/**
 * Copyright 2017 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Check to make sure the appropriate number of arguments are provided for a public function.
 * Throws an error if it fails.
 *
 * @param {!string} fnName The function name
 * @param {!number} minCount The minimum number of arguments to allow for the function call
 * @param {!number} maxCount The maximum number of argument to allow for the function call
 * @param {!number} argCount The actual number of arguments provided.
 */
export const validateArgCount = function(fnName, minCount, maxCount, argCount) {
  var argError;
  if (argCount < minCount) {
    argError = 'at least ' + minCount;
  } else if (argCount > maxCount) {
    argError = maxCount === 0 ? 'none' : 'no more than ' + maxCount;
  }
  if (argError) {
    var error =
      fnName +
      ' failed: Was called with ' +
      argCount +
      (argCount === 1 ? ' argument.' : ' arguments.') +
      ' Expects ' +
      argError +
      '.';
    throw new Error(error);
  }
};

/**
 * Generates a string to prefix an error message about failed argument validation
 *
 * @param {!string} fnName The function name
 * @param {!number} argumentNumber The index of the argument
 * @param {boolean} optional Whether or not the argument is optional
 * @return {!string} The prefix to add to the error thrown for validation.
 */
export function errorPrefix(fnName, argumentNumber, optional) {
  var argName = '';
  switch (argumentNumber) {
    case 1:
      argName = optional ? 'first' : 'First';
      break;
    case 2:
      argName = optional ? 'second' : 'Second';
      break;
    case 3:
      argName = optional ? 'third' : 'Third';
      break;
    case 4:
      argName = optional ? 'fourth' : 'Fourth';
      break;
    default:
      throw new Error(
        'errorPrefix called with argumentNumber > 4.  Need to update it?'
      );
  }

  var error = fnName + ' failed: ';

  error += argName + ' argument ';
  return error;
}

/**
 * @param {!string} fnName
 * @param {!number} argumentNumber
 * @param {!string} namespace
 * @param {boolean} optional
 */
export function validateNamespace(fnName, argumentNumber, namespace, optional) {
  if (optional && !namespace) return;
  if (typeof namespace !== 'string') {
    //TODO: I should do more validation here. We only allow certain chars in namespaces.
    throw new Error(
      errorPrefix(fnName, argumentNumber, optional) +
        'must be a valid firebase namespace.'
    );
  }
}

export function validateCallback(fnName, argumentNumber, callback, optional) {
  if (optional && !callback) return;
  if (typeof callback !== 'function')
    throw new Error(
      errorPrefix(fnName, argumentNumber, optional) +
        'must be a valid function.'
    );
}

export function validateContextObject(
  fnName,
  argumentNumber,
  context,
  optional
) {
  if (optional && !context) return;
  if (typeof context !== 'object' || context === null)
    throw new Error(
      errorPrefix(fnName, argumentNumber, optional) +
        'must be a valid context object.'
    );
}