// (C) Copyright 2015 Moodle Pty 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 { Injectable, Type } from '@angular/core';
import { AddonModForum, AddonModForumProvider } from '../forum';
import { CoreCourse, CoreCourseAnyModuleData } from '@features/course/services/course';
import { CoreCourseModule } from '@features/course/services/course-helper';
import { CoreNavigationOptions, CoreNavigator } from '@services/navigator';
import { makeSingleton, Translate } from '@singletons';
import { CoreEvents } from '@singletons/events';
import { CoreSites } from '@services/sites';
import { CoreUtils } from '@services/utils/utils';
import { CoreCourseModuleHandler, CoreCourseModuleHandlerData } from '@features/course/services/module-delegate';
import { CoreConstants } from '@/core/constants';
import { AddonModForumIndexComponent } from '../../components/index';

/**
 * Handler to support forum modules.
 */
@Injectable({ providedIn: 'root' })
export class AddonModForumModuleHandlerService implements CoreCourseModuleHandler {

    static readonly PAGE_NAME = 'mod_forum';

    name = 'AddonModForum';
    modName = 'forum';

    supportedFeatures = {
        [CoreConstants.FEATURE_GROUPS]: true,
        [CoreConstants.FEATURE_GROUPINGS]: true,
        [CoreConstants.FEATURE_MOD_INTRO]: true,
        [CoreConstants.FEATURE_COMPLETION_TRACKS_VIEWS]: true,
        [CoreConstants.FEATURE_COMPLETION_HAS_RULES]: true,
        [CoreConstants.FEATURE_GRADE_HAS_GRADE]: true,
        [CoreConstants.FEATURE_GRADE_OUTCOMES]: true,
        [CoreConstants.FEATURE_BACKUP_MOODLE2]: true,
        [CoreConstants.FEATURE_SHOW_DESCRIPTION]: true,
        [CoreConstants.FEATURE_RATE]: true,
        [CoreConstants.FEATURE_PLAGIARISM]: true,
    };

    /**
     * Check if the handler is enabled on a site level.
     *
     * @return Whether or not the handler is enabled on a site level.
     */
    isEnabled(): Promise<boolean> {
        return Promise.resolve(true);
    }

    /**
     * Get the data required to display the module in the course contents view.
     *
     * @param module The module object.
     * @param courseId The course ID.
     * @param sectionId The section ID.
     * @return Data to render the module.
     */
    getData(module: CoreCourseAnyModuleData, courseId: number): CoreCourseModuleHandlerData {
        const data: CoreCourseModuleHandlerData = {
            icon: CoreCourse.instance.getModuleIconSrc(this.modName, 'modicon' in module ? module.modicon : undefined),
            title: module.name,
            class: 'addon-mod_forum-handler',
            showDownloadButton: true,
            action(event: Event, module: CoreCourseModule, courseId: number, options?: CoreNavigationOptions): void {
                options = options || {};
                options.params = options.params || {};
                Object.assign(options.params, { module });

                CoreNavigator.instance.navigateToSitePath(
                    `${AddonModForumModuleHandlerService.PAGE_NAME}/${courseId}/${module.id}`,
                    options,
                );
            },
        };

        if ('afterlink' in module && !!module.afterlink) {
            data.extraBadgeColor = '';
            const match = />(\d+)[^<]+/.exec(module.afterlink);
            data.extraBadge = match ? Translate.instance.instant('addon.mod_forum.unreadpostsnumber', { $a : match[1] }) : '';
        } else {
            this.updateExtraBadge(data, courseId, module.id);
        }

        const event = CoreEvents.on(
            AddonModForumProvider.MARK_READ_EVENT,
            eventData => {
                if (eventData.courseId !== courseId || eventData.moduleId !== module.id) {
                    return;
                }

                this.updateExtraBadge(data, eventData.courseId, eventData.moduleId, eventData.siteId);
            },
            CoreSites.instance.getCurrentSiteId(),
        );

        data.onDestroy = () => event.off();

        return data;
    }

    /**
     * Get the component to render the module. This is needed to support singleactivity course format.
     * The component returned must implement CoreCourseModuleMainComponent.
     *
     * @return The component to use, undefined if not found.
     */
    async getMainComponent(): Promise<Type<unknown> | undefined> {
        return AddonModForumIndexComponent;
    }

    /**
     * Whether to display the course refresher in single activity course format. If it returns false, a refresher must be
     * included in the template that calls the doRefresh method of the component. Defaults to true.
     *
     * @return Whether the refresher should be displayed.
     */
    displayRefresherInSingleActivity(): boolean {
        return false;
    }

    /**
     * Triggers an update for the extra badge text.
     *
     * @param data Course Module Handler data.
     * @param courseId Course ID.
     * @param moduleId Course module ID.
     * @param siteId Site ID. If not defined, current site.
     */
    async updateExtraBadge(data: CoreCourseModuleHandlerData, courseId: number, moduleId: number, siteId?: string): Promise<void> {
        siteId = siteId || CoreSites.instance.getCurrentSiteId();

        if (!siteId) {
            return;
        }

        data.extraBadge =  Translate.instance.instant('core.loading');
        data.extraBadgeColor = 'light';

        await CoreUtils.instance.ignoreErrors(AddonModForum.instance.invalidateForumData(courseId));

        try {
            // Handle unread posts.
            const forum = await AddonModForum.instance.getForum(courseId, moduleId, { siteId });

            data.extraBadgeColor = '';
            data.extraBadge = forum.unreadpostscount
                ? Translate.instance.instant(
                    'addon.mod_forum.unreadpostsnumber',
                    { $a : forum.unreadpostscount },
                )
                : '';
        } catch (error) {
            // Ignore errors.
            data.extraBadgeColor = '';
            data.extraBadge = '';
        }
    }

}

export class AddonModForumModuleHandler extends makeSingleton(AddonModForumModuleHandlerService) {}