require 'rubygems'
require 'active_support'
require 'roxml'

# TODO: Untange this inter-dependency...
%w{ browse_node measurement image ordinal price }.each do |type|
  require File.join(File.dirname(__FILE__), '..', 'types', type)
end

module Hpricot
  class Element < OpenHash
    def initialize(value, attributes = {})
      merge! :value => value,
             :attributes => attributes
    end
  end

  # Extend with some convenience methods
  module Traverse
    def self.induce(type, &block)
      raise ArgumentError, "block missing" unless block_given?

      type_at, to_type, types_at = "#{type}_at", "to_#{type}", "#{type.to_s.pluralize}_at"
      if [type_at, to_type, types_at].any? {|m| method_defined?(m) }
        raise ArgumentError, "some methods already defined"
      end

      define_method type_at do |path|
        result = at(path) and yield result
      end
      define_method to_type do
        method(type_at).call('')
      end
      define_method types_at do |path|
        results = search(path) and results.collect {|r| yield r }
      end
    end

    # Get the text value of the given path, leave empty to retrieve current element value.
    induce :text do |result|
      CGI::unescapeHTML(result.inner_html)
    end

    induce :int do |result|
      Integer(result.inner_html)
    end

    induce :bool do |result|
      case result.inner_html
      when '0': false
      when 'False': false
      when '1': true
      when 'True': true
      else
        raise TypeError, "String #{result.inspect} is not convertible to bool"
      end
    end

    induce :element do |result|
      # TODO: Use to_h here?
      attrs = result.attributes.inject({}) do |hash, attr|
        hash[attr[0].to_sym] = attr[1].to_s; hash
      end

      children = result.children
      if children.size == 1 and children.first.is_a? Text
        value = children.first.to_s
      else
        result = children.inject({}) do |hash, item|
          name = item.name.to_sym
          hash[name] ||= []
          hash[name] << item.to_hash
          hash
        end

        value = result.each_pair {|key, value| result[key] = value[0] if value.size == 1 }
      end

      (attrs.empty?) ? value : Element.new(value, attrs)
    end

    # TODO: This probably doesn't belong here...  References to Amazon:: types indicate as much anyway
    # Get the children element text values in hash format with the element names as the hash keys.
    induce :hash do |result|
      # TODO: date?, image? &c
      # TODO: This is super-ugly... is there a better way to map?
      if ['width', 'height', 'length', 'weight'].include? result.name
        Amazon::Measurement.from_xml(result.to_s)
      elsif ['batteriesincluded', 'iseligibleforsupersavershipping', 'isautographed', 'ismemorabilia', 'isvalid'].include? result.name
        result.to_bool
      elsif result.name == 'browsenode'
        Amazon::BrowseNode.from_xml(result.to_s)
      elsif result.name == 'edition'
        begin
          Amazon::Ordinal.from_xml(result.to_s)
        rescue TypeError
          # a few edition types aren't ordinals, but strings (e.g., "First American Edition")
          result.to_text
        end
      elsif result.name.starts_with? 'total' or result.name.starts_with? 'number' or ['quantity'].include? result.name
        result.to_int
      elsif result.name.ends_with? 'price' or result.name.ends_with? 'total'
        Amazon::Price.from_xml(result.to_s)
      elsif result.name.ends_with? 'image'
        Amazon::Image.from_xml(result.to_s)
      else
        if (result.children.size > 1 or !result.children.first.is_a? Text) and names = result.children.collect {|c| c.name }.uniq and names.size == 1 and names[0].pluralize == result.name
          result.children.map(&:to_hash)
        else
          result.to_element
        end
      end
    end
  end
end