import { MATERIAL_PRESETS, PLATE_PRESETS } from "./presets";
import type { ProblemSpec } from "./types";

/** The default problem: a struck A36 steel sheet, 300 x 200 x 2 mm, simply supported. */
export function defaultSpec(): ProblemSpec {
  const mat = MATERIAL_PRESETS[0];
  return {
    plate: { ...PLATE_PRESETS[0].plate },
    material: { ...mat.material },
    bc: "simply-supported",
    damping: { ...mat.damping },
    excitation: { type: "impulse", x: 0.1, y: 0.08, force: 50, duration: 1e-3, radius: 0.012 },
    probe: { x: 0.2, y: 0.12 },
    listener: { x: 0.15, y: 0.1, z: 1.0, c: 343, rho_air: 1.2, patches: [24, 16] },
    output: { fs: 44100, duration: 2.0, nframes: 90, grid: [61, 41] },
    modal: { fmax: 20000, max_modes: 400 },
    // 41 x 27 keeps 20 ms of simulated time to a few seconds of solve time; a finer grid costs (dx_old/dx_new)^4 more
    fd: { nx: 41, ny: 27, cfl: 0.9, duration: 0.02 },
    // no stability limit: the finer grid and longer window cost one factorization plus a sparse solve per step
    implicit: { nx: 61, ny: 41, duration: 0.05, steps_per_sample: 1, theta: 0.25 },
  };
}

/** Deep-copy a spec (specs are plain data). */
export function cloneSpec(spec: ProblemSpec): ProblemSpec {
  return JSON.parse(JSON.stringify(spec)) as ProblemSpec;
}