/// <reference lib="webworker" />
/**
 * Runs a numbl filter script off the main thread so full-resolution images
 * with per-pixel scripts don't freeze the page.
 *
 * Contract: the script defines a function (default name `filterImage`) that
 * takes the image array `img` (H x W x 3 doubles, 0-255) and returns a new
 * image array. If the script has no function header it is run as-is with
 * `img` predefined and `out` read back.
 */
import { executeCode, RTV } from "numbl";
import type { RuntimeValue } from "numbl";
import {
  rgbaToTensorData,
  tensorToRaw,
  extractFunctionName,
} from "./imageConvert.ts";
import type { FilterRequest, FilterResponse } from "./filterTypes.ts";

self.onmessage = (e: MessageEvent<FilterRequest>) => {
  const { id, script, width, height, rgba } = e.data;
  const logs: string[] = [];
  try {
    const { data, shape } = rgbaToTensorData(rgba, width, height);
    const img = RTV.tensor(data, shape);

    const fnName = extractFunctionName(script);
    const source = fnName ? `out = ${fnName}(img);` : script;
    const workspaceFiles = fnName
      ? [{ name: `${fnName}.m`, source: script }]
      : [];

    const t0 = performance.now();
    const result = executeCode(
      source,
      {
        initialVariableValues: { img },
        optimization: "1", // JS-JIT; browser-safe
        displayResults: false,
        onOutput: (text: string) => logs.push(text),
      },
      workspaceFiles,
      "main.m"
    );
    const elapsedMs = performance.now() - t0;

    const out: RuntimeValue | undefined =
      result.variableValues.out ?? result.returnValue;
    const image = tensorToRaw(out);

    const response: FilterResponse = {
      id,
      ok: true,
      width: image.width,
      height: image.height,
      rgba: image.rgba,
      logs,
      elapsedMs,
    };
    self.postMessage(response, [image.rgba.buffer]);
  } catch (err) {
    const response: FilterResponse = {
      id,
      ok: false,
      error: err instanceof Error ? err.message : String(err),
      logs,
    };
    self.postMessage(response);
  }
};