src/controller/solving.js

/** @external {minizinc} https://www.npmjs.com/package/minizinc */
import { Model, init, solvers } from "../../assets/vendor/minizinc.mjs";
/**
 * Initialize the MiniZinc WASM engine; must run before any solveModel() call.
 * @return {Promise<Array<Object>>} List of available solvers (each with id etc.).
 */
export async function initSolvers() {
  await init();
  return solvers();
}
/**
 * Wrap MiniZinc's event-based solver as a Promise.
 * Implements the solve() call from Thesis' Algorithm.
 * @param {string} modelName - Virtual filename for the MZN engine.
 * @param {string} modelString - MZN source: variables + hard constraints (H) + optional objective (S).
 * @param {string} solverId - Backend id (e.g. "gecode").
 * @return {Promise<{solution: ?Object, statistics: ?Object, status: string}>}
 * @throws {Error} If the solver fails to initialize, or wraps any solver-side failure via cause-chain.
 */
export async function solveModel(modelName, modelString, solverId) {
  const model = new Model();
  model.addFile(modelName, modelString);
  const solve = model.solve({
    options: { solver: solverId, statistics: true },
  });
  if (!solve) {
    throw new Error(`Solver '${solverId}' failed to initialize.`);
  }
  let result;
  try {
    result = await solve;
  } catch (e) {
    console.error("Solver error:", e, JSON.stringify(e));
    const detail =
      [e?.message, e?.stderr, e?.output].find(Boolean) ?? JSON.stringify(e);
    throw new Error(
      `Solver failed (code ${e?.code}, type ${e?.type}): ${detail}`,
      { cause: e },
    );
  }
  if (!["SATISFIED", "OPTIMAL_SOLUTION"].includes(result.status)) {
    console.info(`Solver status: ${result.status}`, result);
  }
  const { solution, statistics, status } = result;
  return { solution, statistics, status };
}