// Copyright (C) 2025, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
// 
// Permission is hereby granted, free of charge, to any person obtaining a 
// copy of this software and associated documentation files (the "Software"), 
// to deal in the Software without restriction, including without limitation 
// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
// and/or sell copies of the Software, and to permit persons to whom the 
// Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in 
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.

#nullable enable

using System;
using System.Data;
using System.Collections.Generic;
using Duplicati.Library.Utility;

namespace Duplicati.Library.Main.Database
{
    internal class LocalRepairDatabase : LocalDatabase
    {
        /// <summary>
        /// The tag used for logging
        /// </summary>
        private static readonly string LOGTAG = Logging.Log.LogTagFromType(typeof(LocalRepairDatabase));

        /// <summary>
        /// Creates a new local repair database
        /// </summary>
        /// <param name="path">The path to the database</param>
        /// <param name="pagecachesize">The page cache size</param>
        public LocalRepairDatabase(string path, long pagecachesize)
            : base(path, "Repair", true, pagecachesize)
        {
        }

        /// <summary>
        /// Creates a new local repair database from an existing local database
        /// </summary>
        /// <param name="db">The existing local database</param>
        public LocalRepairDatabase(LocalDatabase db)
            : base(db)
        {
        }

        /// <summary>
        /// Gets the fileset ID from the remote name
        /// </summary>
        /// <param name="filelist">The remote name of the fileset</param>
        /// <param name="transaction">An optional transaction</param>
        /// <returns>>The fileset ID</returns>
        public (long FilesetId, DateTime Time, bool IsFullBackup) GetFilesetFromRemotename(string filelist, IDbTransaction? transaction)
        {
            using (var cmd = m_connection.CreateCommand(transaction))
            {
                var rd = cmd.SetCommandAndParameters(@"SELECT ""Fileset"".""ID"", ""Fileset"".""Timestamp"", ""Fileset"".""IsFullBackup"" FROM ""Fileset"",""RemoteVolume"" WHERE ""Fileset"".""VolumeID"" = ""RemoteVolume"".""ID"" AND ""RemoteVolume"".""Name"" = @Name")
                    .SetParameterValue("@Name", filelist)
                    .ExecuteReader();

                if (!rd.Read())
                    throw new Exception($"No such remote file: {filelist}");

                return (rd.ConvertValueToInt64(0, -1), ParseFromEpochSeconds(rd.ConvertValueToInt64(1)).ToLocalTime(), rd.GetInt32(2) == BackupType.FULL_BACKUP);
            }
        }

        /// <summary>
        /// Moves entries in the FilesetEntry table from previous fileset to current fileset
        /// </summary>
        /// <param name="filesetid">Current fileset ID</param>
        /// <param name="prevFilesetId">Source fileset ID</param>
        /// <param name="transaction">The transaction</param>
        public void MoveFilesFromFileset(long filesetid, long prevFilesetId, IDbTransaction transaction)
        {
            if (filesetid <= 0)
                throw new ArgumentException("filesetid must be > 0");

            if (prevFilesetId <= 0)
                throw new ArgumentException("prevId must be > 0");

            using var cmd = m_connection.CreateCommand(transaction);
            cmd.SetCommandAndParameters(@"UPDATE ""FilesetEntry"" SET ""FilesetID"" = @CurrentFilesetId WHERE ""FilesetID"" = @PreviousFilesetId ")
                .SetParameterValue("@CurrentFilesetId", filesetid)
                .SetParameterValue("@PreviousFilesetId", prevFilesetId)
                .ExecuteNonQuery();
        }

