// Web Worker: runs the numbl script, computes linear modes, and simulates.

import { growthRate, relDiff } from "./sim/analysis";
import { computeModes, isPlanar, modalDamping } from "./sim/modes";
import { numblEig, runScript } from "./sim/runScript";
import { simulateGPU } from "./sim/gpu";
import { simulate, type SimOptions } from "./sim/solver";
import { runTwin } from "./sim/twin";
import type { BeadSystem, SimResult } from "./sim/types";

const helperSources = import.meta.glob("../matlab/helpers/*.m", { query: "?raw", import: "default", eager: true }) as Record<string, string>;
const helpers = Object.entries(helperSources).map(([path, source]) => ({ name: path.split("/").pop()!, source }));

const MAX_MODE_BEADS = 1500; // flat nets: z motion only
const MAX_FULL_DOF = 1200; // curved nets: all three components of every free bead
const MAX_TWIN_BYTES = 400e6;

export interface RunPayload {
  sys: {
    n: number;
    pos0: Float64Array;
    pinned: Uint8Array;
    si: Int32Array;
    sj: Int32Array;
    nDashpots: number;
    nBends: number;
    nHinges: number;
    listenQuantity: string;
    engine: string;
    listenBeads: Int32Array;
    hitBeads: Int32Array;
    method: string;
    duration: number;
  };
  result: SimResult;
  modeFreqs: Float64Array | null;
  modeKind: "transverse" | "full" | null;
  modeDecay: Float64Array | null; // small-amplitude amplitude decay rate of each mode (1/s)
  notes: string[];
  check: { dt: number; windows: { t: number; rel: number }[] } | null;
  // the same run with every hit scaled by 1e-3, its output scaled back up
  linear: { audio: Float32Array; windows: { t: number; rel: number }[] } | null;
  // the same run with every hit scaled by (1 + eps): separation of the bead
  // positions (max over coordinates, relative to the largest displacement)
  twin: { eps: number; audio: Float32Array; times: Float64Array; sep: Float64Array; rate: number | null } | null;
}

export interface RunRequest {
  type: "run";
  script: string;
  dtCheck: boolean;
  linear: boolean;
  twin: boolean;
  modes: boolean; // the page's "linear modes" toggle (sys.modes in the script overrides it)
  gpu: boolean;
}

export type FromWorker =
  | { type: "log"; text: string }
  | { type: "stage"; text: string }
  | { type: "progress"; t: number; duration: number; label: string }
  | { type: "result"; payload: RunPayload }
  | { type: "error"; message: string };

const post = (m: FromWorker, transfer: Transferable[] = []) => (self as unknown as Worker).postMessage(m, transfer);

const windowsOf = (duration: number) =>
  [0.01, 0.03, 0.1, 0.3, 1, duration].filter((t, i, a) => t <= duration && a.indexOf(t) === i);

self.onmessage = async (ev: MessageEvent<RunRequest>) => {
  const { script, dtCheck, linear, twin: twinWanted, modes: modesToggle, gpu } = ev.data;
  // the GPU path for the main run and the checks; the CPU otherwise
  const sim = (s: BeadSystem, o: SimOptions) => (gpu ? simulateGPU(s, o) : Promise.resolve(simulate(s, o)));
  try {
    post({ type: "stage", text: "Running script" });
    const { sys, warnings } = runScript(script, helpers, text => post({ type: "log", text }));
    const notes = [...warnings];

    let modes = null;
    const nFree = sys.pinned.reduce((a, p) => a + (p ? 0 : 1), 0);
    if (sys.modes ?? modesToggle) {
      const planar = isPlanar(sys);
      if (planar && nFree > MAX_MODE_BEADS) notes.push(`Linear modes skipped: ${nFree} free beads (limit ${MAX_MODE_BEADS} for a flat net).`);
      else if (!planar && 3 * nFree > MAX_FULL_DOF) {
        notes.push(
          `Linear modes skipped: the net is curved, so its modes need all ${3 * nFree} coordinates of the free beads (limit ${MAX_FULL_DOF}, about ${MAX_FULL_DOF / 3} free beads).`
        );
      } else {
        post({ type: "stage", text: planar ? `Computing linear modes (${nFree} free beads)` : `Computing 3D linear modes (${3 * nFree} coordinates)` });
        modes = computeModes(sys, numblEig, planar ? "transverse" : "full");
        const fTop = modes.freqs[modes.freqs.length - 1];
        const nZero = modes.freqs.filter(f => f < 1e-6 * fTop).length;
        if (nZero > 0) {
          notes.push(
            `${nZero} mode${nZero > 1 ? "s are" : " is"} at (nearly) 0 Hz: the beads can move or tilt freely as a whole. ` +
              "Pin more beads (a cluster rather than one bead), or tie the object to pinned anchor beads with soft springs."
          );
        }
      }
    }

