// (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 { CoreSitesProvider } from '@providers/sites';
import { CoreUtilsProvider } from '@providers/utils/utils';
import { CoreAppProvider } from '@providers/app';
import { CoreFilepoolProvider } from '@providers/filepool';
import { CoreCourseLogHelperProvider } from '@core/course/providers/log-helper';
import { AddonModChoiceOfflineProvider } from './offline';
import { CoreSiteWSPreSets } from '@classes/site';

/**
 * Service that provides some features for choices.
 */
@Injectable()
export class AddonModChoiceProvider {
    static COMPONENT = 'mmaModChoice';

    static RESULTS_NOT = 0;
    static RESULTS_AFTER_ANSWER = 1;
    static RESULTS_AFTER_CLOSE = 2;
    static RESULTS_ALWAYS = 3;

    static PUBLISH_ANONYMOUS = false;
    static PUBLISH_NAMES = true;

    protected ROOT_CACHE_KEY = 'mmaModChoice:';

    constructor(private sitesProvider: CoreSitesProvider, private appProvider: CoreAppProvider,
            private filepoolProvider: CoreFilepoolProvider, private utils: CoreUtilsProvider,
            private choiceOffline: AddonModChoiceOfflineProvider, private logHelper: CoreCourseLogHelperProvider) {}

    /**
     * Check if results can be seen by a student. The student can see the results if:
     *     - they're always published, OR
     *     - they're published after the choice is closed and it's closed, OR
     *     - they're published after answering and the user has answered.
     *
     * @param  {any}     choice      Choice to check.
     * @param  {boolean} hasAnswered True if user has answered the choice, false otherwise.
     * @return {boolean} True if the students can see the results.
     */
    canStudentSeeResults(choice: any, hasAnswered: boolean): boolean {
        const now = new Date().getTime();

        return choice.showresults === AddonModChoiceProvider.RESULTS_ALWAYS ||
            choice.showresults === AddonModChoiceProvider.RESULTS_AFTER_CLOSE &&
                choice.timeclose !== 0 && choice.timeclose <= now ||
            choice.showresults === AddonModChoiceProvider.RESULTS_AFTER_ANSWER && hasAnswered;
    }

    /**
     * Delete responses from a choice.
     *
     * @param  {number}   choiceId    Choice ID.
     * @param  {string}   name        Choice name.
     * @param  {number}   courseId    Course ID the choice belongs to.
     * @param  {number[]} [responses] IDs of the answers. If not defined, delete all the answers of the current user.
     * @param  {string}   [siteId]    Site ID. If not defined, current site.
     * @return {Promise<boolean>} Promise resolved with boolean: true if response was sent to server, false if stored in device.
     */
    deleteResponses(choiceId: number, name: string, courseId: number, responses?: number[], siteId?: string): Promise<boolean> {
        siteId = siteId || this.sitesProvider.getCurrentSiteId();
        responses = responses || [];

        // Convenience function to store a message to be synchronized later.
        const storeOffline = (): Promise<any> => {
            return this.choiceOffline.saveResponse(choiceId, name, courseId, responses, true, siteId).then(() => {
                return false;
            });
        };

        if (!this.appProvider.isOnline()) {
            // App is offline, store the action.
            return storeOffline();
        }

        // If there's already a response to be sent to the server, discard it first.
        return this.choiceOffline.deleteResponse(choiceId, siteId).then(() => {
            return this.deleteResponsesOnline(choiceId, responses, siteId).then(() => {
                return true;
            }).catch((error) => {
                if (this.utils.isWebServiceError(error)) {
                    // The WebService has thrown an error, this means that responses cannot be submitted.
                    return Promise.reject(error);
                }

                // Couldn't connect to server, store in offline.
                return storeOffline();
            });
        });
    }

    /**
     * Delete responses from a choice. It will fail if offline or cannot connect.
     *
     * @param  {number}   choiceId    Choice ID.
     * @param  {number[]} [responses] IDs of the answers. If not defined, delete all the answers of the current user.
     * @param  {string}   [siteId]    Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved when responses are successfully deleted.
     */
    deleteResponsesOnline(choiceId: number, responses?: number[], siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(siteId).then((site) => {
            const params = {
                choiceid: choiceId,
                responses: responses
            };

            return site.write('mod_choice_delete_choice_responses', params).then((response) => {
                // Other errors ocurring.
                if (!response || response.status === false) {
                    return Promise.reject(this.utils.createFakeWSError(''));
                }

                // Invalidate related data.
                const promises = [
                    this.invalidateOptions(choiceId, site.id),
                    this.invalidateResults(choiceId, site.id)
                ];

                return Promise.all(promises).catch(() => {
                    // Ignore errors.
                });
            });
        });
    }

    /**
     * Get cache key for choice data WS calls.
     *
     * @param  {number} courseId Course ID.
     * @return {string} Cache key.
     */
    protected getChoiceDataCacheKey(courseId: number): string {
        return this.ROOT_CACHE_KEY + 'choice:' + courseId;
    }

