const assert = require('assert');
const is = require('is-type-of');

exports.getProperties = (filepath, { caseStyle }) => {
  // if caseStyle is function, return the result of function
  if (is.function(caseStyle)) {
    const result = caseStyle(filepath);
    assert(is.array(result), `caseStyle expect an array, but got ${result}`);
    return result;
  }
  // use default camelize
  return this.defaultCamelize(filepath, caseStyle);
}

exports.defaultCamelize = (filepath, caseStyle) => {
  const properties = filepath.substring(0, filepath.lastIndexOf('.')).split('/');
  return properties.map(property => {
    if (!/^[a-z][a-z0-9_-]*$/i.test(property)) {
      throw new Error(`${property} is not match 'a-z0-9_-' in ${filepath}`);
    }

    property = property.replace(/[_-][a-z]/ig, s => s.substring(1).toUpperCase());
    let first = property[0];
    switch (caseStyle) {
      case 'lower':
        first = first.toLowerCase();
        break;
      case 'upper':
        first = first.toUpperCase();
        break;
      case 'camel':
      default:
    }
    return first + property.substring(1);
  });
}