using System;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Security.Cryptography.X509Certificates;
using System.Threading.Tasks;
using Microsoft.Identity.Client;
using Microsoft.Identity.Client.Extensions.Msal;
using Microsoft.InformationProtection;

namespace AipGateway.AIP
{
    public class AuthDelegateImplementation : IAuthDelegate
    {
        public int LastErrNo { get; set; }
        public string LastErrMsg { get; set; }

        private readonly AipConfig _aipConfig;
        private readonly IConfidentialClientApplication _confidentialApp = null;
        private readonly IPublicClientApplication _publicApp = null;


        public AuthDelegateImplementation(AipConfig aipConfig)
        {
            _aipConfig = aipConfig;
            LastErrNo = 0;
            LastErrMsg = String.Empty;

            var storageProperties =
                new StorageCreationPropertiesBuilder(
                        "AIPGateway.Cache",
                        Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location))
                    .Build();
            var cacheHelper = MsalCacheHelper.CreateAsync(storageProperties).GetAwaiter().GetResult();

            if (_aipConfig.LoginType == AipAuthLoginType.authLoginPassword)
            {
                _confidentialApp = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
                    .WithClientSecret(_aipConfig.SecretValue)
                    // .WithAuthority($"https://login.microsoftonline.com/{_aipConfig.TenantId}")
                    // .WithCacheOptions(CacheOptions.EnableSharedCacheOptions)
                    .WithRedirectUri("https://login.microsoftonline.com/common/oauth2/nativeclient")
                    .Build();
                cacheHelper.RegisterCache(_confidentialApp.UserTokenCache);
            }
            else if (_aipConfig.LoginType == AipAuthLoginType.authLoginCert)
            {
                var authority = $"https://login.windows.net/{_aipConfig.TenantId}";
                // var certificate = Utilities.ReadCertificateFromStore(_aipConfig.CertThumbPrint);
                var myCertificate = X509Certificate2.CreateFromCertFile(_aipConfig.CertThumbPrint);
                X509Certificate2 certificate = new X509Certificate2(myCertificate);
                _confidentialApp = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
                    .WithCertificate(certificate)
                    .WithAuthority(new Uri(authority))
                    .Build();
                cacheHelper.RegisterCache(_confidentialApp.UserTokenCache);
            }
            else
            {
                _publicApp = PublicClientApplicationBuilder.Create(_aipConfig.ClientId)
                    .WithRedirectUri("https://login.microsoftonline.com/common/oauth2/nativeclient")
                    .WithAuthority(AzureCloudInstance.AzurePublic, _aipConfig.TenantId)
                    .Build();
                cacheHelper.RegisterCache(_publicApp.UserTokenCache);
            }
        }

        public void ResetError()
        {
            LastErrNo = 0;
            LastErrMsg = string.Empty;
        }
        private void SetError(int errNo, string errMsg1, string errMsg2 = "No Exception Message.")
        {
            LastErrNo = errNo;
            LastErrMsg = errMsg1 + "\r\n" + errMsg2;
            Console.WriteLine("AuthDelegateImplementation::SetError ==> {0}, {1}, {2}", errNo, errMsg1, errMsg2);
        }

        public string AcquireToken(Identity identity, string authority, string resource, string claim)
        {
            Console.WriteLine("AuthDelegateImplementation::AcquireToken ==> LoginType: {0}", _aipConfig.LoginType);
            
            // var app = PublicClientApplicationBuilder.Create(_aipConfig.ClientId)
            //     .WithAuthority(authority)
            //     .Build();
            //
            // var scopes = new[] { resource[resource.Length - 1].Equals('/') ? $"{resource}.default" : $"{resource}/.default" };
            // try
            // {
            //     var accounts = app.GetAccountsAsync().GetAwaiter().GetResult();
            //     var result = app.AcquireTokenSilent(scopes, accounts.FirstOrDefault())
            //         .ExecuteAsync().Result;
            //
            //     Console.WriteLine("AuthDelegateImplementation::AcquireToken ==> AcquireTokenSilent Succeed.");
            //     return result.AccessToken;
            // }
            // catch (MsalUiRequiredException)
            // {
            //     Console.WriteLine("AuthDelegateImplementation::AcquireToken ==> AcquireTokenSilent Failed.");
            // }

            if (_aipConfig.LoginType == AipAuthLoginType.authLoginPassword)
            {
                return AcquireTokenByPassword(identity, authority, resource, claim);
            }
            
            if (_aipConfig.LoginType == AipAuthLoginType.authLoginCert)
            {
                return AcquireTokenByCert(identity, authority, resource, claim);
            }

            return AcquireTokenById(identity, authority, resource, claim);
        }

        private string AcquireTokenByPassword(Identity identity, string authority, string resource, string claims)
        {
            Console.WriteLine("AuthDelegateImplementation::AcquireTokenByPassword");

