using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;

namespace AdvertsingProfitControl
{
    public partial class FrmIntegrityCheck : Form
    {
        //Dictionary<objectId, object>
        private readonly Dictionary<int, DatabaseTable> _databaseObjectsDictionary = new Dictionary<int, DatabaseTable>();
        private readonly Dictionary<int, DatabaseTable.RepairLevel> _errorsDictionary = new Dictionary<int, DatabaseTable.RepairLevel>();
        private readonly List<DatabaseDbCcResult> _databaseDbCcResults = new List<DatabaseDbCcResult>();

        public FrmIntegrityCheck(string connectionString)
        {
            InitializeComponent();
            RunDbCheck(connectionString);
        }

        private void RunDbCheck(string connectionString)
        {
            var reportsTable = new DataTable();
            try
            {
                using (var connection = new SqlConnection(connectionString))
                {
                    var query = @"IF NOT OBJECT_ID('tempdb..#CheckDB') IS NULL  
                            DROP TABLE #CheckDB;
                        -- Creating temporary table for CheckDB result. 
                        CREATE TABLE #CheckDB 
                            ([Error] int ,[Level] int ,[State] int 
                            ,[MessageText] varchar(7000) 
                            ,[RepairLevel] varchar(512) 
                            ,[Status] int ,[DbId] int ,[DbFragId] bigint 
                            ,[ObjectID] bigint ,[IndexId] bigint 
                            ,[PartitionId] bigint ,[AllocUnitId] bigint 
                            ,[RidDbId] int ,[RidPruId] int ,[File] int 
                            ,[Page] int ,[Slot] int ,[RefDbID] int 
                            ,[RefPruId] int ,[RefFile] int ,[RefPage] int 
                            ,[RefSlot] int ,[Allocation] int); 
                        -- Execute CheckDB and insert result to temp table 
                        INSERT INTO #CheckDB 
	                        ([Error], [Level], [State], [MessageText], [RepairLevel], 
		                        [Status], [DbId], [DbFragId], [ObjectID], [IndexId], [PartitionId], 
		                        [AllocUnitId], [RidDbId], [RidPruId], [File], [Page], [Slot], [RefDbID], 
		                        [RefPruId], [RefFile], [RefPage], [RefSlot], [Allocation]) 
                        EXEC ('DBCC CHECKDB(''AdvertisingProfitControl'') WITH TABLERESULTS'); 
                        -- Show final summary message first with total count of errors 
                        -- and warnings. Error number 8989 is for the summary messages,
                        -- the messages that begin with 'CHECKDB'. 
                        -- Query the relevant data from the DBCC result set.
                        SELECT OBJ.name AS Name, OBJ.type_desc AS Type, 
	                           IDX.Name AS PrimaryKey,
	                           CDB.RepairLevel, MessageText, CDB.Error, CDB.ObjectID
                        FROM #CheckDB AS CDB 
	                        LEFT JOIN sys.objects AS OBJ
                                ON CDB.ObjectId = OBJ.object_id

                            LEFT JOIN sys.indexes AS IDX
                                ON CDB.ObjectId = IDX.object_id

