import threading
import StringIO

from lxml import etree
from path import path
NS_MAP = {'svg': "http://www.w3.org/2000/svg",
        'inkscape': "http://www.inkscape.org/namespaces/inkscape"}

# thread safe parser storage
class ParserTLS(threading.local):
    def getParser(self):
        parser = getattr(self, "parser", None)
        if parser is not None:
            return parser
        self.parser = parser = etree.XMLParser()
        return parser

parsel_tls = ParserTLS()

def TreeToString(tree, pretty=False, encoding=None, method="xml"):
    return  etree.tostring(tree, pretty_print=pretty, encoding=encoding, method=method)

def TreeToFile(tree, fname, encoding='utf-8'):
    tree.write(fname, encoding=encoding, xml_declaration=True, method="xml")

def FileToTree(fname):
    return etree.parse(fname, parsel_tls.getParser())

def StringToTree(s):
    if not s:
        raise ValueError("Empty or invalid string %r (%s)'" % (s, type(s)))
    return etree.parse(StringIO.StringIO(s), parsel_tls.getParser())


def subelement(destEl, tag, pos=None, attribs=None):
    e = etree.SubElement(destEl, tag)

    if pos is not None:
        e.getparent().insert(pos, e)

    if attribs is not None:
        e.attrib.update(dict(((k, unicode(v)) for k, v in attribs.items())))

    return e

prettyXSL = """<?xml version="1.0" encoding="UTF-8"?>
                <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
                    <xsl:output encoding="UTF-8" method="xml"/>
                    <xsl:param name="indent-increment" select="'   '"/>
                    <xsl:template match="* | comment()|processing-instruction()">
                        <xsl:param name="indent" select="'&#xA;'"/>
                        <xsl:value-of select="$indent"/>
                        <xsl:copy>
                            <xsl:copy-of select="@*"/>
                            <xsl:apply-templates>
                                <xsl:with-param name="indent" select="concat($indent, $indent-increment)"/>
                            </xsl:apply-templates>
                            <xsl:if test="*">
                                <xsl:value-of select="$indent"/>
                            </xsl:if>
                        </xsl:copy>
                    </xsl:template>
                    <!-- WARNING: this is dangerous. Handle with care -->
                    <xsl:template match="text()[normalize-space(.)='']"/>
                </xsl:stylesheet>"""

def prettyPrint(data):
    ''' pretty-print data - can be a:
    * xml string
    * list of etree.elements (return single pretty-prints that will be \n concatenated)
    * single etree or single element
    '''

    xslt_doc = etree.fromstring(prettyXSL)
    transform = etree.XSLT(xslt_doc)

    if isinstance(data, basestring):
        doc = etree.fromstring(data)
        return etree.tostring(transform(doc))

    elif isinstance(data, (tuple, list)): #assume data is list of etree.elements
        return '\n'.join(etree.tostring(transform(e)) for e in data)
    else:
        return etree.tostring(transform(data))