        /// <summary>
        /// Gets the list of index files that reference a given block file
        /// </summary>
        /// <param name="blockfileid">The block file ID</param>
        /// <returns>>A list of index file IDs</returns>
        public IEnumerable<string> GetIndexFilesReferencingBlockFile(long blockfileid, IDbTransaction? transaction)
        {
            using var cmd = m_connection.CreateCommand(transaction, @"SELECT ""RemoteVolume"".""Name"" FROM ""RemoteVolume"", ""IndexBlockLink"" WHERE ""IndexBlockLink"".""BlockVolumeID"" = @BlockFileId AND ""RemoteVolume"".""ID"" = ""IndexBlockLink"".""IndexVolumeID"" AND ""RemoteVolume"".""Type"" = @Type")
                .SetParameterValue("@BlockFileId", blockfileid)
                .SetParameterValue("@Type", RemoteVolumeType.Index.ToString());

            foreach (var rd in cmd.ExecuteReaderEnumerable())
                yield return rd.ConvertValueToString(0) ?? throw new Exception("RemoteVolume name was null");
        }

        /// <summary>
        /// Gets a list of filesets that are missing files
        /// </summary>
        /// <param name="transaction">An optional transaction</param>
        /// <returns>A list of fileset IDs and timestamps</returns>
        public IEnumerable<KeyValuePair<long, DateTime>> GetFilesetsWithMissingFiles(IDbTransaction transaction)
        {
            using (var cmd = m_connection.CreateCommand(transaction))
            using (var rd = cmd.ExecuteReader(@"SELECT ID, Timestamp FROM Fileset WHERE ID IN (SELECT FilesetID FROM ""FilesetEntry"" WHERE ""FileID"" NOT IN (SELECT ""ID"" FROM ""FileLookup""))"))
                while (rd.Read())
                {
                    yield return new KeyValuePair<long, DateTime>(
                        rd.ConvertValueToInt64(0),
                        ParseFromEpochSeconds(rd.ConvertValueToInt64(1)).ToLocalTime()
                    );
                }
        }

        /// <summary>
        /// Deletes all fileset entries for a given fileset
        /// </summary>
        /// <param name="filesetid">The fileset ID</param>
        /// <param name="transaction">An optional transaction</param>
        /// <returns>The number of deleted entries</returns>
        public int DeleteFilesetEntries(long filesetid, IDbTransaction? transaction = null)
        {
            using (var cmd = m_connection.CreateCommand(transaction))
                return cmd.SetCommandAndParameters(@"DELETE FROM ""FilesetEntry"" WHERE ""FilesetID"" = @FilesetId")
                    .SetParameterValue("@FilesetId", filesetid)
                    .ExecuteNonQuery();
        }

        private class RemoteVolume : IRemoteVolume
        {
            public string Name { get; private set; }
            public string Hash { get; private set; }
            public long Size { get; private set; }

            public RemoteVolume(string name, string hash, long size)
            {
                this.Name = name;
                this.Hash = hash;
                this.Size = size;
            }
        }

        public IEnumerable<IRemoteVolume> GetBlockVolumesFromIndexName(string indexName)
        {
            using var cmd = m_connection.CreateCommand(@"SELECT ""Name"", ""Hash"", ""Size"" FROM ""RemoteVolume"" WHERE ""ID"" IN (SELECT ""BlockVolumeID"" FROM ""IndexBlockLink"" WHERE ""IndexVolumeID"" IN (SELECT ""ID"" FROM ""RemoteVolume"" WHERE ""Name"" = @Name)) ")
                .SetParameterValue("@Name", indexName);

            foreach (var rd in cmd.ExecuteReaderEnumerable())
                yield return new RemoteVolume(rd.ConvertValueToString(0) ?? "", rd.ConvertValueToString(1) ?? "", rd.ConvertValueToInt64(2));
        }

        /// <summary>
        /// A single block with source data for repair
        /// </summary>
        /// <param name="Hash">The block hash</param>
        /// <param name="Size">The block size</param>
        /// <param name="File">The file that contains the block</param>
        /// <param name="Offset">The offset of the block in the file</param>
        public sealed record BlockWithSourceData(string Hash, long Size, string File, long Offset);

        /// <summary>
        /// A single block with metadata source data for repair
        /// </summary>
        /// <param name="Hash">The block hash</param>
        /// <param name="Size">The block size</param>
        /// <param name="Path">The path of the file or directory that contains the block</param>
        public sealed record BlockWithMetadataSourceData(string Hash, long Size, string Path);

