# Copyright (C) 2001  Bastian Kleineidam
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

import re, StringUtil, linkname
from debuglevels import *
from linkcheck.parser.htmllib import HtmlParser
from linkcheck.Config import debug

# ripped mainly from HTML::Tagset.pm
LinkTags = {
    'a':        ['href'],
    'applet':   ['archive', 'src'],
    'area':     ['href'],
    'bgsound':  ['src'],
    'blockquote': ['cite'],
    'body':     ['background'],
    'del':      ['cite'],
    'embed':    ['pluginspage', 'src'],
    'form':     ['action'],
    'frame':    ['src', 'longdesc'],
    'head':     ['profile'],
    'iframe':   ['src', 'longdesc'],
    'ilayer':   ['background'],
    'img':      ['src', 'lowsrc', 'longdesc', 'usemap'],
    'input':    ['src', 'usemap'],
    'ins':      ['cite'],
    'isindex':  ['action'],
    'layer':    ['background', 'src'],
    'link':     ['href'],
    'meta':     ['content'],
    'object':   ['classid', 'data', 'archive', 'usemap'],
    'q':        ['cite'],
    'script':   ['src', 'for'],
    'table':    ['background'],
    'td':       ['background'],
    'th':       ['background'],
    'tr':       ['background'],
    'xmp':      ['href'],
}

# matcher for <meta http-equiv=refresh> tags
_refresh_re = re.compile(r"(?i)^\d+;\s*url=(?P<url>.+)$")

class LinkParser (HtmlParser):
    """Parse the content for a list of links. After parsing, the urls
    will have a list of parsed links entries with the format
    (url, lineno, column, name, base)
    """

    def __init__ (self, content, tags=LinkTags):
        HtmlParser.__init__(self)
        self.content = content
        self.tags = tags
        self.urls = []
        self.feed(self.content)
        debug(HURT_ME_PLENTY, "flushing")
        self.flush()


    def startElement (self, tag, attrs):
        debug(NIGHTMARE, "LinkParser tag", tag, "attrs", attrs)
        debug(ALWAYS, "line", self.lineno(), "col", self.column(),
              "old line", self.last_lineno(), "old col", self.last_column())
        if not self.tags.has_key(tag): return
        for attr in self.tags[tag]:
            if attr in attrs:
                # name of this link
                if tag=='a' and attr=='href':
                    name = StringUtil.unquote(attrs.get('title', ''))
                    if not name:
                        name = linkname.href_name(self.content[self.pos():])
                elif tag=='img':
                    name = StringUtil.unquote(attrs.get('alt', ''))
                else:
                    name = ""
                # possible codebase
                if tag in ('applet', 'object'):
                    base = StringUtil.unquote(attrs.get('codebase'))
                else:
                    base = ""
                # add link to url list
                value = StringUtil.unquote(attrs[attr])
                self.addLink(tag, attr, value, name, base)


    def addLink (self, tag, attr, url, name, base):
        debug(NIGHTMARE, "LinkParser add link", tag, attr, url, name, base)
        # look for meta refresh
        if tag=='meta':
            metamatch = _refresh_re.match(url)
            if metamatch:
                url = metamatch.group("url")
            else:
                # only meta refresh has an url, so return
                return
        self.urls.append((url, self.last_lineno(), self.last_column(),
                          name, base))