using System;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Text;
using System.Xml;
using System.Xml.XPath;
using System.IO;
using DotNetOpenId.Yadis;
using System.Diagnostics;
using DotNetOpenId.Extensions;
using System.Globalization;

namespace DotNetOpenId.RelyingParty {
	/// <summary>
	/// Represents information discovered about a user-supplied Identifier.
	/// </summary>
	[DebuggerDisplay("ClaimedIdentifier: {ClaimedIdentifier}, ProviderEndpoint: {ProviderEndpoint}, OpenId: {Protocol.Version}")]
	internal class ServiceEndpoint : IXrdsProviderEndpoint {
		/// <summary>
		/// The URL which accepts OpenID Authentication protocol messages.
		/// </summary>
		/// <remarks>
		/// Obtained by performing discovery on the User-Supplied Identifier. 
		/// This value MUST be an absolute HTTP or HTTPS URL.
		/// </remarks>
		public Uri ProviderEndpoint { get; private set; }
		Uri IProviderEndpoint.Uri { get { return ProviderEndpoint; } }
		/*
		/// <summary>
		/// An Identifier for an OpenID Provider.
		/// </summary>
		public Identifier ProviderIdentifier { get; private set; }
		*/
		/// <summary>
		/// An Identifier that was presented by the end user to the Relying Party, 
		/// or selected by the user at the OpenID Provider. 
		/// During the initiation phase of the protocol, an end user may enter 
		/// either their own Identifier or an OP Identifier. If an OP Identifier 
		/// is used, the OP may then assist the end user in selecting an Identifier 
		/// to share with the Relying Party.
		/// </summary>
		public Identifier UserSuppliedIdentifier { get; private set; }
		/// <summary>
		/// The Identifier that the end user claims to own.
		/// </summary>
		public Identifier ClaimedIdentifier { get; private set; }
		/// <summary>
		/// An alternate Identifier for an end user that is local to a 
		/// particular OP and thus not necessarily under the end user's 
		/// control.
		/// </summary>
		public Identifier ProviderLocalIdentifier { get; private set; }
		string friendlyIdentifierForDisplay;
		/// <summary>
		/// Supports the <see cref="IAuthenticationResponse.FriendlyIdentifierForDisplay"/> property.
		/// </summary>
		public string FriendlyIdentifierForDisplay {
			get {
				if (friendlyIdentifierForDisplay == null) {
					XriIdentifier xri = ClaimedIdentifier as XriIdentifier;
					UriIdentifier uri = ClaimedIdentifier as UriIdentifier;
					if (xri != null) {
						if (UserSuppliedIdentifier == null || String.Equals(UserSuppliedIdentifier, ClaimedIdentifier, StringComparison.OrdinalIgnoreCase)) {
							friendlyIdentifierForDisplay = ClaimedIdentifier;
						} else {
							friendlyIdentifierForDisplay = String.Format(CultureInfo.CurrentCulture, "{0} ({1})",
								ClaimedIdentifier, UserSuppliedIdentifier);
						}
					} else if (uri != null) {
						string displayUri = uri.Uri.Authority + uri.Uri.PathAndQuery;
						displayUri = displayUri.TrimEnd('/');
						// Multi-byte unicode characters get encoded by the Uri class for transit.
						// Since this is for display purposes, we want to reverse this and display a readable
						// representation of these foreign characters.  
						friendlyIdentifierForDisplay = Uri.UnescapeDataString(displayUri);
					} else {
						Debug.Fail("Doh!  We never should have reached here.");
						friendlyIdentifierForDisplay = ClaimedIdentifier;
					}
				}
				return friendlyIdentifierForDisplay;
			}
		}
		/// <summary>
		/// Gets the list of services available at this OP Endpoint for the
		/// claimed Identifier.
		/// </summary>
		public string[] ProviderSupportedServiceTypeUris { get; private set; }