            AuthenticationResult result;
            var authorityUri = new Uri(authority);
            authority = $"https://{authorityUri.Host}/{_aipConfig.TenantId}";
            
            // var app = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
            //     .WithClientSecret(_aipConfig.SecretValue)
            //     // .WithAuthority($"https://login.microsoftonline.com/{_aipConfig.TenantId}")
            //     // .WithCacheOptions(CacheOptions.EnableSharedCacheOptions)
            //     .WithRedirectUri("https://login.microsoftonline.com/common/oauth2/nativeclient")
            //     .Build();

            // Create confidential client using client secret.
            // var app = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
            //     .WithRedirectUri(resource)
            //     .WithAuthority(authority)
            //     .WithClientSecret(_aipConfig.SecretValue)
            //     .Build();

            var scopes = new[] { resource[resource.Length - 1].Equals('/') ? $"{resource}.default" : $"{resource}/.default" };

            //app.AddInMemoryTokenCache();
            try
            {
                var accounts = (_confidentialApp.GetAccountsAsync()).GetAwaiter().GetResult();

                result = _confidentialApp.AcquireTokenSilent(scopes, accounts.FirstOrDefault())
                    .ExecuteAsync().GetAwaiter().GetResult();

                Console.WriteLine("AuthDelegateImplementation::AcquireTokenByPassword ==> AcquireTokenSilent Succeed.");
                return result.AccessToken;
            }
            catch (MsalUiRequiredException)
            {
                Console.WriteLine("AuthDelegateImplementation::AcquireTokenByPassword ==> AcquireTokenSilent Failed.");
                try
                {
                    result = _confidentialApp.AcquireTokenForClient(scopes)
                        .WithTenantId(_aipConfig.TenantId)
                        .ExecuteAsync()
                        .GetAwaiter()
                        .GetResult();
                }
                catch (MsalServiceException ex) when (ex.Message.Contains("AADSTS70011"))
                {
                    // Invalid scope. The scope has to be of the form "https://resourceurl/.default"
                    // Mitigation: change the scope to be as expected
                    SetError(1, "AcquireTokenByPassword.Scope provided is not supported.", ex.Message);
                    return null;
                }
            }

            return result.AccessToken;
        }

        private string AcquireTokenByCert(Identity identity, string authority, string resource, string claims)
        {
            Console.WriteLine("AuthDelegateImplementation::AcquireTokenByPassword");

            AuthenticationResult result;
            var authorityUri = new Uri(authority);
            authority = $"https://{authorityUri.Host}/{_aipConfig.TenantId}";

            // Read cert from local machine
            // var certificate = Utilities.ReadCertificateFromStore(_aipConfig.CertThumbPrint);
            var myCertificate = X509Certificate2.CreateFromCertFile(_aipConfig.CertThumbPrint);
            X509Certificate2 certificate = new X509Certificate2(myCertificate);

            // Use cert to build ClientAssertionCertificate
            // var app = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
            //     .WithCertificate(certificate)
            //     .WithAuthority(new Uri(authority))
            //     .Build();

            // var app = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
            //     .WithCertificate(certificate)
            //     .WithRedirectUri("https://login.microsoftonline.com/common/oauth2/nativeclient")
            //     .Build();
            // Append .default to the resource passed in to AcquireToken().
            var scopes = new[] { resource[resource.Length - 1].Equals('/') ? $"{resource}.default" : $"{resource}/.default" };

            try
            {
                result = _confidentialApp.AcquireTokenForClient(scopes).ExecuteAsync().Result;
            }
            catch (MsalServiceException ex) when (ex.Message.Contains("AADSTS70011"))
            {
                // Invalid scope. The scope has to be of the form "https://resourceurl/.default"
                // Mitigation: change the scope to be as expected
                SetError(1, "AcquireTokenByCert.Scope provided is not supported.", ex.Message);
                return null;
            }
            return result.AccessToken;
        }

        private string AcquireTokenById(Identity identity, string authority, string resource, string claims)
        {
            Console.WriteLine("AcquireTokenById::AcquireTokenByPassword");

