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

using System.Collections;
using System.Security.Cryptography;
using System.Text;
using System.Xml;

namespace System.Security.Cryptography.Xml {

public class Signature {

	private ArrayList list;
	private SignedInfo info;
	private KeyInfo key;
	private string id;
	private byte[] signature;

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

	public Signature() 
	{
		list = new ArrayList ();
	}

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

	public KeyInfo KeyInfo {
		get { return key; }
		set { key = value; }
	}

	public IList ObjectList {
		get { return list; }
		set { list = ArrayList.Adapter (value); }
	}

	public byte[] SignatureValue {
		get { return signature; }
		set { signature = value; }
	}

	public SignedInfo SignedInfo {
		get { return info; }
		set { info = value; }
	}

	public void AddObject (DataObject dataObject) 
	{
		list.Add (dataObject);
	}

	public XmlElement GetXml () 
	{
		if (info == null)
			throw new CryptographicException ("SignedInfo");
		if (signature == null)
			throw new CryptographicException ("SignatureValue");

		StringBuilder sb = new StringBuilder ();
		sb.Append ("<Signature");
		if (id != null) {
			sb.Append (" Id = \"");
			sb.Append (id);
			sb.Append ("\"");
		}
		sb.Append (" xmlns=\"");
		sb.Append (xmldsig);
/*		if (info != null) {
			sb.Append ("\">");
			sb.Append (info.GetXml ().OuterXml);
			sb.Append ("</Signature>");
		}
		else*/
			sb.Append ("\" />");

		XmlDocument doc = new XmlDocument ();
		doc.LoadXml (sb.ToString ());

		XmlNode xn = null;
		XmlNode newNode = null;

		if (info != null) {
			// this adds the xmlns=xmldsig
			xn = info.GetXml ();
			newNode = doc.ImportNode (xn, true);
			doc.DocumentElement.AppendChild (newNode);
		}

		if (signature != null) {
			XmlElement sv = doc.CreateElement ("SignatureValue", xmldsig);
			sv.InnerText = Convert.ToBase64String (signature);
			doc.DocumentElement.AppendChild (sv);
		}

		if (key != null) {
			xn = key.GetXml ();
			newNode = doc.ImportNode (xn, true);
			doc.DocumentElement.AppendChild (newNode);
		}

		if (list.Count > 0) {
			foreach (DataObject obj in list) {
				xn = obj.GetXml ();
				newNode = doc.ImportNode (xn, true);
				doc.DocumentElement.AppendChild (newNode);
			}
		}

		return doc.DocumentElement;
	}

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

	public void LoadXml (XmlElement value) 
	{
		if (value == null)
			throw new ArgumentNullException ("value");

		if ((value.LocalName == "Signature") && (value.NamespaceURI == xmldsig)) {
			id = GetAttribute (value, "Id");

			XmlNodeList xnl = value.GetElementsByTagName ("SignedInfo");
			if ((xnl != null) && (xnl.Count == 1)) {
				info = new SignedInfo ();
				info.LoadXml ((XmlElement) xnl[0]);
			}

			xnl = value.GetElementsByTagName ("SignatureValue");
			if ((xnl != null) && (xnl.Count == 1)) {
				signature = Convert.FromBase64String (xnl[0].InnerText);
			}

			xnl = value.GetElementsByTagName ("KeyInfo");
			if ((xnl != null) && (xnl.Count == 1)) {
				key = new KeyInfo ();
				key.LoadXml ((XmlElement) xnl[0]);
			}

			xnl = value.GetElementsByTagName ("Object");
			if ((xnl != null) && (xnl.Count > 0)) {
				foreach (XmlNode xn in xnl) {
					DataObject obj = new DataObject ();
					obj.LoadXml ((XmlElement) xn);
					AddObject (obj);
				}
			}
		}

		// if invalid
		if (info == null)
			throw new CryptographicException ("SignedInfo");
		if (signature == null)
			throw new CryptographicException ("SignatureValue");
	}
}

}