/********************************************************
  Xpress-BCL C# Example Problems
  ==============================

  file xbcontr1.cs
  ````````````````
  Contract allocation example.
  Combining BCL problem input with problem solving
  in Xpress-Optimizer.

  (c) 2008-2024 Fair Isaac Corporation
      authors: S.Heipcke, D.Brett.
********************************************************/

using System;
using System.Text;
using System.IO;
using Optimizer;
using BCL;


namespace Examples
{

    public class TestUGContr1
    {
        const int District = 6;               /* Number of districts */
        const int Contract = 10;              /* Number of contracts */

        /**** DATA ****/
        int[] OUTPUT = {50, 40, 10, 20, 70, 50}; /* Max. output per district */
        int[] COST   = {50, 20, 25, 30, 45, 40}; /* Cost per district */
        int[] VOLUME   = {20, 10, 30, 15, 20, 30, 10, 50, 10, 20};
        /* Volume of contracts */

        /*********************************************************************/

        public static void Main()
        {
            XPRB.init();
            int d,c;
            XPRBexpr l1,l2,lobj;

            /* Variables indicating whether a project is chosen */
            XPRBvar[,] x = new XPRBvar[District,Contract];

            /* Quantities allocated to contractors */
            XPRBvar[,] y = new XPRBvar[District,Contract];

            int i, ncol, len, stat;
            double[] sol;
            double val;

            /* Initialize a new problem in BCL */
            XPRBprob p = new XPRBprob("Contr1");

            XPRSprob xprsp;
            TestUGContr1 TestInstance = new TestUGContr1();

            /**** VARIABLES ****/
            for(d=0;d<District;d++)
                for(c=0;c<Contract;c++)
                {
                    x[d,c] = p.newVar("x_d" + (d+1) + "c" + (c+1),
                              BCLconstant.XPRB_BV);
                    y[d,c] = p.newVar("q_d" + (d+1) + "c" + (c+1),
                              BCLconstant.XPRB_SC, 0, TestInstance.OUTPUT[d]);
                    y[d,c].setLim(5);
                }

            /****OBJECTIVE****/
            lobj = new XPRBexpr();
            for(d=0;d<District;d++)
                for(c=0;c<Contract;c++)
                    lobj += TestInstance.COST[d]*y[d,c];

            p.setObj(p.newCtr("OBJ",lobj));    /* Set the objective function */

            /**** CONSTRAINTS ****/
            for(c=0;c<Contract;c++)
            {
                l1 = new XPRBexpr();
                l2 = new XPRBexpr();
                for(d=0;d<District;d++)
                {
                    l1 += y[d,c];
                    l2 += x[d,c];
                }

                /* "Size": cover the required volume */
                p.newCtr("Size", l1 >= TestInstance.VOLUME[c]);

                /* "Min": at least 2 districts per contract */
                p.newCtr("Min", l2 >= 2 );
            }

        /* Do not exceed max. output of any district */
            for(d=0;d<District;d++)
            {
                l1 = new XPRBexpr();
                for(c=0;c<Contract;c++)
                l1 += y[d,c];
                p.newCtr("Output", l1 <= TestInstance.OUTPUT[d]);
            }

            /* If a contract is allocated to a district,
               then at least 1 unit is allocated to it */
            for(d=0;d<District;d++)
                for(c=0;c<Contract;c++)
                    p.newCtr("XY", x[d,c] <= y[d,c]);

            /****SOLVING + OUTPUT****/
            p.loadMat();                   /* Load the matrix explicitly */
            xprsp = p.getXPRSprob();
            xprsp.ChgObjSense(ObjSense.Minimize);
            xprsp.MipOptimize();              /* Solve the MIP problem */

            stat = (int)xprsp.MIPStatus;
            /* Get the global (MIP) status */

        /* Test whether an integer solution was found */
            if (((int)MIPStatus.Solution==stat) ||
                ((int)MIPStatus.Optimal==stat))
            {
                val = xprsp.MIPObjVal;
                System.Console.WriteLine("Objective: " + val);

                ncol = xprsp.Cols;
                sol = new double[ncol];

                xprsp.GetMipSol(sol);
                /* Get the primal solution values */
                len = xprsp.NameLength;
                /* Get the maximum name length */


                string[] names = xprsp.GetNames(2, 0, ncol - 1);
                // Get the variable names
                for (i = 0; i < ncol; i++)         // Print out the solution
                    if (sol[i] != 0)
                    {
                        System.Console.Write(names[i] + ": " + sol[i] + ", ");
                    }
                System.Console.WriteLine();

            }

            return;
        }

    }

}