require 'rexml/xmltokens'

# [ :element, parent, name, attributes, children* ]
  # a = Node.new
  # a << "B"            # => <a>B</a>
  # a.b                 # => <a>B<b/></a>
  # a.b[1]                      # => <a>B<b/><b/><a>
  # a.b[1]["x"] = "y"   # => <a>B<b/><b x="y"/></a>
  # a.b[0].c            # => <a>B<b><c/></b><b x="y"/></a>
  # a.b.c << "D"                # => <a>B<b><c>D</c></b><b x="y"/></a>
module REXML
  module Light
    # Represents a tagged XML element.  Elements are characterized by
    # having children, attributes, and names, and can themselves be
    # children.
    class Node
      NAMESPLIT = /^(?:(#{XMLTokens::NCNAME_STR}):)?(#{XMLTokens::NCNAME_STR})/u
      PARENTS = [ :element, :document, :doctype ]
      # Create a new element.
      def initialize node=nil
        @node = node
        if node.kind_of? String
          node = [ :text, node ]
        elsif node.nil?
          node = [ :document, nil, nil ]
        elsif node[0] == :start_element
          node[0] = :element
        elsif node[0] == :start_doctype
          node[0] = :doctype
        elsif node[0] == :start_document
          node[0] = :document
        end
      end

      def size
        if PARENTS.include? @node[0]
          @node[-1].size
        else
          0
        end
      end

      def each( &block )
        size.times { |x| yield( at(x+4) ) }
      end

      def name
        at(2)
      end

      def name=( name_str, ns=nil )
        pfx = ''
        pfx = "#{prefix(ns)}:" if ns
        _old_put(2, "#{pfx}#{name_str}")
      end

      def parent=( node )
        _old_put(1,node)
      end

      def local_name
        namesplit
        @name
      end

      def local_name=( name_str )
        _old_put( 1, "#@prefix:#{name_str}" )
      end

      def prefix( namespace=nil )
        prefix_of( self, namespace )
      end

      def namespace( prefix=prefix() )
        namespace_of( self, prefix )
      end

      def namespace=( namespace )
        @prefix = prefix( namespace )
        pfx = ''
        pfx = "#@prefix:" if @prefix.size > 0
        _old_put(1, "#{pfx}#@name")
      end

      def []( reference, ns=nil )
        if reference.kind_of? String
          pfx = ''
          pfx = "#{prefix(ns)}:" if ns
          at(3)["#{pfx}#{reference}"]
        elsif reference.kind_of? Range
          _old_get( Range.new(4+reference.begin, reference.end, reference.exclude_end?) )
        else
          _old_get( 4+reference )
        end
      end

      def =~( path )
        XPath.match( self, path )
      end

      # Doesn't handle namespaces yet
      def []=( reference, ns, value=nil )
        if reference.kind_of? String
          value = ns unless value
          at( 3 )[reference] = value
        elsif reference.kind_of? Range
          _old_put( Range.new(3+reference.begin, reference.end, reference.exclude_end?), ns )
        else
          if value
            _old_put( 4+reference, ns, value )
          else
            _old_put( 4+reference, ns )
          end
        end
      end

      # Append a child to this element, optionally under a provided namespace.
      # The namespace argument is ignored if the element argument is an Element
      # object.  Otherwise, the element argument is a string, the namespace (if
      # provided) is the namespace the element is created in.
      def << element
        if node_type() == :text
          at(-1) << element
        else
          newnode = Node.new( element )
          newnode.parent = self
          self.push( newnode )
        end
        at(-1)
      end

      def node_type
        _old_get(0)
      end

      def text=( foo )
        replace = at(4).kind_of?(String)? 1 : 0
        self._old_put(4,replace, normalizefoo)
      end

      def root
        context = self
        context = context.at(1) while context.at(1)
      end

      def has_name?( name, namespace = '' )
        at(3) == name and namespace() == namespace
      end

      def children
        self
      end

      def parent
        at(1)
      end

      def to_s

      end

      private

      def namesplit
        return if @name.defined?
        at(2) =~ NAMESPLIT
        @prefix = '' || $1
        @name = $2
      end

      def namespace_of( node, prefix=nil )
        if not prefix
          name = at(2)
          name =~ NAMESPLIT
          prefix = $1
        end
        to_find = 'xmlns'
        to_find = "xmlns:#{prefix}" if not prefix.nil?
        ns = at(3)[ to_find ]
        ns ? ns : namespace_of( @node[0], prefix )
      end

      def prefix_of( node, namespace=nil )
        if not namespace
          name = node.name
          name =~ NAMESPLIT
          $1
        else
          ns = at(3).find { |k,v| v == namespace }
          ns ? ns : prefix_of( node.parent, namespace )
        end
      end
    end
  end
end
