"""

XML Writer to be used by the L{PrettyXMLSerializer} module. This is a slightly modified version of RDFLib's 
original XML Writer module, the changes are essentially aesthetic in nature (removing the unnecessary CDATA sections, 
using double quotes everywhere for attributes (both for namespaces and attributes in general).

"""

import codecs
from xml.sax.saxutils import quoteattr, escape

class XMLWriter(object):
	def __init__(self, stream, namespace_manager, encoding=None, decl=1):
		encoding = encoding or 'utf-8'
		encoder, decoder, stream_reader, stream_writer = codecs.lookup(encoding)
		self.stream = stream = stream_writer(stream)
		if decl:
			stream.write('<?xml version="1.0" encoding="%s"?>' % encoding)
		self.element_stack = []
		self.nm = namespace_manager
		self.closed = True

	def __get_indent(self):
		return "  " * len(self.element_stack)
	indent = property(__get_indent)

	def __close_start_tag(self):
		if not self.closed: # TODO:
			self.closed = True
			self.stream.write(">")

	def push(self, uri):
		nm = self.nm
		self.__close_start_tag()
		write = self.stream.write
		write("\n")
		write(self.indent)
		write("<%s" % nm.qname(uri))
		self.element_stack.append(uri)
		self.closed = False
		self.parent = False

	def pop(self, uri=None):
		top = self.element_stack.pop()
		if uri:
			assert uri==top
		write = self.stream.write
		if not self.closed:
			self.closed = True
			write("/>")
		else:
			if self.parent:
				write("\n")
				write(self.indent)
			write("</%s>" % self.nm.qname(uri))
		self.parent = True

	def namespaces(self, namespaces):
		write = self.stream.write
		write("\n")
		for prefix, namespace in namespaces:
			if prefix:
				write('  xmlns:%s="%s"\n' % (prefix, namespace))
			else:
				write('  xmlns="%s"\n' % namespace)

	def attribute(self, uri, value):
		write = self.stream.write
		write(" %s=%s" % (self.nm.qname(uri), quoteattr(value)))

	def text(self, text, to_escape):
		self.__close_start_tag()
		if to_escape :
			self.stream.write(escape(text))
		else :
			self.stream.write(text)
#		if "<" in text and ">" in text and not "]]>" in text:
#			#self.stream.write("<![CDATA[")
#			self.stream.write(text)
#			#self.stream.write("]]>")
#		else:
#			self.stream.write(escape(text))