// (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 { Component, Optional, OnInit, OnDestroy, ViewChild, AfterViewInit } from '@angular/core';
import { ActivatedRoute, ActivatedRouteSnapshot, Params } from '@angular/router';
import { IonContent } from '@ionic/angular';
import { CoreCourseModuleMainActivityComponent } from '@features/course/classes/main-activity-component';
import {
    AddonModForum,
    AddonModForumData,
    AddonModForumProvider,
    AddonModForumSortOrder,
    AddonModForumDiscussion,
} from '@addons/mod/forum/services/forum.service';
import { AddonModForumOffline, AddonModForumOfflineDiscussion } from '@addons/mod/forum/services/offline.service';
import { Translate } from '@singletons';
import { CoreCourseContentsPage } from '@features/course/pages/contents/contents';
import { AddonModForumHelper } from '@addons/mod/forum/services/helper.service';
import { CoreGroups, CoreGroupsProvider } from '@services/groups';
import { CoreEvents } from '@singletons/events';
import { AddonModForumSyncProvider } from '@addons/mod/forum/services/sync.service';
import { CoreSites } from '@services/sites';
import { CoreUser } from '@features/user/services/user';
import { CoreDomUtils } from '@services/utils/dom';
import { CoreUtils } from '@services/utils/utils';
import { CoreCourse } from '@features/course/services/course';
import { CorePageItemsListManager } from '@classes/page-items-list-manager';
import { CoreSplitViewComponent } from '@components/split-view/split-view';

/**
 * Component that displays a forum entry page.
 */
@Component({
    selector: 'addon-mod-forum-index',
    templateUrl: 'index.html',
    styleUrls: ['index.scss'],
})
export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityComponent implements OnInit, AfterViewInit, OnDestroy {

    @ViewChild(CoreSplitViewComponent) splitView!: CoreSplitViewComponent;

    component = AddonModForumProvider.COMPONENT;
    moduleName = 'forum';
    descriptionNote?: string;
    forum?: AddonModForumData;
    canLoadMore = false;
    loadMoreError = false;
    discussions: AddonModForumDiscussionsManager;
    offlineDiscussions: AddonModForumOfflineDiscussion[] = [];
    selectedDiscussion = 0; // Disucssion ID or negative timecreated if it's an offline discussion.
    canAddDiscussion = false;
    addDiscussionText!: string;
    availabilityMessage: string | null = null;
    sortingAvailable!: boolean;
    sortOrders: AddonModForumSortOrder[] = [];
    selectedSortOrder: AddonModForumSortOrder | null = null;
    sortOrderSelectorExpanded = false;
    canPin = false;

    protected syncEventName = AddonModForumSyncProvider.AUTO_SYNCED;
    protected page = 0;
    trackPosts = false;
    protected usesGroups = false;
    protected syncManualObserver: any; // It will observe the sync manual event.
    protected replyObserver: any;
    protected newDiscObserver: any;
    protected viewDiscObserver: any;
    protected changeDiscObserver: any;

    hasOfflineRatings?: boolean;
    protected ratingOfflineObserver: any;
    protected ratingSyncObserver: any;

    constructor(
        route: ActivatedRoute,
        @Optional() protected content?: IonContent,
        @Optional() courseContentsPage?: CoreCourseContentsPage,
    ) {
        super('AddonModForumIndexComponent', content, courseContentsPage);

        this.discussions = new AddonModForumDiscussionsManager(
            route.component,
            this,
            courseContentsPage ? 'mod_forum/' : '',
        );
    }