		ServiceEndpoint(Identifier claimedIdentifier, Identifier userSuppliedIdentifier,
			Uri providerEndpoint, Identifier providerLocalIdentifier,
			string[] providerSupportedServiceTypeUris, int? servicePriority, int? uriPriority) {
			if (claimedIdentifier == null) throw new ArgumentNullException("claimedIdentifier");
			if (providerEndpoint == null) throw new ArgumentNullException("providerEndpoint");
			if (providerSupportedServiceTypeUris == null) throw new ArgumentNullException("providerSupportedServiceTypeUris");
			ClaimedIdentifier = claimedIdentifier;
			UserSuppliedIdentifier = userSuppliedIdentifier;
			ProviderEndpoint = providerEndpoint;
			ProviderLocalIdentifier = providerLocalIdentifier ?? claimedIdentifier;
			ProviderSupportedServiceTypeUris = providerSupportedServiceTypeUris;
			this.servicePriority = servicePriority;
			this.uriPriority = uriPriority;
		}
		/// <summary>
		/// Used for deserializing <see cref="ServiceEndpoint"/> from authentication responses.
		/// </summary>
		ServiceEndpoint(Identifier claimedIdentifier, Identifier userSuppliedIdentifier, 
			Uri providerEndpoint, Identifier providerLocalIdentifier, Protocol protocol) {
			ClaimedIdentifier = claimedIdentifier;
			UserSuppliedIdentifier = userSuppliedIdentifier;
			ProviderEndpoint = providerEndpoint;
			ProviderLocalIdentifier = providerLocalIdentifier ?? claimedIdentifier;
			this.protocol = protocol;
		}

		internal static ServiceEndpoint CreateForProviderIdentifier(
			Identifier providerIdentifier, Uri providerEndpoint,
			string[] providerSupportedServiceTypeUris, int? servicePriority, int? uriPriority) {

			Protocol protocol = Protocol.Detect(providerSupportedServiceTypeUris);

			return new ServiceEndpoint(protocol.ClaimedIdentifierForOPIdentifier, providerIdentifier,
				providerEndpoint, protocol.ClaimedIdentifierForOPIdentifier,
				providerSupportedServiceTypeUris, servicePriority, uriPriority);
		}

		internal static ServiceEndpoint CreateForClaimedIdentifier(
			Identifier claimedIdentifier, Identifier providerLocalIdentifier,
			Uri providerEndpoint,
			string[] providerSupportedServiceTypeUris, int? servicePriority, int? uriPriority) {

			return CreateForClaimedIdentifier(claimedIdentifier, null, providerLocalIdentifier, 
				providerEndpoint, providerSupportedServiceTypeUris, servicePriority, uriPriority);
		}

		internal static ServiceEndpoint CreateForClaimedIdentifier(
			Identifier claimedIdentifier, Identifier userSuppliedIdentifier, Identifier providerLocalIdentifier,
			Uri providerEndpoint,
			string[] providerSupportedServiceTypeUris, int? servicePriority, int? uriPriority) {

			return new ServiceEndpoint(claimedIdentifier, userSuppliedIdentifier, providerEndpoint,
				providerLocalIdentifier, providerSupportedServiceTypeUris, servicePriority, uriPriority);
		}

		Protocol protocol;
		/// <summary>
		/// Gets the OpenID protocol used by the Provider.
		/// </summary>
		public Protocol Protocol {
			get {
				if (protocol == null) {
					protocol = Protocol.Detect(ProviderSupportedServiceTypeUris);
				}
				if (protocol != null) return protocol;
				throw new InvalidOperationException("Unable to determine the version of OpenID the Provider supports.");
			}
		}

		public bool IsExtensionSupported(string extensionUri) {
			if (ProviderSupportedServiceTypeUris == null)
				throw new InvalidOperationException("Cannot lookup extension support on a rehydrated ServiceEndpoint.");
			return Array.IndexOf(ProviderSupportedServiceTypeUris, extensionUri) >= 0;
		}

		public bool IsExtensionSupported(IExtension extension) {
			if (extension == null) throw new ArgumentNullException("extension");

			// Consider the primary case.
			if (IsExtensionSupported(extension.TypeUri)) {
				return true;
			}
			// Consider the secondary cases.
			if (extension.AdditionalSupportedTypeUris != null) {
				foreach (string extensionTypeUri in extension.AdditionalSupportedTypeUris) {
					if (IsExtensionSupported(extensionTypeUri)) {
						return true;
					}
				}
			}
			return false;
		}

		public bool IsExtensionSupported<T>() where T : Extensions.IExtension, new() {
			T extension = new T();
			return IsExtensionSupported(extension);
		}

		public bool IsExtensionSupported(Type extensionType) {
			if (extensionType == null) throw new ArgumentNullException("extensionType");
			if (!typeof(Extensions.IExtension).IsAssignableFrom(extensionType))
				throw new ArgumentException(string.Format(CultureInfo.CurrentCulture,
					Strings.TypeMustImplementX, typeof(Extensions.IExtension).FullName),
					"extensionType");
			var extension = (Extensions.IExtension)Activator.CreateInstance(extensionType);
			return IsExtensionSupported(extension);
		}