            AuthenticationResult result;
            var authorityUri = new Uri(authority);
            authority = $"https://{authorityUri.Host}/{_aipConfig.TenantId}";

            // var app = PublicClientApplicationBuilder.Create(_aipConfig.ClientId)
            //     .WithRedirectUri("https://login.microsoftonline.com/common/oauth2/nativeclient")
            //     .WithAuthority(AzureCloudInstance.AzurePublic, _aipConfig.TenantId)
            //     .Build();

            var accounts = (_publicApp.GetAccountsAsync()).GetAwaiter().GetResult();

            // Append .default to the resource passed in to AcquireToken().
            var scopes = new[] { resource[resource.Length - 1].Equals('/') ? $"{resource}.default" : $"{resource}/.default" };
            try
            {
                result = _publicApp.AcquireTokenInteractive(scopes)
                    .WithAccount(accounts.FirstOrDefault())
                    .WithPrompt(Prompt.SelectAccount)
                    .ExecuteAsync()
                    .ConfigureAwait(false)
                    .GetAwaiter()
                    .GetResult();
            }
            catch (Exception ex)
            {
                SetError(1, "AcquireTokenById.Login Failed.", ex.Message);
                return null;
            }

            return result.AccessToken;
        }
        // public X509Certificate2 LoadCertificate(string certificateName)
        // {
        //     string vaultUrl = "";
        //     string clientId = _aipConfig.ClientId;
        //     string tenantId = _aipConfig.TenantId;
        //     string secret = "";
        //
        //     Console.WriteLine($"Loading certificate '{certificateName}' from Azure Key Vault");
        //
        //     var credentials = new ClientSecretCredential(tenantId: tenantId, clientId: clientId, clientSecret: secret);
        //     var certClient = new CertificateClient(new Uri(vaultUrl), credentials);
        //     var secretClient = new SecretClient(new Uri(vaultUrl), credentials);
        //
        //     var cert = GetCertificateAsync(certClient, secretClient, certificateName);
        //
        //     Console.WriteLine("Certificate loaded");
        //     return cert;
        // }
    //     private static X509Certificate2 GetCertificateAsync(CertificateClient certificateClient,
    //         SecretClient secretClient,
    //         string certificateName)
    //     {
    //
    //         KeyVaultCertificateWithPolicy certificate = certificateClient.GetCertificate(certificateName);
    //
    //         // Return a certificate with only the public key if the private key is not exportable.
    //         if (certificate.Policy?.Exportable != true)
    //         {
    //             return new X509Certificate2(certificate.Cer);
    //         }
    //
    //         // Parse the secret ID and version to retrieve the private key.
    //         string[] segments = certificate.SecretId.AbsolutePath.Split('/', StringSplitOptions.RemoveEmptyEntries);
    //         if (segments.Length != 3)
    //         {
    //             throw new InvalidOperationException($"Number of segments is incorrect: {segments.Length}, URI: {certificate.SecretId}");
    //         }
    //
    //         string secretName = segments[1];
    //         string secretVersion = segments[2];
    //
    //         KeyVaultSecret secret = secretClient.GetSecret(secretName, secretVersion);
    //
    //         // For PEM, you'll need to extract the base64-encoded message body.
    //         // .NET 5.0 preview introduces the System.Security.Cryptography.PemEncoding class to make this easier.
    //         if ("application/x-pkcs12".Equals(secret.Properties.ContentType, StringComparison.InvariantCultureIgnoreCase))
    //         {
    //             byte[] pfx = Convert.FromBase64String(secret.Value);
    //             return new X509Certificate2(pfx);
    //         }
    //
    //         throw new NotSupportedException($"Only PKCS#12 is supported. Found Content-Type: {secret.Properties.ContentType}");
    //     }
    // }
    private X509Certificate2 ReadCertificateFromStore(string thumbprint)
        {
            X509Certificate2 cert = null;
            X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
            store.Open(OpenFlags.ReadOnly);
            X509Certificate2Collection certCollection = store.Certificates;

