var producers = new Array();
var consumers = new Array();

/* The URL encoding changes all of our double quotes to ", so we
 * have to convert them back before we do anything with the JSON
 * data. */
var locations_json = "${c.json}";
locations_json = locations_json.replace(/"/g, '"');
var locations = JSON.parse(locations_json);

for (var location_idx = 0; location_idx < locations.length; location_idx++) {
  if (locations[location_idx].type == 'producer') {
    producers.push(locations[location_idx]);
  }
  else {
    consumers.push(locations[location_idx]);
  }
}


// Start another JSON array, this time containing our route data.
var json_string = '[';
var completed_requests = 0;
var total_requests = (producers.length * consumers.length);

function routing_callback(result, status) {
  /* This is the callback that gets applied to each
   * DirectionsResult. It occurs asynchronously, which is why we keep
   * track of the total/completed requests. Only the last call to
   * complete should actually do something with the final result. */
  if (status == google.maps.DirectionsStatus.OK) {
    json_string += JSON.stringify(result);

    for (var trip_idx = 0; trip_idx < result.trips.length; trip_idx++) {
      num_routes = result.trips[trip_idx].routes.length;
      if (num_routes > 1) {
	  alert("Unexpected number of routes (" +
	      result.trips.routes.length.toString() +
	      ") on trip number " + trip_idx.toString() + '.');
      }
    }
  }
  else {
    alert("Error, status: " + status);
  }

  completed_requests += 1;

  if (completed_requests == total_requests) {
    // Close the array, and do something with the result.
    json_string += ']';
    mu = new MapUtils();
    mu.post_data('/directions/json_to_kml', json_string);
  }
  else {
    // Continue the array.
    json_string += ',';
  }
  
}



function get_directions(pairs_to_skip) {
  /* We can only get directions for 10 producer/consumer pairs at a
   * time. We pass the pairs_to_skip variable back to this function
   * via setTimeout so that we can skip the ones we've already
   * submitted. */

  // Create the object that will do the direction-getting.
  var directions_service = new google.maps.DirectionsService();
  var requests_submitted = 0;
  
  // And ask it to get directions for each producer/consumer pair.
  for (var i = 0; i < producers.length; i++) {
    for (var j = 0; j < consumers.length; j++) {

      var pair_number = (i * consumers.length) + (j+1);

      if (pair_number <= pairs_to_skip || requests_submitted > 9) {
	continue;
      }

      var producer_latlng = new google.maps.LatLng(producers[i].latitude,
						   producers[i].longitude);
      
      var consumer_latlng = new google.maps.LatLng(consumers[i].latitude,
						   consumers[i].longitude);

      var directions_request = {
	origin: producer_latlng,
	destination: consumer_latlng,
	provideTripAlternatives: true,

	travelMode: google.maps.DirectionsTravelMode.DRIVING
      }

      /* The function routing_callback(...) gets applied to the result
       * of route(). Ideally, that result will be a DirectionsResult
       * object containing directions. This executes
       * asynchronously. */
      directions_service.route(directions_request, routing_callback);

      requests_submitted += 1;      
    }
  }

  if (pairs_to_skip < total_requests) {
    // Next time around, skip whatever requests we submitted this
    // time.
    pairs_to_skip += requests_submitted;

    /* 5 seconds is the smallest timeout that will work here. */
    window.setTimeout("get_directions(" + pairs_to_skip + ");", 5000);
  }
      
  return;
}


function onload_handler(e) {
  // Avoid problems with the implicit event argument to onload
  // handlers.
  get_directions(0);
}


window.onload = onload_handler;