/********************************************************
 * Xpress-BCL Java Example Problems
 * ================================
 *
 * file xbexpl3.java
 * `````````````````
 * Error handling and output redirection.
 *
 * (c) 2008-2024 Fair Isaac Corporation
 * author: S.Heipcke, 2005, rev. Jan. 2012
 ********************************************************/

import com.dashoptimization.*;
import java.io.*;

/* This small, infeasible example shows how all printed messages can
be intercepted by the user's program. */

public class xbexpl3 {
  static XPRB bcl;

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

  public static void modexpl3(XPRBprob prob) throws XPRBerror {
    XPRBvar[] x;
    XPRBexpr cobj;
    int i;

    x = new XPRBvar[3]; /* Create the variables */
    for (i = 0; i < 2; i++) x[i] = prob.newVar("x_" + i, XPRB.UI, 0, 100);

    /* Create the constraints:
    C1: 2x0 + 3x1 >= 41
    C2:  x0 + 2x1  = 13 */
    prob.newCtr("C1", x[0].mul(2).add(x[1].mul(3)).gEql(41));
    prob.newCtr("C2", x[0].add(x[1].mul(2)).eql(13));

    /* Uncomment the following line to cause an error in the model that
    triggers the error handling: */

    //  x[2] = prob.newVar("x_2", XPRB.UI, 10, 1);

    /* Objective: minimize x0+x1 */
    cobj = new XPRBexpr();
    for (i = 0; i < 2; i++) cobj.add(x[i]);
    prob.setObj(cobj); /* Select objective function */
    prob.setSense(XPRB.MINIM); /* Set objective sense to minimization */

    prob.print(); /* Print current problem definition */

    prob.lpOptimize(""); /* Solve the LP */
    System.out.println(
        "Problem status: "
            + prob.getProbStat()
            + "  LP status: "
            + prob.getLPStat()
            + "  MIP status: "
            + prob.getMIPStat());

    /* This problem is infeasible, that means the following command will fail.
    It prints a warning if the message level is at least 2 */

    System.out.println("Objective: " + prob.getObjVal());

    for (i = 0; i < 2; i++) /* Print solution values */
      System.out.print(x[i].getName() + ":" + x[i].getSol() + ", ");
    System.out.println();
  }

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

  public static void main(String[] args) {
    try (XPRB bcl = new XPRB()) {
        /* Initialize BCL */

      bcl.setMsgLevel(2); /* Set the printing flag. Try other values:
                                              0 - no printed output,
                                              2 - print warnings, 3 - all messages */
      try (XPRBprob prob = bcl.newProb("Expl3"); /* Create a new problem */
          XPRBexprContext context =
              new XPRBexprContext() /* Release XPRBexpr instance at end of block. */) {
        FileWriter f = new FileWriter("expl3out.txt");
        bcl.setOutputStream(f); /* Redirect all output from BCL to a file */

        prob.setOutputStream(); /* Output for this prob. on standard output */
        modexpl3(prob); /* Formulate and solve the problem */

        prob.setOutputStream(f); /* Redirect problem output to file */
        prob.print(); /* Write to the output file */
        prob.setOutputStream(); /* Re-establish standard output for prob */
        bcl.setOutputStream(); /* Re-establish standard output for BCL */
        f.close();

        System.err.flush();
      } catch (IOException e) {
        System.err.println(e.getMessage());
        System.exit(1);
      } catch (XPRBerror e) {
        System.err.println("BCL error " + e.getErrorCode() + ": " + e.getMessage());
        System.exit(1);
      }
    } catch (XPRBlicenseError e) {
      System.err.println("BCL error " + e.getErrorCode() + ": " + e.getMessage());
      System.exit(1);
    }
  }
}