		Version IProviderEndpoint.Version { get { return Protocol.Version; } }

		/// <summary>
		/// Saves the discovered information about this endpoint
		/// for later comparison to validate assertions.
		/// </summary>
		internal void Serialize(TextWriter writer) {
			writer.WriteLine(ClaimedIdentifier);
			writer.WriteLine(ProviderLocalIdentifier);
			writer.WriteLine(UserSuppliedIdentifier);
			writer.WriteLine(ProviderEndpoint);
			writer.WriteLine(Protocol.Version);
			// No reason to serialize priority. We only needed priority to decide whether to use this endpoint.
		}

		/// <summary>
		/// Reads previously discovered information about an endpoint
		/// from a solicited authentication assertion for validation.
		/// </summary>
		/// <returns>
		/// A <see cref="ServiceEndpoint"/> object that has everything
		/// except the <see cref="ProviderSupportedServiceTypeUris"/>
		/// deserialized.
		/// </returns>
		internal static ServiceEndpoint Deserialize(TextReader reader) {
			var claimedIdentifier = Identifier.Parse(reader.ReadLine());
			var providerLocalIdentifier = Identifier.Parse(reader.ReadLine());
			string userSuppliedIdentifier = reader.ReadLine();
			if (userSuppliedIdentifier.Length == 0) userSuppliedIdentifier = null;
			var providerEndpoint = new Uri(reader.ReadLine());
			var protocol = Util.FindBestVersion(p => p.Version, new[] { new Version(reader.ReadLine()) });
			return new ServiceEndpoint(claimedIdentifier, userSuppliedIdentifier,
				providerEndpoint, providerLocalIdentifier, protocol);
		}
		internal static ServiceEndpoint ParseFromAuthResponse(IDictionary<string, string> query, Identifier userSuppliedIdentifier) {
			Protocol protocol = Protocol.Detect(query);
			Debug.Assert(protocol.openid.op_endpoint != null, "This method should only be called in OpenID 2.0 contexts.");
			return new ServiceEndpoint(
				Util.GetRequiredArg(query, protocol.openid.claimed_id),
				userSuppliedIdentifier,
				new Uri(Util.GetRequiredArg(query, protocol.openid.op_endpoint)),
				Util.GetRequiredArg(query, protocol.openid.identity),
				protocol);
		}

		public static bool operator ==(ServiceEndpoint se1, ServiceEndpoint se2) {
			if ((object)se1 == null ^ (object)se2 == null) return false;
			if ((object)se1 == null) return true;
			return se1.Equals(se2);
		}
		public static bool operator !=(ServiceEndpoint se1, ServiceEndpoint se2) {
			return !(se1 == se2);
		}
		public override bool Equals(object obj) {
			ServiceEndpoint other = obj as ServiceEndpoint;
			if (other == null) return false;
			// We specifically do not check our ProviderSupportedServiceTypeUris array
			// or the priority field
			// as that is not persisted in our tokens, and it is not part of the 
			// important assertion validation that is part of the spec.
			return
				this.ClaimedIdentifier == other.ClaimedIdentifier &&
				this.ProviderEndpoint == other.ProviderEndpoint &&
				this.ProviderLocalIdentifier == other.ProviderLocalIdentifier &&
				this.Protocol == other.Protocol;
		}
		public override int GetHashCode() {
			return ClaimedIdentifier.GetHashCode();
		}
		public override string ToString() {
			return ProviderEndpoint.AbsoluteUri;
		}

		#region IXrdsProviderEndpoint Members

		private int? servicePriority;
		/// <summary>
		/// Gets the priority associated with this service that may have been given
		/// in the XRDS document.
		/// </summary>
		int? IXrdsProviderEndpoint.ServicePriority {
			get { return servicePriority; }
		}
		private int? uriPriority;
		/// <summary>
		/// Gets the priority associated with the service endpoint URL.
		/// </summary>
		int? IXrdsProviderEndpoint.UriPriority {
			get { return uriPriority; }
		}

		#endregion
	}
}