require 'rubygems'
require 'bundler/setup'

require 'date'
require 'active_support/core_ext/date_and_time/calculations'
require 'icalendar/recurrence'
require 'open-uri'
require 'json'

class SublabCalendar

  URL = "https://sublab.org:5232/calendars/events"

  class Event < SimpleDelegator

    BASIC_ATTRIBUTES = [:summary, :dtstart, :dtend]

    def to_h
      BASIC_ATTRIBUTES.inject({}) {|hsh, attr| hsh[attr] = send(attr).to_s; hsh }
    end

    def to_json(*args)
      to_h.to_json(*args)
    end

    def to_s
      "<#{self.class} #{self.to_h}>"
    end

    def inspect
      to_s
    end

    def recurring?
      ! rrule.empty?
    end

    def occurrences_this_month
      return nil unless recurring?
      occurrences_between(*this_month).map {|occ| Occurrence.new(occ, self) }
    end

    private

    def this_month
      [Date.today.beginning_of_month, Date.today.end_of_month]
    end

  end

  class Occurrence < SimpleDelegator

    attr_reader :event

    def initialize(occurrence, event)
      @event = event
      super(occurrence)
    end

    def to_h
      {
        summary: summary,
        start:   start_time,
        end:     end_time
      }
    end

    def inspect
      to_s
    end

    def summary
      event.summary
    end

    def description
      event.description
    end

    def to_s
      "<#{self.class} #{self.to_h}>"
    end

  end

  attr_reader :calendar

  def initialize(ical)
    @calendar = Icalendar.parse(ical).first
  end

  def self.load(url=URL)
    ical = open(url, {ssl_verify_mode: OpenSSL::SSL::VERIFY_NONE})
    new(ical)
  end

  def events
    calendar.events.map(&method(:readable))
  end

  def future
    calendar.events.select {|ev| ev.dtstart >= DateTime.now}.map(&method(:readable))
  end

  def past
    calendar.events.select {|ev| ev.dtstart < DateTime.now}.map(&method(:readable))
  end

  def recurring
    events.select(&:"recurring?")
  end

  def next(count=1)
    future.take(count)
  end

  def readable(event)
    Event.new(event)
  end

end