// HashDataInfo.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;
using System.Xml;

namespace Microsoft.Xades
{
    /// <summary>
    /// The HashDataInfo class contains a uri attribute referencing a data object
    /// and a ds:Transforms element indicating the transformations to make to this
    /// data object.
    /// The sequence of HashDataInfo elements will be used to produce the input of
    /// the hash computation process whose result will be included in the
    /// timestamp request to be sent to the TSA.
    /// </summary>
    public class HashDataInfo
    {
        #region Private variables
        private string uriAttribute;
        private Transforms transforms;
        #endregion

        #region Public properties
        /// <summary>
        /// Uri referencing a data object
        /// </summary>
        public string UriAttribute
        {
            get
            {
                return this.uriAttribute;
            }
            set
            {
                this.uriAttribute = value;
            }
        }

        /// <summary>
        /// Transformations to make to this data object
        /// </summary>
        public Transforms Transforms
        {
            get
            {
                return this.transforms;
            }
            set
            {
                this.transforms = value;
            }
        }
        #endregion

        #region Constructors
        /// <summary>
        /// Default constructor
        /// </summary>
        public HashDataInfo()
        {
            this.transforms = new Transforms();
        }
        #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.uriAttribute))
            {
                retVal = true;
            }

            if (this.transforms != null && this.transforms.HasChanged())
            {
                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)
        {
            XmlNamespaceManager xmlNamespaceManager;
            XmlNodeList xmlNodeList;

            if (xmlElement == null)
            {
                throw new ArgumentNullException("xmlElement");
            }
            if (xmlElement.HasAttribute("uri"))
            {
                this.uriAttribute = xmlElement.GetAttribute("uri");
            }
            else
            {
                this.uriAttribute = "";
                throw new CryptographicException("uri attribute missing");
            }

            xmlNamespaceManager = new XmlNamespaceManager(xmlElement.OwnerDocument.NameTable);
            xmlNamespaceManager.AddNamespace("xsd", XadesSignedXml.XadesNamespaceUri);

            xmlNodeList = xmlElement.SelectNodes("xsd:Transforms", xmlNamespaceManager);
            if (xmlNodeList.Count != 0)
            {
                this.transforms = new Transforms();
                this.transforms.LoadXml((XmlElement)xmlNodeList.Item(0));
            }
        }

        /// <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("xades", "HashDataInfo", XadesSignedXml.XadesNamespaceUri);

            retVal.SetAttribute("uri", this.uriAttribute);

            if (this.transforms != null && this.transforms.HasChanged())
            {
                retVal.AppendChild(creationXmlDocument.ImportNode(this.transforms.GetXml(), true));
            }

            return retVal;
        }
        #endregion
    }
}