using System;
using System.Data.SqlClient;
using System.IO;
using System.IO.Compression;
using System.Runtime.ExceptionServices;
using Centron.BusinessLogic;
using Centron.BusinessLogic.Administration.Scripts;
using Centron.BusinessLogic.Sales.Receipts;
using Centron.Common;
using Centron.Core.Extensions;
using Centron.Core.Utils;
using Centron.DAO;
using Centron.DAO.DAOConnections;
using Centron.Interfaces.BL;
using Xunit;

namespace Centron.Tests.EndToEnd.Infrastructure
{
    public class Database
    {
        #region Database Server
        public static string Server
        {
            get
            {
                var server = GetEnvironmentVariable("CENTRON_TESTS_DATABASE_SERVER");
  
                if (string.IsNullOrWhiteSpace(server) == false)
                    return server;

                throw new Exception("You have to configure the SQL server for EndToEndTests");
                // return "YOUR-MACHINE\\SQL2017"; //Enter your local SQL server here
            }
        }
        public static string Username
        {
            get
            {
                var username = GetEnvironmentVariable("CENTRON_TESTS_DATABASE_USERNAME");
               
                if (string.IsNullOrWhiteSpace(username) == false)
                    return username;

                throw new Exception("You have to configure the SQL server username for EndToEndTests");
                // return "sql-username"; //Enter your local SQL username here
            }
        }
        public static string Password
        {
            get
            {
                var password = GetEnvironmentVariable("CENTRON_TESTS_DATABASE_PASSWORD");
 
                if (string.IsNullOrWhiteSpace(password) == false)
                    return password;

                throw new Exception("You have to configure the SQL server password for EndToEndTests");
                // return "password"; //Enter your local SQL password here
            }
        }
        #endregion

        private static object _lock = new object();
        private static Exception _initializeException;
        private static string _databaseName;
        private static string _snapshotName;

        public static IDisposable Initialize()
        {
            lock (_lock)
            {
                if (string.IsNullOrWhiteSpace(_databaseName) == false || string.IsNullOrWhiteSpace(_snapshotName) == false)
                    throw new Exception("Database.Initialize can only be called once.");
                
                // If there was an error when initializing the Database before
                // Rethrow that exception here, so we don't waste a lot of time restoring the database again
                if (_initializeException is not null)
                    ExceptionDispatchInfo.Throw(_initializeException); // This keeps the original exception stack-trace

                // Start database initialization in the beginning to let it run parallel to database restore
                DAOFactory.Instance.InitializeAsync();
                    
                string databaseName = GetDatabaseName();
                string snapshotName = GetSnapshotName(databaseName);
                
                RestoreDatabase(databaseName);
                try
                {
                    Connect(databaseName);
                    UpdateDatabase();
                }
                catch (Exception e)
                {
                    try
                    {
                        // If something fails when connecting to the database, or executing scripts
                        // we want to Drop the database again.
                        // The test will not be able to run, but we were leaving old database backups behind.
                        // So, lets clean up after ourselves and Drop the database if something goes wrong.
                        DropDatabase(databaseName);
                    }
                    catch
                    {
                        // Dropping the database failed. Unlucky, but not much we can do.
                    }

                    _initializeException = e;
                    throw;
                }

                try
                {
                    CreateSnapshot(snapshotName, databaseName);
                }
                catch (Exception e)
                {
                    // The test will not be able to run, but we were leaving old database backups behind.
                    // So, lets clean up after ourselves and Drop the database if something goes wrong.
                    
                    try
                    {
                        DropSnapshot(snapshotName);
                    }
                    catch
                    {
                        //Dropping the snapshot failed. Unlucky, but not much we can do.
                    }

                    try 
                    {
                        DropDatabase(databaseName);
                    }
                    catch
                    {
                        //Dropping the database failed. Unlucky, but not much we can do.
                    }

                    _initializeException = e;
                    throw;
                }

                _databaseName = databaseName;
                _snapshotName = snapshotName;

                return new DisposableAction(() =>
                {
                    DropSnapshot(snapshotName);
                    DropDatabase(databaseName);
                });
            }
        }

        public static void RestoreFromSnapshot()
        {
            RestoreFromSnapshot(_databaseName, _snapshotName);
            ReceiptItemSpecialArticleHelperBL.ClearSpecialArticlesCache();
        }
        
        #region Names
        private static string GetDatabaseName()
        {
            var user = Environment.UserName;
            var time = DateTime.Now.ToString("dd-MM-yyyy-HH:mm:ss");
            var guid = Guid.NewGuid().ToString("N");

            return $"EndToEndTests-{user}-{time}-{guid}".Truncate(120); // The MSSQL server database name max length is 128 characters, just make sure to not go too long
        }
        private static string GetSnapshotName(string databaseName)
        {
            return databaseName + "-snapshot";
        }
        #endregion

        #region Snapshots
        private static void CreateSnapshot(string snapshotName, string databaseName)
        {
            ExecuteSql(command =>
            {
                command.CommandText = GetCreateSnapshotSQL(snapshotName, databaseName);
                command.ExecuteNonQuery();
            });
        }
        private static string GetCreateSnapshotSQL(string snapshotName, string databaseName)
        {
            string dataPath = null;
            
