"""
HTML Sanitizer (ripped from feedparser)
"""

import re, sgmllib

# reversable htmlentitydefs mappings for Python 2.2
try:
    from htmlentitydefs import name2codepoint, codepoint2name
except:
    import htmlentitydefs
    name2codepoint={}
    codepoint2name={}
    for (name,codepoint) in htmlentitydefs.entitydefs.iteritems():
      if codepoint.startswith('&#'): codepoint=unichr(int(codepoint[2:-1]))
      name2codepoint[name]=ord(codepoint)
      codepoint2name[ord(codepoint)]=name

_cp1252 = {
  unichr(128): unichr(8364), # euro sign
  unichr(130): unichr(8218), # single low-9 quotation mark
  unichr(131): unichr( 402), # latin small letter f with hook
  unichr(132): unichr(8222), # double low-9 quotation mark
  unichr(133): unichr(8230), # horizontal ellipsis
  unichr(134): unichr(8224), # dagger
  unichr(135): unichr(8225), # double dagger
  unichr(136): unichr( 710), # modifier letter circumflex accent
  unichr(137): unichr(8240), # per mille sign
  unichr(138): unichr( 352), # latin capital letter s with caron
  unichr(139): unichr(8249), # single left-pointing angle quotation mark
  unichr(140): unichr( 338), # latin capital ligature oe
  unichr(142): unichr( 381), # latin capital letter z with caron
  unichr(145): unichr(8216), # left single quotation mark
  unichr(146): unichr(8217), # right single quotation mark
  unichr(147): unichr(8220), # left double quotation mark
  unichr(148): unichr(8221), # right double quotation mark
  unichr(149): unichr(8226), # bullet
  unichr(150): unichr(8211), # en dash
  unichr(151): unichr(8212), # em dash
  unichr(152): unichr( 732), # small tilde
  unichr(153): unichr(8482), # trade mark sign
  unichr(154): unichr( 353), # latin small letter s with caron
  unichr(155): unichr(8250), # single right-pointing angle quotation mark
  unichr(156): unichr( 339), # latin small ligature oe
  unichr(158): unichr( 382), # latin small letter z with caron
  unichr(159): unichr( 376)} # latin capital letter y with diaeresis

class _BaseHTMLProcessor(sgmllib.SGMLParser):
    special = re.compile('''[<>'"]''')
    bare_ampersand = re.compile("&(?!#\d+;|#x[0-9a-fA-F]+;|\w+;)")
    elements_no_end_tag = ['area', 'base', 'basefont', 'br', 'col', 'frame', 'hr',
      'img', 'input', 'isindex', 'link', 'meta', 'param']

    def __init__(self, encoding, type):
        self.encoding = encoding
        self.type = type
        ## if _debug: sys.stderr.write('entering BaseHTMLProcessor, encoding=%s\n' % self.encoding)
        sgmllib.SGMLParser.__init__(self)

    def reset(self):
        self.pieces = []
        sgmllib.SGMLParser.reset(self)

    def _shorttag_replace(self, match):
        tag = match.group(1)
        if tag in self.elements_no_end_tag:
            return '<' + tag + ' />'
        else:
            return '<' + tag + '></' + tag + '>'

    def parse_starttag(self,i):
        j=sgmllib.SGMLParser.parse_starttag(self, i)
        if self.type == 'application/xhtml+xml':
            if j>2 and self.rawdata[j-2:j]=='/>':
                self.unknown_endtag(self.lasttag)
        return j

    def feed(self, data):
        data = re.compile(r'<!((?!DOCTYPE|--|\[))', re.IGNORECASE).sub(r'&lt;!\1', data)
        #data = re.sub(r'<(\S+?)\s*?/>', self._shorttag_replace, data) # bug [ 1399464 ] Bad regexp for _shorttag_replace
        data = re.sub(r'<([^<>\s]+?)\s*/>', self._shorttag_replace, data)
        data = data.replace('&#39;', "'")
        data = data.replace('&#34;', '"')
        if self.encoding and type(data) == type(u''):
            data = data.encode(self.encoding)
        sgmllib.SGMLParser.feed(self, data)
        sgmllib.SGMLParser.close(self)

    def normalize_attrs(self, attrs):
        if not attrs: return attrs
        # utility method to be called by descendants
        attrs = dict([(k.lower(), v) for k, v in attrs]).items()
        attrs = [(k, k in ('rel', 'type') and v.lower() or v) for k, v in attrs]
        attrs.sort()
        return attrs

