require 'restclient'

module Medivo
  class Appointment

    LABCORP_FORMAT = "%m/%d/%Y|%H:%M %p" unless defined? LABCORP_FORMAT
    MDY_FORMAT = "%m/%d/%Y" unless defined? MDY_FORMAT

    class << self

      ##
      # Find a labcorp appointment
      #
      # @param lab_code   lab code
      # @param date       date to seek
      # @param am_pm      optional time of day value ( 'AM' or 'PM' )
      #
      # @return Array     of times ['time1', 'time2']
      #
      # @throws exception mainly Restclient::Exception types
      def find(lab_code, date, am_pm='')
        if real_data?
          data = resource.get :params=>{:labcorp_id=>lab_code, :appointment_date=>date}
          # data is json encoded hash: { :times => ['time1', 'time2'] }
          data = JSON.parse(data)['times']
        else
          data = build_fake_data(date)
        end
        # filter the hash before returning
        search_date = Time.parse(date)
        filter_data(data, am_pm, search_date)
      end

      ##
      # Make the labcorp appointment
      #
      # @param lab_code   lab code
      # @param time       time
      # @param user       user info  must include date_of_birth, first_name, last_name,
      #                   email_address, phone_number
      #
      # @return String    confirmation number or nil if none made
      #
      # @throws exception   mainly Restclient::Exception types
      def make(lab_code, time, user)
        time_id = time.strftime(LABCORP_FORMAT)
        if real_data?
          data = resource.post :labcorp_id=>lab_code, :time_id=>time_id, :user=>user
          # data is json  { :confimation => ( 'real number' or nil if no appointment made ) }
          JSON.parse(data)['confirmation']
        else
          nil
        end
      end

      def resource
        @resource ||= begin
          @config = ResourceConfig.find 'appointment_resource.yml'
          RestClient::Resource.new @config.href, :timeout => (@config.timeout || 12)
        rescue => e
          Rails.logger.error e.inspect
          # blow up later, so the server can start
        end
      end

      ## using real data?
      # the flag is set in the config/appointment_resource.yml
      def real_data?
        resource # to init the resource and config file
        true unless !Rails.env.test? and @config.real_data == false
      end

      def filter_data(times, am_pm, search_date)
        times.collect { |time| AppointmentTime.new(time) }
            .select { |at| at.match(am_pm, Time.now) }
            .sort_by {|at| at.nearness_to_date(search_date) }
            .collect { |at| at.time_str }
      end

      def build_fake_data(date)
        date = date.is_a?(String) ? Date.strptime(date, MDY_FORMAT) : date
        [
          build_date(date, "08:30 AM"), build_date(date, "10:30 AM"),
          build_date((date + 1), "03:30 PM"), build_date((date+1), "01:30 PM"),
          build_date((date + 2), "10:30 AM"), build_date((date+1), "03:00 PM"),
        ]
      end

      def build_date(date, time)
        "#{date.strftime(MDY_FORMAT)}|#{time}"
      end
    end
  end
end

class AppointmentTime
  attr_reader :time, :time_str

  def initialize(time_str)
    @time_str = time_str
    @time = Time.strptime(time_str, Medivo::Appointment::LABCORP_FORMAT) rescue nil
  end

  def match(am_pm, current_time)
    time and time_str.match(/#{am_pm}/) and (time >= current_time)
  end

  def nearness_to_date(date)
    (time - date).to_i.abs
  end
end