// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Collections.Generic;
using System.IdentityModel.Claims;
using System.Xml;
 
namespace System.ServiceModel
{
    public abstract class EndpointIdentity
    {
        private Claim _identityClaim;
        private IEqualityComparer<Claim> _claimComparer;
 
        protected EndpointIdentity()
        {
        }
 
        protected void Initialize(Claim identityClaim)
        {
            if (identityClaim == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull(nameof(identityClaim));
            }
 
            Initialize(identityClaim, null);
        }
 
        protected void Initialize(Claim identityClaim, IEqualityComparer<Claim> claimComparer)
        {
            _identityClaim = identityClaim ?? throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull(nameof(identityClaim));
            _claimComparer = claimComparer;
        }
 
        public Claim IdentityClaim
        {
            get
            {
                if (_identityClaim == null)
                {
                    EnsureIdentityClaim();
                }
                return _identityClaim;
            }
        }
 
        public static EndpointIdentity CreateIdentity(Claim identity)
        {
            if (identity == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull(nameof(identity));
            }
 
            if (identity.ClaimType.Equals(ClaimTypes.Dns))
            {
                return new DnsEndpointIdentity(identity);
            }
            else if (identity.ClaimType.Equals(ClaimTypes.Spn))
            {
                return new SpnEndpointIdentity(identity);
            }
            else if (identity.ClaimType.Equals(ClaimTypes.Upn))
            {
                return new UpnEndpointIdentity(identity);
            }
            else if (identity.ClaimType.Equals(ClaimTypes.Rsa))
            {
                return new RsaEndpointIdentity(identity);
            }
            else
            {
                return new GeneralEndpointIdentity(identity);
            }
        }
 
        public static EndpointIdentity CreateDnsIdentity(string dnsName)
        {
            return new DnsEndpointIdentity(dnsName);
        }
 
        public static EndpointIdentity CreateSpnIdentity(string spnName)
        {
            return new SpnEndpointIdentity(spnName);
        }
 
        public static EndpointIdentity CreateUpnIdentity(string upnName)
        {
            return new UpnEndpointIdentity(upnName);
        }
 
        internal virtual void EnsureIdentityClaim()
        {
        }
 
        public override bool Equals(object obj)
        {
            if (obj == (object)this)
            {
                return true;
            }
 
            // as handles null do we need the double null check?
            if (obj == null)
            {
                return false;
            }
 
            EndpointIdentity otherIdentity = obj as EndpointIdentity;
            if (otherIdentity == null)
            {
                return false;
            }
 
            return Matches(otherIdentity.IdentityClaim);
        }
 
        public override int GetHashCode()
        {
            return GetClaimComparer().GetHashCode(IdentityClaim);
        }
 
        public override string ToString()
        {
            return "identity(" + IdentityClaim + ")";
        }
 
        internal bool Matches(Claim claim)
        {
            return GetClaimComparer().Equals(IdentityClaim, claim);
        }
 
        private IEqualityComparer<Claim> GetClaimComparer()
        {
            if (_claimComparer == null)
            {
                throw ExceptionHelper.PlatformNotSupported("EndpointIdentity.GetClaimComparer is not supported.");
            }
 
            return _claimComparer;
        }
 
 
        internal static EndpointIdentity ReadIdentity(XmlDictionaryReader reader)
        {
            if (reader == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull(nameof(reader));
            }
 
            EndpointIdentity readIdentity = null;
 
            reader.MoveToContent();
            if (reader.IsEmptyElement)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new XmlException(SRP.Format(SRP.UnexpectedEmptyElementExpectingClaim, XD.AddressingDictionary.Identity.Value, XD.AddressingDictionary.IdentityExtensionNamespace.Value)));
            }
 
            reader.ReadStartElement(XD.AddressingDictionary.Identity, XD.AddressingDictionary.IdentityExtensionNamespace);
 
            if (reader.IsStartElement(XD.AddressingDictionary.Spn, XD.AddressingDictionary.IdentityExtensionNamespace))
            {
                readIdentity = new SpnEndpointIdentity(reader.ReadElementString());
            }
            else if (reader.IsStartElement(XD.AddressingDictionary.Upn, XD.AddressingDictionary.IdentityExtensionNamespace))
            {
                readIdentity = new UpnEndpointIdentity(reader.ReadElementString());
            }
            else if (reader.IsStartElement(XD.AddressingDictionary.Dns, XD.AddressingDictionary.IdentityExtensionNamespace))
            {
                readIdentity = new DnsEndpointIdentity(reader.ReadElementString());
            }
            else if (reader.IsStartElement(XD.XmlSignatureDictionary.KeyInfo, XD.XmlSignatureDictionary.Namespace))
            {
                reader.ReadStartElement();
                if (reader.IsStartElement(XD.XmlSignatureDictionary.X509Data, XD.XmlSignatureDictionary.Namespace))
                {
                    readIdentity = new X509CertificateEndpointIdentity(reader);
                }
                else if (reader.IsStartElement(XD.XmlSignatureDictionary.RsaKeyValue, XD.XmlSignatureDictionary.Namespace))
                {
                    readIdentity = new RsaEndpointIdentity(reader);
                }
                else
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new XmlException(SRP.Format(SRP.UnrecognizedIdentityType, reader.Name, reader.NamespaceURI)));
                }
                reader.ReadEndElement();
            }
            else if (reader.NodeType == XmlNodeType.Element)
            {
                //
                // Something unknown
                //
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new XmlException(SRP.Format(SRP.UnrecognizedIdentityType, reader.Name, reader.NamespaceURI)));
            }
            else
            {
                //
                // EndpointIdentity element is empty or some other invalid xml
                //
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new XmlException(SRP.InvalidIdentityElement));
            }
 
            reader.ReadEndElement();
 
            return readIdentity;
        }
 
        internal void WriteTo(XmlDictionaryWriter writer)
        {
            if (writer == null)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull(nameof(writer));
            }
 
            writer.WriteStartElement(XD.AddressingDictionary.Identity, XD.AddressingDictionary.IdentityExtensionNamespace);
 
            WriteContentsTo(writer);
 
            writer.WriteEndElement();
        }
 
        internal virtual void WriteContentsTo(XmlDictionaryWriter writer)
        {
            throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SRP.Format(SRP.UnrecognizedIdentityPropertyType, IdentityClaim.GetType().ToString())));
        }
    }
}