require "rexml/element"
require "rexml/xmldecl"
require "rexml/source"
require "rexml/comment"
require "rexml/doctype"
require "rexml/instruction"
require "rexml/rexml"
require "rexml/parseexception"
require "rexml/output"
require "rexml/parsers/baseparser"
require "rexml/parsers/streamparser"
require "rexml/parsers/treeparser"

module REXML
  # Represents a full XML document, including PIs, a doctype, etc.  A
  # Document has a single child that can be accessed by root().
  # Note that if you want to have an XML declaration written for a document
  # you create, you must add one; REXML documents do not write a default
	# declaration for you.  See |DECLARATION| and |write|.
	class Document < Element
		# A convenient default XML declaration.  If you want an XML declaration,
		# the easiest way to add one is mydoc << Document::DECLARATION
    # +DEPRECATED+
    # Use: mydoc << XMLDecl.default
		DECLARATION = XMLDecl.default

		# Constructor
		# @param source if supplied, must be a Document, String, or IO. 
		# Documents have their context and Element attributes cloned.
	  # Strings are expected to be valid XML documents.  IOs are expected
	  # to be sources of valid XML documents.
	  # @param context if supplied, contains the context of the document;
	  # this should be a Hash.
		def initialize( source = nil, context = {} )
      @entity_expansion_count = 0
			super()
			@context = context
			return if source.nil?
			if source.kind_of? Document
				@context = source.context
				super source
			else
				build(  source )
			end
		end

    def node_type
      :document
    end

		# Should be obvious
		def clone
			Document.new self
		end

		# According to the XML spec, a root node has no expanded name
		def expanded_name
			''
			#d = doc_type
			#d ? d.name : "UNDEFINED"
		end

		alias :name :expanded_name

		# We override this, because XMLDecls and DocTypes must go at the start
		# of the document
		def add( child )
			if child.kind_of? XMLDecl
				@children.unshift child
        child.parent = self
			elsif child.kind_of? DocType
        # Find first Element or DocType node and insert the decl right 
        # before it.  If there is no such node, just insert the child at the
        # end.  If there is a child and it is an DocType, then replace it.
        insert_before_index = 0
        @children.find { |x| 
          insert_before_index += 1
          x.kind_of?(Element) || x.kind_of?(DocType)
        }
        if @children[ insert_before_index ] # Not null = not end of list
          if @children[ insert_before_index ].kind_of DocType
            @children[ insert_before_index ] = child
          else
            @children[ index_before_index-1, 0 ] = child
          end
        else  # Insert at end of list
          @children[insert_before_index] = child
        end
				child.parent = self
			else
				rv = super
				raise "attempted adding second root element to document" if @elements.size > 1
				rv
			end
		end
		alias :<< :add

		def add_element(arg=nil, arg2=nil)
			rv = super
			raise "attempted adding second root element to document" if @elements.size > 1
			rv
		end

		# @return the root Element of the document, or nil if this document
		# has no children.
		def root
      elements[1]
      #self
      #@children.find { |item| item.kind_of? Element }
		end

		# @return the DocType child of the document, if one exists,
		# and nil otherwise.
		def doctype
			@children.find { |item| item.kind_of? DocType }
		end

		# @return the XMLDecl of this document; if no XMLDecl has been
		# set, the default declaration is returned.
		def xml_decl
			rv = @children[0]
      return rv if rv.kind_of? XMLDecl
      rv = @children.unshift(XMLDecl.default)[0]
		end

		# @return the XMLDecl version of this document as a String.
		# If no XMLDecl has been set, returns the default version.
		def version
			xml_decl().version
		end

		# @return the XMLDecl encoding of this document as a String.
		# If no XMLDecl has been set, returns the default encoding.
		def encoding
			xml_decl().encoding
		end

		# @return the XMLDecl standalone value of this document as a String.
		# If no XMLDecl has been set, returns the default setting.
		def stand_alone?
			xml_decl().stand_alone?
		end

    # Write the XML tree out, optionally with indent.  This writes out the
    # entire XML document, including XML declarations, doctype declarations,
    # and processing instructions (if any are given).
    #
    # A controversial point is whether Document should always write the XML
    # declaration (<?xml version='1.0'?>) whether or not one is given by the
    # user (or source document).  REXML does not write one if one was not
    # specified, because it adds unnecessary bandwidth to applications such
    # as XML-RPC.
    #
    # See also the classes in the rexml/formatters package for the proper way
    # to change the default formatting of XML output
    #
    # _Examples_
    #   Document.new("<a><b/></a>").serialize
    #
    #   output_string = ""
    #   tr = Transitive.new( output_string )
    #   Document.new("<a><b/></a>").serialize( tr )
    #
    # output::
    #	  output an object which supports '<< string'; this is where the
    #   document will be written.
    # indent::
    #   An integer.  If -1, no indenting will be used; otherwise, the
    #   indentation will be twice this number of spaces, and children will be
    #   indented an additional amount.  For a value of 3, every item will be 
    #   indented 3 more levels, or 6 more spaces (2 * 3). Defaults to -1
    # trans::
    #   If transitive is true and indent is >= 0, then the output will be
    #   pretty-printed in such a way that the added whitespace does not affect
    #   the absolute *value* of the document -- that is, it leaves the value
    #   and number of Text nodes in the document unchanged.
    # ie_hack::
    #   Internet Explorer is the worst piece of crap to have ever been
    #   written, with the possible exception of Windows itself.  Since IE is
    #   unable to parse proper XML, we have to provide a hack to generate XML
    #   that IE's limited abilities can handle.  This hack inserts a space 
    #   before the /> on empty tags.  Defaults to false
		def write( output=$stdout, indent=-1, trans=false, ie_hack=false )
      if xml_decl.encoding != "UTF-8" && !output.kind_of?(Output)
        output = Output.new( output, xml_decl.encoding )
      end
      formatter = if indent > -1
          if trans
            REXML::Formatters::Transitive.new( indent, ie_hack )
          else
            REXML::Formatters::Pretty.new( indent, ie_hack )
          end
        else
          REXML::Formatters::Default.new( ie_hack )
        end
      formatter.write( self, output )
		end

		
		def Document::parse_stream( source, listener )
			Parsers::StreamParser.new( source, listener ).parse
		end

    @@entity_expansion_limit = 10_000

    # Set the entity expansion limit. By default the limit is set to 10000.
    def Document::entity_expansion_limit=( val )
      @@entity_expansion_limit = val
    end

    # Get the entity expansion limit. By default the limit is set to 10000.
    def Document::entity_expansion_limit
      return @@entity_expansion_limit
    end

    attr_reader :entity_expansion_count
    
    def record_entity_expansion
      @entity_expansion_count += 1
      if @entity_expansion_count > @@entity_expansion_limit
        raise "number of entity expansions exceeded, processing aborted."
      end
    end

		private
		def build( source )
      Parsers::TreeParser.new( source, self ).parse
		end
	end
end