// Runs one solver at one resolution on one instance and measures it.
// The timing protocol (see docs/problems/laplace-dirichlet-2d.md): one
// untimed warmup run absorbs JIT compilation, then `repeats` timed runs
// whose median is the reported solve time. The warmup itself is timed
// and reported as the cold time. All timing is MATLAB tic/toc inside the
// numbl session, so browser and node measure the same thing.

import { runNumblScript } from "./numblRun";
import type { Laplace2dInstance } from "../problems/laplace2d/spec";
import { evalErrors } from "../problems/laplace2d/exact";

export interface MatlabSources {
  /** build_problem.m source */
  buildProblem: string;
  /** laplace2d_bdata.m source */
  bdata: string;
  /** solver.m source of the solver under test */
  solver: string;
}

export interface RunPointRequest {
  instance: Laplace2dInstance;
  n: number;
  /** Timed repeats after the warmup (default 3). */
  repeats?: number;
  /** Also evaluate the solution on the visualization grid. */
  wantGrid?: boolean;
  sources: MatlabSources;
}

export interface RunPoint {
  n: number;
  solveSeconds: number;
  solveSecondsAll: number[];
  coldSeconds: number;
  relMax: number;
  relL2: number;
  uEval: Float64Array;
  uGrid: Float64Array | null;
}

function numLiteral(x: number): string {
  if (!Number.isFinite(x)) throw new Error(`bad numeric literal: ${x}`);
  return String(x);
}

export function runPoint(req: RunPointRequest): RunPoint {
  const { instance, n } = req;
  const repeats = req.repeats ?? 3;
  const wantGrid = req.wantGrid ?? false;
  const main = [
    "% generated by the fastandaccurate harness",
    `prob = build_problem(${numLiteral(instance.a)}, ${numLiteral(instance.k)}, ${numLiteral(instance.d)}, ${wantGrid ? 1 : 0});`,
    `tic; out = solver(prob, ${n}); res_cold = toc;`,
    `res_times = zeros(${repeats}, 1);`,
    `for irep = 1:${repeats}`,
    `  tic; out = solver(prob, ${n}); res_times(irep) = toc;`,
    "end",
    "res_ueval = out.uEval;",
    "res_ugrid = out.uGrid;",
    "",
  ].join("\n");
  const { vars } = runNumblScript(
    main,
    {
      "build_problem.m": req.sources.buildProblem,
      "laplace2d_bdata.m": req.sources.bdata,
      "solver.m": req.sources.solver,
    },
    ["res_cold", "res_times", "res_ueval", "res_ugrid"]
  );
  const times = Array.from(vars.res_times);
  const sorted = [...times].sort((x, y) => x - y);
  const median =
    sorted.length % 2 === 1
      ? sorted[(sorted.length - 1) / 2]
      : (sorted[sorted.length / 2 - 1] + sorted[sorted.length / 2]) / 2;
  const { relMax, relL2 } = evalErrors(instance, vars.res_ueval);
  return {
    n,
    solveSeconds: median,
    solveSecondsAll: times,
    coldSeconds: vars.res_cold[0],
    relMax,
    relL2,
    uEval: vars.res_ueval,
    uGrid: wantGrid ? vars.res_ugrid : null,
  };
}