conversions.rb

require 'date'
require 'cgi'
require 'base64'
require 'builder'
require 'xmlsimple'

# Extensions needed for Hash#to_query
class Object
  def to_param #:nodoc:
    to_s
  end

  def to_query(key) #:nodoc:
    "#{CGI.escape(key.to_s)}=#{CGI.escape(to_param.to_s)}"
  end
end

class Array
  def to_query(key) #:nodoc:
    collect { |value| value.to_query("#{key}[]") } * '&'
  end
end

# Locked down XmlSimple#xml_in_string
class XmlSimple
  # Same as xml_in but doesn't try to smartly shoot itself in the foot.
  def xml_in_string(string, options = nil)
    handle_options('in', options)

    @doc = parse(string)
    result = collapse(@doc.root)

    if @options['keeproot']
      merge({}, @doc.root.name, result)
    else
      result
    end
  end

  def self.xml_in_string(string, options = nil)
    new.xml_in_string(string, options)
  end
end

module ActiveSupport #:nodoc:
  module CoreExtensions #:nodoc:
    module Hash #:nodoc:
      module Conversions
        XML_TYPE_NAMES = {
          "Fixnum"     => "integer",
          "Bignum"     => "integer",
          "BigDecimal" => "decimal",
          "Float"      => "float",
          "Date"       => "date",
          "DateTime"   => "datetime",
          "Time"       => "datetime",
          "TrueClass"  => "boolean",
          "FalseClass" => "boolean"
        } unless defined?(XML_TYPE_NAMES)

        XML_FORMATTING = {
          "date"     => Proc.new { |date| date.to_s(:db) },
          "datetime" => Proc.new { |time| time.xmlschema },
          "binary"   => Proc.new { |binary| Base64.encode64(binary) },
          "yaml"     => Proc.new { |yaml| yaml.to_yaml }
        } unless defined?(XML_FORMATTING)

        unless defined?(XML_PARSING)
          XML_PARSING = {
            "date"         => Proc.new  { |date|    ::Date.parse(date) },
            "datetime"     => Proc.new  { |time|    ::Time.parse(time).utc },
            "integer"      => Proc.new  { |integer| integer.to_i },
            "float"        => Proc.new  { |float|   float.to_f },
            "decimal"      => Proc.new  { |number|  BigDecimal(number) },
            "boolean"      => Proc.new  { |boolean| %w(1 true).include?(boolean.strip) },
            "string"       => Proc.new  { |string|  string.to_s },
            "yaml"         => Proc.new  { |yaml|    YAML::load(yaml) rescue yaml },
            "base64Binary" => Proc.new  { |bin|     Base64.decode64(bin) },
            # FIXME: Get rid of eval and institute a proper decorator here
            "file"         => Proc.new do |file, entity|
              f = StringIO.new(Base64.decode64(file))
              eval "def f.original_filename() '#{entity["name"]}' || 'untitled' end"
              eval "def f.content_type()      '#{entity["content_type"]}' || 'application/octet-stream' end"
              f
            end
          }

          XML_PARSING.update(
            "double"   => XML_PARSING["float"],
            "dateTime" => XML_PARSING["datetime"]
          )
        end

        def self.included(klass)
          klass.extend(ClassMethods)
        end

        def to_query(namespace = nil)
          collect do |key, value|
            value.to_query(namespace ? "#{namespace}[#{key}]" : key)
          end.sort * '&'
        end

        def to_xml(options = {})
          options[:indent] ||= 2
          options.reverse_merge!({ :builder => Builder::XmlMarkup.new(:indent => options[:indent]),
                                   :root => "hash" })
          options[:builder].instruct! unless options.delete(:skip_instruct)
          dasherize = !options.has_key?(:dasherize) || options[:dasherize]
          root = dasherize ? options[:root].to_s.dasherize : options[:root].to_s