            ExecuteSql(command =>
            {
                command.CommandText = "SELECT serverproperty('InstanceDefaultDataPath')";
                using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        dataPath = reader.GetString(0);
                    }
                }
            });
            
            return $@"CREATE DATABASE [{snapshotName}] ON 
( 
    NAME = CentronWork_Data, 
    FILENAME = N'{dataPath}{databaseName.Replace("-", "").Replace(":", "")}.ss'
) 
AS SNAPSHOT OF [{databaseName}]";
        }
        
        private static void DropSnapshot(string snapshotName)
        {
            ExecuteSql(command =>
            {
                command.CommandText = GetDropSnapshotSQL(snapshotName);
                command.ExecuteNonQuery();
            });
        }
        private static string GetDropSnapshotSQL(string snapshotName)
        {
            return $"DROP DATABASE [{snapshotName}]";
        }

        private static void RestoreFromSnapshot(string databaseName, string snapshotName)
        {
            ExecuteSql(command =>
            {
                command.CommandText = GetRestoreFromSnapshotSQL(databaseName, snapshotName);
                command.ExecuteNonQuery();
            });
        }
        private static string GetRestoreFromSnapshotSQL(string databaseName, string snapshotName)
        {
            return $@"
ALTER DATABASE [{databaseName}] SET SINGLE_USER WITH ROLLBACK IMMEDIATE;

RESTORE DATABASE [{databaseName}] 
FROM DATABASE_SNAPSHOT = '{snapshotName}';

ALTER DATABASE [{databaseName}] SET MULTI_USER WITH ROLLBACK IMMEDIATE; ";
        }
        #endregion

        #region Database
        private static void RestoreDatabase(string databaseName)
        {
            ExecuteSql(command =>
            {
                command.CommandText = GetRestoreDatabaseSQL(databaseName);
                command.CommandTimeout = (int)TimeSpan.FromMinutes(2).TotalSeconds;
                command.ExecuteNonQuery();
            });
        }
        private static string GetRestoreDatabaseSQL(string databaseName)
        {
            var backupPath = GetEnvironmentVariable("DATABASE_BACKUP_PATH");
            if (string.IsNullOrEmpty(backupPath))
                backupPath = Path.GetFullPath(".\\Infrastructure\\DatabaseBackup.bak");
            string dataPath = null;
            string logPath = null;

            ExecuteSql(command =>
            {
                command.CommandText = "SELECT serverproperty('InstanceDefaultDataPath'), serverproperty('InstanceDefaultLogPath')";
                using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        dataPath = reader.GetString(0);
                        logPath = reader.GetString(1);
                    }
                }
            });

            return $@"RESTORE DATABASE [{databaseName}] FROM DISK = N'{backupPath}'
WITH
    REPLACE,
    MOVE N'CentronWork_Data' TO N'{dataPath}{databaseName.Replace("-", "").Replace(":", "")}.mdf',
    MOVE N'CentronWork_Log' TO N'{logPath}{databaseName.Replace("-", "").Replace(":", "")}.ldf'";
        }
        
        private static void DropDatabase(string databaseName)
        {
            ExecuteSql(command =>
            {
                command.CommandText = GetDropDatabaseSQL(databaseName);
                command.ExecuteNonQuery();
            });
        }
        private static string GetDropDatabaseSQL(string databaseName)
        {
            return $"ALTER DATABASE [{databaseName}] SET SINGLE_USER WITH ROLLBACK IMMEDIATE; DROP DATABASE [{databaseName}]";
        }
        #endregion

        #region Private Methods
        private static void Connect(string databaseName)
        {
            DAOFactory.Instance.SetConnection(new InCodeDAOConnection(Server, databaseName, Username, Password), "c-entron Tests");
            DAOFactory.Instance.InitializeAsync().Wait();

            Assert.True(DAOFactory.Instance.IsInitialized, "DAOFactory.Instance.IsInitialized");
            Assert.True(DAOFactory.Instance.HasConnection, "DAOFactory.Instance.HasConnection");
        }

        private static void UpdateDatabase()
        {
            using (var session = new BLSession())
            {
                var scriptEngineBL = session.GetBL<ScriptEngineBL>();
                var version = new Version(20, 0, 0, 0);
                var result = scriptEngineBL.ExecuteScripts(currentVersionOverride: version);

                Assert.Null(result.Message);
                Assert.Equal(ResultStatus.Success, result.Status);
            }
        }

        private static void ExecuteSql(Action<SqlCommand> execute)
        {
            var builder = new SqlConnectionStringBuilder
            {
                DataSource = Server,
                UserID = Username,
                Password = Password,
                InitialCatalog = "master"
            };

            using (var connection = new SqlConnection(builder.ToString()))
            {
                connection.Open();

                using (var command = connection.CreateCommand())
                {
                    execute(command);
                }
            }
        }
        
        private static string GetEnvironmentVariable(string name)
        {
            var targets = new[]
            {
                EnvironmentVariableTarget.Process,
                EnvironmentVariableTarget.User,
                EnvironmentVariableTarget.Machine
            };

            foreach (var target in targets)
            {
                var value = Environment.GetEnvironmentVariable(name, target);

                if (string.IsNullOrWhiteSpace(value) == false)
                    return value;
            }

            return null;
        }
        #endregion
    }
}