require 'nokogiri'
require_relative '../core_ext.rb'

module Vamper
  class BadVersionFile < StandardError; end

  class VersionFile
    attr_reader :tags

    def initialize(io)
      if io
        @doc = Nokogiri::XML(io, &:noblanks)

        unless @doc.root.name == 'Version'
          raise BadVersionFile, 'Root element must be Version'
        end
      else
        @doc = Nokogiri::XML::Document.new
        @doc.root.add_child(Nokogiri::XML::Element.new('Version', @doc))
      end

      add_attribute @doc.root, :BuildValueType => :JDate
      add_child_list_element @doc.root, :Files, :Tags
      add_child_element tags_element,
        :Major => 1, :Minor => 0, :Build => 0, :Patch => 0, :Revision => 0, :TimeZone => 'UTC'
      add_child_element tags_element, {:StartYear => TZInfo::Timezone.get(self.time_zone).now.year}
    end

    def add_attribute(parent_node, attr_definitions)
      attr_definitions.each { |attr_symbol, attr_default|
        method_name = attr_symbol.to_s.underscore
        unless parent_node[attr_symbol]
          parent_node[attr_symbol] = attr_default
        end
        define_singleton_method(method_name.to_sym) {
          parent_node[attr_symbol].to_sym
        }
        define_singleton_method((method_name + '=').to_sym) { |value|
          parent_node[attr_symbol] = value.to_s
        }
      }
    end

    def add_child_list_element(parent_element, *element_symbols)
      element_symbols.each { |element_symbol|
        name = element_symbol.to_s
        elem = parent_element.at(name)
        unless elem
          elem = parent_element.add_child(Nokogiri::XML::Element.new(name, @doc))
        end

        method_name = name.underscore + '_element'
        define_singleton_method(method_name.to_sym) {
          elem
        }
      }
    end

    def add_child_element(parent_element, element_definitions)
      element_definitions.each { |element_symbol, element_default|
        name = element_symbol.to_s
        elem = parent_element.at(name)
        unless elem
          elem = parent_element.add_child(Nokogiri::XML::Element.new(name, @doc))
          elem.content = element_default.to_s
        end

        method_name = name.underscore
        case element_default
          when Fixnum
            define_singleton_method(method_name.to_sym) {
              Integer(elem.content)
            }
          when String
            define_singleton_method(method_name.to_sym) {
              elem.content.to_s
            }
        end
        define_singleton_method((method_name + '=').to_sym) { |value|
          elem.content = value.to_s
        }
      }
    end

    def write_to(io)
      @doc.write_xml_to(io, :indent_text => ' ', :indent => 2)
    end

    def tags
      Hash[tags_element.children.select {|node| node.name != 'text'}.map {|node| [node.name.to_sym, node.content]}]
    end
    def files
      files_element.children.select {|node| node.name != 'text'}.map {|node| node.content}
    end

  end
end