading' and stops navigation working.
            this.content = '<div></div>';
            this.onContentLoaded.emit(refresh);

            this.domUtils.showErrorModalDefault(error, 'core.errorloadingcontent', true);
        }).finally(() => {
            this.dataLoaded = true;
        });
    }

    /**
     * Open a new page with a new content.
     *
     * @param title The title to display with the new content.
     * @param args New params.
     * @param component New component. If not provided, current component
     * @param method New method. If not provided, current method
     * @param jsData JS variables to pass to the new view so they can be used in the template or JS.
     *               If true is supplied instead of an object, all initial variables from current page will be copied.
     * @param preSets The preSets for the WS call of the new content.
     */
    openContent(title: string, args: any, component?: string, method?: string, jsData?: any, preSets?: any): void {
        if (jsData === true) {
            jsData = this.data;
        }

        this.navCtrl.push('CoreSitePluginsPluginPage', {
            title: title,
            component: component || this.component,
            method: method || this.method,
            args: args,
            initResult: this.initResult,
            jsData: jsData,
            preSets: preSets
        });
    }

    /**
     * Refresh the data.
     *
     * @param showSpinner Whether to show spinner while refreshing.
     */
    refreshContent(showSpinner: boolean = true): Promise<any> {
        if (showSpinner) {
            this.dataLoaded = false;
        }

        this.invalidateObservable.next(); // Notify observers.

        return this.sitePluginsProvider.invalidateContent(this.component, this.method, this.args).finally(() => {
            return this.fetchContent(true);
        });
    }

    /**
     * Update the content, usually with a different method or params.
     *
     * @param args New params.
     * @param component New component. If not provided, current component
     * @param method New method. If not provided, current method
     * @param jsData JS variables to pass to the new view so they can be used in the template or JS.
     */
    updateContent(args: any, component?: string, method?: string, jsData?: any): void {
        this.component = component || this.component;
        this.method = method || this.method;
        this.args = args;
        this.dataLoaded = false;
        if (jsData) {
            Object.assign(this.data, jsData);
        }

        this.fetchContent();
    }

    /**
     * Call a certain function on the component instance.
     *
     * @param name Name of the function to call.
     * @param params List of params to send to the function.
     * @return Result of the call. Undefined if no component instance or the function doesn't exist.
     */
    callComponentFunction(name: string, params?: any[]): any {
        if (this.compileComponent) {
            return (<any> this.compileComponent).callComponentFunction(name, params);
        }
    }
}