          options[:builder].__send__(:method_missing, root) do
            each do |key, value|
              case value
                when ::Hash
                  value.to_xml(options.merge({ :root => key, :skip_instruct => true }))
                when ::Array
                  value.to_xml(options.merge({ :root => key, :children => key.to_s.singularize, :skip_instruct => true}))
                when ::Method, ::Proc
                  # If the Method or Proc takes two arguments, then
                  # pass the suggested child element name.  This is
                  # used if the Method or Proc will be operating over
                  # multiple records and needs to create an containing
                  # element that will contain the objects being
                  # serialized.
                  if 1 == value.arity
                    value.call(options.merge({ :root => key, :skip_instruct => true }))
                  else
                    value.call(options.merge({ :root => key, :skip_instruct => true }), key.to_s.singularize)
                  end
                else
                  if value.respond_to?(:to_xml)
                    value.to_xml(options.merge({ :root => key, :skip_instruct => true }))
                  else
                    type_name = XML_TYPE_NAMES[value.class.name]

                    key = dasherize ? key.to_s.dasherize : key.to_s

                    attributes = options[:skip_types] || value.nil? || type_name.nil? ? { } : { :type => type_name }
                    if value.nil?
                      attributes[:nil] = true
                    end

                    options[:builder].tag!(key,
                      XML_FORMATTING[type_name] ? XML_FORMATTING[type_name].call(value) : value,
                      attributes
                    )
                end
              end
            end
            
            yield options[:builder] if block_given?
          end

        end

        module ClassMethods
          def from_xml(xml)
            # TODO: Refactor this into something much cleaner that doesn't rely on XmlSimple
            typecast_xml_value(undasherize_keys(XmlSimple.xml_in_string(xml,
              'forcearray'   => false,
              'forcecontent' => true,
              'keeproot'     => true,
              'contentkey'   => '__content__')
            ))
          end

          private
            def typecast_xml_value(value)
              case value.class.to_s
                when 'Hash'
                  if value.has_key?("__content__")
                    content = value["__content__"]
                    if parser = XML_PARSING[value["type"]]
                      if parser.arity == 2
                        XML_PARSING[value["type"]].call(content, value)
                      else
                        XML_PARSING[value["type"]].call(content)
                      end
                    else
                      content
                    end
                  elsif value['type'] == 'array'
                    child_key, entries = value.detect { |k,v| k != 'type' }   # child_key is throwaway
                    if entries.nil?
                      []
                    else
                      case entries.class.to_s   # something weird with classes not matching here.  maybe singleton methods breaking is_a?
                      when "Array"
                        entries.collect { |v| typecast_xml_value(v) }
                      when "Hash"
                        [typecast_xml_value(entries)]
                      else
                        raise "can't typecast #{entries.inspect}"
                      end
                    end
                  elsif value['type'] == 'string' && value['nil'] != 'true'
                    ""
                  # blank or nil parsed values are represented by nil
                  elsif value.blank? || value['nil'] == 'true'
                    nil
                  # If the type is the only element which makes it then 
                  # this still makes the value nil
                  elsif value['type'] && value.size == 1
                    nil
                  else
                    xml_value = value.inject({}) do |h,(k,v)|
                      h[k] = typecast_xml_value(v)
                      h
                    end
                    
                    # Turn { :files => { :file => #<StringIO> } into { :files => #<StringIO> } so it is compatible with
                    # how multipart uploaded files from HTML appear
                    xml_value["file"].is_a?(StringIO) ? xml_value["file"] : xml_value
                  end
                when 'Array'
                  value.map! { |i| typecast_xml_value(i) }
                  case value.length
                    when 0 then nil
                    when 1 then value.first
                    else value
                  end
                when 'String'
                  value
                else
                  raise "can't typecast #{value.class.name} - #{value.inspect}"
              end
            end

            def undasherize_keys(params)
              case params.class.to_s
                when "Hash"
                  params.inject({}) do |h,(k,v)|
                    h[k.to_s.tr("-", "_")] = undasherize_keys(v)
                    h
                  end
                when "Array"
                  params.map { |v| undasherize_keys(v) }
                else
                  params
              end
            end
        end
      end
    end
  end
end