[#2] Adding reservation parsing proxy method

This is what I don't like. But for now, let's make it work and fix
tech debt in the future.

deustorb.gemspec

@@ -19,6 +19,7 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency "rest-client", "~> 1.6.7"
   gem.add_dependency "json", "~> 1.7.5"
+  gem.add_dependency "activesupport"
 
   gem.add_development_dependency 'rack', '~> 1.4.1'
   gem.add_development_dependency 'rake', '~> 10.0.2'

lib/deustorb/reservation.rb

@@ -1,3 +1,6 @@
+require 'active_support'
+require 'active_support/core_ext/string'
+
 require 'deustorb/reservations/waiting'
 require 'deustorb/reservations/confirmed'
 require 'deustorb/reservations/post_reservation'
@@ -11,5 +14,48 @@ module Reservation
     POST_RESERVATION = 'post_reservation'
     WAITING_INSTANCES = 'waiting_instances'
     WAITING_CONFIRMATION = 'waiting_confirmation'
+
+    TOKEN = 'Reservation::'
+    def self.new_from_hash(data = {})
+      reservation_type = data.delete('status'){ raise ::KeyError.new('key not found: "status"') }
+      reservation_type.sub!(TOKEN, "")
+      data = normalize_data_hash(data)
+      unless valid_types.include?(reservation_type)
+        raise InvalidReservation.new("Invalid reservation type: '#{reservation_type}'\n\nValid Types: #{valid_types.join(", ")}")
+      end
+      if reservation_type == WAITING_INSTANCES
+        WaitingInstances.new data
+      else
+        "Deustorb::Reservation::#{reservation_type.classify}".constantize.new(data)
+      end
+    end
+
+    def self.valid_types
+      [
+        WAITING,
+        CONFIRMED,
+        POST_RESERVATION,
+        WAITING_INSTANCES,
+        WAITING_CONFIRMATION
+      ]
+    end
+
+    private
+    def self.normalize_data_hash(data)
+      # force both keys to be present
+      data['id'] = data.fetch("reservation_id").fetch("id")
+      data.delete("reservation_id")
+      simbolize_hash_keys(data)
+    end
+
+    def self.simbolize_hash_keys(hash)
+      hash.keys.each do |key|
+        if key.is_a?(String)
+          hash[key.to_sym] = hash[key]
+          hash.delete(key)
+        end
+      end
+      hash
+    end
   end
 end

spec/deustorb/reservation_spec.rb

@@ -2,5 +2,32 @@
 
 module Deustorb
   describe Reservation do
+    describe ".new_from_hash" do
+      let(:params) do
+        {
+          url: 'example.com',
+          time: 'some-time-somewhen',
+          finished: true,
+          position: 3,
+          end_data: 'end data',
+          initial_data: 'initial data',
+          initial_configuration: 'initial configuration',
+          remote_reservation_id: 'remote-reservation-id',
+          "reservation_id" => {"id" => 'some-reservation-id'}
+        }
+      end
+
+      Reservation.valid_types.each do |type|
+        it "instantiates a #{type} reservation" do
+          params['status'] = type
+          expect(Reservation.new_from_hash(params.clone).status).to eql(type)
+        end
+      end
+
+      it "raises an exception for an invalid type" do
+        params['status'] = "An invalid type"
+        expect{Reservation.new_from_hash(params.clone)}.to raise_error(Deustorb::InvalidReservation)
+      end
+    end
   end
 end