    // positions at every frame, kept for the perturbed twin
    const saved: Float64Array[] = [];
    const savedBytes = Math.round(sys.duration * sys.frameRate + 1) * 3 * sys.n * 8;
    if (twinWanted && gpu) {
      notes.push("Perturbed twin skipped: a perturbation of one part in 1e9 is below single precision; turn off WebGPU to run it.");
    }
    const twin = twinWanted && !gpu;
    const keep = twin && savedBytes <= MAX_TWIN_BYTES;
    if (twin && !keep) notes.push(`Perturbed twin skipped: it would store ${(savedBytes / 1e6).toFixed(0)} MB of positions (limit ${MAX_TWIN_BYTES / 1e6} MB). Lower sys.frameRate or sys.duration.`);

    post({ type: "stage", text: gpu ? "Simulating (WebGPU)" : "Simulating" });
    const result = await sim(sys, {
      modes,
      onProgress: t => post({ type: "progress", t, duration: sys.duration, label: "Simulating" }),
      onFrame: keep ? (_f, _t, x) => saved.push(x.slice()) : undefined,
    });

    let checkOut: RunPayload["check"] = null;
    if (dtCheck && !result.aborted) {
      post({ type: "stage", text: "Simulating again with dt/2" });
      const half: BeadSystem = { ...sys, dt: result.dt / 2 };
      const r2 = await sim(half, {
        maxAnimBytes: 0,
        onProgress: t => post({ type: "progress", t, duration: sys.duration, label: "Simulating with dt/2" }),
      });
      const fs = result.sampleRate;
      const windows = windowsOf(sys.duration).map(t => ({ t, rel: relDiff(r2.audio, result.audio, Math.round(t * fs)) }));
      checkOut = { dt: r2.dt, windows };
    }

    let linearOut: RunPayload["linear"] = null;
    if (linear && !result.aborted) {
      post({ type: "stage", text: "Simulating the small-strike reference" });
      const s = 1e-3;
      const small: BeadSystem = {
        ...sys,
        dt: result.dt,
        hits: sys.hits.map(h => ({
          ...h,
          velocity: [h.velocity[0] * s, h.velocity[1] * s, h.velocity[2] * s],
          force: [h.force[0] * s, h.force[1] * s, h.force[2] * s],
        })),
      };
      const r3 = await sim(small, {
        maxAnimBytes: 0,
        onProgress: t => post({ type: "progress", t, duration: sys.duration, label: "Small-strike reference" }),
      });
      const audio = r3.audio.map(v => v / s);
      const fs = result.sampleRate;
      const windows = windowsOf(sys.duration).map(t => ({ t, rel: relDiff(audio, result.audio, Math.round(t * fs)) }));
      linearOut = { audio, windows };
    }

    let twinOut: RunPayload["twin"] = null;
    if (keep && !result.aborted) {
      post({ type: "stage", text: "Simulating the perturbed twin" });
      const eps = 1e-9;
      const { audio, sep } = runTwin(sys, saved, result.dt, eps, t =>
        post({ type: "progress", t, duration: sys.duration, label: "Perturbed twin" })
      );
      const times = result.frameTimes.slice(0, saved.length);
      twinOut = { eps, audio, times, sep, rate: growthRate(times, sep, eps) };
    }

    const hitBeads = Int32Array.from(new Set(sys.hits.flatMap(h => Array.from(h.beads))));
    const payload: RunPayload = {
      sys: {
        n: sys.n,
        pos0: sys.pos0,
        pinned: sys.pinned,
        si: sys.si,
        sj: sys.sj,
        nDashpots: sys.dc.filter((c, d) => c !== 0 || sys.dca[d] !== 0).length,
        nBends: sys.bi.length,
        nHinges: sys.hi.length,
        listenQuantity: sys.listenQuantity,
        engine: gpu ? "WebGPU, single precision" : "CPU, double precision",
        listenBeads: sys.listenBeads,
        hitBeads,
        method: sys.method,
        duration: sys.duration,
      },
      result,
      modeFreqs: modes ? modes.freqs : null,
      modeKind: modes ? modes.kind : null,
      modeDecay: modes ? modalDamping(sys, modes) : null,
      notes,
      check: checkOut,
      linear: linearOut,
      twin: twinOut,
    };
    const transfer: Transferable[] = [result.audio.buffer, ...result.animFrames.map(f => f.buffer)];
    if (result.modeEnergy) transfer.push(result.modeEnergy.buffer);
    if (linearOut) transfer.push(linearOut.audio.buffer);
    if (twinOut) transfer.push(twinOut.audio.buffer, twinOut.sep.buffer);
    post({ type: "result", payload }, transfer);
  } catch (e) {
    const err = e as { message?: string; line?: number; file?: string };
    const where = err.line ? ` (line ${err.line})` : "";
    post({ type: "error", message: `${err.message ?? String(e)}${where}` });
  }
};