        /// <summary>
        /// A single blocklist hash entry
        /// </summary>
        /// <param name="BlocksetId">The blockset id</param>
        /// <param name="BlocklistHash">The hash of the blocklist entry (when done)</param>
        /// <param name="BlocklistHashLength">The total length of the blockset</param>
        /// <param name="BlocklistHashIndex">The index of the blocklist hash</param>
        /// <param name="Index">The index of the block in the blockset</param>
        /// <param name="Hash">The hash of the entry</param>
        public sealed record BlocklistHashesEntry(
            long BlocksetId,
            string BlocklistHash,
            long BlocklistHashLength,
            long BlocklistHashIndex,
            int Index,
            string Hash);

        /// <summary>
        /// Helper interface for the missing block list
        /// </summary>
        public interface IMissingBlockList : IDisposable
        {
            /// <summary>
            /// Registers a block as restored
            /// </summary>
            /// <param name="hash">The block hash</param>
            /// <param name="size">The block size</param>
            /// <param name="volumeId">The volume ID of the new target volume</param>
            /// <returns>The restored blocks</returns>
            bool SetBlockRestored(string hash, long size, long volumeId);
            /// <summary>
            /// Gets the list of files that contains missing blocks
            /// </summary>
            /// <param name="blocksize">The blocksize setting</param>
            /// <returns>A list of files with missing blocks</returns>
            IEnumerable<BlockWithSourceData> GetSourceFilesWithBlocks(long blocksize);
            /// <summary>
            /// Gets a list for filesystem entries that contain missing blocks in metadata
            /// </summary>
            /// <returns>A list of filesystem entries with missing blocks</returns>
            IEnumerable<BlockWithMetadataSourceData> GetSourceItemsWithMetadataBlocks();
            /// <summary>
            /// Gets missing blocklist hashes
            /// </summary>
            /// <param name="hashesPerBlock">The number of hashes for each block</param>
            /// <returns>>A list of blocklist hashes</returns>
            IEnumerable<BlocklistHashesEntry> GetBlocklistHashes(long hashesPerBlock);
            /// <summary>
            /// Gets the number of missing blocks
            /// </summary>
            /// <returns>>The number of missing blocks</returns>
            long GetMissingBlockCount();
            /// <summary>
            /// Gets all the filesets that are affected by missing blocks
            /// </summary>
            /// <returns>>A list of filesets</returns>
            IEnumerable<IRemoteVolume> GetFilesetsUsingMissingBlocks();
            /// <summary>
            /// Gets a list of remote files that may contain missing blocks
            /// </summary>
            /// <returns>>A list of remote files</returns>
            IEnumerable<IRemoteVolume> GetMissingBlockSources();
        }

        /// <summary>
        /// Implementation of the missing block list
        /// </summary>
        private class MissingBlockList : IMissingBlockList
        {
            /// <summary>
            /// The connection to the database
            /// </summary>
            private readonly IDbConnection m_connection;
            /// <summary>
            /// The transaction to use
            /// </summary>
            private readonly ReusableTransaction m_transaction;
            /// <summary>
            /// The insert command to use for restoring blocks
            /// </summary>
            private readonly IDbCommand m_insertCommand;
            /// <summary>
            /// The command to copy blocks into the duplicate block table
            /// </summary>
            private readonly IDbCommand m_copyIntoDuplicatedBlocks;
            /// <summary>
            /// The command to assign blocks to a new volume
            /// </summary>
            private readonly IDbCommand m_assignBlocksToNewVolume;
            /// <summary>
            /// The name of the temporary table
            /// </summary>
            private readonly string m_tablename;
            /// <summary>
            /// The name of the volume where blocks are missing
            /// </summary>
            private readonly string m_volumename;
            /// <summary>
            /// The query to use for getting missing blocks
            /// </summary>
            private readonly string m_missingBlocksQuery;

            /// <summary>
            /// Whether the object has been disposed
            /// </summary>
            private bool m_isDisposed = false;

