bdlg-planner-backend/src/main/java/fr/jaquin/bdlg/planner/controller/SolverController.java

package fr.jaquin.bdlg.planner.controller;

import java.util.UUID;
import java.util.concurrent.ExecutionException;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import org.optaplanner.core.api.score.ScoreExplanation;
import org.optaplanner.core.api.score.ScoreManager;
import org.optaplanner.core.api.score.buildin.hardmediumsoft.HardMediumSoftScore;
import org.optaplanner.core.api.solver.SolverJob;
import org.optaplanner.core.api.solver.SolverManager;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import fr.jaquin.bdlg.planner.solver.domain.Assignement;
import fr.jaquin.bdlg.planner.solver.domain.MealAssignement;
import fr.jaquin.bdlg.planner.solver.domain.MealSlot;
import fr.jaquin.bdlg.planner.solver.domain.Planning;
import fr.jaquin.bdlg.planner.solver.domain.PlanningInput;
import fr.jaquin.bdlg.planner.solver.domain.PlanningSolution;

@RestController
public class SolverController {

  @Autowired
  private SolverManager<Planning, UUID> solverManager;
  @Autowired
  private ScoreManager<Planning, HardMediumSoftScore> scoreManager;
  private Collector<CharSequence, ?, String> listCollector = Collectors.joining(",", "[", "]");

  @PostMapping("/planning/solve")
  public PlanningSolution solve(@RequestBody PlanningInput inputs) {
    Planning problem = inputs.generatePlanningProblem();

    UUID problemId = UUID.randomUUID();
    // Submit the problem to start solving
    SolverJob<Planning, UUID> solverJob = solverManager.solve(problemId, problem);

    Planning solution;
    try {
      // Wait until the solving ends
      solution = solverJob.getFinalBestSolution();
    } catch (InterruptedException | ExecutionException e) {
      throw new IllegalStateException("Solving failed.", e);
    }

    ScoreExplanation<Planning, HardMediumSoftScore> explanation =
        scoreManager.explainScore(solution);
    PlanningSolution output = PlanningSolution.from(solution);
    output.setExplanation(stringifyExplanation(explanation));
    // System.out.println(explanation.getSummary());
    return output;
  }

  private String stringifyExplanation(ScoreExplanation<Planning, HardMediumSoftScore> explanation) {
    return explanation.getConstraintMatchTotalMap().values().stream()
        // Return only Hard Constraint
        .filter(predicate -> predicate.getScore().getHardScore() < 0)
        // Create a dictionnary with the name of the constraint as key
        .map(constraint -> "\"" + constraint.getConstraintName() + "\":"
        // Populate the value with an array of justification objects
            + constraint.getConstraintMatchSet().stream()
                // Filter pair that have a negative impact on the score
                .filter(matchElt -> matchElt.getScore().getHardScore() < 0)
                .map(match -> match.getJustificationList().stream()
                    .map(elt -> stringifyConstraint(elt)).collect(listCollector))
                .collect(listCollector))
        .collect(Collectors.joining(",", "{", "}"));
  }

  private String stringifyConstraint(Object val) {
    if (val instanceof Assignement) {
      Assignement casted = (Assignement) val;
      return "{\"type\":\"Assignement\",\"slotId\":\"" + casted.getSlot().getId()
          + "\",\"volonteerId\":" + casted.getVolonteer().getId().toString() + "}";
    }
    if (val instanceof MealAssignement) {
      MealAssignement casted = (MealAssignement) val;
      return "{\"type\":\"MealAssignement\",\"slotId\":\"" + casted.getMealSlot().getId()
          + "\",\"volonteerId\":" + casted.getVolonteer().getId().toString() + "}";
    }
    if (val instanceof MealSlot) {
      MealSlot casted = (MealSlot) val;
      return "{\"type\":\"MealSlot\",\"slotId\":\"" + casted.getId() + "\"}";
    }
    if (val instanceof Integer) {
      return val.toString();
    }
    return "\"" + val.getClass().getName() + "\"";
  }

}