"""
zurlparser.py - experimental Z39.50 url parser, see rfc 2056 for more info

requires web.py. incomplete implementation.

example: http://localhost:8080/validate/z39.50s://z3950.loc.gov:7090/VOYAGER?au="van rossum guido"
"""

import web

class ParseError(Exception):
  """Base class for exceptions from this module"""
  pass

class URIParseError(ParseError):
  """Class for parsing URI errors"""
  def __init__(self, _reason):
    self.reason = _reason
    ParseError.__init__(self)
    
  def __str__(self):
    return self.reason

class URLParser:
  """URL Parser class"""

  def parse_uri(self):
    """Parse a Z39.50 URL in RFC 2056 format - not completely implemented"""
    uri = self

    def pull(v, q, index):
      _i = index + 1, v.find(q, index)
      return v[_i[0]:_i[1]], _i[1]
    
    if uri[0:10] == 'z39.50s://':
      host, _index = pull(uri, ':', 9)
      port, _index = pull(uri, '/', _index)
      if uri.find('?') == -1:
        db = uri[_index + 1:]
        query = None
      else:
        db, _index = pull(uri, '?', _index)
        query = uri[_index + 1:]
        if uri.find('&') <> -1:
          #to be implemented...
          pass
      return {'host': host, 'port': int(port), 'db': db, 'query': query}

    elif uri[0:10] == 'z39.50r://':
      raise URIParseError('URI scheme "z39.50r:" not yet implemented')

    else:
      raise URIParseError('%s is not a valid Z39.50 URI' % uri)

class validate:
  """web.py class to validate Z39.50 URIs"""
  def GET(self, uri):
    print URLParser().parse_uri(uri)

web.webapi.internalerror = web.debugerror
if __name__ == '__main__':
  web.run(urls, globals())