# -*- coding: utf-8 -*-
require 'rubygems'
require 'hpricot'

# Apricot eats Gorilla is a helper for working with XML and SOAP messages.
# It's based on CobraVsMongoose but without REXML and the BadgerFish convention.
# Also it offers some extras for working with SOAP messages.
class ApricotEatsGorilla
  class << self

    # Flag to enable optional sorting of Hash keys. Especially useful for
    # comparing expected values with actual results while testing.
    attr_accessor :sort_keys

    # Converts XML into a Hash. Starts parsing at root node by default.
    # Call with XPath expession (Hpricot search) as second parameter to define
    # a custom root node. The root node itself will not be included in the Hash.
    #
    #  xml = "<dude><likes>beer</likes><hates>appletini</hates></dude>"
    #  ApricotEatsGorilla.xml_to_hash(xml)
    #  # => { "hates" => "appletini", "likes" => "beer" }
    def xml_to_hash(xml, root_node = nil)
      xml = clean_xml(xml)
      doc = Hpricot.XML(xml)
      root = root_node ? doc.at(root_node) : doc.root
      xml_node_to_hash(root)
    end

    # Converts a Hash to XML.
    # 
    #  hash = { "dude" => { "likes" => "beer", "hates" => "appletini" } }
    #  ApricotEatsGorilla.hash_to_xml(hash)
    #  # => "<dude><hates>appletini</hates><likes>beer</likes></dude>"
    def hash_to_xml(hash)
      nested_data_to_xml(hash.keys.first, hash.values.first)
    end

    # Builds a SOAP envelope and includes the content from an expected block
    # into the envelope body. Pass in a Hash of namespaces and their URI to
    # set custom namespaces.
    #
    #  <env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/">
    #    <env:Body>
    #      yield
    #    </env:Body>
    #  </env:Envelope>
    def soap_envelope(namespaces = {})
      namespaces["env"] = "http://schemas.xmlsoap.org/soap/envelope/"
      tag("env:Envelope", namespaces) do
        tag("env:Body") do
          yield if block_given?
        end
      end
    end

    # Creates an XML tag. Expects a block for tag content.
    # Defaults to an empty element tag in case no block was supplied.
    def tag(name, attributes = {})
      return "<#{name} />" unless block_given?

      attr = opt_order(attributes).map { |k, v| %Q( xmlns:#{k}="#{v}") }.to_s
      body = (yield && !yield.empty?) ? yield : ""
      "<#{name}#{attr}>" << body << "</#{name}>"
    end

  private

    # Converts XML into a Hash.
    def xml_node_to_hash(node)
      this_node = {}
      node.each_child do |child|
        # hpricot 0.6.1 returns an empty array, while 0.8 returns nil
        if child.children.nil? || child.children.empty?
          key, value = child.name, nil
        elsif child.children.size == 1 && child.children.first.text?
          key, value = child.name, booleanize(child.children.first.inner_text)
        else
          key, value = child.name, xml_node_to_hash(child)
        end

        key = remove_namespace(key)
        key = to_snake_case(key)
        current = this_node[key]
        case current
          when Array
            this_node[key] << value
          when nil
            this_node[key] = value
          else
            this_node[key] = [current.dup, value]
        end
      end
      this_node
    end

    # Converts a Hash to XML.
    def nested_data_to_xml(name, item)
      case item
      when String
        tag(name) { item }
      when Array
        item.map { |subitem| nested_data_to_xml(name, subitem) }.join
      when Hash
        tag(name) do
          opt_order(item).map { |tag, value|
            case value
            when String
              tag(tag) { value }
            when Array
              value.map { |subitem| nested_data_to_xml(tag, subitem) }.join
            when Hash
              nested_data_to_xml(tag, value)
            end
          }.join
        end
      end
    end

    # Returns a sorted version of a given Hash in case :sort_keys is enabled.
    def opt_order(hash)
      return hash unless sort_keys
      hash.sort_by { |kv| kv.first }
    end

    # Removes line breaks and whitespace between XML tags.
    def clean_xml(xml)
      xml = xml.gsub(/\n+/, "")
      xml.gsub(/(>)\s*(<)/, '\1\2')
    end

    # Removes namespaces from XML tags.
    def remove_namespace(tag)
      tag.sub(/.+:(.+)/, '\1')
    end

    # Converts CamelCase and lowerCamelCase to snake_case.
    def to_snake_case(string)
      string = string.gsub(/[A-Z]+/, '\1_\0').downcase
      string = string[1, string.length-1] if string[0, 1] == "_"
      string
    end

    # Converts "true" and "false" strings to boolean values.
    # Returns the original string in case it doesn't match "true" or "false".
    def booleanize(string)
      return true if string == "true"
      return false if string == "false"
      string
    end

  end
end

# Shortcut method for translating between XML documents and Hashes.
# Calls xml_to_hash in case the first parameter is of type String.
# Calls hash_to_xml in case the first parameter is of type Hash.
# Returns nil otherwise.
def ApricotEatsGorilla(source, root_node = nil)
  case source
  when String
    ApricotEatsGorilla.xml_to_hash(source, root_node)
  when Hash
    ApricotEatsGorilla.hash_to_xml(source)
  else
    nil
  end
end