// SignaturePolicyId.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.Security.Cryptography.Xml;
using System.Xml;

namespace Microsoft.Xades
{
    /// <summary>
    /// The SignaturePolicyId element is an explicit and unambiguous identifier
    /// of a Signature Policy together with a hash value of the signature
    /// policy, so it can be verified that the policy selected by the signer is
    /// the one being used by the verifier. An explicit signature policy has a
    /// globally unique reference, which, in this way, is bound to an
    /// electronic signature by the signer as part of the signature
    /// calculation.
    /// </summary>
    public class SignaturePolicyId
    {
        #region Private variables
        private ObjectIdentifier sigPolicyId;
        private Transforms transforms;
        private DigestAlgAndValueType sigPolicyHash;
        private SigPolicyQualifiers sigPolicyQualifiers;
        #endregion

        #region Public properties
        /// <summary>
        /// The SigPolicyId element contains an identifier that uniquely
        /// identifies a specific version of the signature policy
        /// </summary>
        public ObjectIdentifier SigPolicyId
        {
            get
            {
                return this.sigPolicyId;
            }
            set
            {
                this.sigPolicyId = value;
            }
        }

        /// <summary>
        /// The optional Transforms element can contain the transformations
        /// performed on the signature policy document before computing its
        /// hash
        /// </summary>
        public Transforms Transforms
        {
            get
            {
                return this.transforms;
            }
            set
            {
                this.transforms = value;
            }
        }

        /// <summary>
        /// The SigPolicyHash element contains the identifier of the hash
        /// algorithm and the hash value of the signature policy
        /// </summary>
        public DigestAlgAndValueType SigPolicyHash
        {
            get
            {
                return this.sigPolicyHash;
            }
            set
            {
                this.sigPolicyHash = value;
            }
        }

        /// <summary>
        /// The SigPolicyQualifier element can contain additional information
        /// qualifying the signature policy identifier
        /// </summary>
        public SigPolicyQualifiers SigPolicyQualifiers
        {
            get
            {
                return this.sigPolicyQualifiers;
            }
            set
            {
                this.sigPolicyQualifiers = value;
            }
        }
        #endregion

        #region Constructors
        /// <summary>
        /// Default constructor
        /// </summary>
        public SignaturePolicyId()
        {
            this.sigPolicyId = new ObjectIdentifier("SigPolicyId");
            this.transforms = new Transforms();
            this.sigPolicyHash = new DigestAlgAndValueType("SigPolicyHash");
            this.sigPolicyQualifiers = new SigPolicyQualifiers();
        }
        #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.sigPolicyId != null && this.sigPolicyId.HasChanged())
            {
                retVal = true;
            }

            if (this.transforms != null && this.transforms.HasChanged())
            {
                retVal = true;
            }

            if (this.sigPolicyHash != null && this.sigPolicyHash.HasChanged())
            {
                retVal = true;
            }

            if (this.sigPolicyQualifiers != null && this.sigPolicyQualifiers.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");
            }

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

            xmlNodeList = xmlElement.SelectNodes("xsd:SigPolicyId", xmlNamespaceManager);
            if (xmlNodeList.Count == 0)
            {
                throw new CryptographicException("SigPolicyId missing");
            }
            this.sigPolicyId = new ObjectIdentifier("SigPolicyId");
            this.sigPolicyId.LoadXml((XmlElement)xmlNodeList.Item(0));

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

            xmlNodeList = xmlElement.SelectNodes("xsd:SigPolicyHash", xmlNamespaceManager);
            if (xmlNodeList.Count == 0)
            {
                throw new CryptographicException("SigPolicyHash missing");
            }
            this.sigPolicyHash = new DigestAlgAndValueType("SigPolicyHash");
            this.sigPolicyHash.LoadXml((XmlElement)xmlNodeList.Item(0));

            xmlNodeList = xmlElement.SelectNodes("xsd:SigPolicyQualifiers", xmlNamespaceManager);
            if (xmlNodeList.Count != 0)
            {
                this.sigPolicyQualifiers = new SigPolicyQualifiers();
                this.sigPolicyQualifiers.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", "SignaturePolicyId", XadesSignedXml.XadesNamespaceUri);

            if (this.sigPolicyId != null && this.sigPolicyId.HasChanged())
            {
                retVal.AppendChild(creationXmlDocument.ImportNode(this.sigPolicyId.GetXml(), true));
            }
            else
            {
                throw new CryptographicException("SigPolicyId element missing in SignaturePolicyId");
            }

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

            if (this.sigPolicyHash != null && this.sigPolicyHash.HasChanged())
            {
                retVal.AppendChild(creationXmlDocument.ImportNode(this.sigPolicyHash.GetXml(), true));
            }
            else
            {
                throw new CryptographicException("SigPolicyHash element missing in SignaturePolicyId");
            }

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

            return retVal;
        }
        #endregion
    }
}