            /// <summary>
            /// Creates a new missing block list
            /// </summary>
            /// <param name="volumename">The name of the volume with missing blocks</param>
            /// <param name="connection">The connection to the database</param>
            /// <param name="transaction">The transaction to use</param>
            public MissingBlockList(string volumename, IDbConnection connection, ReusableTransaction transaction)
            {
                m_connection = connection;
                m_transaction = transaction;
                m_volumename = volumename;
                var tablename = "MissingBlocks-" + Library.Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());
                using (var cmd = m_connection.CreateCommand(m_transaction.Transaction))
                {
                    cmd.ExecuteNonQuery(FormatInvariant($@"CREATE TEMPORARY TABLE ""{tablename}"" (""Hash"" TEXT NOT NULL, ""Size"" INTEGER NOT NULL, ""Restored"" INTEGER NOT NULL) "));
                    m_tablename = tablename;

                    var blockCount = cmd.SetCommandAndParameters(FormatInvariant($@"INSERT INTO ""{m_tablename}"" (""Hash"", ""Size"", ""Restored"") SELECT DISTINCT ""Block"".""Hash"", ""Block"".""Size"", 0 AS ""Restored"" FROM ""Block"",""Remotevolume"" WHERE ""Block"".""VolumeID"" = ""Remotevolume"".""ID"" AND ""Remotevolume"".""Name"" = @Name "))
                        .SetParameterValue("@Name", volumename)
                        .ExecuteNonQuery();

                    if (blockCount == 0)
                        throw new Exception($"Unexpected empty block volume: {0}");

                    cmd.ExecuteNonQuery(FormatInvariant($@"CREATE UNIQUE INDEX ""{tablename}-Ix"" ON ""{tablename}"" (""Hash"", ""Size"", ""Restored"")"));
                }

                m_insertCommand = m_connection.CreateCommand(FormatInvariant($@"UPDATE ""{tablename}"" SET ""Restored"" = @NewRestoredValue WHERE ""Hash"" = @Hash AND ""Size"" = @Size AND ""Restored"" = @PreviousRestoredValue "));
                m_copyIntoDuplicatedBlocks = m_connection.CreateCommand(@"INSERT OR IGNORE INTO ""DuplicateBlock"" (""BlockID"", ""VolumeID"") SELECT ""Block"".""ID"", ""Block"".""VolumeID"" FROM ""Block"" WHERE ""Block"".""Hash"" = @Hash AND ""Block"".""Size"" = @Size");
                m_assignBlocksToNewVolume = m_connection.CreateCommand(@"UPDATE ""Block"" SET ""VolumeID"" = @TargetVolumeId WHERE ""Hash"" = @Hash AND ""Size"" = @Size");
                m_missingBlocksQuery = FormatInvariant($@"SELECT ""{m_tablename}"".""Hash"", ""{m_tablename}"".""Size"" FROM ""{m_tablename}"" WHERE ""{m_tablename}"".""Restored"" = @Restored ");
            }

            /// <inheritdoc/>
            public bool SetBlockRestored(string hash, long size, long targetVolumeId)
            {
                var restored = m_insertCommand.SetTransaction(m_transaction.Transaction).SetParameterValue("@NewRestoredValue", 1)
                    .SetParameterValue("@Hash", hash)
                    .SetParameterValue("@Size", size)
                    .SetParameterValue("@PreviousRestoredValue", 0)
                    .ExecuteNonQuery() == 1;

                if (restored)
                {
                    m_copyIntoDuplicatedBlocks.SetTransaction(m_transaction.Transaction)
                        .SetParameterValue("@Hash", hash)
                        .SetParameterValue("@Size", size)
                        .ExecuteNonQuery();

                    var c = m_assignBlocksToNewVolume.SetTransaction(m_transaction.Transaction)
                        .SetParameterValue("@TargetVolumeId", targetVolumeId)
                        .SetParameterValue("@Hash", hash)
                        .SetParameterValue("@Size", size)
                        .ExecuteNonQuery();

                    if (c != 1)
                        throw new Exception($"Unexpected number of updated blocks: {c} != 1");
                }

