/*
 * Copyright (C) 2018 StApps
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.
 */
import {Injectable} from '@angular/core';
import {SCSetting, SCSettingMultipleChoice, SCSettingSingleChoice, SCSettingValue} from '@openstapps/core';
import {StorageProvider} from '../storage/storage.provider';

export const STORAGE_KEY_SETTINGS = 'settings';
export const STORAGE_KEY_SETTINGS_SEPARATOR = '.';
export const STORAGE_KEY_SETTING_VALUES = STORAGE_KEY_SETTINGS + STORAGE_KEY_SETTINGS_SEPARATOR + 'values';

/**
 * Category structure of settings cache
 */
export interface CategoryWithSettings {
  category: string;
  settings: { [key: string]: SCSetting };
}

/**
 * Structure of SettingsCache
 */
export interface SettingsCache {
  [key: string]: CategoryWithSettings;
}

/**
 * Provider for app settings
 */
@Injectable()
export class SettingsProvider {
  private categoriesOrder: string[];
  private initialized = false;
  private settingsCache: SettingsCache;

  /**
   * Return true if all given values are valid to possible values in given settingInput
   * @param settingInput
   * @param values
   */
  public static checkMultipleChoiceValue(settingInput: SCSettingMultipleChoice, values: SCSettingValue[]): boolean {
    for (const value of values) {
      if (!settingInput.values.includes(value)) {
        return false;
      }
    }
    return true;
  }

  /**
   * Returns true if given value is valid to possible values in given settingInput
   * @param settingInput
   * @param value
   */
  public static checkSingleChoiceValue(settingInput: SCSettingSingleChoice, value: SCSettingValue): boolean {
    return settingInput.values !== undefined
      && settingInput.values.includes(value);
  }

  /**
   * Validates value for given settings inputType. Returns true if value is valid.
   * @param setting setting to check value against
   * @param value value to validate
   */
  public static validateValue(setting: SCSetting, value: any): boolean {
    let isValueValid: boolean = false;
    switch (setting.input.inputType) {
      case 'number':
        if (typeof value === 'number') {
          isValueValid = true;
        }
        break;
      case 'multipleChoice':
        if (!value.isArray) {
          isValueValid = false;
        } else {
          isValueValid = SettingsProvider.checkMultipleChoiceValue(setting.input, value);
        }
        break;
      case 'password':
      case 'text':
        if (typeof value === 'string') {
          isValueValid = true;
        }
        break;
      case 'singleChoice':
        isValueValid = SettingsProvider.checkSingleChoiceValue(setting.input, value);
        break;
      default:
    }
    return isValueValid;
  }

  constructor(public storage: StorageProvider) {
    this.categoriesOrder = [];
    this.settingsCache = {};
  }

  /**
   * Initializes settings cache from storage
   */
  private async initSettings(): Promise<void> {
    try {
      this.settingsCache = await this.storage.get<SettingsCache>(STORAGE_KEY_SETTING_VALUES);
      for (const category of Object.keys(this.settingsCache)) {
        if (!this.categoriesOrder.includes(category)) {
          this.categoriesOrder.push(category);
        }
      }
    } catch (error) {
      this.settingsCache = {};
    }
    await this.saveSettings();
    this.initialized = true;
  }

  /**
   * Add category if not exists
   * @param category the category to provide
   */
  private async provideCategory(category: string): Promise<void> {
    if (!this.categoryExists(category)) {
      if (!this.categoriesOrder.includes(category)) {
        this.categoriesOrder.push(category);
      }
      this.settingsCache[category] = {
        category: category,
        settings: {},
      };
    }
  }

  /**
   * Returns true if category exists
   * @param category
   */
  public categoryExists(category: string): boolean {
    return this.settingsCache[category] !== undefined;
  }

  /**
   * Removes all provided settings
   */
  public async clear(): Promise<void> {
    await this.init();
    this.settingsCache = {};
    await this.saveSettings();
  }

