Planner.py

   1 #
   2 # vi: set softtabstop=4 shiftwidth=4 tabstop=8 expandtab:
   3
   4 """A frontend for the OC Transpo Travel Planner."""
   5
   6 import cookielib
   7 import urllib2
   8 import urllib
   9 import sre
  10
  11 def plan(start, end, time):
  12     """Plans a route between two Locations at a certain PlanTime."""
  13     planner = TravelPlannerClient()
  14     planner.feedStartLocation(start)
  15     planner.feedEndLocation(end)
  16     planner.feedTime(time)
  17
  18 class TravelPlannerException(Exception):
  19     """Generic parent exception for anything thrown by us, as opposed to
  20        things thrown by the network layer."""
  21
  22     def _init_(self, value):
  23         Exception._init_(self, value)
  24
  25 class InvalidLocationException(TravelPlannerException):
  26     """Thrown when a source or destination can't be found.
  27
  28        The "args" value of the exception is the original Location."""
  29
  30     def _init(self, location):
  31         TravelPlannerException._init_(self, location)
  32
  33 class TravelPlannerClient:
  34     def _init_(self):
  35         # Set up a cookie-aware client.
  36         self.cj = cookielib.CookieJar()
  37         self.opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(self.cj))
  38
  39         # Initialize the session.
  40         r = self._sendRequest(self.START_PAGE, None)
  41
  42     def feedStartLocation(self, loc):
  43         # name="tp_fromAddress" method="get" action="FromAddress.oci"
  44         # fromAddress text
  45         # streetType=Other
  46         params = (("fromAddress", loc), ("streetType", "Other"))
  47         r = self._sendRequest("FromAddress.oci", params)
  48
  49     def feedEndLocation(self, loc):
  50         params = (("toAddress", loc), ("streetType", "Other"))
  51         r = self._sendRequest("ToAddress.oci", params)
  52
  53     def feedTime(self, time):
  54         # name="tp_time" action="SelectTime.oci"
  55         # dateSelect="
  56         # requestCode=3 for must leave after
  57         # time
  58         # timePeriod=am or pm
  59         r = self._sendRequest("SelectTime.oci", time.toPlannerParams())
  60
  61         for line in r:
  62             print line.rstrip()
  63
  64     def _sendRequest(self, page, params):
  65         url = self.URL_BASE + page
  66         if params is not None:
  67             url += "?" + urllib.urlencode(params)
  68
  69         print dir(self)
  70         response = self.opener.open(url)
  71         self._checkObviousBadness(response)
  72
  73         html = self._grabLimitedResponse(response)
  74         self._scanForError(html)
  75         return html
  76
  77     def _checkObviousBadness(self, response):
  78         if response.code != 200:
  79             raise TravelPlannerException("Got HTTP " + response.code
  80                                          + " error from server")
  81         if "errorPage.oci" in response.geturl():
  82             raise TravelPlannerException("Redirected to error page")
  83
  84     def _grabLimitedResponse(self, response):
  85         count = 0
  86
  87         accum = ""
  88         for line in response:
  89             count += len(line)
  90             if (count <= self.RESPONSE_SIZE_LIMIT):
  91                 accum += line
  92             else:
  93                 break
  94         return accum
  95
  96
  97
  98     # Regular expressions: probably the worst way to parse HTML
  99     # Probably the best thing to put in your breakfast cereal.
 100
 101     def _scanForError(self, text):
 102         match = error_rx.search(text)
 103         if match:
 104             raise TravelPlannerException(match.group("msg"))
 105
 106     URL_BASE = "http://www.octranspo.com/tps/jnot/"
 107     START_PAGE = "startEN.oci"
 108     RESPONSE_SIZE_LIMIT = 100000
 109
 110
 111
 112 # Scan for an error.
 113 # <table cellpadding="0" cellspacing="0" summary="Warning message" class="warning" width="85%">
 114 #   <tr>
 115 #       <td><img src="tripPlanning/images/imgWarning.gif"></td>
 116 #       <td>The address you specified was not found.  Please enter another.</td>
 117 #   </tr>
 118 # </table>
 119 _error_re = ('<table[^>]*class="(?:warning|error)[^>]*>\s*'
 120                 '<tr>(?:\s*<td>\s*<img[^>]*>\s*</td>)?'
 121                     # ?s: DOTALL: . matches \n
 122                     # *? is non-greedy
 123                     '\s*<td>(?s)\s*(?P<msg>[\d\D]*?)\s*</td>')
 124 _error_rx = sre.compile(_error_re)