                                AND CDB.IndexID = IDX.index_id

                            LEFT JOIN sys.allocation_units AS ALU
                                ON CDB.AllocUnitId = ALU.allocation_unit_id
                        ORDER BY Name;
                        --Post cleanup.
                        DROP TABLE #CheckDB;";
                    using (var command = new SqlCommand(query, connection))
                    {
                        connection.Open();
                        reportsTable.Load(command.ExecuteReader());
                    }
                }
                /*OBJ.name AS Name, OBJ.type_desc AS Type, IDX.Name AS PrimaryKey,
                CDB.RepairLevel, MessageText, CDB.Error, CDB.ObjectID */
                //<object ID, repair level>
                _errorsDictionary.Clear();
                foreach (DataRow row in reportsTable.Rows)
                {
                    var objectId = int.Parse(row[6].ToString());
                    var objectTypeId = int.Parse(row[5].ToString()); //The Error column
                    var repairLevel = row[3].ToString();
                    //Check if the object is a service message.
                    if (objectTypeId == (int) DatabaseObjectType.ServiceBrokerMessage)
                    {
                        //newObject.Type = DatabaseObjectType.ServiceBrokerMessage;
                        //Do nothing, we don't care about service broker messages.
                    }
                    //Or a DBCC summary statement.
                    else if (objectTypeId == (int) DatabaseObjectType.DbCcResult)
                    {
                        var dbCcResult = ParseDbCcResultMessage(row[4].ToString());
                        _databaseDbCcResults.Add(dbCcResult);
                    }
                    //Check to see if the object is a database table
                    else if (objectTypeId == (int) DatabaseObjectType.Table)
                    {
                        var table = ParseDatabaseTableMessage(row[4].ToString());
                        table.Id = objectId;
                        table.Error = objectTypeId;
                        if (_errorsDictionary.ContainsKey(objectId))
                        {
                            table.RecommenedRepairLevel = _errorsDictionary[objectId];
                            //_errorsDictionary.Remove(objectId);
                        }
                        _databaseObjectsDictionary.Add(table.Id, table);
                    }
                    //Check to see if there is a repair level present, this should only occur in error messages
                    //outside of the DBCC summary messages.
                    if (repairLevel != string.Empty)
                    {
                        var recommenedRepairLevel = DatabaseTable.RepairLevel.None;
                        //Use the above ID number to as an index in the dictionary.
                        //repair_allow_data_loss
                        //repair_rebuild
                        if (repairLevel == "repair_allow_data_loss")
                        {
                            recommenedRepairLevel = DatabaseTable.RepairLevel.AllowDataLoss;
                        }
                        else if (repairLevel == "repair_rebuild")
                        {
                            recommenedRepairLevel = DatabaseTable.RepairLevel.Rebuild;
                        }

                        if (!_errorsDictionary.ContainsKey(objectId))
                        {
                            _errorsDictionary.Add(objectId, recommenedRepairLevel);
                        }
                        else
                        {
                            _errorsDictionary[objectId] = recommenedRepairLevel < _errorsDictionary[objectId]
                                ? recommenedRepairLevel
                                : _errorsDictionary[objectId];
                        }
                    }
                }

                foreach (var table in _databaseObjectsDictionary)
                {
                    if (table.Value.TypeOfTable == DatabaseTable.TableType.UserTable)
                    {
                        userTablesListBox.Items.Add(table.Value.FullMessage);
                    }
                    else
                    {
                        systemTablesListBox.Items.Add(table.Value.FullMessage);
                    }

                    if (table.Value.RecommenedRepairLevel != DatabaseTable.RepairLevel.None)
                    {
                        var item = new ListViewItem
                        {
                            Text = $@"{table.Value.Name} has corruption, recommended repair option: {table.Value.RecommenedRepairLevel}."
                        };
                        damagedTablesListView.Items.Add(item);
                    }
                }
                //Set the main message for the user.
                if (damagedTablesListView.Items.Count == 0)
                {
                    dbCcResultLabel.Text = @"No errors in the database have been detected.";
                    repairButton.Enabled = false;
                }
                else
                {
                    dbCcResultLabel.Text = @"One or more errors have been found, refer to the 'Damaged Tables' section for details.";
                    repairButton.Enabled = true;
                }
            }
            catch (SqlException e)
            {
                MessageBox.Show(e.Message);
            }
        }

        //https://gallery.technet.microsoft.com/scriptcenter/59bc1fb6-68de-4624-b338-83dd5461da25
        private static DatabaseDbCcResult ParseDbCcResultMessage(string message)
        {
            //0         1   2  3          4      5  6  7          8       9 10        11
            //CHECKDB found 0 allocation errors and 0 consistency errors in database 'AdvertisingProfitControl'.
            //CHECKDB found 0 allocation errors and 3 consistency errors in table 'sys.sysowners'(object ID 27).
            //NOTE: In the event of errors being found, multiple CHECKDB messages can be found.
            var connection = new SqlConnection(Properties.Settings.Default.ConnectionString);
            if (message == string.Empty) return new DatabaseDbCcResult();

            var textArray = message.Split(' ');
            var allocationErrors = int.Parse(textArray[2]);
            var consistencyErrors = int.Parse(textArray[6]);
            var tableName = textArray[11].Replace("'", ""); //Remove all quotes.
            tableName = tableName.Remove(tableName.Length - 1); //Strip out the period.
            var objectId = 0;
            if (tableName != connection.Database)
            {
                //This indicates that a specific table has an error in it.
                ParseTableObjectIdNumber(tableName, out objectId, out tableName);
            }
            var dbCc = new DatabaseDbCcResult
            {
                AllocationErrorCount = allocationErrors,
                ConsistencyErrorCount = consistencyErrors,
                FullMessage = message,
                AffectedTableId = objectId
            };
            return dbCc;
        }

        private static DatabaseTable ParseDatabaseTableMessage(string message)
        {
            //0     1    2    3    4  5 6      7   8      9      
            //There are 1271 rows in 17 pages for object "sys.sysrscols".
            //There are 425 rows in 6 pages for object "ActualSales".
            var tempText = message.Split(' ');
            var tableDetails = new DatabaseTable();
            var rowCount = int.Parse(tempText[2]);
            var pageCount = int.Parse(tempText[5]);
            var tableName = tempText[9].Replace("\"", "");//Remove all quotes.
            tableName = tableName.Remove(tableName.Length - 1);//Strip out the period.