    /**
     * Get cache key for choice options WS calls.
     *
     * @param  {number} choiceId Choice ID.
     * @return {string} Cache key.
     */
    protected getChoiceOptionsCacheKey(choiceId: number): string {
        return this.ROOT_CACHE_KEY + 'options:' + choiceId;
    }

    /**
     * Get cache key for choice results WS calls.
     *
     * @param  {number} choiceId Choice ID.
     * @return {string} Cache key.
     */
    protected getChoiceResultsCacheKey(choiceId: number): string {
        return this.ROOT_CACHE_KEY + 'results:' + choiceId;
    }

    /**
     * Get a choice with key=value. If more than one is found, only the first will be returned.
     *
     * @param  {string}  siteId             Site ID.
     * @param  {number}  courseId           Course ID.
     * @param  {string}  key                Name of the property to check.
     * @param  {any}     value              Value to search.
     * @param  {boolean} [forceCache] True to always get the value from cache, false otherwise. Default false.
     * @param {boolean} [ignoreCache] True if it should ignore cached data (it will always fail in offline or server down).
     * @return {Promise<any>} Promise resolved when the choice is retrieved.
     */
    protected getChoiceByDataKey(siteId: string, courseId: number, key: string, value: any, forceCache?: boolean,
            ignoreCache?: boolean): Promise<any> {

        return this.sitesProvider.getSite(siteId).then((site) => {
            const params = {
                courseids: [courseId]
            };
            const preSets: CoreSiteWSPreSets = {
                cacheKey: this.getChoiceDataCacheKey(courseId),
                omitExpires: forceCache
            };

            if (forceCache) {
                preSets.omitExpires = true;
            } else if (ignoreCache) {
                preSets.getFromCache = false;
                preSets.emergencyCache = false;
            }

            return site.read('mod_choice_get_choices_by_courses', params, preSets).then((response) => {
                if (response && response.choices) {
                    const currentChoice = response.choices.find((choice) => choice[key] == value);
                    if (currentChoice) {
                        return currentChoice;
                    }
                }

                return Promise.reject(null);
            });
        });
    }

    /**
     * Get a choice by course module ID.
     *
     * @param  {number}  courseId           Course ID.
     * @param  {number}  cmId               Course module ID.
     * @param  {string}  [siteId]           Site ID. If not defined, current site.
     * @param  {boolean} [forceCache] True to always get the value from cache, false otherwise. Default false.
     * @param {boolean} [ignoreCache] True if it should ignore cached data (it will always fail in offline or server down).
     * @return {Promise<any>} Promise resolved when the choice is retrieved.
     */
    getChoice(courseId: number, cmId: number, siteId?: string, forceCache?: boolean, ignoreCache?: boolean): Promise<any> {
        return this.getChoiceByDataKey(siteId, courseId, 'coursemodule', cmId, forceCache, ignoreCache);
    }

    /**
     * Get a choice by ID.
     *
     * @param  {number}  courseId           Course ID.
     * @param  {number}  choiceId           Choice ID.
     * @param  {string}  [siteId]           Site ID. If not defined, current site.
     * @param  {boolean} [forceCache] True to always get the value from cache, false otherwise. Default false.
     * @param {boolean} [ignoreCache] True if it should ignore cached data (it will always fail in offline or server down).
     * @return {Promise<any>} Promise resolved when the choice is retrieved.
     */
    getChoiceById(courseId: number, choiceId: number, siteId?: string, forceCache?: boolean, ignoreCache?: boolean): Promise<any> {
        return this.getChoiceByDataKey(siteId, courseId, 'id', choiceId, forceCache, ignoreCache);
    }

    /**
     * Get choice options.
     *
     * @param {number} choiceId Choice ID.
     * @param {boolean} [ignoreCache] True if it should ignore cached data (it will always fail in offline or server down).
     * @param {string} [siteId] Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved with choice options.
     */
    getOptions(choiceId: number, ignoreCache?: boolean, siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(siteId).then((site) => {
            const params = {
                choiceid: choiceId
            };
            const preSets: CoreSiteWSPreSets = {
                cacheKey: this.getChoiceOptionsCacheKey(choiceId)
            };

            if (ignoreCache) {
                preSets.getFromCache = false;
                preSets.emergencyCache = false;
            }

            return site.read('mod_choice_get_choice_options', params, preSets).then((response) => {
                if (response.options) {
                    return response.options;
                }

                return Promise.reject(null);
            });
        });
    }

    /**
     * Get choice results.
     *
     * @param {number} choiceId Choice ID.
     * @param {boolean} [ignoreCache] True if it should ignore cached data (it will always fail in offline or server down).
     * @param {string} [siteId] Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved with choice results.
     */
    getResults(choiceId: number, ignoreCache?: boolean, siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(siteId).then((site) => {
            const params = {
                choiceid: choiceId
            };
            const preSets: CoreSiteWSPreSets = {
                cacheKey: this.getChoiceResultsCacheKey(choiceId)
            };

            if (ignoreCache) {
                preSets.getFromCache = false;
                preSets.emergencyCache = false;
            }

            return site.read('mod_choice_get_choice_results', params, preSets).then((response) => {
                if (response.options) {
                    return response.options;
                }

                return Promise.reject(null);
            });
        });
    }

    /**
     * Invalidate choice data.
     *
     * @param  {number} courseId Course ID.
     * @param  {string} [siteId] Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved when the data is invalidated.
     */
    invalidateChoiceData(courseId: number, siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(null).then((site) => {
            return site.invalidateWsCacheForKey(this.getChoiceDataCacheKey(courseId));
        });
    }

