using System.IdentityModel.Tokens;
using System.Xml;

namespace System.IdentityModel.Tokens
{
    public class GenericXmlSecurityKeyIdentifierClause : SecurityKeyIdentifierClause
    {
        XmlElement referenceXml;

        public GenericXmlSecurityKeyIdentifierClause(XmlElement referenceXml)
            : this(referenceXml, null, 0)
        {
        }

        public GenericXmlSecurityKeyIdentifierClause(XmlElement referenceXml, byte[] derivationNonce, int derivationLength)
            : base(null, derivationNonce, derivationLength)
        {
            if (referenceXml == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("referenceXml");
            }
            this.referenceXml = referenceXml;
        }

        public XmlElement ReferenceXml
        {
            get { return this.referenceXml; }
        }

        public override bool Matches(SecurityKeyIdentifierClause keyIdentifierClause)
        {
            GenericXmlSecurityKeyIdentifierClause that = keyIdentifierClause as GenericXmlSecurityKeyIdentifierClause;

            // PreSharp Bug: Parameter 'that' to this public method must be validated: A null-dereference can occur here.
#pragma warning suppress 56506
            return ReferenceEquals(this, that) || (that != null && that.Matches(this.ReferenceXml));
        }

        private bool Matches(XmlElement xmlElement)
        {
            if (xmlElement == null)
                return false;

            return CompareNodes(this.referenceXml, xmlElement);
        }

        private bool CompareNodes(XmlNode originalNode, XmlNode newNode)
        {
            if (originalNode.OuterXml == newNode.OuterXml)
                return true;

            if (originalNode.LocalName != newNode.LocalName || originalNode.InnerText != newNode.InnerText)
                return false;

            if (originalNode.InnerXml == newNode.InnerXml)
                return true;

            if (originalNode.HasChildNodes)
            {
                if (!newNode.HasChildNodes || originalNode.ChildNodes.Count != newNode.ChildNodes.Count)
                    return false;

                bool childrenStatus = true;
                for (int i = 0; i < originalNode.ChildNodes.Count; i++)
                {
                    childrenStatus = childrenStatus & CompareNodes(originalNode.ChildNodes[i], newNode.ChildNodes[i]);
                }

                return childrenStatus;
            }
            else if (newNode.HasChildNodes)
                return false;

            return true;
        }
    }
}