    /**
     * Component being initialized.
     */
    async ngOnInit(): Promise<void> {
        this.addDiscussionText = Translate.instance.instant('addon.mod_forum.addanewdiscussion');
        this.sortingAvailable = AddonModForum.instance.isDiscussionListSortingAvailable();
        this.sortOrders = AddonModForum.instance.getAvailableSortOrders();

        await super.ngOnInit();
    }

    async ngAfterViewInit(): Promise<void> {
        await this.loadContent(false, true);

        if (!this.forum) {
            return;
        }

        CoreUtils.instance.ignoreErrors(
            AddonModForum.instance
                .logView(this.forum.id, this.forum.name)
                .then(async () => {
                    CoreCourse.instance.checkModuleCompletion(this.courseId!, this.module!.completiondata);

                    return;
                }),
        );

        this.discussions.start(this.splitView);
    }

    /**
     * Component being destroyed.
     */
    ngOnDestroy(): void {
        super.ngOnDestroy();

        this.syncManualObserver && this.syncManualObserver.off();
        this.newDiscObserver && this.newDiscObserver.off();
        this.replyObserver && this.replyObserver.off();
        this.viewDiscObserver && this.viewDiscObserver.off();
        this.changeDiscObserver && this.changeDiscObserver.off();
        this.ratingOfflineObserver && this.ratingOfflineObserver.off();
        this.ratingSyncObserver && this.ratingSyncObserver.off();
    }

    /**
     * Download the component contents.
     *
     * @param refresh Whether we're refreshing data.
     * @param sync If the refresh needs syncing.
     * @param showErrors Wether to show errors to the user or hide them.
     */
    protected async fetchContent(refresh: boolean = false, sync: boolean = false): Promise<void> {
        this.loadMoreError = false;

        const promises: Promise<void>[] = [];

        promises.push(this.fetchForum());
        promises.push(this.fetchSortOrderPreference());

        try {
            await Promise.all(promises);
            await Promise.all([
                this.fetchOfflineDiscussions(),
                this.fetchDiscussions(refresh),
            ]);
        } catch (error) {
            if (refresh) {
                CoreDomUtils.instance.showErrorModalDefault(error, 'addon.mod_forum.errorgetforum', true);

                this.loadMoreError = true; // Set to prevent infinite calls with infinite-loading.
            } else {
                // Get forum failed, retry without using cache since it might be a new activity.
                await this.refreshContent(sync);
            }
        }

        this.fillContextMenu(refresh);
    }

    private async fetchForum(refresh: boolean = false, sync: boolean = false, showErrors: boolean = false): Promise<void> {
        if (!this.courseId || !this.module) {
            return;
        }

        this.loadMoreError = false;

        const promises: Promise<void>[] = [];

        promises.push(
            AddonModForum.instance
                .getForum(this.courseId, this.module.id)
                .then(async (forum) => {
                    this.forum = forum;

                    this.description = forum.intro || this.description;
                    this.descriptionNote = Translate.instant('addon.mod_forum.numdiscussions', {
                        numdiscussions: forum.numdiscussions,
                    });
                    if (typeof forum.istracked != 'undefined') {
                        this.trackPosts = forum.istracked;
                    }

                    this.availabilityMessage = AddonModForumHelper.instance.getAvailabilityMessage(forum);

                    this.dataRetrieved.emit(forum);

                    switch (forum.type) {
                        case 'news':
                        case 'blog':
                            this.addDiscussionText = Translate.instant('addon.mod_forum.addanewtopic');
                            break;
                        case 'qanda':
                            this.addDiscussionText = Translate.instant('addon.mod_forum.addanewquestion');
                            break;
                        default:
                            this.addDiscussionText = Translate.instant('addon.mod_forum.addanewdiscussion');
                    }

                    if (!sync) {
                        return;
                    }

                    // Try to synchronize the forum.
                    const updated = await this.syncActivity(showErrors);

                    if (!updated) {
                        return;
                    }

                    // Sync successful, send event.
                    CoreEvents.trigger(AddonModForumSyncProvider.MANUAL_SYNCED, {
                        forumId: forum.id,
                        userId: CoreSites.instance.getCurrentSiteUserId(),
                        source: 'index',
                    }, CoreSites.instance.getCurrentSiteId());

                    const promises: Promise<void>[] = [];