            // Find unexpired certificates.
            X509Certificate2Collection currentCerts = certCollection.Find(X509FindType.FindByTimeValid, DateTime.Now, false);

            // From the collection of unexpired certificates, find the ones with the correct name.
            X509Certificate2Collection signingCert = currentCerts.Find(X509FindType.FindByThumbprint, thumbprint, false);

            // Return the first certificate in the collection, has the right name and is current.
            cert = signingCert.OfType<X509Certificate2>().OrderByDescending(c => c.NotBefore).FirstOrDefault();
            store.Close();
            return cert;
        }

        public async Task<AuthenticationResult> AcquireTokenAsync(string authority, string resource, string claims)
        {
            AuthenticationResult result = null;

            if (authority.ToLower().Contains("common"))
            {
                var authorityUri = new Uri(authority);
                authority = String.Format("https://{0}/{1}", authorityUri.Host, _aipConfig.TenantId);
            }
            
            var app = PublicClientApplicationBuilder.Create(_aipConfig.ClientId)
                .WithAuthority(authority)
                .WithDefaultRedirectUri()
                .Build();

            var accounts = (app.GetAccountsAsync()).GetAwaiter().GetResult();

            // Append .default to the resource passed in to AcquireToken().
            string[] scopes = { resource[resource.Length - 1].Equals('/') ? $"{resource}.default" : $"{resource}/.default" };

            try
            {
                result = await app.AcquireTokenSilent(new[] { "https://aadrm.com/user_impersonation" }, accounts.FirstOrDefault()).ExecuteAsync();

                // result = await _app.AcquireTokenSilent(scopes, 
                //         accounts.FirstOrDefault())
                //     .ExecuteAsync();
            }
            catch (MsalUiRequiredException)
            {
                result = app.AcquireTokenInteractive(scopes)
                    .WithAccount(accounts.FirstOrDefault())
                    .WithPrompt(Prompt.SelectAccount)
                    .ExecuteAsync()
                    .ConfigureAwait(false)
                    .GetAwaiter()
                    .GetResult();
            }

            // Return the token. The token is sent to the resource.                           
            return result;
        }

        // private async Task<string> GetAccessTokenOnBehalfOfUser(string authority, string resource)
        // {
        //     IConfidentialClientApplication app;
        //     
        //     if (false)
        //     {
        //         // Read X509 cert from local store and build ClientAssertionCertificate.
        //         X509Certificate2 cert = Utilities.ReadCertificateFromStore(_aipConfig.CertThumbPrint);
        //         
        //         // Create confidential client using certificate.
        //         app = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
        //                                         .WithRedirectUri(resource)
        //                                         .WithAuthority(authority)
        //                                         .WithCertificate(cert)
        //                                         .Build();                               
        //     }
        //
        //     else
        //     {
        //         // Create confidential client using client secret.
        //         app = ConfidentialClientApplicationBuilder.Create(_aipConfig.ClientId)
        //                                        .WithRedirectUri(resource)
        //                                        .WithAuthority(authority)
        //                                        .WithClientSecret(_aipConfig.SecretValue)
        //                                        .Build();                                
        //     }
        //
        //     // Store user access token of authenticated user.
        //     var ci = (ClaimsIdentity)_claimsPrincipal.Identity;
        //     string userAccessToken = (string)ci.BootstrapContext;
        //
        //
        //     // Generate a user assertion with the UPN and access token.            
        //     UserAssertion userAssertion = new UserAssertion(userAccessToken, "urn:ietf:params:oauth:grant-type:jwt-bearer");
        //
        //     // Append .default to the resource passed in to AcquireToken().
        //     List<string> scopes = new List<string>() { resource[resource.Length - 1].Equals('/') ? $"{resource}.default" : $"{resource}/.default" };
        //
        //     AuthenticationResult result = await app.AcquireTokenOnBehalfOf(scopes, userAssertion)
        //       .ExecuteAsync();              
        //
        //     // Return the token to the API caller
        //     return (result.AccessToken);
        // }      
    }
}