    def unknown_starttag(self, tag, attrs):
        # called for each start tag
        # attrs is a list of (attr, value) tuples
        # e.g. for <pre class='screen'>, tag='pre', attrs=[('class', 'screen')]
        ## if _debug: sys.stderr.write('_BaseHTMLProcessor, unknown_starttag, tag=%s\n' % tag)
        uattrs = []
        strattrs=''
        if attrs:
            for key, value in attrs:
                value=value.replace('>','&gt;').replace('<','&lt;').replace('"','&quot;')
                value = self.bare_ampersand.sub("&amp;", value)
                # thanks to Kevin Marks for this breathtaking hack to deal with (valid) high-bit attribute values in UTF-8 feeds
                if type(value) != type(u''):
                    try:
                        value = unicode(value, self.encoding)
                    except:
                        value = unicode(value, 'iso-8859-1')
                uattrs.append((unicode(key, self.encoding), value))
            strattrs = u''.join([u' %s="%s"' % (key, value) for key, value in uattrs])
            if self.encoding:
                try:
                    strattrs=strattrs.encode(self.encoding)
                except:
                    pass
        if tag in self.elements_no_end_tag:
            self.pieces.append('<%(tag)s%(strattrs)s />' % locals())
        else:
            self.pieces.append('<%(tag)s%(strattrs)s>' % locals())

    def unknown_endtag(self, tag):
        # called for each end tag, e.g. for </pre>, tag will be 'pre'
        # Reconstruct the original end tag.
        if tag not in self.elements_no_end_tag:
            self.pieces.append("</%(tag)s>" % locals())

    def handle_charref(self, ref):
        # called for each character reference, e.g. for '&#160;', ref will be '160'
        # Reconstruct the original character reference.
        if ref.startswith('x'):
            value = unichr(int(ref[1:],16))
        else:
            value = unichr(int(ref))

        if value in _cp1252.keys():
            self.pieces.append('&#%s;' % hex(ord(_cp1252[value]))[1:])
        else:
            self.pieces.append('&#%(ref)s;' % locals())

    def handle_entityref(self, ref):
        # called for each entity reference, e.g. for '&copy;', ref will be 'copy'
        # Reconstruct the original entity reference.
        if name2codepoint.has_key(ref):
            self.pieces.append('&%(ref)s;' % locals())
        else:
            self.pieces.append('&amp;%(ref)s' % locals())

    def handle_data(self, text):
        # called for each block of plain text, i.e. outside of any tag and
        # not containing any character or entity references
        # Store the original text verbatim.
        ## if _debug: sys.stderr.write('_BaseHTMLProcessor, handle_text, text=%s\n' % text)
        self.pieces.append(text)

    def handle_comment(self, text):
        # called for each HTML comment, e.g. <!-- insert Javascript code here -->
        # Reconstruct the original comment.
        self.pieces.append('<!--%(text)s-->' % locals())

    def handle_pi(self, text):
        # called for each processing instruction, e.g. <?instruction>
        # Reconstruct original processing instruction.
        self.pieces.append('<?%(text)s>' % locals())

    def handle_decl(self, text):
        # called for the DOCTYPE, if present, e.g.
        # <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        #     "http://www.w3.org/TR/html4/loose.dtd">
        # Reconstruct original DOCTYPE
        self.pieces.append('<!%(text)s>' % locals())

    _new_declname_match = re.compile(r'[a-zA-Z][-_.a-zA-Z0-9:]*\s*').match
    def _scan_name(self, i, declstartpos):
        rawdata = self.rawdata
        n = len(rawdata)
        if i == n:
            return None, -1
        m = self._new_declname_match(rawdata, i)
        if m:
            s = m.group()
            name = s.strip()
            if (i + len(s)) == n:
                return None, -1  # end of buffer
            return name.lower(), m.end()
        else:
            self.handle_data(rawdata)
#            self.updatepos(declstartpos, i)
            return None, -1

    def convert_charref(self, name):
        return '&#%s;' % name

    def convert_entityref(self, name):
        return '&%s;' % name

    def output(self):
        '''Return processed HTML as a single string'''
        return ''.join([str(p) for p in self.pieces])

