using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;

namespace BeWoFileExporter
{
    internal class Program
    {
        private static MySqlConnection _MySqlConnection;

        private static string BwpRootFileDirectory { get; set; }

        /// <summary>
        /// Sucht alle Datenbanken nach Blobs in der Tabelle FileAttachment ab, exportiert diese in das BWP-File-Verzeichnis und löscht den Blob aus der Datenbank.
        /// </summary>
        /// <param name="args">Enthält Kundennummern. Wenn keine Übergeben wird, werden alle Datenbanken auf dem Server durchgegangen.
        /// Hat die Position 0 den Wert 'm', wird nach der Kundennummer gefragt.</param>
        private static void Main(string[] args)
        {
            try
            {
                var selectedTenants = new List<string>();

                BwpRootFileDirectory = Utils.GetFileRootDirectoryPath();

                var configPath = Utils.GetMultitenancyDirectoryPath();

//#if DEBUG
//                BwpRootFileDirectory = @"C:\BWP-Files";
//                configPath = @"C:\Users\lyndo\BeWo\Host\Multitenancy";
//#endif

                // Prüfen, ob die Kundennummer abgefragt werden soll:
                if(args.Length > 0 && args[0] == "m")
                {
                    string tenants = null;

                    while(tenants == null)
                    {
                        Console.Write("Kundennummer (mehrere durch Komma trennen): ");
                        tenants = Console.ReadLine();

                        if(tenants != null)
                        {
                            var tenantList = tenants.Split(',');
                            selectedTenants = tenantList.ToList().Select(s => s.Trim()).ToList();
                        }
                    }
                }
                else
                {
                    if(args.Length > 0)
                    {
                        // Kann durch Kommata getrennt sein
                        var tenants = args[0];
                        if(tenants != null)
                        {
                            var tenantList = tenants.Split(',');
                            selectedTenants = tenantList.ToList();
                        }
                    }
                }

                var configFileNames = selectedTenants.Select(tenant => $"{tenant}.config").ToList();

                var configFiles = Directory.EnumerateFiles(configPath).Where(filePath =>
                {
                    var fileName = Path.GetFileName(filePath);

                    var isSelected = !configFileNames.Any();
                    if(configFileNames.Count > 0)
                    {
                        isSelected = configFileNames.Contains(fileName);
                    }

                    return filePath.EndsWith(".config") && isSelected;
                }).ToList();

                var connections = GetConnectionObjects(configFiles).ToList();

                var datenbankplural = connections.Count != 1 ? "en" : string.Empty;

                Console.WriteLine($"Exportiere Dateien aus {connections.Count} Datenbank{datenbankplural}\n");

                foreach(var connection in connections)
                {
                    _MySqlConnection = new MySqlConnection(connection.ToMySqlConnectionString());

                    ExtractFiles(connection);
                }
            }
            catch(Exception exception)
            {
                Console.WriteLine(exception);
            }
            finally
            {
                if(_MySqlConnection != null)
                {
                    CloseConnection();
                }

                Console.Read();
            }
        }

        private static bool OpenConnection()
        {
            try
            {
                _MySqlConnection.Open();
                return true;
            }
            catch(MySqlException exception)
            {
                Console.WriteLine($"Fehler: {exception}\n");

                return false;
            }
        }

        private static IEnumerable<Connection> GetConnectionObjects(IEnumerable<string> configFiles)
        {
            var connections = new List<Connection>();

            foreach(var configFile in configFiles)
            {
                var connectionString = Utils.GetConnectionStringFromConfigFile(configFile)?.Trim();

                if(connectionString != null &&
                   connectionString.Contains("Server=") &&
                   connectionString.Contains("Password=") &&
                   connectionString.Contains("User ID=") &&
                   connectionString.Contains("Initial Catalog="))
                {
                    var server = Utils.GetConnectionStringValue("Server", connectionString);
                    var password = Utils.GetConnectionStringValue("Password", connectionString);
                    var uid = Utils.GetConnectionStringValue("User ID", connectionString);
                    var database = Utils.GetConnectionStringValue("Initial Catalog", connectionString);

                    connections.Add(new Connection(server, uid, database, password));
                }
            }

            return connections;
        }

        private static void ExtractFiles(Connection connection)
        {
            _MySqlConnection = new MySqlConnection(connection.ToMySqlConnectionString());

            try
            {
                if(OpenConnection())
                {
                    LoadFileAttachmentData(connection.Database);
                }
            }
            catch(Exception exception)
            {
                Console.WriteLine(exception+ "\n");
            }
            finally
            {
                CloseConnection();
            }
        }

        private static void LoadFileAttachmentData(string connectionDatabase)
        {
            const string queryString = "SELECT Oid, Data FROM fileattachment WHERE Data IS NOT NULL;";

            if(_MySqlConnection.State == ConnectionState.Open)
            {
                var mySqlCommand = new MySqlCommand(queryString, _MySqlConnection);

                var reader = mySqlCommand.ExecuteReader();

                var fileAttachments = new List<FileAttachment>();

                while(reader.Read())
                {
                    var data = reader["Data"];

                    var oid = reader["Oid"];

                    if(data == null || oid == null)
                    {
                        continue;
                    }

                    if(data is byte[] byteArray && long.TryParse(oid.ToString(), out var fileAttachmentOid))
                    {
                        var tenant = connectionDatabase;

                        fileAttachments.Add(new FileAttachment(fileAttachmentOid, tenant, byteArray));
                    }
                }

                reader.Close();

                var fileCount = fileAttachments.Count;

                var word = fileCount > 1 ?
                    $"{fileCount} Dateien werden exportiert" : fileCount == 0 ?
                    "Keine Dateien exportiert" :
                    "Eine Datei wird exportiert";

                Console.WriteLine($"{connectionDatabase}: {word}\n");

                SaveDataToDirectory(fileAttachments, connectionDatabase);
            }
        }

        private static void SaveDataToDirectory(IReadOnlyCollection<FileAttachment> fileAttachments, string connectionDatabase)
        {
            if(_MySqlConnection.State == ConnectionState.Open && fileAttachments?.Count > 0)
            {
                Utils.CheckForFileRootDirectory(connectionDatabase, BwpRootFileDirectory);

                var updateStringBuilder = new StringBuilder("UPDATE fileattachment SET Data = NULL WHERE Oid IN (");

                var oidString = string.Empty;

                foreach(var fileAttachment in fileAttachments)
                {
                    File.WriteAllBytes(Utils.GetFilePath(connectionDatabase, fileAttachment.Oid.ToString()), fileAttachment.Data);
                    oidString += fileAttachment.Oid + ",";
                }

                updateStringBuilder.Append(oidString.TrimEnd(','));

                updateStringBuilder.Append(");");

                var updateCommand = new MySqlCommand(updateStringBuilder.ToString()) { Connection = _MySqlConnection };

                updateCommand.ExecuteNonQuery();
            }
        }

        private static void CloseConnection()
        {
            try
            {
                _MySqlConnection.Close();
            }
            catch(MySqlException exception)
            {
                Console.WriteLine(exception+ "\n");
            }
        }
    }
}