import initWasm, { Core } from "./pkg/yawn_core.js";
import { SharedProfile } from "./profile.js";

let core;
let profile;
// While a relocation is staged, every request except its commit waits here.
let awaitingCommit = false;
const queue = [];

const fail = code => { throw new Error(code); };

async function handle(message) {
  try {
    let result;
    if (message?.type === "init") {
      if (core || !(message.canvas instanceof OffscreenCanvas)) fail("INIT");
      const wasm = await initWasm();
      core = new Core(message.arenaBytes);
      profile = new SharedProfile(message.profileBuffer);
      core.on_profile(json => profile.write(json));
      await core.initialize(message.canvas);
      const buffer = wasm.memory.buffer;
      if (!(buffer instanceof SharedArrayBuffer)) fail("WASM_MEMORY_NOT_SHARED");
      result = { buffer, rows: JSON.parse(core.rows()), features: JSON.parse(core.features()) };
    } else {
      if (!core) fail("UNINITIALIZED");
      switch (message?.type) {
        case "create-rows":
          result = JSON.parse(core.create_rows(message.name, message.rows, message.stride, message.format));
          awaitingCommit = result.commit;
          break;
        case "create-rows-batch":
          result = JSON.parse(core.create_rows_batch(JSON.stringify(message.rows)));
          awaitingCommit = result.commit.length > 0;
          break;
        case "commit-rows":
          awaitingCommit = false;
          core.commit_rows(JSON.stringify(message.names));
          break;
        case "delete-rows":
          core.delete_rows(message.name);
          break;
        case "allocate-object":
          result = JSON.parse(core.allocate_object(message.name, message.count ?? 1));
          awaitingCommit = result.commit;
          break;
        case "delete-object":
          core.delete_object(message.name, message.id);
          break;
        case "sync-rows":
          core.sync_rows(message.name, message.first ?? 0, message.count);
          break;
        case "compile-graph":
          result = core.compile_graph(message.serialized);
          break;
        case "switch-loadout":
          core.switch_loadout(message.id);
          break;
        case "upload-texture":
          core.upload_texture(message.name, message.mipLevel, message.image);
          break;
        case "delete-texture":
          core.delete_texture(message.name);
          break;
        case "play":
          core.play();
          break;
        case "pause":
          core.pause();
          break;
        case "set-fps":
          core.set_fps(message.fps);
          break;
        case "set-profiler":
          result = core.set_profiler(Boolean(message.enabled));
          profile.clear();
          break;
        default:
          fail("MESSAGE");
      }
    }
    postMessage({ request: message.request, result });
  } catch (error) {
    postMessage({ request: message?.request, error: error?.message ?? "CORE_ERROR" });
  }
}

addEventListener("message", async ({ data: message }) => {
  if (awaitingCommit && message?.type !== "commit-rows") {
    queue.push(message);
    return;
  }
  await handle(message);
  while (!awaitingCommit && queue.length) await handle(queue.shift());
});