
import cStringIO
import StringIO

from xml.sax import make_parser, ErrorHandler, SAXParseException
from xml.sax import InputSource as SaxInput
from xml.dom.minidom import parseString as domParseString
from xml.parsers.expat import ExpatError
from lxml import etree

from cheshire3.baseObjects import Parser
from cheshire3.record import (
    SaxRecord,
    SaxContentHandler,
    DomRecord,
    MinidomRecord,
    MarcRecord
    )
from cheshire3.record import LxmlRecord
from cheshire3.utils import nonTextToken
from exceptions import XMLSyntaxError


class BaseParser(Parser):

    def _copyData(self, doc, rec):
        # Utility function to update data on record from document
        rec.id = doc.id
        rec.filename = doc.filename
        rec.tagName = doc.tagName
        rec.processHistory = doc.processHistory
        rec.processHistory.append(self.id)
        if doc.documentStore:
            rec.parent = ('document', doc.documentStore, doc.id)
        elif doc.parent:
            rec.parent = doc.parent


class MinidomParser(BaseParser):
    """Use default Python Minidom implementation to parse document."""

    def process_document(self, session, doc):
        xml = doc.get_raw(session)
        try:
            dom = domParseString(xml)
        except ExpatError as e:
            raise XMLSyntaxError(e.message)
        rec = MinidomRecord(dom, xml)
        self._copyData(doc, rec)
        return rec


class SaxParser(BaseParser):
    """Default SAX based parser. Creates SaxRecord."""

    _possibleSettings = {
        'namespaces': {
            'docs': "Enable namespace processing in SAX"
        },
        'stripWhitespace': {
            'docs': "Strip additional whitespace when processing."
        },
        'attrHash': {
            'docs': "Tag/Attribute combinations to include in hash."
        }
    }

    def __init__(self, session, config, parent):
        Parser.__init__(self, session, config, parent)
        self.parser = make_parser()
        self.errorHandler = ErrorHandler()
        self.parser.setErrorHandler(self.errorHandler)
        self.inputSource = SaxInput()
        ch = SaxContentHandler()
        self.contentHandler = ch
        self.parser.setContentHandler(ch)
        self.keepError = 1

        if (self.get_setting(session, 'namespaces')):
            self.parser.setFeature('http://xml.org/sax/features/namespaces',
                                   1)
        p = self.get_setting(session, 'attrHash')
        if (p):
            l = p.split()
            for i in l:
                (a, b) = i.split("@")
                try:
                    ch.hashAttributesNames[a].append(b)
                except:
                    ch.hashAttributesNames[a] = [b]
        if self.get_setting(session, 'stripWhitespace'):
            ch.stripWS = 1

    def process_document(self, session, doc):
        xml = doc.get_raw(session)
        if type(xml) == unicode:
            # SAX parser cannot deal with unicode
            xml = xml.encode('utf-8')
        self.inputSource.setByteStream(cStringIO.StringIO(xml))
        ch = self.contentHandler
        ch.reinit()
        try:
            self.parser.parse(self.inputSource)
        except SAXParseException as e:
            # Splat.  Reset self and reraise
            if self.keepError:
                # Work out path
                path = []
                for l in ch.pathLines:
                    line = ch.currentText[l]
                    elemName = line[2:line.index('{') - 1]
                    path.append("%s[@SAXID='%s']" % (elemName, l))
                self.errorPath = '/'.join(path)
            else:
                ch.reinit()
            raise XMLSyntaxError(str(e))
        rec = SaxRecord(ch.currentText, xml, wordCount=ch.recordWordCount)
        rec.elementHash = ch.elementHash
        rec.byteCount = len(xml)
        self._copyData(doc, rec)
        ch.reinit()
        return rec


class StoredSaxParser(BaseParser):

    def process_document(self, session, doc):
        data = doc.get_raw(session)
        data = unicode(data, 'utf-8')
        sax = data.split(nonTextToken)
        if sax[-1][0] == "9":
            line = sax.pop()
            elemHash = pickle.loads(str(line[2:]))
        else:
            elemHash = {}
        rec = SaxRecord(sax)
        rec.elementHash = elemHash
        return rec


class LxmlParser(BaseParser):
    """ lxml based Parser.  Creates LxmlRecords """

    _possibleSettings = {
        'validateDTD': {
            'docs': ("Validate to DTD while parsing (if a DTD was "
                     "referenced by the Document.)"),
            'type': int,
            'options': "0|1"
        },
        'allowNetwork': {
            'docs': ("Allow network access to look up external documents "
                     "(DTDs etc.)"),
            'type': int,
            'options': "0|1"
        }
    }

    def __init__(self, session, config, parent):
        BaseParser.__init__(self, session, config, parent)
        dtdVal = bool(self.get_setting(session, 'validateDTD', 0))
        noNetwork = not self.get_setting(session, 'allowNetwork', 0)
        self.parser = etree.XMLParser(dtd_validation=dtdVal,
                                      no_network=noNetwork)

    def process_document(self, session, doc):
        # Input must be string or stream
        data = doc.get_raw(session)
        try:
            try:
                et = etree.parse(StringIO.StringIO(data), self.parser)
            except AssertionError:
                data = data.decode('utf8')
                et = etree.parse(StringIO.StringIO(data), self.parser)
        except etree.XMLSyntaxError as e:
            raise XMLSyntaxError(e.message)
        rec = LxmlRecord(et)
        rec.byteCount = len(data)
        self._copyData(doc, rec)
        return rec


class LxmlSchemaParser(Parser):
    pass


class LxmlRelaxNGParser(Parser):
    pass


class LxmlHtmlParser(BaseParser):
    """lxml based parser for HTML documents."""

    def __init__(self, session, config, parent):
        BaseParser.__init__(self, session, config, parent)
        self.parser = etree.HTMLParser()

    def process_document(self, session, doc):
        data = doc.get_raw(session)
        et = etree.parse(StringIO.StringIO(data), self.parser)
        rec = LxmlRecord(et)
        rec.byteCount = len(data)
        self._copyData(doc, rec)
        return rec


class PassThroughParser(BaseParser):
    """Take a Document that already contains parsed data and return a Record.

    Copy the data from a document (eg list of sax events or a dom tree) into
    an appropriate record object.
    """

    def process_document(self, session, doc):
        # Simply copy data into a record of appropriate type
        data = doc.get_raw(session)
        if isinstance(data, list):
            rec = SaxRecord(data)
        else:
            rec = DomRecord(data)
        self._copyData(doc, rec)
        return rec


class MarcParser(BaseParser):
    """Creates MarcRecords which fake the Record API for Marc."""

    def process_document(self, session, doc):
        return MarcRecord(doc)
