require 'json'

class HyperResource
  class Adapter
    class HAL_JSON < Adapter
      class << self

        def serialize(object)
          JSON.dump(object)
        end

        def deserialize(string)
          JSON.parse(string)
        end

        def apply(response, resource, opts={})
          if !response.kind_of?(Hash)
            raise ArgumentError, "'response' argument must be a Hash"
          end
          if !resource.kind_of?(HyperResource)
            raise ArgumentError, "'resource' argument must be a HyperResource"
          end

          apply_objects(response, resource)
          apply_links(response, resource)
          apply_attributes(response, resource)
          resource.loaded = true
          resource.href = response['_links']['self']['href'] rescue nil
          resource
        end


      private

        def apply_objects(resp, rsrc)
          return unless resp['_embedded']
          rc = rsrc.class
          rsrc.objects = rc::Objects.new(rsrc)
          objs = rsrc.objects

          resp['_embedded'].each do |name, collection|
            if collection.is_a? Hash
              r = rc.new
              r.response_object = collection
              objs[name] = apply(collection, r)
            else
              objs[name] = collection.map do |obj|
                r = rc.new
                r.response_object = obj
                apply(obj, r)
              end
            end
          end

          objs.create_methods!
        end


        def apply_links(resp, rsrc)
          return unless resp['_links']
          rsrc.links = rsrc.get_response_class::Links.new(rsrc)
          links = rsrc.links

          resp['_links'].each do |rel, link_spec|
            if link_spec.is_a? Array
              links[rel] = link_spec.map do |link|
                new_link_from_spec(rsrc, link)
              end
            else
              links[rel] = new_link_from_spec(rsrc, link_spec)
            end
          end

          links.create_methods!
        end

        def new_link_from_spec(resource, link_spec) # :nodoc:
          resource.class::Link.new(resource, link_spec)
        end


        def apply_attributes(resp, rsrc)
          rsrc.attributes = rsrc.get_response_class::Attributes.new(rsrc)
          attrs = rsrc.attributes

          (resp.keys - ['_links', '_embedded']).map(&:to_s).each do |attr|
            attrs[attr] = resp[attr]
          end

          attrs.create_methods!
        end

      end
    end
  end
end