                return restored;
            }

            /// <inheritdoc/>
            public IEnumerable<BlockWithSourceData> GetSourceFilesWithBlocks(long blocksize)
            {
                using var cmd = m_connection.CreateCommand(m_transaction.Transaction, FormatInvariant($@"SELECT DISTINCT ""{m_tablename}"".""Hash"", ""{m_tablename}"".""Size"", ""File"".""Path"", ""BlocksetEntry"".""Index"" * {blocksize} FROM  ""{m_tablename}"", ""Block"", ""BlocksetEntry"", ""File"" WHERE ""File"".""BlocksetID"" = ""BlocksetEntry"".""BlocksetID"" AND ""Block"".""ID"" = ""BlocksetEntry"".""BlockID"" AND ""{m_tablename}"".""Hash"" = ""Block"".""Hash"" AND ""{m_tablename}"".""Size"" = ""Block"".""Size"" AND ""{m_tablename}"".""Restored"" = @Restored ORDER BY ""{m_tablename}"".""Hash"", ""{m_tablename}"".""Size"", ""File"".""Path"", ""BlocksetEntry"".""Index"" * {blocksize}"))
                    .SetParameterValue("@Restored", 0);

                foreach (var rd in cmd.ExecuteReaderEnumerable())
                {
                    var hash = rd.ConvertValueToString(0) ?? throw new Exception("Hash value was null");
                    var size = rd.ConvertValueToInt64(1);
                    var file = rd.ConvertValueToString(2) ?? throw new Exception("File value was null");
                    var offset = rd.ConvertValueToInt64(3);

                    yield return new BlockWithSourceData(hash, size, file, offset);
                }
            }

            /// <inheritdoc/>
            public IEnumerable<BlockWithMetadataSourceData> GetSourceItemsWithMetadataBlocks()
            {
                using var cmd = m_connection.CreateCommand(m_transaction.Transaction, FormatInvariant($@"SELECT DISTINCT ""{m_tablename}"".""Hash"", ""{m_tablename}"".""Size"", ""File"".""Path"" FROM  ""{m_tablename}"", ""Block"", ""BlocksetEntry"", ""Metadataset"", ""File"" WHERE ""File"".""MetadataID"" == ""Metadataset"".""ID"" AND ""Metadataset"".""BlocksetID"" = ""BlocksetEntry"".""BlocksetID"" AND ""Block"".""ID"" = ""BlocksetEntry"".""BlockID"" AND ""{m_tablename}"".""Hash"" = ""Block"".""Hash"" AND ""{m_tablename}"".""Size"" = ""Block"".""Size"" AND ""{m_tablename}"".""Restored"" = @Restored ORDER BY ""{m_tablename}"".""Hash"", ""{m_tablename}"".""Size"", ""File"".""Path"""))
                    .SetParameterValue("@Restored", 0);

                foreach (var rd in cmd.ExecuteReaderEnumerable())
                {
                    var hash = rd.ConvertValueToString(0) ?? throw new Exception("Hash value was null");
                    var size = rd.ConvertValueToInt64(1);
                    var path = rd.ConvertValueToString(2) ?? throw new Exception("File value was null");

                    yield return new BlockWithMetadataSourceData(hash, size, path);
                }
            }

