scheduler.rb

# frozen_string_literal: true

class AvailabilitiesController < AuthenticatedController
  before_action :authenticate_interviewer!

  def index
    respond_to do |format|
      format.json do
        render json: Availability.where(interviewer: @interviewer)
      end
    end
  end

  def create
    merge_times = overlap
    if merge_times.empty?
      Availability.create! availability_params
    else
      all_times = merge_times + [availability_params]
      new_start_at = all_times.min_by { |mt| mt[:slot].begin }[:slot].begin
      new_end_at = all_times.max_by { |mt| mt[:slot].end }[:slot].end

      Availability.transaction do
        Availability.create!(slot: (new_start_at..new_end_at), interviewer: @interviewer)
        merge_times.each(&:destroy!)
      end
    end
    head :ok
  end

  def delete
    range = availability_params[:slot]
    overlap.each do |availability|
      curr_slot = availability[:slot]
      if range.begin <= curr_slot.begin && range.end <= curr_slot.end
        availability.update!(slot: (range.end..curr_slot.end))
      elsif range.begin >= curr_slot.begin && range.end >= curr_slot.end
        availability.update!(slot: (curr_slot.begin..range.end))
      else
        remove_overlap(curr_slot, range, availability)
      end
    end
  end

  private

  def remove_overlap(curr_slot, range, availability)
    Availability.transaction do
      Availability.create!(slot: (curr_slot.begin..range.begin), interviewer: @interviewer)
      Availability.create!(slot: (range.end..curr_slot.begin), interviewer: @interviewer)
      availability.destroy!
    end
  end

  def overlap
    start_at = availability_params[:slot].begin
    end_at = availability_params[:slot].end
    merge_times = Availability.where('slot -|- tstzrange(?, ?)', start_at, end_at)
    merge_times + Availability.where('slot && tstzrange(?, ?)', start_at, end_at)
  end

  def availability_params
    start_at = DateTime.parse(params.require(:start))
    end_at = DateTime.parse(params.require(:end))

    raise 'Date to early' if start_at < DateTime.now || end_at < DateTime.now
    raise 'Bad range' if start_at >= end_at

    {
      slot: (start_at..end_at),
      interviewer: @interviewer
    }
  rescue StandardError
    render json: { message: 'Bad date params' }, status: :unprocessable_entity
  end
end