//******************************************************************************************************//  ValidationService.cs - Gbtc////  Copyright © 2012, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), 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.opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  08/19/2010 - Pinal C. Patel//       Generated original version of source code.//  12/14/2012 - Starlynn Danyelle Gilliam//       Modified Header.////****************************************************************************************************** using System;using System.Collections.Generic;using System.Text; namespace GSF.Validation{    /// <summary>    /// A class that facilitates value validation using <see cref="IValidator"/> implementations.    /// </summary>    /// <example>    /// This example shows how to use <see cref="ValidationService"/> for input validation:    /// <code>    /// using System;    /// using System.Collections.Generic;    /// using GSF.Validation;    ///     /// class Program    /// {    ///     static void Main(string[] args)    ///     {    ///         // Dictionary where captured user input is saved.    ///         Dictionary&lt;string, string&gt; input = new Dictionary&lt;string, string&gt;();    ///     ///         // Validation service that will validate user input.    ///         ValidationService validation = new ValidationService(delegate(string source)    ///             {    ///                 string value;    ///                 if (input.TryGetValue(source, out value))    ///                     return input[source];    ///                 else    ///                     return string.Empty;    ///             });    ///     ///         // Add validation rules to the validation service.    ///         validation.AddValidation("Name", new NonNullStringValidator());    ///         validation.AddValidation("Email", new EmailAddressValidator());    ///     ///         // Capture user input.    ///         Console.Write("Enter name: ");    ///         input["Name"] = Console.ReadLine();    ///         Console.Write("Enter email: ");    ///         input["Email"] = Console.ReadLine();    ///         Console.WriteLine("");    ///         ///         // Validate user input.    ///         string errors;    ///         if (!validation.Validate(out errors))    ///             Console.WriteLine(errors);    ///         else    ///             Console.WriteLine("No validation errors were found!");    ///     ///         Console.ReadLine();    ///     }    /// }    /// </code>    /// </example>    /// <seealso cref="IValidator"/>    public class ValidationService    {        #region [ Members ]         // Fields        private readonly Func<string, object> m_lookup;        private readonly Dictionary<string, IValidator> m_validations;         #endregion         #region [ Constructors ]         /// <summary>        /// Initializes a new instance of the <see cref="ValidationService"/> class.        /// </summary>        /// <param name="valueLookupHandler"><see cref="Delegate"/> that will lookup the value to be validated.</param>        public ValidationService(Func<string, object> valueLookupHandler)        {            m_lookup = valueLookupHandler;            m_validations = new Dictionary<string, IValidator>();        }         #endregion         #region [ Methods ]         /// <summary>        /// Adds a new validation.        /// </summary>        /// <param name="source">The source that will provide the value to be validated.</param>        /// <param name="validator">The <see cref="IValidator"/> that will validate the value.</param>        /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="validator"/> is null.</exception>        public void AddValidation(string source, IValidator validator)        {            if (string.IsNullOrEmpty(source))                throw new ArgumentNullException(nameof(source));             if ((object)validator == null)                throw new ArgumentNullException(nameof(validator));             m_validations.Add(string.Format("{0}+{1}", source, validator.GetType().Name), validator);        }         /// <summary>        /// Executes all validations.        /// </summary>        /// <param name="validationErrors">Errors messages returned by one or more of the validations.</param>        /// <returns><strong>true</strong> if the validation completes without errors; otherwise <strong>false</strong>.</returns>        public bool Validate(out string validationErrors)        {            string error;            string source;            StringBuilder result = new StringBuilder();            foreach (string key in m_validations.Keys)            {                source = key.Split('+')[0];                if (!m_validations[key].Validate(m_lookup(source), out error))                {                    if (result.Length == 0)                        result.Append("One or more validation errors were encountered:\r\n");                     result.AppendFormat("    {0} - {1}\r\n", source, error);                }            }             validationErrors = result.ToString();            if (string.IsNullOrEmpty(validationErrors))                return true;            else                return false;        }         #endregion    }}