#!/usr/bin/node --experimental-wasi-unstable-preview1
///
/// Simple WASI executor, adapted from the NodeJS WASI module API docs [1].
///
/// Usage: wasi-node <command> [<args> .. ]
///
/// Environment variables:
///
/// WASI_NODE_PREOPENS - optional JSON file defining the application sandbox
/// directory structure. See [1] for details.
///
/// WASI_NODE_ENV - optional JSON file defining the application environment.
/// If omitted then the process's POSIX environment is used; this may leak
/// information. If a clean environment is required then set this to /dev/null
/// or some other empty file.
///
/// [1] https://nodejs.org/api/wasi.html

'use strict';
const fs = require('fs');
const { WASI } = require('wasi');

// argv[0] is nodejs
// argv[1] is this script
var args = process.argv.slice(2); // inner argv includes cmd

if (!args[0]) {
  console.warn(process.argv[1] + ": no command given");
  process.exit(1);
}

var preopens = {};
var preopens_json = process.env["WASI_NODE_PREOPENS"];
if (preopens_json) {
  var preopens_data = fs.readFileSync(preopens_json);
  preopens = preopens_data.length ? JSON.parse(preopens_data) : {};
}

var env = process.env;
var env_json = process.env["WASI_NODE_ENV"];
if (env_json) {
  var env_data = fs.readFileSync(env_json);
  env = env_data.length ? JSON.parse(env_data) : {};
}

const wasi = new WASI({ args: args, env: env, preopens: preopens });
const importObject = { wasi_snapshot_preview1: wasi.wasiImport };

(async () => {
  const wasm = await WebAssembly.compile(fs.readFileSync(args[0]));
  const instance = await WebAssembly.instantiate(wasm, importObject);

  wasi.start(instance);
})();