/*!
 * gana-compile <https://github.com/tunnckoCore/gana-compile>
 *
 * Copyright (c) 2016 Charlike Mike Reagent <@tunnckoCore> (http://www.tunnckocore.tk)
 * Released under the MIT license.
 */
'use strict'

var isObject = require('isobject')

/**
 * > Compiles a `template` to a function, which
 * accepts `locals` object to populate the template.
 *
 * **Example**
 *
 * ```js
 * var ganaCompile = require('gana-compile')
 *
 * var template = 'Welcome here, ${ucfirst(name)}! And have fun!'
 * var locals = {
 *   name: 'charlike',
 *   ucfirst: function ucfirst (val) {
 *     return val.charAt(0).toUpperCase() + val.slice(1)
 *   }
 * }
 *
 * var fn = ganaCompile(template)
 * var str = fn(locals)
 *
 * console.log(str)
 * // => 'Welcome here, Charlike! And have fun!'
 * ```
 *
 * @param  {String} `template` string to compile to a function
 * @return {Function} like `compileFn(locals)`, where `locals` must be `object`
 * @throws {TypeError} if `template` not a string
 * @throws {TypeError} if `locals` not an object
 * @throws {ReferenceError} if key not exists in `locals` object
 * @api public
 */

module.exports = function ganaCompile (template) {
  if (typeof template !== 'string') {
    throw new TypeError('ganaCompile: expect `template` to be a string')
  }

  return function compileFn (locals) {
    if (!isObject(locals)) {
      throw new TypeError('ganaCompile: expect `locals` to be an object')
    }

    var keys = []
    var vals = []

    for (var key in locals) {
      keys.push(key)
      vals.push(locals[key])
    }

    /* eslint-disable no-new-func */
    var fn = new Function(keys, 'return `' + template + '`')
    return fn.apply(locals, vals)
  }
}