  /**
   * returns an array with the order of categories
   */
  public getCategoriesOrder(): string[] {
    return this.categoriesOrder;
  }

  /**
   * Returns copy of a setting if exist
   * @param category the category of requested setting
   * @param name the name of requested setting
   *
   * @throws Exception if setting is not provided
   */
  public async getSetting(category: string, name: string): Promise<any> {
    await this.init();
    if (this.settingExists(category, name)) {
      return JSON.parse(JSON.stringify(this.settingsCache[category].settings[name]));
    } else {
      throw new Error('Setting "' + name + '" not provided');
    }
  }

  /**
   * Returns copy of cached settings
   */
  public async getSettingsCache(): Promise<SettingsCache> {
    await this.init();
    return JSON.parse(JSON.stringify(this.settingsCache));
  }

  /**
   * Returns copy of a setting if exist
   * @param category the category of requested setting
   * @param name the name of requested setting
   *
   * @throws Exception if setting is not provided
   */
  public async getSettingValue(category: string, name: string): Promise<any> {
    await this.init();
    if (this.settingExists(category, name)) {
      return JSON.parse(JSON.stringify(this.settingsCache[category].settings[name].input.value));
    } else {
      throw new Error('Setting "' + name + '" not provided');
    }
  }

  /**
   * initializes settingsProvider
   */
  public async init(): Promise<void> {
    if (!this.initialized) {
      await this.initSettings();
    }
  }

  /**
   * Adds given setting and its category if not exist
   * @param setting the setting to add
   */
  public async provideSetting(setting: SCSetting): Promise<void> {
    await this.init();
    if (!this.categoryExists(setting.categories[0])) {
      await this.provideCategory(setting.categories[0]);
    }
    if (!this.settingExists(setting.categories[0], setting.name)) {
      // set value to default
      if (setting.input.value === undefined) {
        setting.input.value = setting.input.defaultValue;
      }
      this.settingsCache[setting.categories[0]].settings[setting.name] = setting;
      await this.saveSettings();
    }
  }

  /**
   * Sets values of all settings to defaultValue
   */
  public async resetDefault(): Promise<void> {
    await this.init();
    for (const catKey of Object.keys(this.settingsCache)) {
      for (const settingKey of Object.keys(this.settingsCache[catKey].settings)) {
        const settingInput = this.settingsCache[catKey].settings[settingKey].input;
        settingInput.value = settingInput.defaultValue;
      }
    }
  }

  /**
   * Saves cached settings in app storage
   */
  public async saveSettings(): Promise<void> {
    await this.storage.put(STORAGE_KEY_SETTING_VALUES, this.settingsCache);
  }

  /**
   * Sets the order the given categories showup in the settings page
   * @param categoryNames the order of the categories
   */
  public setCategoriesOrder(categoryNames: string[]) {
    this.categoriesOrder = categoryNames;
  }

  /**
   * Sets a valid value of a setting and persists changes in storage
   * @param category
   * @param name
   * @param value
   *
   * @throws Exception if setting is not provided or value not valid to the settings inputType
   */
  public async setSettingValue(category: string, name: string, value: any): Promise<void> {
    await this.init();
    if (this.settingExists(category, name)) {
      const setting: SCSetting = this.settingsCache[category].settings[name];
      const isValueValid = SettingsProvider.validateValue(setting, value);
      if (isValueValid) {
        this.settingsCache[category].settings[name].input.value = value;
        await this.saveSettings();
      } else {
        throw new Error('Value "' + value + '" of type ' +
          typeof value + ' is not valid for ' + setting.input.inputType);
        }
    } else {
      throw new Error('setting ' + name + ' is not provided');
    }
  }

  /**
   * Returns true if setting in category exists
   * @param category
   * @param setting
   */
  public settingExists(category: string, setting: string): boolean {
    return this.categoryExists(category) && this.settingsCache[category].settings[setting] !== undefined;
  }
}