                    // Check if the activity uses groups.
                    promises.push(
                        // eslint-disable-next-line promise/no-nesting
                        CoreGroups.instance
                            .getActivityGroupMode(this.forum.cmid)
                            .then(async mode => {
                                this.usesGroups = mode === CoreGroupsProvider.SEPARATEGROUPS
                                    || mode === CoreGroupsProvider.VISIBLEGROUPS;

                                return;
                            }),
                    );

                    promises.push(
                        // eslint-disable-next-line promise/no-nesting
                        AddonModForum.instance
                            .getAccessInformation(this.forum.id, { cmId: this.module!.id })
                            .then(async accessInfo => {
                                // Disallow adding discussions if cut-off date is reached and the user has not the
                                // capability to override it.
                                // Just in case the forum was fetched from WS when the cut-off date was not reached but it is now.
                                const cutoffDateReached = AddonModForumHelper.instance.isCutoffDateReached(this.forum!)
                                    && !accessInfo.cancanoverridecutoff;
                                this.canAddDiscussion = !!this.forum?.cancreatediscussions && !cutoffDateReached;

                                return;
                            }),
                    );

                    if (AddonModForum.instance.isSetPinStateAvailableForSite()) {
                        // Use the canAddDiscussion WS to check if the user can pin discussions.
                        promises.push(
                            // eslint-disable-next-line promise/no-nesting
                            AddonModForum.instance
                                .canAddDiscussionToAll(this.forum.id, { cmId: this.module!.id })
                                .then(async response => {
                                    this.canPin = !!response.canpindiscussions;

                                    return;
                                })
                                .catch(async () => {
                                    this.canPin = false;

                                    return;
                                }),
                        );
                    } else {
                        this.canPin = false;
                    }

                    await Promise.all(promises);

                    return;
                }),
        );

        promises.push(this.fetchSortOrderPreference());

        try {
            await Promise.all(promises);
            await Promise.all([
                this.fetchOfflineDiscussions(),
                this.fetchDiscussions(refresh),
            ]);
        } catch (message) {
            if (!refresh) {
                // Get forum failed, retry without using cache since it might be a new activity.
                return this.refreshContent(sync);
            }

            CoreDomUtils.instance.showErrorModalDefault(message, 'addon.mod_forum.errorgetforum', true);

            this.loadMoreError = true; // Set to prevent infinite calls with infinite-loading.
        }

        this.fillContextMenu(refresh);
    }

    /**
     * Convenience function to fetch offline discussions.
     *
     * @return Promise resolved when done.
     */
    protected async fetchOfflineDiscussions(): Promise<void> {
        const forum = this.forum!;
        let offlineDiscussions = await AddonModForumOffline.instance.getNewDiscussions(forum.id);
        this.hasOffline = !!offlineDiscussions.length;

        if (!this.hasOffline) {
            this.offlineDiscussions = [];

            return;
        }

        if (this.usesGroups) {
            offlineDiscussions = await AddonModForum.instance.formatDiscussionsGroups(forum.cmid, offlineDiscussions);
        }

        // Fill user data for Offline discussions (should be already cached).
        const promises = offlineDiscussions.map(async (discussion: any) => {
            if (discussion.parent === 0 || forum.type === 'single') {
                // Do not show author for first post and type single.
                return;
            }

            try {
                const user = await CoreUser.instance.getProfile(discussion.userid, this.courseId, true);

                discussion.userfullname = user.fullname;
                discussion.userpictureurl = user.profileimageurl;
            } catch (error) {
                // Ignore errors.
            }
        });

        await Promise.all(promises);

