//
// SignedInfo.cs - SignedInfo implementation for XML Signature
//
// Author:
//	Sebastien Pouliot (spouliot@motus.com)
//
// (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
//

using System.Collections;
using System.Text;
using System.Xml;

namespace System.Security.Cryptography.Xml { 

	public class SignedInfo : ICollection, IEnumerable {

		static private string xmldsig = "http://www.w3.org/2000/09/xmldsig#";

		private ArrayList references;
		private string c14nMethod;
		private string id;
		private string signatureMethod;
		private string signatureLength;

		public SignedInfo() 
		{
			references = new ArrayList ();
			c14nMethod = "http://www.w3.org/TR/2001/REC-xml-c14n-20010315";
		}

		public string CanonicalizationMethod {
			get { return c14nMethod; }
			set { c14nMethod = value; }
		}

		// documented as not supported (and throwing exception)
		public int Count {
			get { throw new NotSupportedException (); }
		}

		public string Id {
			get { return id; }
			set { id = value; }
		}

		// documented as not supported (and throwing exception)
		public bool IsReadOnly {
			get { throw new NotSupportedException (); }
		}

		// documented as not supported (and throwing exception)
		public bool IsSynchronized {
			get { throw new NotSupportedException (); }
		}

		public ArrayList References {
			get { return references; }
		}

		public string SignatureLength {
			get { return signatureLength; }
			set { signatureLength = value; }
		}

		public string SignatureMethod {
			get { return signatureMethod; }
			set { signatureMethod = value; }
		}

		// documented as not supported (and throwing exception)
		public object SyncRoot {
			get { throw new NotSupportedException (); }
		}

		public void AddReference (Reference reference) 
		{
			references.Add (reference);
		}

		// documented as not supported (and throwing exception)
		public void CopyTo (Array array, int index) 
		{
			throw new NotSupportedException ();
		}

		public IEnumerator GetEnumerator () 
		{
			return references.GetEnumerator ();
		}

		public XmlElement GetXml() 
		{
			if (signatureMethod == null)
				throw new CryptographicException ("SignatureMethod");
			if (references.Count == 0)
				throw new CryptographicException ("References empty");

			StringBuilder sb = new StringBuilder ();
			sb.Append ("<SignedInfo");
			if (id != null) {
				sb.Append (" Id=\"");
				sb.Append (id);
				sb.Append ("\"");
			}
			sb.Append (" xmlns=\"");
			sb.Append (xmldsig);
			sb.Append ("\">");
			if (c14nMethod != null) {
				sb.Append ("<CanonicalizationMethod Algorithm=\"");
				sb.Append (c14nMethod);
				sb.Append ("\" />");
			}
			if (signatureMethod != null) {
				sb.Append ("<SignatureMethod Algorithm=\"");
				sb.Append (signatureMethod);
				if (signatureLength != null) {
					sb.Append ("\">");
					sb.Append ("<HMACOutputLength>");
					sb.Append (signatureLength);
					sb.Append ("</HMACOutputLength>");
					sb.Append ("</SignatureMethod>");
				}
				else
					sb.Append ("\" />");
			}
			sb.Append ("</SignedInfo>");

			XmlDocument doc = new XmlDocument ();
			doc.LoadXml (sb.ToString ());
			// we add References afterward so we don't end up with extraneous
			// xmlns="..." in each reference elements.
			foreach (Reference r in references) {
				XmlNode xn = r.GetXml ();
				XmlNode newNode = doc.ImportNode (xn, true);
				doc.DocumentElement.AppendChild (newNode);
			}

			return doc.DocumentElement;
		}

		private string GetAttributeFromElement (XmlElement xel, string attribute, string element) 
		{
			string result = null;
			XmlNodeList xnl = xel.GetElementsByTagName (element);
			if ((xnl != null) && (xnl.Count > 0)) {
				XmlAttribute xa = xnl[0].Attributes [attribute];
				if (xa != null)
					result = xa.InnerText;
			}
			return result;
		}

		private string GetAttribute (XmlElement xel, string attribute) 
		{
			XmlAttribute xa = xel.Attributes [attribute];
			return ((xa != null) ? xa.InnerText : null);
		}

		[MonoTODO("signatureLength for HMAC")]
		public void LoadXml (XmlElement value) 
		{
			if (value == null)
				throw new ArgumentNullException ("value");

			if ((value.LocalName == "SignedInfo") && (value.NamespaceURI == xmldsig)) {
				id = GetAttribute (value, "Id");
				c14nMethod = GetAttributeFromElement (value, "Algorithm", "CanonicalizationMethod");
				signatureMethod = GetAttributeFromElement (value, "Algorithm", "SignatureMethod");
				// TODO signatureLength for HMAC
				XmlNodeList xnl = value.GetElementsByTagName ("Reference");
				foreach (XmlNode xn in xnl) {
					Reference r = new Reference ();
					r.LoadXml ((XmlElement) xn);
					AddReference (r);
				}
			}
			else
				throw new CryptographicException ();
		}
	}
}