'use strict';

/**

* Responsible for loading / finding Mocha's "rc" files.
* This doesn't have anything to do with `mocha.opts`.
*
* @private
* @module
*/

const fs = require('fs'); const path = require('path'); const debug = require('debug')('mocha:cli:config'); const findUp = require('find-up');

/**

* These are the valid config files, in order of precedence;
* e.g., if `.mocharc.js` is present, then `.mocharc.yaml` and the rest
* will be ignored.
* The user should still be able to explicitly specify a file.
* @private
*/

exports.CONFIG_FILES = [

'.mocharc.js',
'.mocharc.yaml',
'.mocharc.yml',
'.mocharc.jsonc',
'.mocharc.json'

];

const isModuleNotFoundError = err =>

err.code !== 'MODULE_NOT_FOUND' ||
err.message.indexOf('Cannot find module') !== -1;

/**

* Parsers for various config filetypes. Each accepts a filepath and
* returns an object (but could throw)
*/

const parsers = (exports.parsers = {

yaml: filepath =>
  require('js-yaml').safeLoad(fs.readFileSync(filepath, 'utf8')),
js: filepath => {
  const cwdFilepath = path.resolve(filepath);
  try {
    debug(`parsers: load using cwd-relative path: "${cwdFilepath}"`);
    return require(cwdFilepath);
  } catch (err) {
    if (isModuleNotFoundError(err)) {
      debug(`parsers: retry load as module-relative path: "${filepath}"`);
      return require(filepath);
    } else {
      throw err; // rethrow
    }
  }
},
json: filepath =>
  JSON.parse(
    require('strip-json-comments')(fs.readFileSync(filepath, 'utf8'))
  )

});

/**

* Loads and parses, based on file extension, a config file.
* "JSON" files may have comments.
*
* @private
* @param {string} filepath - Config file path to load
* @returns {Object} Parsed config object
*/

exports.loadConfig = filepath => {

let config = {};
debug(`loadConfig: "${filepath}"`);

const ext = path.extname(filepath);
try {
  if (ext === '.yml' || ext === '.yaml') {
    config = parsers.yaml(filepath);
  } else if (ext === '.js') {
    config = parsers.js(filepath);
  } else {
    config = parsers.json(filepath);
  }
} catch (err) {
  throw new Error(`failed to parse config "${filepath}": ${err}`);
}
return config;

};

/**

* Find ("find up") config file starting at `cwd`
*
* @param {string} [cwd] - Current working directory
* @returns {string|null} Filepath to config, if found
*/

exports.findConfig = (cwd = process.cwd()) => {

const filepath = findUp.sync(exports.CONFIG_FILES, {cwd});
if (filepath) {
  debug(`findConfig: found "${filepath}"`);
}
return filepath;

};