        // Sort discussion by time (newer first).
        offlineDiscussions.sort((a, b) => b.timecreated - a.timecreated);

        this.offlineDiscussions = offlineDiscussions;
    }

    /**
     * Convenience function to get forum discussions.
     *
     * @param refresh Whether we're refreshing data.
     * @return Promise resolved when done.
     */
    protected async fetchDiscussions(refresh: boolean): Promise<void> {
        const forum = this.forum!;
        this.loadMoreError = false;

        if (refresh) {
            this.page = 0;
        }

        const response = await AddonModForum.instance.getDiscussions(forum.id, {
            cmId: forum.cmid,
            sortOrder: this.selectedSortOrder!.value,
            page: this.page,
        });
        let discussions = response.discussions;

        if (this.usesGroups) {
            discussions = await AddonModForum.instance.formatDiscussionsGroups(forum.cmid, discussions);
        }

        // Hide author for first post and type single.
        if (forum.type === 'single') {
            for (const discussion of discussions) {
                if (discussion.userfullname && discussion.parent === 0) {
                    (discussion as any).userfullname = false;
                    break;
                }
            }
        }

        // If any discussion has unread posts, the whole forum is being tracked.
        if (typeof forum.istracked === 'undefined' && !this.trackPosts) {
            for (const discussion of discussions) {
                if (discussion.numunread > 0) {
                    this.trackPosts = true;
                    break;
                }
            }
        }

        this.discussions.setItems(this.page === 0 ? discussions : this.discussions.items.concat(discussions));
        this.canLoadMore = response.canLoadMore;
        this.page++;

        // Check if there are replies for discussions stored in offline.
        const hasOffline = await AddonModForumOffline.instance.hasForumReplies(forum.id);

        this.hasOffline = this.hasOffline || hasOffline;

        if (hasOffline) {
            // Only update new fetched discussions.
            const promises = discussions.map(async (discussion: any) => {
                // Get offline discussions.
                const replies = await AddonModForumOffline.instance.getDiscussionReplies(discussion.discussion);

                discussion.numreplies = Number(discussion.numreplies) + replies.length;
            });

            await Promise.all(promises);
        }
    }

    /**
     * Convenience function to load more forum discussions.
     *
     * @param infiniteComplete Infinite scroll complete function. Only used from core-infinite-loading.
     * @return Promise resolved when done.
     */
    fetchMoreDiscussions(infiniteComplete?: any): Promise<any> {
        return this.fetchDiscussions(false).catch((message) => {
            CoreDomUtils.instance.showErrorModalDefault(message, 'addon.mod_forum.errorgetforum', true);

            this.loadMoreError = true; // Set to prevent infinite calls with infinite-loading.
        }).finally(() => {
            infiniteComplete && infiniteComplete();
        });
    }

    /**
     * Convenience function to fetch the sort order preference.
     *
     * @return Promise resolved when done.
     */
    protected async fetchSortOrderPreference(): Promise<void> {
        const getSortOrder = async () => {
            if (!this.sortingAvailable) {
                return null;
            }

            const value = await CoreUtils.instance.ignoreErrors(
                CoreUser.instance.getUserPreference(AddonModForumProvider.PREFERENCE_SORTORDER),
            );

            return value ? parseInt(value, 10) : null;
        };

        const value = await getSortOrder();

        this.selectedSortOrder = this.sortOrders.find(sortOrder => sortOrder.value === value) || this.sortOrders[0];
    }

    /**
     * Perform the invalidate content function.
     *
     * @return Resolved when done.
     */
    protected invalidateContent(): Promise<any> {
        const promises: Promise<void>[] = [];

        promises.push(AddonModForum.instance.invalidateForumData(this.courseId!));

        if (this.forum) {
            promises.push(AddonModForum.instance.invalidateDiscussionsList(this.forum.id));
            promises.push(CoreGroups.instance.invalidateActivityGroupMode(this.forum.cmid));
            promises.push(AddonModForum.instance.invalidateAccessInformation(this.forum.id));
        }

        if (this.sortingAvailable) {
            promises.push(CoreUser.instance.invalidateUserPreference(AddonModForumProvider.PREFERENCE_SORTORDER));
        }

        return Promise.all(promises);
    }

    /**
     * Checks if sync has succeed from result sync data.
     *
     * @param result Data returned on the sync function.
     * @return Whether it succeed or not.
     */
    protected hasSyncSucceed(result: any): boolean {
        return result.updated;
    }


