// Identifier.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.Xml;

namespace Microsoft.Xades
{
    /// <summary>
    /// Possible values for Qualifier
    /// </summary>
    public enum KnownQualifier
    {
        /// <summary>
        /// Value has not been set
        /// </summary>
        Uninitalized,
        /// <summary>
        /// OID encoded as Uniform Resource Identifier (URI)
        /// </summary>
        OIDAsURI,
        /// <summary>
        /// OID encoded as Uniform Resource Name (URN)
        /// </summary>
        OIDAsURN
    }

    /// <summary>
    /// The Identifier element contains a permanent identifier. Once assigned the
    /// identifier can never be re-assigned	again. It supports both the mechanism
    /// that is used to identify objects in ASN.1 and the mechanism that is
    /// usually used to identify objects in an XML environment.
    /// </summary>
    public class Identifier
    {
        #region Private variables
        private KnownQualifier qualifier;
        private string identifierUri;
        #endregion

        #region Public properties
        /// <summary>
        /// The optional Qualifier attribute can be used to provide a hint about the
        /// applied encoding (values OIDAsURN or OIDAsURI)
        /// </summary>
        public KnownQualifier Qualifier
        {
            get
            {
                return this.qualifier;
            }
            set
            {
                this.qualifier = value;
            }
        }

        /// <summary>
        /// Identification of the XML environment object
        /// </summary>
        public string IdentifierUri
        {
            get
            {
                return this.identifierUri;
            }
            set
            {
                this.identifierUri = value;
            }
        }
        #endregion

        #region Constructors
        /// <summary>
        /// Default constructor
        /// </summary>
        public Identifier()
        {
            this.qualifier = KnownQualifier.Uninitalized;
        }
        #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 (this.qualifier != KnownQualifier.Uninitalized)
            {
                retVal = true;
            }

            if (!String.IsNullOrEmpty(this.identifierUri))
            {
                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");
            }

            if (xmlElement.HasAttribute("Qualifier"))
            {
                this.qualifier = (KnownQualifier)KnownQualifier.Parse(typeof(KnownQualifier), xmlElement.GetAttribute("Qualifier"), true);
            }
            else
            {
                this.qualifier = KnownQualifier.Uninitalized;
            }

            this.identifierUri = xmlElement.InnerText;
        }

        /// <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", "Identifier", XadesSignedXml.XadesNamespaceUri);

            if (this.qualifier != KnownQualifier.Uninitalized)
            {
                retVal.SetAttribute("Qualifier", this.qualifier.ToString());
            }

            retVal.InnerText = this.identifierUri;

            return retVal;
        }
        #endregion
    }
}