#!/usr/bin/env node
/* Embeds the Node island host (packages/runtime/src/scr_node_island_host.cjs)
 * into scr_node_island_host.h as a C string, which scr_node_island.c passes
 * to `node -e` when it starts the helper.
 *
 *   node scripts/node-island-host.mjs           rewrite the header
 *   node scripts/node-island-host.mjs --check   fail when it is stale */
import { readFileSync, writeFileSync } from "node:fs";
import { fileURLToPath } from "node:url";

const srcDir = fileURLToPath(new URL("../packages/runtime/src/", import.meta.url));
const SOURCE = `${srcDir}scr_node_island_host.cjs`;
// The loader hooks of shared modules (NI-6) run in the bootstrap's scope.
const HOOKS = `${srcDir}scr_node_island_hooks.cjs`;
const HEADER = `${srcDir}scr_node_island_host.h`;

/** One C string literal per source line, every byte outside printable
 * ASCII as a three-digit octal escape. */
function cLiteral(line) {
  let out = "";
  for (const byte of Buffer.from(line, "utf8")) {
    if (byte === 0x22 || byte === 0x5c) out += `\\${String.fromCharCode(byte)}`;
    else if (byte >= 0x20 && byte < 0x7f && byte !== 0x3f) out += String.fromCharCode(byte);
    else out += `\\${byte.toString(8).padStart(3, "0")}`;
  }
  return `"${out}"`;
}

export function renderHeader(source) {
  const lines = source.split("\n");
  if (lines.at(-1) === "") lines.pop();
  const body = lines.map((line) => `    ${cLiteral(`${line}\n`)}`).join("\n");
  return `/* Generated by scripts/node-island-host.mjs from scr_node_island_host.cjs
 * and scr_node_island_hooks.cjs.
 * Do not edit: change the .cjs file and rerun the script. */
#ifndef SCR_NODE_ISLAND_HOST_H
#define SCR_NODE_ISLAND_HOST_H

static const char scr_node_island_host_js[] =
${body};

#endif /* SCR_NODE_ISLAND_HOST_H */
`;
}

if (process.argv[1] === fileURLToPath(import.meta.url)) {
  const expected = renderHeader(`${readFileSync(SOURCE, "utf8")}\n${readFileSync(HOOKS, "utf8")}`);
  if (process.argv.includes("--check")) {
    if (readFileSync(HEADER, "utf8") !== expected) {
      console.error(`${HEADER} is stale: run node scripts/node-island-host.mjs`);
      process.exit(1);
    }
  } else {
    writeFileSync(HEADER, expected);
  }
}