const qs = require('querystring');

/**
 * Slack Payload
 *
 * @class Payload
 */
class Payload {
  /**
   * The payload constructor
   *
   * @param {string} body the request body
   * @param {object} query the request querystring
   * @memberof Payload
   */
  constructor(body, query) {
    if (typeof body === 'string') {
      body = this.constructor.parse(body);
    }

    Object.assign(this, body, query);
  }

  static parse(body) {
    try {
      body = JSON.parse(body);
    } catch (e) {
      body = qs.parse(body);
    }

    // interactive messages
    if (body.payload) body = JSON.parse(body.payload);

    return body;
  }

  /**
   * Get an interactive message's selected action
   *
   * @return {object} the action
   * @memberof Payload
   */
  get action() {
    if (this.actions) return this.actions[0];
  }

  /**
   * Get a message's selected option
   *
   * @return {object} the selected option
   * @memberof Payload
   */
  get selection() {
    if (this.action && this.action.selected_options) return this.action.selected_options[0];
  }

  /**
   * Get the sub-command arguments for a command
   *
   * @param {string} name the sub-command name
   * @return {string} the sub-command arguments
   * @memberof Payload
   */
  subcommand(name) {
    if (this.isSubCommand(name)) return this.text.substring(name.length);
  }

  /**
   * Match the message text against a regex
   *
   * @param {RegExp} regex the regex to test
   * @return {Array} the regex match
   * @memberof Payload
   */
  match(regex) {
    if (typeof regex !== 'object') regex = new RegExp(regex, 'im');
    if (this.text) return this.text.match(regex);
  }

  /**
   * Check if the payload is a type of event
   *
   * @param {String} type the event type to check
   * @return {Boolean} does the payload match the type
   * @memberof Payload
   */
  is(type) {
    return this.event_types.includes(type) || this.match(type);
  }

  /**
   * Check if the a slash command contains a sub-command
   *
   * @param {String} name the sub-command name
   * @return {Boolean} is the command a sub-command
   * @memberof Payload
   */
  isSubCommand(name) {
    const regex = new RegExp('^' + name, 'i');
    return this.match(regex);
  }

  /**
   * Get the message text
   *
   * @return {String} the message text
   * @memberof Payload
   */
  get text() {
    // Slash Commands
    if (super.text) return super.text;

    // Events API
    if (this.event && this.event.text) return this.event.text;
  }

  /**
   * Set the text
   *
   * @param {String} text the text
   * @memberof Payload
   */
  set text(text) {
    super.text = text;
  }

  /**
   * Get the bot id the payload was sent from (if applicable)
   *
   * @return {String} the bot id
   * @memberof Payload
   */
  get bot_id() {
    return super.bot_id || (this.event && this.event.bot_id);
  }

  /**
   * Set the bot id
   *
   * @param {String} bot_id the bot id
   * @memberof Payload
   */
  set bot_id(bot_id) {
    super.bot_id = bot_id;
  }

  /**
   * Get the channel id the payload was sent from
   *
   * @return {String} the channel id
   * @memberof Payload
   */
  get channel_id() {
    // Interactive Messages
    if (this.channel) return this.channel.id;

    // Slash Commands
    if (super.channel_id) return super.channel_id;

    // Events API
    let event = this.event;
    if (event && event.channel) return event.channel;
    if (event && event.item) return event.item.channel;
  }

  /**
   * Set the channel id
   *
   * @param {String} channel_id the channel id
   * @memberof Payload
   */
  set channel_id(channel_id) {
    super.channel_id = channel_id;
  }

  /**
   * Get the team id the payload was sent from
   *
   * @return {String} the team id
   * @memberof Payload
   */
  get team_id() {
    // Interactive Messages
    if (this.team) return this.team.id;

    // Slash Commands
    if (super.team_id) return super.team_id;

    // Events API
    let event = this.event;
    if (event && event.team) return event.team;
    if (event && event.item) return event.item.team;
  }

  /**
   * Set the team id
   *
   * @param {String} team_id the team id
   * @memberof Payload
   */
  set team_id(team_id) {
    super.team_id = team_id;
  }

  /**
   * Get the user id that sent the payload
   *
   * @return {String} the user id
   * @memberof Payload
   */
  get user_id() {
    // Interactive Messages
    if (this.user) return this.user.id;

    // Slash Commands
    if (super.user_id) return super.user_id;

    // Events API
    let event = this.event;
    if (event && event.user) return event.user;
    if (event && event.item) return event.item.user;
  }

  /**
   * Set the user id
   *
   * @param {String} user_id the user id
   * @memberof Payload
   */
  set user_id(user_id) {
    super.user_id = user_id;
  }

  /**
   * Get event types that triggered this payload
   *
   * @return {Array} the event types
   * @memberof Payload
   */
  get event_types() {
    let events = [];

    // incoming message by type
    if (this.type) events.push(this.type);

    // message came from a bot
    if (this.bot_id) events.push('bot_message');

    // app install event
    if (this.code) events.push('app_installed');

    // event triggered by event type
    if (this.event) events.push('event', this.event.type);

    // url challenge request
    if (this.challenge) events.push('challenge', this.challenge);

    // slash command by command
    if (this.command) events.push('slash_command', this.command);

    // webhook triggered by trigger word
    if (this.trigger_word) events.push('webhook', this.trigger_word);

    // interactive message triggered by callback_id
    if (this.callback_id) events.push('interactive_message', this.callback_id);

    // message selection
    if (this.selection) events.push('message_select', this.selection.value);

    // message button triggered by callback_id
    if (this.action) events.push('message_button', this.action.value);

    // ensure unique values
    events = events.filter((v, i, a) => a.indexOf(v) === i);

    return events;
  }
}

module.exports = Payload;