// DigestMethod.cs
//
// XAdES Starter Kit for Microsoft .NET 3.5 (and above)
// 2010 Microsoft France
// Published under the CECILL-B Free Software license agreement.
// (http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.txt)
// 
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, 
// WHETHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED 
// WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE. 
// THE ENTIRE RISK OF USE OR RESULTS IN CONNECTION WITH THE USE OF THIS CODE 
// AND INFORMATION REMAINS WITH THE USER.

using System;
using System.Security.Cryptography.Xml;
using System.Xml;

namespace Microsoft.Xades
{
    /// <summary>
    /// DigestMethod indicates the digest algorithm
    /// </summary>
    public class DigestMethod
    {
        #region Private variables
        private string algorithm;
        #endregion

        #region Public properties
        /// <summary>
        /// Contains the digest algorithm
        /// </summary>
        public string Algorithm
        {
            get
            {
                return this.algorithm;
            }
            set
            {
                this.algorithm = value;
            }
        }
        #endregion

        #region Constructors
        /// <summary>
        /// Default constructor
        /// </summary>
        public DigestMethod()
        {
        }
        #endregion

        #region Public methods
        /// <summary>
        /// Check to see if something has changed in this instance and needs to be serialized
        /// </summary>
        /// <returns>Flag indicating if a member needs serialization</returns>
        public bool HasChanged()
        {
            bool retVal = false;

            if (!String.IsNullOrEmpty(this.algorithm))
            {
                retVal = true;
            }

            return retVal;
        }

        /// <summary>
        /// Load state from an XML element
        /// </summary>
        /// <param name="xmlElement">XML element containing new state</param>
        public void LoadXml(System.Xml.XmlElement xmlElement)
        {
            if (xmlElement == null)
            {
                throw new ArgumentNullException("xmlElement");
            }

            this.algorithm = xmlElement.GetAttribute("Algorithm");
        }

        /// <summary>
        /// Returns the XML representation of the this object
        /// </summary>
        /// <returns>XML element containing the state of this object</returns>
        public XmlElement GetXml()
        {
            XmlDocument creationXmlDocument;
            XmlElement retVal;

            creationXmlDocument = new XmlDocument();
            retVal = creationXmlDocument.CreateElement("ds", "DigestMethod", SignedXml.XmlDsigNamespaceUrl);

            retVal.SetAttribute("Algorithm", this.algorithm);

            return retVal;
        }
        #endregion
    }
}