require "rexml/parent"
require "rexml/parseexception"
require "rexml/namespace"
require 'rexml/entity'
require 'rexml/attlistdecl'
require 'rexml/xmltokens'

module REXML
  # Represents an XML DOCTYPE declaration; that is, the contents of <!DOCTYPE
  # ... >.  DOCTYPES can be used to declare the DTD of a document, as well as
  # being used to declare entities used in the document.
  class DocType < Parent
    include XMLTokens
    START = "<!DOCTYPE"
    STOP = ">"
    SYSTEM = "SYSTEM"
    PUBLIC = "PUBLIC"
    DEFAULT_ENTITIES = { 
      'gt'=>EntityConst::GT, 
      'lt'=>EntityConst::LT, 
      'quot'=>EntityConst::QUOT, 
      "apos"=>EntityConst::APOS 
    }

    # name is the name of the doctype
    # external_id is the referenced DTD, if given
    attr_reader :name, :external_id, :entities, :namespaces

    # Constructor
    #
    #   dt = DocType.new( 'foo', '-//I/Hate/External/IDs' )
    #   # <!DOCTYPE foo '-//I/Hate/External/IDs'>
    #   dt = DocType.new( doctype_to_clone )
    #   # Incomplete.  Shallow clone of doctype
    #
    # +Note+ that the constructor: 
    #
    #  Doctype.new( Source.new( "<!DOCTYPE foo 'bar'>" ) )
    #
    # is _deprecated_.  Do not use it.  It will probably disappear.
    def initialize( first, parent=nil )
      @entities = DEFAULT_ENTITIES
      @long_name = @uri = nil
      if first.kind_of? String
        super()
        @name = first
        @external_id = parent
      elsif first.kind_of? DocType
        super( parent )
        @name = first.name
        @external_id = first.external_id
      elsif first.kind_of? Array
        super( parent )
        @name = first[0]
        @external_id = first[1]
        @long_name = first[2]
        @uri = first[3]
      elsif first.kind_of? Source
        super( parent )
        parser = Parsers::BaseParser.new( first )
        event = parser.pull
        if event[0] == :start_doctype
          @name, @external_id, @long_name, @uri, = event[1..-1]
        end
      else
        super()
      end
    end

    def node_type
      :doctype
    end

    def attributes_of element
      rv = []
      each do |child|
        child.each do |key,val|
          rv << Attribute.new(key,val)
        end if child.kind_of? AttlistDecl and child.element_name == element
      end
      rv
    end

    def attribute_of element, attribute
      att_decl = find do |child|
        child.kind_of? AttlistDecl and
        child.element_name == element and
        child.include? attribute
      end
      return nil unless att_decl
      att_decl[attribute]
    end

    def clone
      DocType.new self
    end

    # output::
    #   Where to write the string
    # indent::
    #   An integer.  If -1, no indenting will be used; otherwise, the
    #   indentation will be this number of spaces, and children will be
    #   indented an additional amount.
    # transitive::
    #   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.
    #
    def write( output, indent=0, transitive=false, ie_hack=false )
      indent( output, indent )
      output << START
      output << ' '
      output << @name
      output << " #@external_id" if @external_id
      output << " #@long_name" if @long_name
      output << " #@uri" if @uri
      unless @children.empty?
        next_indent = indent + 1
        output << ' ['
        child = nil    # speed
        @children.each { |child|
          output << "\n"
          child.write( output, next_indent )
        }
        #output << '   '*next_indent
        output << "\n]"
      end
      output << STOP
    end

    def context
      @parent.context
    end

    def entity( name )
      @entities[name].unnormalized if @entities[name]
    end

    def add child
      super(child)
      @entities = DEFAULT_ENTITIES.clone if @entities == DEFAULT_ENTITIES
      @entities[ child.name ] = child if child.kind_of? Entity
    end
    
    # This method retrieves the public identifier identifying the document's 
    # DTD.
    #
    # Method contributed by Henrik Martensson
    def public
      case @external_id
      when "SYSTEM"
        nil
      when "PUBLIC"
        strip_quotes(@long_name)
      end
    end
    
    # This method retrieves the system identifier identifying the document's DTD
    #
    # Method contributed by Henrik Martensson
    def system
      case @external_id
      when "SYSTEM"
        strip_quotes(@long_name)
      when "PUBLIC"
        @uri.kind_of?(String) ? strip_quotes(@uri) : nil
      end
    end
    
    # This method returns a list of notations that have been declared in the
    # _internal_ DTD subset. Notations in the external DTD subset are not 
    # listed.
    #
    # Method contributed by Henrik Martensson
    def notations
      children().select {|node| node.kind_of?(REXML::NotationDecl)}
    end
    
    # Retrieves a named notation. Only notations declared in the internal
    # DTD subset can be retrieved.
    #
    # Method contributed by Henrik Martensson
    def notation(name)
      notations.find { |notation_decl|
        notation_decl.name == name
      }
    end
    
    private
    
    # Method contributed by Henrik Martensson
    def strip_quotes(quoted_string)
      quoted_string =~ /^[\'\"].*[\´\"]$/ ?
        quoted_string[1, quoted_string.length-2] :
        quoted_string
    end
  end

  # We don't really handle any of these since we're not a validating
  # parser, so we can be pretty dumb about them.  All we need to be able
  # to do is spew them back out on a write()

  # This is an abstract class.  You never use this directly; it serves as a
  # parent class for the specific declarations.
  class Declaration < Child
    def initialize src
      super()
      @string = src
    end

    def to_s
      @string+'>'
    end

    def write( output, indent )
      output << ('   '*indent) if indent > 0
      output << to_s
    end
  end
  
  public
  class ElementDecl < Declaration
    def initialize( src )
      super
    end
  end

  class ExternalEntity < Child
    def initialize( src )
      super()
      @entity = src
    end
    def to_s
      @entity
    end
    def write( output, indent )
      output << @entity
    end
  end

  class NotationDecl < Child
    attr_accessor :public, :system
    def initialize name, middle, pub, sys
      super(nil)
      @name = name
      @middle = middle
      @public = pub
      @system = sys
    end

    def to_s
      "<!NOTATION #@name #@middle#{
        @public ? ' ' + public.inspect : '' 
      }#{
        @system ? ' ' +@system.inspect : ''
      }>"
    end

    def write( output, indent=-1 )
      output << ('   '*indent) if indent > 0
      output << to_s
    end
    
    # This method retrieves the name of the notation.
    #
    # Method contributed by Henrik Martensson
    def name
      @name
    end
  end
end
