require 'rexml/document'
require 'rexml/streamlistener'

require 'facet/string/capitalized%3F'

module Nitro

# A programmatically generated element.
# 
# === Design
#
# An underscore is used for the standard attibutes to
# avoid name clashes.
#--
# TODO: 
# * separate 'view' template files.
#++

class Element
	# The parent of this element.
	
	attr_accessor :_parent
	
	# The childrens of this element.
	
	attr_accessor :_children
	
	# The text of this element.
	
	attr_accessor :_text

	# The view of this element.
	
	attr_accessor :_view

	def initialize(*args)
		@_children = []
		@_text = ''
	end
		
	def open
	end
	
	def content
#		"#{@_text}#{render_children}"
		@_text
	end
	
	def close
	end	

	def render
		"#{open}#{content}#{close}"
	end

	def render_children
		str = ''
		for c in @_children
			str << c.render
		end
		
		return str
	end	
	
	def add_child(child)
		child._parent = self	
		@_children << child
	end
end

# Processes a page containing elements.

class ElementProcessor # :nodoc: all

	class Listener # :nodoc: all
		include REXML::StreamListener
		
		attr_accessor :buffer
		attr_accessor :stack
		
		def initialize
			super
			@buffer = ''
			@stack = []
		end
		
		def tag_start(name, attributes)		
			if name =~ /^[A-Z]/ # .capitalized?		
				obj = Object.const_get(name).new
				
	    	attributes.each do | k, v | 
	    		obj.instance_variable_set("@#{k}", v)
	    	end	    	
	    	
	    	@stack.push [obj, @buffer]
	    	
	    	@buffer = obj._text
		    @parent.add_child(obj) if @parent
		    @parent = obj
	    else # This is a static element.
	    	attrs = []
	    	
	    	attributes.each do | k, v | 
	    		attrs << %|#{k}="#{v}"|
	    	end
	    	
	    	attrs = attrs.empty? ? nil : " #{attrs.join(' ')}"
	    	
				@buffer << "<#{name}#{attrs}>"
			end
		end

		def tag_end(name)		
			if name =~ /^[A-Z]/ # .capitalized?		
				obj, @buffer = @stack.pop
				@buffer << obj.render
			else
				@buffer << "</#{name}>"
			end
		end
		
		def text(str)
			@buffer << str
		end
		
		def instruction(name, attributes)
			@buffer << "<?#{name}#{attributes}?>"
		end
	end
	
	class << self
		def parse(source)
			self.new.parse(source)
		end
		
		def render(source)
			self.new.render(source)
		end

	end

	# Expand the elemens found in source.
		
	def render(source)
		listener = Listener.new
		REXML::Document.parse_stream(source, listener)
		# gmosx, FIXME: optimize this, how?
		listener.buffer.gsub! /<(.*) ([^>]*)><\/\1>/, '<\1 \2 />'
		return listener.buffer
	end
end

end