using GostCryptography.Config;
using System.Security;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography.Xml;
using System.Xml;

namespace GostCryptography.Xml
{
    /// <summary>
    /// Объект для работы с подписями XML по ГОСТ 34.10
    /// </summary>
    /// <remarks>
    /// Данный класс реализует стандарт XML-DSig с использованием ГОСТ 34.10. Стандарт XML-DSig разработан консорциумом W3C
    /// и определяет рекомендации по формированию подписанных сообщений в формате XML. Фактически XML-DSig решает те же вопросы,
    /// что и CMS/PKCS#7.  Основное отличие в том, что в CMS/PKCS#7 данные хранятся в структурах, сформированных в соответствии 
    /// с разметкой ANS.1 (фактически, бинарные данные), а в XML-DSig данные хранятся в текстовом формате в соответствии с правилами
    /// документа "XML Signature Syntax and Processing". Основное применение XML-DSig - это XML-ориентированные протоколы, например,
    /// Web- и SOAP-сервисы.
    /// </remarks>
    public sealed class GostSignedXml
    {
        static GostSignedXml()
        {
            GostCryptoConfig.Initialize();
        }

        /// <inheritdoc cref="SignedXml()"/>
        public GostSignedXml()
        {
            _signedXml = new GostSignedXmlImpl();
        }

        /// <inheritdoc cref="SignedXml(XmlElement)"/>
        public GostSignedXml(XmlElement element)
        {
            if (element == null)
            {
                throw ExceptionUtility.ArgumentNull(nameof(element));
            }

            _signedXml = new GostSignedXmlImpl(element);
        }

        /// <inheritdoc cref="SignedXml(XmlDocument)"/>
        public GostSignedXml(XmlDocument document)
        {
            if (document == null)
            {
                throw ExceptionUtility.ArgumentNull(nameof(document));
            }

            _signedXml = new GostSignedXmlImpl(document);
        }

        private readonly GostSignedXmlImpl _signedXml;

        /// <inheritdoc cref="SignedXml.SignedInfo"/>
        public SignedInfo SignedInfo => _signedXml.SignedInfo;

        /// <inheritdoc cref="SignedXml.KeyInfo"/>
        public KeyInfo KeyInfo
        {
            get => _signedXml.KeyInfo;
            set => _signedXml.KeyInfo = value;
        }

        /// <inheritdoc cref="SignedXml.SigningKey"/>
        public AsymmetricAlgorithm SigningKey
        {
            get => _signedXml.SigningKey;
            set => _signedXml.SigningKey = value;
        }

#if !NET40
        /// <inheritdoc cref="SignedXml.SafeCanonicalizationMethods"/>
        public System.Collections.ObjectModel.Collection<string> SafeCanonicalizationMethods
        {
            get => _signedXml.SafeCanonicalizationMethods;
        }
#endif

        /// <summary>
        /// Обработчик для перекрытия метода <see cref="GetIdElement"/>
        /// </summary>
        public GetIdElementDelegate GetIdElementHandler
        {
            get => _signedXml.GetIdElementHandler;
            set => _signedXml.GetIdElementHandler = value;
        }

        /// <summary>
        /// Устанавливает сертификат для вычисления цифровой подписи
        /// </summary>
        [SecuritySafeCritical]
        public void SetSigningCertificate(X509Certificate2 certificate)
        {
            SigningKey = certificate.GetPrivateKeyAlgorithm();
        }

        /// <inheritdoc cref="SignedXml.AddReference"/>
        public void AddReference(Reference reference)
        {
            _signedXml.AddReference(reference);
        }

        /// <inheritdoc cref="SignedXml.ComputeSignature()"/>
        public void ComputeSignature()
        {
            _signedXml.ComputeSignatureGost();
        }

        /// <inheritdoc cref="SignedXml.CheckSignature()"/>
        public bool CheckSignature()
        {
            return _signedXml.CheckSignature();
        }

        /// <inheritdoc cref="SignedXml.CheckSignature(AsymmetricAlgorithm)"/>
        public bool CheckSignature(AsymmetricAlgorithm publicKey)
        {
            return _signedXml.CheckSignature(publicKey);
        }

        /// <inheritdoc cref="SignedXml.LoadXml(XmlElement)"/>
        public void LoadXml(XmlElement element)
        {
            _signedXml.LoadXml(element);
        }

        /// <inheritdoc cref="SignedXml.GetXml()"/>
        public XmlElement GetXml()
        {
            return _signedXml.GetXml();
        }

        /// <inheritdoc cref="SignedXml.GetIdElement(XmlDocument,string)"/>
        public XmlElement GetIdElement(XmlDocument document, string idValue)
        {
            return _signedXml.GetIdElement(document, idValue);
        }
    }
}