class _HTMLSanitizer(_BaseHTMLProcessor):
    acceptable_elements = ['a', 'abbr', 'acronym', 'address', 'area', 'article',
      'aside', 'audio', 'b', 'big', 'blockquote', 'br', 'button', 'canvas',
      'caption', 'center', 'cite', 'code', 'col', 'colgroup', 'command',
      'datagrid', 'datalist', 'dd', 'del', 'details', 'dfn', 'dialog', 'dir',
      'div', 'dl', 'dt', 'em', 'event-source', 'fieldset', 'figure', 'footer',
      'font', 'form', 'header', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i',
      'img', 'input', 'ins', 'keygen', 'kbd', 'label', 'legend', 'li', 'm', 'map',
      'menu', 'meter', 'multicol', 'nav', 'nextid', 'ol', 'output', 'optgroup',
      'option', 'p', 'pre', 'progress', 'q', 's', 'samp', 'section', 'select',
      'small', 'sound', 'source', 'spacer', 'span', 'strike', 'strong', 'sub',
      'sup', 'table', 'tbody', 'td', 'textarea', 'time', 'tfoot', 'th', 'thead',
      'tr', 'tt', 'u', 'ul', 'var', 'video', 'noscript']

    acceptable_attributes = ['abbr', 'accept', 'accept-charset', 'accesskey',
      'action', 'align', 'alt', 'autocomplete', 'autofocus', 'axis',
      'background', 'balance', 'bgcolor', 'bgproperties', 'border',
      'bordercolor', 'bordercolordark', 'bordercolorlight', 'bottompadding',
      'cellpadding', 'cellspacing', 'ch', 'challenge', 'char', 'charoff',
      'choff', 'charset', 'checked', 'cite', 'class', 'clear', 'color', 'cols',
      'colspan', 'compact', 'contenteditable', 'controls', 'coords', 'data',
      'datafld', 'datapagesize', 'datasrc', 'datetime', 'default', 'delay',
      'dir', 'disabled', 'draggable', 'dynsrc', 'enctype', 'end', 'face', 'for',
      'form', 'frame', 'galleryimg', 'gutter', 'headers', 'height', 'hidefocus',
      'hidden', 'high', 'href', 'hreflang', 'hspace', 'icon', 'id', 'inputmode',
      'ismap', 'keytype', 'label', 'leftspacing', 'lang', 'list', 'longdesc',
      'loop', 'loopcount', 'loopend', 'loopstart', 'low', 'lowsrc', 'max',
      'maxlength', 'media', 'method', 'min', 'multiple', 'name', 'nohref',
      'noshade', 'nowrap', 'open', 'optimum', 'pattern', 'ping', 'point-size',
      'prompt', 'pqg', 'radiogroup', 'readonly', 'rel', 'repeat-max',
      'repeat-min', 'replace', 'required', 'rev', 'rightspacing', 'rows',
      'rowspan', 'rules', 'scope', 'selected', 'shape', 'size', 'span', 'src',
      'start', 'step', 'summary', 'suppress', 'tabindex', 'target', 'template',
      'title', 'toppadding', 'type', 'unselectable', 'usemap', 'urn', 'valign',
      'value', 'variable', 'volume', 'vspace', 'vrml', 'width', 'wrap',
      'xml:lang']

    unacceptable_elements_with_end_tag = ['script', 'applet', 'style']

    acceptable_css_properties = ['azimuth', 'background-color',
      'border-bottom-color', 'border-collapse', 'border-color',
      'border-left-color', 'border-right-color', 'border-top-color', 'clear',
      'color', 'cursor', 'direction', 'display', 'elevation', 'float', 'font',
      'font-family', 'font-size', 'font-style', 'font-variant', 'font-weight',
      'height', 'letter-spacing', 'line-height', 'overflow', 'pause',
      'pause-after', 'pause-before', 'pitch', 'pitch-range', 'richness',
      'speak', 'speak-header', 'speak-numeral', 'speak-punctuation',
      'speech-rate', 'stress', 'text-align', 'text-decoration', 'text-indent',
      'unicode-bidi', 'vertical-align', 'voice-family', 'volume',
      'white-space', 'width']

    # survey of common keywords found in feeds
    acceptable_css_keywords = ['auto', 'aqua', 'black', 'block', 'blue',
      'bold', 'both', 'bottom', 'brown', 'center', 'collapse', 'dashed',
      'dotted', 'fuchsia', 'gray', 'green', '!important', 'italic', 'left',
      'lime', 'maroon', 'medium', 'none', 'navy', 'normal', 'nowrap', 'olive',
      'pointer', 'purple', 'red', 'right', 'solid', 'silver', 'teal', 'top',
      'transparent', 'underline', 'white', 'yellow']

    valid_css_values = re.compile('^(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|' +
      '\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$')

    mathml_elements = ['annotation', 'annotation-xml', 'maction', 'math',
      'merror', 'mfenced', 'mfrac', 'mi', 'mmultiscripts', 'mn', 'mo', 'mover', 'mpadded',
      'mphantom', 'mprescripts', 'mroot', 'mrow', 'mspace', 'msqrt', 'mstyle',
      'msub', 'msubsup', 'msup', 'mtable', 'mtd', 'mtext', 'mtr', 'munder',
      'munderover', 'none', 'semantics']

