// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.

using System.Diagnostics.CodeAnalysis;
using System.IdentityModel.Selectors;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Description;
using System.ServiceModel.Security;
using System.Web.Http.SelfHost.Channels;
using System.Web.Http.SelfHost.Properties;
using System.Web.Http.SelfHost.ServiceModel;
using System.Web.Http.SelfHost.ServiceModel.Channels;

namespace System.Web.Http.SelfHost
{
    /// <summary>
    /// The configuration class for Http Services
    /// </summary>
    public class HttpSelfHostConfiguration : HttpConfiguration
    {
        private const int DefaultMaxConcurrentRequests = 100;
        private const int DefaultMaxBufferSize = 64 * 1024;
        private const int DefaultReceivedMessageSize = 64 * 1024;

        private const int PendingContextFactor = 100;
        private const int MinConcurrentRequests = 1;
        private const int MinBufferSize = 1;
        private const int MinReceivedMessageSize = 1;

        private Uri _baseAddress;
        private int _maxConcurrentRequests;
        private ServiceCredentials _credentials = new ServiceCredentials();
        private bool _useWindowsAuth;
        private TransferMode _transferMode;
        private int _maxBufferSize = DefaultMaxBufferSize;
        private bool _maxBufferSizeIsInitialized;
        private long _maxReceivedMessageSize = DefaultReceivedMessageSize;
        private HostNameComparisonMode _hostNameComparisonMode;

        /// <summary>
        /// Initializes a new instance of the <see cref="HttpSelfHostConfiguration"/> class.
        /// </summary>
        /// <param name="baseAddress">The base address.</param>
        public HttpSelfHostConfiguration(string baseAddress)
            : this(CreateBaseAddress(baseAddress))
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="HttpSelfHostConfiguration"/> class.
        /// </summary>
        /// <param name="baseAddress">The base address.</param>
        [SuppressMessage("Microsoft.Reliability", "CA2000:Dispose objects before losing scope", Justification = "caller owns object")]
        public HttpSelfHostConfiguration(Uri baseAddress)
            : base(new HttpRouteCollection(ValidateBaseAddress(baseAddress).AbsolutePath))
        {
            _baseAddress = ValidateBaseAddress(baseAddress);
            _maxConcurrentRequests = GetDefaultMaxConcurrentRequests();
            _maxBufferSize = TransportDefaults.MaxBufferSize;
            _maxReceivedMessageSize = TransportDefaults.MaxReceivedMessageSize;
        }

        /// <summary>
        /// Gets the base address.
        /// </summary>
        /// <value>
        /// The base address.
        /// </value>
        public Uri BaseAddress
        {
            get { return _baseAddress; }
        }

        /// <summary>
        /// Gets or sets the upper limit of how many concurrent <see cref="T:System.Net.Http.HttpRequestMessage"/> instances 
        /// can be processed at any given time. The default is 100 times the number of CPU cores.
        /// </summary>
        /// <value>
        /// The maximum concurrent <see cref="T:System.Net.Http.HttpRequestMessage"/> instances processed at any given time.
        /// </value>
        public int MaxConcurrentRequests
        {
            get { return _maxConcurrentRequests; }

            set
            {
                if (value < MinConcurrentRequests)
                {
                    throw Error.ArgumentGreaterThanOrEqualTo("value", value, MinConcurrentRequests);
                }
                _maxConcurrentRequests = value;
            }
        }

        /// <summary>
        /// Gets or sets the transfer mode.
        /// </summary>
        /// <value>
        /// The transfer mode.
        /// </value>
        public TransferMode TransferMode
        {
            get { return _transferMode; }

            set
            {
                TransferModeHelper.Validate(value);
                _transferMode = value;
            }
        }

        /// <summary>
        /// Specifies how the host name should be used in URI comparisons when dispatching an incoming message.
        /// </summary>
        public HostNameComparisonMode HostNameComparisonMode
        {
            get { return _hostNameComparisonMode; }

            set
            {
                HostNameComparisonModeHelper.Validate(value);
                _hostNameComparisonMode = value;
            }
        }

        /// <summary>
        /// Gets or sets the size of the max buffer.
        /// </summary>
        /// <value>
        /// The size of the max buffer.
        /// </value>
        public int MaxBufferSize
        {
            get
            {
                if (_maxBufferSizeIsInitialized || TransferMode != TransferMode.Buffered)
                {
                    return _maxBufferSize;
                }

                long maxReceivedMessageSize = MaxReceivedMessageSize;
                if (maxReceivedMessageSize > Int32.MaxValue)
                {
                    return Int32.MaxValue;
                }
                return (int)maxReceivedMessageSize;
            }

            set
            {
                if (value < MinBufferSize)
                {
                    throw Error.ArgumentGreaterThanOrEqualTo("value", value, MinBufferSize);
                }
                _maxBufferSizeIsInitialized = true;
                _maxBufferSize = value;
            }
        }

        /// <summary>
        /// Gets or sets the size of the max received message.
        /// </summary>
        /// <value>
        /// The size of the max received message.
        /// </value>
        public long MaxReceivedMessageSize
        {
            get { return _maxReceivedMessageSize; }

            set
            {
                if (value < MinReceivedMessageSize)
                {
                    throw Error.ArgumentGreaterThanOrEqualTo("value", value, MinReceivedMessageSize);
                }
                _maxReceivedMessageSize = value;
            }
        }