            tableDetails.TypeOfTable = tableName.StartsWith("sys") ? DatabaseTable.TableType.SystemTable : DatabaseTable.TableType.UserTable;
            tableDetails.RowCount = rowCount;
            tableDetails.PageCount = pageCount;
            tableDetails.FullMessage = message;
            tableDetails.Name = tableName;

            return tableDetails;
        }

        private static void ParseTableObjectIdNumber(string text, out int objectId, out string tableName)
        {
            //FORMAT IN: sys.sysowners(object ID 27)
            var tempText = text.Split('('); //tempText[0] = sys.sysowners | tempText[1] = object ID 27)
            tableName = tempText[0];
            tempText = tempText[1].Split(' '); //tempText[2] = 27)
            tempText[0] = tempText[2].Remove(tempText[2].Length - 1); //tempText[0] = 27
            objectId = int.Parse(tempText[0]);
        }
        //Reference for DBCC operations: https://docs.microsoft.com/en-us/sql/t-sql/database-console-commands/dbcc-checkdb-transact-sql
        public enum DatabaseObjectType
        {
            Table = 2593,                   //A database table object has this value.
            DbCcResult = 8989,              //This value indicates that DBCHECK has printed a summary statement.
            ServiceBrokerMessage = 8997,    //This value indicated that the message text was made by a service broker.
            Unkown = 0
        }
        //
        internal class DatabaseTable
        {
            public string Name;
            public int Id;
            public int Error;   //Error seems to indicate the objects category int the database and isn't a unique number.
            public int RowCount;
            public int PageCount;
            public string FullMessage;
            public TableType TypeOfTable = TableType.Unkown;
            public RepairLevel RecommenedRepairLevel = RepairLevel.None;

            public enum TableType
            {
                UserTable = 0,
                SystemTable = 1, //Note: Internal_Tables will be counted as system tables.
                Unkown = 2
            }

            //Zero is the most sever repair option with possible data loss.
            public enum RepairLevel
            {
                AllowDataLoss = 0,
                Rebuild = 1,
                None = 2
            }
        }

        internal class DatabaseDbCcResult
        {
            private int _allocationErrorsCount;
            private int _consistencyErrorsCount;
            public string FullMessage;
            public int AffectedTableId;

            public int AllocationErrorCount
            {
                get { return _allocationErrorsCount; }
                set
                {
                    HasErrors = value != 0;
                    _allocationErrorsCount = value;
                }
            }

            public int ConsistencyErrorCount
            {
                get { return _consistencyErrorsCount; }
                set
                {
                    HasErrors = value != 0;
                    _consistencyErrorsCount = value;
                }
            }

            public bool HasErrors { get; private set; }
        }

        private void repairButton_Click(object sender, EventArgs e)
        {
            //var allowDataLossOnAll = false;
            foreach (var repairLevel in _errorsDictionary)
            {
                var s = _databaseObjectsDictionary[repairLevel.Key];
                var repairOption = string.Empty;
                if (s.RecommenedRepairLevel == DatabaseTable.RepairLevel.AllowDataLoss)
                {
                    repairOption = "repair_allow_data_loss";
                }
                else if (s.RecommenedRepairLevel == DatabaseTable.RepairLevel.Rebuild)
                {
                    repairOption = "repair_rebuild";
                }
                var query = $"USE AdvertisingProfitControl\r\nALTER DATABASE AdvertisingProfitControl\r\nSET SINGLE_USER\r\nWITH ROLLBACK IMMEDIATE;\r\ndbcc checktable (\'{s.Name}\', {repairOption})\r\nALTER DATABASE AdvertisingProfitControl\r\nSET MULTI_USER;";
                using (var connection = new SqlConnection(Properties.Settings.Default.ConnectionString))
                {
                    using (var command = new SqlCommand(query, connection))
                    {
                        connection.Open();
                        command.ExecuteNonQuery();
                    }
                }
            }
        }
    }
}