    mathml_attributes = ['actiontype', 'align', 'columnalign', 'columnalign',
      'columnalign', 'close', 'columnlines', 'columnspacing', 'columnspan', 'depth',
      'display', 'displaystyle', 'encoding', 'equalcolumns', 'equalrows',
      'fence', 'fontstyle', 'fontweight', 'frame', 'height', 'linethickness',
      'lspace', 'mathbackground', 'mathcolor', 'mathvariant', 'mathvariant',
      'maxsize', 'minsize', 'open', 'other', 'rowalign', 'rowalign', 'rowalign',
      'rowlines', 'rowspacing', 'rowspan', 'rspace', 'scriptlevel', 'selection',
      'separator', 'separators', 'stretchy', 'width', 'width', 'xlink:href',
      'xlink:show', 'xlink:type', 'xmlns', 'xmlns:xlink']

    # svgtiny - foreignObject + linearGradient + radialGradient + stop
    svg_elements = ['a', 'animate', 'animateColor', 'animateMotion',
      'animateTransform', 'circle', 'defs', 'desc', 'ellipse', 'foreignObject',
      'font-face', 'font-face-name', 'font-face-src', 'g', 'glyph', 'hkern',
      'linearGradient', 'line', 'marker', 'metadata', 'missing-glyph', 'mpath',
      'path', 'polygon', 'polyline', 'radialGradient', 'rect', 'set', 'stop',
      'svg', 'switch', 'text', 'title', 'tspan', 'use']

    # svgtiny + class + opacity + offset + xmlns + xmlns:xlink
    svg_attributes = ['accent-height', 'accumulate', 'additive', 'alphabetic',
       'arabic-form', 'ascent', 'attributeName', 'attributeType',
       'baseProfile', 'bbox', 'begin', 'by', 'calcMode', 'cap-height',
       'class', 'color', 'color-rendering', 'content', 'cx', 'cy', 'd', 'dx',
       'dy', 'descent', 'display', 'dur', 'end', 'fill', 'fill-opacity',
       'fill-rule', 'font-family', 'font-size', 'font-stretch', 'font-style',
       'font-variant', 'font-weight', 'from', 'fx', 'fy', 'g1', 'g2',
       'glyph-name', 'gradientUnits', 'hanging', 'height', 'horiz-adv-x',
       'horiz-origin-x', 'id', 'ideographic', 'k', 'keyPoints', 'keySplines',
       'keyTimes', 'lang', 'mathematical', 'marker-end', 'marker-mid',
       'marker-start', 'markerHeight', 'markerUnits', 'markerWidth', 'max',
       'min', 'name', 'offset', 'opacity', 'orient', 'origin',
       'overline-position', 'overline-thickness', 'panose-1', 'path',
       'pathLength', 'points', 'preserveAspectRatio', 'r', 'refX', 'refY',
       'repeatCount', 'repeatDur', 'requiredExtensions', 'requiredFeatures',
       'restart', 'rotate', 'rx', 'ry', 'slope', 'stemh', 'stemv',
       'stop-color', 'stop-opacity', 'strikethrough-position',
       'strikethrough-thickness', 'stroke', 'stroke-dasharray',
       'stroke-dashoffset', 'stroke-linecap', 'stroke-linejoin',
       'stroke-miterlimit', 'stroke-opacity', 'stroke-width', 'systemLanguage',
       'target', 'text-anchor', 'to', 'transform', 'type', 'u1', 'u2',
       'underline-position', 'underline-thickness', 'unicode', 'unicode-range',
       'units-per-em', 'values', 'version', 'viewBox', 'visibility', 'width',
       'widths', 'x', 'x-height', 'x1', 'x2', 'xlink:actuate', 'xlink:arcrole',
       'xlink:href', 'xlink:role', 'xlink:show', 'xlink:title', 'xlink:type',
       'xml:base', 'xml:lang', 'xml:space', 'xmlns', 'xmlns:xlink', 'y', 'y1',
       'y2', 'zoomAndPan']

    svg_attr_map = None
    svg_elem_map = None

    acceptable_svg_properties = [ 'fill', 'fill-opacity', 'fill-rule',
      'stroke', 'stroke-width', 'stroke-linecap', 'stroke-linejoin',
      'stroke-opacity']

    def reset(self):
        _BaseHTMLProcessor.reset(self)
        self.unacceptablestack = 0
        self.mathmlOK = 0
        self.svgOK = 0

    def unknown_starttag(self, tag, attrs):
        acceptable_attributes = self.acceptable_attributes
        keymap = {}
        if not tag in self.acceptable_elements or self.svgOK:
            if tag in self.unacceptable_elements_with_end_tag:
                self.unacceptablestack += 1