        /// <summary>
        /// Gets or sets UserNamePasswordValidator so that it can be used to validate the username and password
        /// sent over HTTP or HTTPS
        /// </summary>
        /// <value>
        /// The server certificate.
        /// </value>
        public UserNamePasswordValidator UserNamePasswordValidator
        {
            get { return _credentials.UserNameAuthentication.CustomUserNamePasswordValidator; }

            set { _credentials.UserNameAuthentication.CustomUserNamePasswordValidator = value; }
        }

        /// <summary>
        /// Use this flag to indicate that you want to use windows authentication. This flag can
        /// not be used together with UserNamePasswordValidator property since you can either use
        /// Windows or Username Password as client credential.
        /// </summary>
        /// <value>
        /// set it true if you want to use windows authentication
        /// </value>
        public bool UseWindowsAuthentication
        {
            get { return _useWindowsAuth; }

            set { _useWindowsAuth = value; }
        }

        /// <summary>
        /// Internal method called to configure <see cref="HttpBinding"/> settings.
        /// </summary>
        /// <param name="httpBinding">Http binding.</param>
        /// <returns>The <see cref="BindingParameterCollection"/> to use when building the <see cref="IChannelListener"/> or null if no binding parameters are present.</returns>
        internal BindingParameterCollection ConfigureBinding(HttpBinding httpBinding)
        {
            return OnConfigureBinding(httpBinding);
        }

        /// <summary>
        /// Called to apply the configuration on the endpoint level.
        /// </summary>
        /// <param name="httpBinding">Http endpoint.</param>
        /// <returns>The <see cref="BindingParameterCollection"/> to use when building the <see cref="IChannelListener"/> or null if no binding parameters are present.</returns>
        protected virtual BindingParameterCollection OnConfigureBinding(HttpBinding httpBinding)
        {
            if (httpBinding == null)
            {
                throw Error.ArgumentNull("httpBinding");
            }

            if (_useWindowsAuth && _credentials.UserNameAuthentication.CustomUserNamePasswordValidator != null)
            {
                throw Error.InvalidOperation(SRResources.CannotUseWindowsAuthWithUserNamePasswordValidator);
            }

            httpBinding.MaxBufferSize = MaxBufferSize;
            httpBinding.MaxReceivedMessageSize = MaxReceivedMessageSize;
            httpBinding.TransferMode = TransferMode;
            httpBinding.HostNameComparisonMode = HostNameComparisonMode;

            if (_baseAddress.Scheme == Uri.UriSchemeHttps)
            {
                // we need to use SSL
                httpBinding.Security = new HttpBindingSecurity()
                {
                    Mode = HttpBindingSecurityMode.Transport,
                };
            }

            // Set up binding parameters
            if (_credentials.UserNameAuthentication.CustomUserNamePasswordValidator != null)
            {
                _credentials.UserNameAuthentication.UserNamePasswordValidationMode = UserNamePasswordValidationMode.Custom;
                if (httpBinding.Security == null || httpBinding.Security.Mode == HttpBindingSecurityMode.None)
                {
                    // Basic over HTTP case
                    httpBinding.Security = new HttpBindingSecurity()
                    {
                        Mode = HttpBindingSecurityMode.TransportCredentialOnly,
                    };
                }

                // We have validator, so we can set the client credential type to be basic
                httpBinding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic;

                return AddCredentialsToBindingParameters();
            }
            else if (_useWindowsAuth)
            {
                if (httpBinding.Security == null || httpBinding.Security.Mode == HttpBindingSecurityMode.None)
                {
                    // Basic over HTTP case, should we even allow this?
                    httpBinding.Security = new HttpBindingSecurity()
                    {
                        Mode = HttpBindingSecurityMode.TransportCredentialOnly,
                    };
                }

                // We have validator, so we can set the client credential type to be windows
                httpBinding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Windows;

                return AddCredentialsToBindingParameters();
            }

            return null;
        }

        private BindingParameterCollection AddCredentialsToBindingParameters()
        {
            BindingParameterCollection bindingParameters = new BindingParameterCollection();
            bindingParameters.Add(_credentials);
            return bindingParameters;
        }

        private static Uri CreateBaseAddress(string baseAddress)
        {
            if (baseAddress == null)
            {
                throw Error.ArgumentNull("baseAddress");
            }

            return new Uri(baseAddress, UriKind.RelativeOrAbsolute);
        }

        private static Uri ValidateBaseAddress(Uri baseAddress)
        {
            if (baseAddress == null)
            {
                throw Error.ArgumentNull("baseAddress");
            }

            if (!baseAddress.IsAbsoluteUri)
            {
                throw Error.ArgumentUriNotAbsolute("baseAddress", baseAddress);
            }

            if (!String.IsNullOrEmpty(baseAddress.Query) || !String.IsNullOrEmpty(baseAddress.Fragment))
            {
                throw Error.ArgumentUriHasQueryOrFragment("baseAddress", baseAddress);
            }

            if (!ReferenceEquals(baseAddress.Scheme, Uri.UriSchemeHttp) && !ReferenceEquals(baseAddress.Scheme, Uri.UriSchemeHttps))
            {
                throw Error.ArgumentUriNotHttpOrHttpsScheme("baseAddress", baseAddress);
            }

            return baseAddress;
        }

        [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "We never want to fail here so we have to catch all exceptions.")]
        private static int GetDefaultMaxConcurrentRequests()
        {
            try
            {
                return Math.Max(Environment.ProcessorCount * DefaultMaxConcurrentRequests, DefaultMaxConcurrentRequests);
            }
            catch
            {
                return DefaultMaxConcurrentRequests;
            }
        }
    }
}