const ICAL = require('ical.js')
const shows = require('./shows.js')

/**
 * Represent a schedule (ie: a .ics file)
 */
class RadioSchedule {
  constructor (calendar, radio) {
    this.calendar = calendar  // ICAL.Calendar
    this.radio = radio  // radiomanifest.Radio
  }

  /**
   * Get a list of all known {@link vEvent}s
   *
   * @returns {Array<external:ICAL~Component>}
   * */
  getEvents() {
    return this.calendar.getAllSubcomponents('vevent');

  }

  /**
   * @returns {external:ICAL~Component} if nothing is going on right now, `null` is returned
   */
  getNowEvent(now) {
    var ev_now = this.getEvents().filter(function(vevent) {
      const ev = new ICAL.Event(vevent)
      return isNow(ev, now)
    })
    if(ev_now.length === 0)
      return null
    if(ev_now.length > 1)
      console.log("More than one event right now?!")
    return ev_now[0]
  }

  /**
   * @returns {RadioShow} if nothing is going on right now, `null` is returned
   */
  getNowShow(now) {
    var ev = this.getNowEvent(now)

    if (ev === null) return null
    if (this.radio !== undefined) {
      const showid = RadioSchedule.veventGetShowID(ev)
      var show = this.radio.getShowByName(showid)
      if (show === null || show === undefined) {
        return new shows.RadioShow(RadioSchedule.veventGetSummary(ev))
      }
      return show;
    }
    return new shows.RadioShow(RadioSchedule.veventGetSummary(ev))
  }

  /**
   * @todo To be implemented
   */
  getNextEvent(now) {
    // XXX
  }


  /**
   * @todo To be implemented
   * @returns {NextShow} if there is no next show, nothing will be returned
   */
  getNextShow(now) {
    // XXX
  }
  static veventGetSummary(vevent) {
      return vevent.getFirstProperty('summary').getFirstValue()
  }
  static veventGetShowID(vevent) {
      return RadioSchedule.veventGetSummary(vevent)  // XXX: X-Show-ID
  }

}


function isNow(vEvent, now) {
    if (now === undefined) {
          now = ICAL.Time.now()
        }
    if (vEvent.isRecurring()) {
          return isNowRecurring(vEvent, now)
        }
    return (now < vEvent.endDate) && (now > event.startDate);
}


function isNowRecurring(vEvent, now) {
  var expand = vEvent.iterator(vEvent.startDate)
  var next, next_end;

  while ((next = expand.next())) {
    next_end = next.clone()
    next_end.addDuration(vEvent.duration)

    if (next_end > now) {
      break;
    }
  }
  return (now < next_end && now > next);
}


async function get(manifest) {
  if (manifest.scheduleURL) {
    let resp = null
    try {
      resp = await fetch(manifest.scheduleURL)
    } catch (e) {
      true
    }
    if (resp !== null) {
      try {
        text = await resp.text()
        return parse(text)
      } catch (e) {
        console.error('Error while parsing schedule', e)
        throw e
      }
    }
  }
}

/**
 * Parse ICAL and get a RadioSchedule
 *
 * @param {string} text The text, in ICS format
 * @returns {RadioSchedule}
 */
function parse(text) {
  var jcalData = ICAL.parse(text);
  var vcalendar = new ICAL.Component(jcalData);

  return new RadioSchedule(vcalendar)
}


module.exports = {
  get: get,
  parse: parse,
  RadioSchedule: RadioSchedule,
}

/**
 * @typedef {Object} NextShow
 * @property {RadioShow} show The next show scheduled
 * @property {external:ICAL~Time} time When it will start
 */

/**
 * @external ICAL
 * @see https://mozilla-comm.github.io/ical.js/api/index.html
 */

/**
 * @class Component
 * @memberof external:ICAL
 * @inner
 * @see https://mozilla-comm.github.io/ical.js/api/ICAL.Component.html
 */

/**
 * @class Time
 * @memberof external:ICAL
 * @inner
 * @see https://mozilla-comm.github.io/ical.js/api/ICAL.Time.html
 */