            # not otherwise acceptable, perhaps it is MathML or SVG?
            if tag=='math' and ('xmlns','http://www.w3.org/1998/Math/MathML') in attrs:
                self.mathmlOK += 1
            if tag=='svg' and ('xmlns','http://www.w3.org/2000/svg') in attrs:
                self.svgOK += 1

            # chose acceptable attributes based on tag class, else bail
            if  self.mathmlOK and tag in self.mathml_elements:
                acceptable_attributes = self.mathml_attributes
            elif self.svgOK and tag in self.svg_elements:
                # for most vocabularies, lowercasing is a good idea.  Many
                # svg elements, however, are camel case
                if not self.svg_attr_map:
                    lower=[attr.lower() for attr in self.svg_attributes]
                    mix=[a for a in self.svg_attributes if a not in lower]
                    self.svg_attributes = lower
                    self.svg_attr_map = dict([(a.lower(),a) for a in mix])

                    lower=[attr.lower() for attr in self.svg_elements]
                    mix=[a for a in self.svg_elements if a not in lower]
                    self.svg_elements = lower
                    self.svg_elem_map = dict([(a.lower(),a) for a in mix])
                acceptable_attributes = self.svg_attributes
                tag = self.svg_elem_map.get(tag,tag)
                keymap = self.svg_attr_map
            elif not tag in self.acceptable_elements:
                return

        # declare xlink namespace, if needed
        if self.mathmlOK or self.svgOK:
            if filter(lambda (n,v): n.startswith('xlink:'),attrs):
                if not ('xmlns:xlink','http://www.w3.org/1999/xlink') in attrs:
                    attrs.append(('xmlns:xlink','http://www.w3.org/1999/xlink'))

        clean_attrs = []
        for key, value in self.normalize_attrs(attrs):
            if key=="href" and value.strip().startswith("javascript"):
                pass
            elif key in acceptable_attributes:
                key=keymap.get(key,key)
                clean_attrs.append((key,value))
            elif key=='style':
                pass
                ## clean_value = self.sanitize_style(value)
                ## if clean_value: clean_attrs.append((key,clean_value))
        _BaseHTMLProcessor.unknown_starttag(self, tag, clean_attrs)

    def unknown_endtag(self, tag):
        if not tag in self.acceptable_elements:
            if tag in self.unacceptable_elements_with_end_tag:
                self.unacceptablestack -= 1
            if self.mathmlOK and tag in self.mathml_elements:
                if tag == 'math' and self.mathmlOK: self.mathmlOK -= 1
            elif self.svgOK and tag in self.svg_elements:
                tag = self.svg_elem_map.get(tag,tag)
                if tag == 'svg' and self.svgOK: self.svgOK -= 1
            else:
                return
        _BaseHTMLProcessor.unknown_endtag(self, tag)

    def handle_pi(self, text):
        pass

    def handle_decl(self, text):
        pass

    def handle_data(self, text):
        if not self.unacceptablestack:
            _BaseHTMLProcessor.handle_data(self, text)

    def sanitize_style(self, style):
        # disallow urls
        style=re.compile('url\s*\(\s*[^\s)]+?\s*\)\s*').sub(' ',style)

        # gauntlet
        if not re.match("""^([:,;#%.\sa-zA-Z0-9!]|\w-\w|'[\s\w]+'|"[\s\w]+"|\([\d,\s]+\))*$""", style): return ''
        if not re.match("^(\s*[-\w]+\s*:\s*[^:;]*(;|$))*$", style): return ''

        clean = []
        for prop,value in re.findall("([-\w]+)\s*:\s*([^:;]*)",style):
          if not value: continue
          if prop.lower() in self.acceptable_css_properties:
              clean.append(prop + ': ' + value + ';')
          elif prop.split('-')[0].lower() in ['background','border','margin','padding']:
              for keyword in value.split():
                  if not keyword in self.acceptable_css_keywords and \
                      not self.valid_css_values.match(keyword):
                      break
              else:
                  clean.append(prop + ': ' + value + ';')
          elif self.svgOK and prop.lower() in self.acceptable_svg_properties:
              clean.append(prop + ': ' + value + ';')

        return ' '.join(clean)


def sanitize_html(htmlSource, encoding="utf-8", type="text/html"):
    p = _HTMLSanitizer(encoding, type)
    p.feed(htmlSource)
    data = p.output()
    data = data.strip().replace('\r\n', '\n')
    return data