// Copyright 2010-2018 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// [START program]
// [START import]
using System;
using System.Collections.Generic;
using Google.OrTools.ConstraintSolver;
// [END import]

/// <summary>
///   Minimal Pickup & Delivery Problem (PDP).
/// </summary>
public class VrpPickupDeliveryLifo {
  // [START data_model]
  class DataModel {
    public long[,] DistanceMatrix = {
      {0, 548, 776, 696, 582, 274, 502, 194, 308, 194, 536, 502, 388, 354, 468, 776, 662},
      {548, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674, 1016, 868, 1210},
      {776, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164, 1130, 788, 1552, 754},
      {696, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822, 1164, 560, 1358},
      {582, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708, 1050, 674, 1244},
      {274, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628, 514, 1050, 708},
      {502, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856, 514, 1278, 480},
      {194, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320, 662, 742, 856},
      {308, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662, 320, 1084, 514},
      {194, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388, 274, 810, 468},
      {536, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764, 730, 388, 1152, 354},
      {502, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114, 308, 650, 274, 844},
      {388, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194, 536, 388, 730},
      {354, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0, 342, 422, 536},
      {468, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536, 342, 0, 764, 194},
      {776, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274, 388, 422, 764, 0, 798},
      {662, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730, 536, 194, 798, 0}
    };
    // [START pickups_deliveries]
    public int[][] PickupsDeliveries = {
      new int[] {1, 6},
      new int[] {2, 10},
      new int[] {4, 3},
      new int[] {5, 9},
      new int[] {7, 8},
      new int[] {15, 11},
      new int[] {13, 12},
      new int[] {16, 14},
    };
    // [END pickups_deliveries]
    public int VehicleNumber = 4;
    public int Depot = 0;
  };
  // [END data_model]

  // [START solution_printer]
  /// <summary>
  ///   Print the solution.
  /// </summary>
  static void PrintSolution(
      in DataModel data,
      in RoutingModel routing,
      in RoutingIndexManager manager,
      in Assignment solution) {
    long totalDistance = 0;
    for (int i = 0; i < data.VehicleNumber; ++i) {
      Console.WriteLine("Route for Vehicle {0}:", i);
      long routeDistance = 0;
      var index = routing.Start(i);
      while (routing.IsEnd(index) == false) {
        Console.Write("{0} -> ", manager.IndexToNode((int)index));
        var previousIndex = index;
        index = solution.Value(routing.NextVar(index));
        routeDistance += routing.GetArcCostForVehicle(previousIndex, index, 0);
      }
      Console.WriteLine("{0}", manager.IndexToNode((int)index));
      Console.WriteLine("Distance of the route: {0}m", routeDistance);
      totalDistance += routeDistance;
    }
    Console.WriteLine("Total Distance of all routes: {0}m", totalDistance);
  }
  // [END solution_printer]

  public static void Main(String[] args) {
    // Instantiate the data problem.
    // [START data]
    DataModel data = new DataModel();
    // [END data]

    // Create Routing Index Manager
    // [START index_manager]
    RoutingIndexManager manager = new RoutingIndexManager(
        data.DistanceMatrix.GetLength(0),
        data.VehicleNumber,
        data.Depot);
    // [END index_manager]

    // Create Routing Model.
    // [START routing_model]
    RoutingModel routing = new RoutingModel(manager);
    // [END routing_model]

    // Create and register a transit callback.
    // [START transit_callback]
    int transitCallbackIndex = routing.RegisterTransitCallback(
      (long fromIndex, long toIndex) => {
        // Convert from routing variable Index to distance matrix NodeIndex.
        var fromNode = manager.IndexToNode(fromIndex);
        var toNode = manager.IndexToNode(toIndex);
        return data.DistanceMatrix[fromNode, toNode]; }
    );
    // [END transit_callback]

    // Define cost of each arc.
    // [START arc_cost]
    routing.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
    // [END arc_cost]

    // Add Distance constraint.
    // [START distance_constraint]
    routing.AddDimension(transitCallbackIndex, 0, 3000,
                         true,  // start cumul to zero
                         "Distance");
    RoutingDimension distanceDimension = routing.GetMutableDimension("Distance");
    distanceDimension.SetGlobalSpanCostCoefficient(100);
    // [END distance_constraint]

    // Define Transportation Requests.
    // [START pickup_delivery_constraint]
    Solver solver = routing.solver();
    for(int i=0; i < data.PickupsDeliveries.GetLength(0); i++) {
      long pickupIndex = manager.NodeToIndex(data.PickupsDeliveries[i][0]);
      long deliveryIndex = manager.NodeToIndex(data.PickupsDeliveries[i][1]);
      routing.AddPickupAndDelivery(pickupIndex, deliveryIndex);
      solver.Add(solver.MakeEquality(
          routing.VehicleVar(pickupIndex),
          routing.VehicleVar(deliveryIndex)));
      solver.Add(solver.MakeLessOrEqual(
          distanceDimension.CumulVar(pickupIndex),
          distanceDimension.CumulVar(deliveryIndex)));
    }
    routing.SetPickupAndDeliveryPolicyOfAllVehicles(
      RoutingModel.PICKUP_AND_DELIVERY_LIFO);
    // [END pickup_delivery_constraint]

    // Setting first solution heuristic.
    // [START parameters]
    RoutingSearchParameters searchParameters =
      operations_research_constraint_solver.DefaultRoutingSearchParameters();
    searchParameters.FirstSolutionStrategy =
      FirstSolutionStrategy.Types.Value.PathCheapestArc;
    // [END parameters]

    // Solve the problem.
    // [START solve]
    Assignment solution = routing.SolveWithParameters(searchParameters);
    // [END solve]

    // Print solution on console.
    // [START print_solution]
    PrintSolution(data, routing, manager, solution);
    // [END print_solution]
  }
}
// [END program]