import {
  type WasmThreadingCapabilities,
} from "../../../protocol/engine-variant";
export { gateWasmThreadingCapability, selectWebEngineVariant } from "../../../protocol/engine-variant";
export type { WasmThreadingCapabilities } from "../../../protocol/engine-variant";

export interface BrowserCapabilities extends WasmThreadingCapabilities {
  webgl2: boolean;
  offscreenCanvas: boolean;
  opfs: boolean;
  wasm: boolean;
  wasmSimd: boolean;
  wasmThreads: boolean;
  storageEstimate: boolean;
  indexedDb: boolean;
}

function supportsWasmFeature(feature: "simd" | "threads"): boolean {
  if (typeof WebAssembly === "undefined") return false;

  const modules: Record<typeof feature, Uint8Array> = {
    simd: new Uint8Array([
      0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x04, 0x01, 0x60,
      0x00, 0x00, 0x03, 0x02, 0x01, 0x00, 0x0a, 0x0b, 0x01, 0x09, 0x00, 0xfd,
      0x00, 0x00, 0x0b,
    ]),
    threads: new Uint8Array([
      0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x04, 0x01, 0x60,
      0x00, 0x00, 0x05, 0x04, 0x01, 0x01, 0x01, 0x00, 0x0a, 0x04, 0x01, 0x02,
      0x00, 0x0b,
    ]),
  };

  try {
    return WebAssembly.validate(modules[feature] as BufferSource);
  } catch {
    return false;
  }
}

export function detectBrowserCapabilities(): BrowserCapabilities {
  const canvas = typeof document === "undefined" ? undefined : document.createElement("canvas");
  const webgl2 = Boolean(canvas?.getContext("webgl2"));
  const storage = typeof navigator === "undefined" ? undefined : navigator.storage;

  return {
    crossOriginIsolated: globalThis.crossOriginIsolated === true,
    webgl2,
    offscreenCanvas: typeof OffscreenCanvas !== "undefined",
    opfs: Boolean(storage?.getDirectory),
    sharedArrayBuffer: typeof SharedArrayBuffer !== "undefined",
    worker: typeof Worker !== "undefined",
    wasm: typeof WebAssembly !== "undefined",
    wasmSimd: supportsWasmFeature("simd"),
    wasmThreads: supportsWasmFeature("threads"),
    storageEstimate: Boolean(storage?.estimate),
    indexedDb: typeof indexedDB !== "undefined",
  };
}