'use strict';

/**
 * Some settings and code related to Mocha's handling of Node.js/V8 flags.
 * @private
 * @module
 */

const nodeFlags = require('node-environment-flags');
const unparse = require('yargs-unparser');

/**
 * These flags are considered "debug" flags.
 * @see {@link impliesNoTimeouts}
 * @private
 */
const debugFlags = new Set(['debug', 'debug-brk', 'inspect', 'inspect-brk']);

/**
 * Mocha has historical support for various `node` and V8 flags which might not
 * appear in `process.allowedNodeEnvironmentFlags`.
 * These include:
 *   - `--preserve-symlinks`
 *   - `--harmony-*`
 *   - `--gc-global`
 *   - `--trace-*`
 *   - `--es-staging`
 *   - `--use-strict`
 *   - `--v8-*` (but *not* `--v8-options`)
 * @summary Whether or not to pass a flag along to the `node` executable.
 * @param {string} flag - Flag to test
 * @param {boolean} [bareword=true] - If `false`, we expect `flag` to have one or two leading dashes.
 * @returns {boolean} If the flag is considered a "Node" flag.
 * @private
 */
exports.isNodeFlag = (flag, bareword = true) => {
  if (!bareword) {
    // check if the flag begins with dashes; if not, not a node flag.
    if (!/^--?/.test(flag)) {
      return false;
    }
    // strip the leading dashes to match against subsequent checks
    flag = flag.replace(/^--?/, '');
  }
  return (
    // treat --require/-r as Mocha flag even though it's also a node flag
    !(flag === 'require' || flag === 'r') &&
    // check actual node flags from `process.allowedNodeEnvironmentFlags`,
    // then historical support for various V8 and non-`NODE_OPTIONS` flags
    // and also any V8 flags with `--v8-` prefix
    (nodeFlags.has(flag) ||
      debugFlags.has(flag) ||
      /(?:preserve-symlinks(?:-main)?|harmony(?:[_-]|$)|(?:trace[_-].+$)|gc(?:[_-]global)?$|es[_-]staging$|use[_-]strict$|v8[_-](?!options).+?$)/.test(
        flag
      ))
  );
};

/**
 * Returns `true` if the flag is a "debug-like" flag.  These require timeouts
 * to be suppressed, or pausing the debugger on breakpoints will cause test failures.
 * @param {string} flag - Flag to test
 * @returns {boolean}
 * @private
 */
exports.impliesNoTimeouts = flag => debugFlags.has(flag);

/**
 * All non-strictly-boolean arguments to node--those with values--must specify those values using `=`, e.g., `--inspect=0.0.0.0`.
 * Unparse these arguments using `yargs-unparser` (which would result in `--inspect 0.0.0.0`), then supply `=` where we have values.
 * Apparently --require in Node.js v8 does NOT want `=`.
 * There's probably an easier or more robust way to do this; fixes welcome
 * @param {Object} opts - Arguments object
 * @returns {string[]} Unparsed arguments using `=` to specify values
 * @private
 */
exports.unparseNodeFlags = opts => {
  var args = unparse(opts);
  return args.length
    ? args
        .join(' ')
        .split(/\b/)
        .map((arg, index, args) =>
          arg === ' ' && args[index - 1] !== 'require' ? '=' : arg
        )
        .join('')
        .split(' ')
    : [];
};
