using GostCryptography.Properties;
using System.Collections;
using System.Reflection;
using System.Security.Cryptography.Xml;
using System.Xml;

namespace GostCryptography.Reflection
{
    static class EncryptedXmlHelper
    {
        private static readonly object DocumentFieldSync = new object();
        private static volatile FieldInfo _documentField;

        public static XmlDocument GetDocument(this EncryptedXml encryptedXml)
        {
            if (_documentField == null)
            {
                lock (DocumentFieldSync)
                {
                    if (_documentField == null)
                    {
                        _documentField = typeof(EncryptedXml).GetField("m_document", BindingFlags.Instance | BindingFlags.NonPublic);
                    }
                }
            }

            if (_documentField == null)
            {
                throw ExceptionUtility.CryptographicException(Resources.XmlCannotFindPrivateMember, "m_document");
            }

            return (XmlDocument)_documentField.GetValue(encryptedXml);
        }

        private static readonly object KeyNameMappingFieldSync = new object();
        private static volatile FieldInfo _keyNameMappingField;

        public static Hashtable GetKeyNameMapping(this EncryptedXml encryptedXml)
        {
            if (_keyNameMappingField == null)
            {
                lock (KeyNameMappingFieldSync)
                {
                    if (_keyNameMappingField == null)
                    {
                        _keyNameMappingField = typeof(EncryptedXml).GetField("m_keyNameMapping", BindingFlags.Instance | BindingFlags.NonPublic);
                    }
                }
            }

            if (_keyNameMappingField == null)
            {
                throw ExceptionUtility.CryptographicException(Resources.XmlCannotFindPrivateMember, "m_keyNameMapping");
            }

            return (Hashtable)_keyNameMappingField.GetValue(encryptedXml);
        }

        private static readonly object GetCipherValueMethodSync = new object();
        private static volatile MethodInfo _getCipherValueMethod;

        public static byte[] GetCipherValue(this EncryptedXml encryptedXml, CipherData cipherData)
        {
            if (_getCipherValueMethod == null)
            {
                lock (GetCipherValueMethodSync)
                {
                    if (_getCipherValueMethod == null)
                    {
                        _getCipherValueMethod = typeof(EncryptedXml).GetMethod("GetCipherValue", BindingFlags.Instance | BindingFlags.NonPublic);
                    }
                }
            }

            if (_getCipherValueMethod == null)
            {
                throw ExceptionUtility.CryptographicException(Resources.XmlCannotFindPrivateMember, "GetCipherValue()");
            }

            return (byte[])_getCipherValueMethod.Invoke(encryptedXml, new object[] { cipherData });
        }
    }
}