    /**
     * Invalidate the prefetched content.
     *
     * @param  {number} moduleId The module ID.
     * @param  {number} courseId Course ID.
     * @param  {string} [siteId] Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved when data is invalidated.
     */
    invalidateContent(moduleId: number, courseId: number, siteId?: string): Promise<any> {
        siteId = siteId || this.sitesProvider.getCurrentSiteId();

        const promises = [];

        promises.push(this.getChoice(courseId, moduleId).then((choice) => {
            return Promise.all([
                this.invalidateChoiceData(courseId),
                this.invalidateOptions(choice.id),
                this.invalidateResults(choice.id),
            ]);
        }));

        promises.push(this.filepoolProvider.invalidateFilesByComponent(siteId, AddonModChoiceProvider.COMPONENT, moduleId));

        return this.utils.allPromises(promises);
    }

    /**
     * Invalidate choice options.
     *
     * @param  {number} choiceId Choice ID.
     * @param  {string} [siteId] Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved when the data is invalidated.
     */
    invalidateOptions(choiceId: number, siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(siteId).then((site) => {
           return site.invalidateWsCacheForKey(this.getChoiceOptionsCacheKey(choiceId));
       });
   }

   /**
    * Invalidate choice results.
    *
    * @param  {number} choiceId Choice ID.
    * @param  {string} [siteId] Site ID. If not defined, current site.
    * @return {Promise<any>} Promise resolved when the data is invalidated.
    */
   invalidateResults(choiceId: number, siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(siteId).then((site) => {
            return site.invalidateWsCacheForKey(this.getChoiceResultsCacheKey(choiceId));
        });
    }

    /**
     * Report the choice as being viewed.
     *
     * @param  {string} id Choice ID.
     * @param {string} [name] Name of the choice.
     * @param {string} [siteId] Site ID. If not defined, current site.
     * @return {Promise<any>}  Promise resolved when the WS call is successful.
     */
    logView(id: number, name?: string, siteId?: string): Promise<any> {
        const params = {
            choiceid: id
        };

        return this.logHelper.logSingle('mod_choice_view_choice', params, AddonModChoiceProvider.COMPONENT, id, name, 'choice',
                {}, siteId);
    }

    /**
     * Send a response to a choice to Moodle.
     *
     * @param  {number}   choiceId  Choice ID.
     * @param  {string}   name      Choice name.
     * @param  {number}   courseId  Course ID the choice belongs to.
     * @param  {number[]} responses IDs of selected options.
     * @param  {string}   [siteId]  Site ID. If not defined, current site.
     * @return {Promise<boolean>} Promise resolved with boolean: true if response was sent to server, false if stored in device.
     */
    submitResponse(choiceId: number, name: string, courseId: number, responses: number[], siteId?: string): Promise<boolean> {
        siteId = siteId || this.sitesProvider.getCurrentSiteId();

        // Convenience function to store a message to be synchronized later.
        const storeOffline = (): Promise<any> => {
            return this.choiceOffline.saveResponse(choiceId, name, courseId, responses, false, siteId).then(() => {
                return false;
            });
        };

        if (!this.appProvider.isOnline()) {
            // App is offline, store the action.
            return storeOffline();
        }

        // If there's already a response to be sent to the server, discard it first.
        return this.choiceOffline.deleteResponse(choiceId, siteId).then(() => {
            return this.submitResponseOnline(choiceId, responses, siteId).then(() => {
                return true;
            }).catch((error) => {
                if (this.utils.isWebServiceError(error)) {
                    // The WebService has thrown an error, this means that responses cannot be submitted.
                    return Promise.reject(error);
                } else {
                    // Couldn't connect to server, store it offline.
                    return storeOffline();
                }
            });
        });
    }

    /**
     * Send a response to a choice to Moodle. It will fail if offline or cannot connect.
     *
     * @param  {number}   choiceId  Choice ID.
     * @param  {number[]} responses IDs of selected options.
     * @param  {string}   [siteId]  Site ID. If not defined, current site.
     * @return {Promise<any>} Promise resolved when responses are successfully submitted.
     */
    submitResponseOnline(choiceId: number, responses: number[], siteId?: string): Promise<any> {
        return this.sitesProvider.getSite(siteId).then((site) => {
            const params = {
                choiceid: choiceId,
                responses: responses
            };

            return site.write('mod_choice_submit_choice_response', params).then(() => {
                // Invalidate related data.
                const promises = [
                    this.invalidateOptions(choiceId, siteId),
                    this.invalidateResults(choiceId, siteId)
                ];

                return Promise.all(promises).catch(() => {
                    // Ignore errors.
                });
            });
        });
    }
}