    /**
     * Opens the new discussion form.
     *
     * @param timeCreated Creation time of the offline discussion.
     */
    openNewDiscussion(timeCreated: number = 0): void {
        alert(`Open new discussion at ${timeCreated} not implemented!`);

        // @todo
        // const params = {
        //     courseId: this.courseId,
        //     cmId: this.module.id,
        //     forumId: this.forum.id,
        //     timeCreated: timeCreated,
        // };
        // this.splitviewCtrl.push('AddonModForumNewDiscussionPage', params);

        this.selectedDiscussion = 0;
    }

    /**
     * Display the sort order selector modal.
     *
     * @param event Event.
     */
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    showSortOrderSelector(event: MouseEvent): void {
        if (!this.sortingAvailable) {
            return;
        }

        alert('Show sort order selector not implemented');

        // @todo
        // const params = { sortOrders: this.sortOrders, selected: this.selectedSortOrder.value };
        // const modal = this.modalCtrl.create('AddonModForumSortOrderSelectorPage', params);
        // modal.onDidDismiss((sortOrder) => {
        //     this.sortOrderSelectorExpanded = false;

        //     if (sortOrder && sortOrder.value != this.selectedSortOrder.value) {
        //         this.selectedSortOrder = sortOrder;
        //         this.page = 0;
        //         this.userProvider.setUserPreference(AddonModForumProvider.PREFERENCE_SORTORDER, sortOrder.value.toFixed(0))
        //             .then(() => {
        //                 this.showLoadingAndFetch();
        //             }).catch((error) => {
        //                 this.domUtils.showErrorModalDefault(error, 'Error updating preference.');
        //             });
        //     }
        // });

        // modal.present({ ev: event });
        // this.sortOrderSelectorExpanded = true;
    }

    /**
     * Show the context menu.
     *
     * @param e Click Event.
     */
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    showOptionsMenu(e: Event, discussion: any): void {
        alert('Show options menu not implemented');

        // @todo
        // e.preventDefault();
        // e.stopPropagation();

        // const popover = this.popoverCtrl.create(AddonForumDiscussionOptionsMenuComponent, {
        //     discussion: discussion,
        //     forumId: this.forum.id,
        //     cmId: this.module.id,
        // });
        // popover.onDidDismiss((data) => {
        //     if (data && data.action) {
        //         switch (data.action) {
        //             case 'lock':
        //                 discussion.locked = data.value;
        //                 break;
        //             case 'pin':
        //                 discussion.pinned = data.value;
        //                 break;
        //             case 'star':
        //                 discussion.starred = data.value;
        //                 break;
        //             default:
        //                 break;
        //         }
        //     }
        // });
        // popover.present({
        //     ev: e,
        // });
    }

}

class AddonModForumDiscussionsManager extends CorePageItemsListManager<AddonModForumDiscussion> {

    private discussionsPathPrefix: string;
    private component: AddonModForumIndexComponent;

    constructor(pageComponent: unknown, component: AddonModForumIndexComponent, discussionsPathPrefix: string) {
        super(pageComponent);

        this.component = component;
        this.discussionsPathPrefix = discussionsPathPrefix;
    }

    getItemQueryParams(discussion: AddonModForumDiscussion): Params {
        return {
            discussion,
            courseId: this.component.courseId,
            cmId: this.component.module!.id,
            forumId: this.component.forum!.id,
            trackPosts: this.component.trackPosts,
        };
    }

    protected getItemPath(discussion: AddonModForumDiscussion): string {
        const discussionId = discussion.id;

        return this.discussionsPathPrefix + discussionId;
    }

    protected getSelectedItemPath(route: ActivatedRouteSnapshot): string | null {
        const discussionId = route.params.discussionId;

        return discussionId ? this.discussionsPathPrefix + discussionId : null;
    }

}