revert file deletion

Author: Feiyang1

packages/util/index.node.ts

@@ -33,4 +33,5 @@ export * from './src/obj';
 export * from './src/query';
 export * from './src/sha1';
 export * from './src/subscribe';
+export * from './src/validation';
 export * from './src/utf8';

packages/util/index.ts

@@ -28,4 +28,5 @@ export * from './src/obj';
 export * from './src/query';
 export * from './src/sha1';
 export * from './src/subscribe';
+export * from './src/validation';
 export * from './src/utf8';

packages/util/src/validation.ts

@@ -0,0 +1,148 @@
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ *
+ * 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 fnName The function name
+ * @param minCount The minimum number of arguments to allow for the function call
+ * @param maxCount The maximum number of argument to allow for the function call
+ * @param argCount The actual number of arguments provided.
+ */
+export const validateArgCount = function (
+  fnName: string,
+  minCount: number,
+  maxCount: number,
+  argCount: number
+): void {
+  let argError;
+  if (argCount < minCount) {
+    argError = 'at least ' + minCount;
+  } else if (argCount > maxCount) {
+    argError = maxCount === 0 ? 'none' : 'no more than ' + maxCount;
+  }
+  if (argError) {
+    const 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 fnName The function name
+ * @param argumentNumber The index of the argument
+ * @param optional Whether or not the argument is optional
+ * @return The prefix to add to the error thrown for validation.
+ */
+export function errorPrefix(
+  fnName: string,
+  argumentNumber: number,
+  optional: boolean
+): string {
+  let 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?'
+      );
+  }
+
+  let error = fnName + ' failed: ';
+
+  error += argName + ' argument ';
+  return error;
+}
+
+/**
+ * @param fnName
+ * @param argumentNumber
+ * @param namespace
+ * @param optional
+ */
+export function validateNamespace(
+  fnName: string,
+  argumentNumber: number,
+  namespace: string,
+  optional: boolean
+): void {
+  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: string,
+  argumentNumber: number,
+  // eslint-disable-next-line @typescript-eslint/ban-types
+  callback: Function,
+  optional: boolean
+): void {
+  if (optional && !callback) {
+    return;
+  }
+  if (typeof callback !== 'function') {
+    throw new Error(
+      errorPrefix(fnName, argumentNumber, optional) +
+        'must be a valid function.'
+    );
+  }
+}
+
+export function validateContextObject(
+  fnName: string,
+  argumentNumber: number,
+  context: unknown,
+  optional: boolean
+): void {
+  if (optional && !context) {
+    return;
+  }
+  if (typeof context !== 'object' || context === null) {
+    throw new Error(
+      errorPrefix(fnName, argumentNumber, optional) +
+        'must be a valid context object.'
+    );
+  }
+}