//
// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements.  See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to You under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License.  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

// TODO: Can I really donate this code? Get approval from Kent and MS LGA.

//-----------------------------------------------------------------------------
//
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
// PARTICULAR PURPOSE.
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
//
//-----------------------------------------------------------------------------


using System;
using System.Security.Cryptography.X509Certificates;

/// <summary>
/// A utility class which helps to retrieve an x509 certificate
/// </summary>
public class CertificateUtil
{
        public static X509Certificate2 GetCertificate( StoreName name, StoreLocation location, string subjectName )
        {   
            X509Store store = new X509Store( name, location );
            X509Certificate2Collection certificates = null;
            store.Open( OpenFlags.ReadOnly );
        
            try
            {
                X509Certificate2 result = null;

                //
                // Every time we call store.Certificates property, a new collection will be returned.
                //
                certificates = store.Certificates; 
                
                for ( int i = 0; i < certificates.Count; i++ )
                {
                    X509Certificate2 cert = certificates[i];

                    if ( cert.SubjectName.Name.ToLower() == subjectName.ToLower() )
                    {
                        if ( result != null )
                            throw new ApplicationException( string.Format( "There are multiple certificates for subject Name {0}", subjectName ) );

                        result = new X509Certificate2(cert);
                    }
                }

                if ( result == null )
                {
                    throw new ApplicationException( string.Format( "No certificate was found for subject Name {0}", subjectName ) );
                }

                return result;
            }
            finally
            {
                if ( certificates != null )
                {
                    for ( int i = 0; i < certificates.Count; i++ )
                    {
                        X509Certificate2 cert = certificates[i];
                        cert.Reset();
                    }
                }

                store.Close();
            }
        }
}