#!/usr/bin/env deno run --allow-read --allow-write
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.

const doNotModify =
  "/* DO NOT MODIFY: use rebuild_async_stubs.js to regenerate */\n";

// The template function we build op_async_N functions from
function __TEMPLATE__(__ARGS_PARAM__) {
  const id = nextPromiseId;
  try {
    const maybeResult = __OP__(__ARGS__);
    if (maybeResult !== undefined) {
      return PromiseResolve(maybeResult);
    }
  } catch (err) {
    __ERR__;
    ErrorCaptureStackTrace(err, __TEMPLATE__);
    return PromiseReject(err);
  }
  if (isLeakTracingEnabled) {
    submitLeakTrace(id);
  }
  nextPromiseId = (id + 1) & 0xffffffff;
  return setPromise(id);
}

const infraJsPath = new URL("00_infra.js", import.meta.url);
const infraJs = Deno.readTextFileSync(infraJsPath);

const infraPristine = infraJs.replaceAll(
  /\/\* BEGIN TEMPLATE ([^ ]+) \*\/.*?\/\* END TEMPLATE \*\//smg,
  "TEMPLATE-$1",
);
const templateString = __TEMPLATE__.toString();
let asyncStubCases = "/* BEGIN TEMPLATE setUpAsyncStub */\n";
asyncStubCases += doNotModify;
const vars = "abcdefghijklm";
for (let i = 0; i < 10; i++) {
  let args = "id";
  for (let j = 0; j < i; j++) {
    args += `, ${vars[j]}`;
  }
  const name = `async_op_${i}`;
  // Replace the name and args, and add a two-space indent
  const func = `fn = ${templateString}`
    .replaceAll(/__TEMPLATE__/g, name)
    .replaceAll(/__ARGS__/g, args)
    .replaceAll(/__ARGS_PARAM__/g, args.replace(/id(, )?/, ""))
    .replaceAll(/__OP__/g, "originalOp")
    .replaceAll(/[\s]*__ERR__;/g, "")
    .replaceAll(/^/gm, "  ");
  asyncStubCases += `
case ${i}:
${func};
  break;
  `.trim() + "\n";
}
asyncStubCases += "/* END TEMPLATE */";

const asyncStubIndent =
  infraPristine.match(/^([\t ]+)(?=TEMPLATE-setUpAsyncStub)/m)[0];

const infraOutput = infraPristine
  .replace(
    /[\t ]+TEMPLATE-setUpAsyncStub/,
    asyncStubCases.replaceAll(/^/gm, asyncStubIndent),
  );

if (Deno.args[0] === "--check") {
  if (infraOutput !== infraJs) {
    Deno.writeTextFileSync("/tmp/mismatch.txt", infraOutput);
    throw new Error(
      "Mismatch between pristine and updated source (wrote mismatch to /tmp/mismatch.txt)",
    );
  } else {
    console.log("✅ Templated sections would not change");
  }
} else {
  Deno.writeTextFileSync(infraJsPath, infraOutput);
}