var apply = require('./_apply'),

createCtor = require('./_createCtor'),
root = require('./_root');

/** Used to compose bitmasks for function metadata. */ var WRAP_BIND_FLAG = 1;

/**

* Creates a function that wraps `func` to invoke it with the `this` binding
* of `thisArg` and `partials` prepended to the arguments it receives.
*
* @private
* @param {Function} func The function to wrap.
* @param {number} bitmask The bitmask flags. See `createWrap` for more details.
* @param {*} thisArg The `this` binding of `func`.
* @param {Array} partials The arguments to prepend to those provided to
*  the new function.
* @returns {Function} Returns the new wrapped function.
*/

function createPartial(func, bitmask, thisArg, partials) {

var isBind = bitmask & WRAP_BIND_FLAG,
    Ctor = createCtor(func);

function wrapper() {
  var argsIndex = -1,
      argsLength = arguments.length,
      leftIndex = -1,
      leftLength = partials.length,
      args = Array(leftLength + argsLength),
      fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;

  while (++leftIndex < leftLength) {
    args[leftIndex] = partials[leftIndex];
  }
  while (argsLength--) {
    args[leftIndex++] = arguments[++argsIndex];
  }
  return apply(fn, isBind ? thisArg : this, args);
}
return wrapper;

}

module.exports = createPartial;