            /// <inheritdoc/>
            public IEnumerable<BlocklistHashesEntry> GetBlocklistHashes(long hashesPerBlock)
            {
                using var cmd = m_connection.CreateCommand(m_transaction.Transaction);
                var blocklistTableName = $"BlocklistHashList-{Library.Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray())}";
                try
                {
                    // We need to create a snapshot as we will be updating the m_tablename table during enumeration
                    cmd.SetCommandAndParameters(FormatInvariant($@"
                        CREATE TEMPORARY TABLE ""{blocklistTableName}"" AS
                        SELECT 
                            b.""Hash"" AS ""BlockHash"", 
                            bs.""Id"" AS ""BlocksetId"",
                            bs.""Length"" AS ""BlocksetLength"", 
                            bse.""Index"" / @HashesPerBlock AS ""BlocklistHashIndex"",
                            (
                                SELECT blh.""Hash""
                                FROM ""BlocklistHash"" blh
                                WHERE blh.""BlocksetID"" = bs.""ID""
                                AND blh.""Index"" == bse.""Index"" / @HashesPerBlock
                                LIMIT 1
                            ) AS ""BlocklistHashHash"",
                            bse.""Index"" AS ""BlocksetEntryIndex""
                        FROM 
                            ""BlocksetEntry"" bse
                        JOIN ""Block"" b ON b.""ID"" = bse.""BlockID""
                        JOIN ""Blockset"" bs ON bs.""ID"" = bse.""BlocksetID""
                        WHERE 
                            EXISTS (
                                SELECT 1
                                FROM ""BlocklistHash"" blh
                                JOIN ""{m_tablename}"" mt ON mt.""Hash"" = blh.""Hash""
                                WHERE blh.""BlocksetID"" = bs.""ID""
                                AND mt.""Restored"" = @Restored
                            )
                "))
                    .SetParameterValue("@HashesPerBlock", hashesPerBlock)
                    .SetParameterValue("@Restored", 0)
                    .ExecuteNonQuery();

                    cmd.SetCommandAndParameters(FormatInvariant($@"
                        SELECT 
                            ""BlockHash"", 
                            ""BlocksetId"", 
                            ""BlocksetLength"", 
                            ""BlocklistHashIndex"", 
                            ""BlocklistHashHash"", 
                            ""BlocksetEntryIndex"" 
                        FROM ""{blocklistTableName}"" 
                        ORDER BY ""BlocksetId"", ""BlocklistHashIndex"", ""BlocksetEntryIndex"""));

                    foreach (var rd in cmd.ExecuteReaderEnumerable())
                    {
                        var hash = rd.ConvertValueToString(0) ?? throw new Exception("Block.Hash is null");
                        var blocksetId = rd.ConvertValueToInt64(1);
                        var length = rd.ConvertValueToInt64(2);
                        var blocklistHashIndex = rd.ConvertValueToInt64(3);
                        var blocklistHash = rd.ConvertValueToString(4) ?? throw new Exception("BlocklistHash is null");
                        var index = rd.ConvertValueToInt64(5);

                        yield return new BlocklistHashesEntry(blocksetId, blocklistHash, length, blocklistHashIndex, (int)index, hash);
                    }
                }
                finally
                {
                    try { cmd.ExecuteNonQuery(FormatInvariant($@"DROP TABLE IF EXISTS ""{blocklistTableName}"" ")); }
                    catch { }
                }
            }

            /// <inheritdoc/>
            public long GetMissingBlockCount()
            {
                using var cmd = m_connection.CreateCommand(m_transaction.Transaction, FormatInvariant($@"SELECT COUNT(*) FROM ({m_missingBlocksQuery})"))
                    .SetParameterValue("@Restored", 0);

                return cmd.ExecuteScalarInt64(0);
            }

            /// <summary>
            /// Gets the list of missing blocks
            /// </summary>
            /// <returns>>A list of missing blocks</returns>
            public IEnumerable<(string Hash, long Size)> GetMissingBlocks()
            {
                using var cmd = m_connection.CreateCommand(m_transaction.Transaction, m_missingBlocksQuery)
                    .SetParameterValue("@Restored", 0);

                foreach (var rd in cmd.ExecuteReaderEnumerable())
                    yield return (rd.ConvertValueToString(0) ?? "", rd.ConvertValueToInt64(1));
            }

            /// <inheritdoc/>
            public long MoveBlocksToNewVolume(long targetVolumeId, long sourceVolumeId, IDbTransaction? transaction = null)
            {
                if (targetVolumeId <= 0)
                    throw new ArgumentOutOfRangeException(nameof(targetVolumeId), "Target volume ID must be greater than 0");

                // Move the source blocks into the DuplicateBlock table
                using var cmd = m_connection.CreateCommand(transaction, FormatInvariant($@"
                    INSERT OR IGNORE INTO ""DuplicateBlock"" (""BlockID"", ""VolumeID"")
                    SELECT b.""ID"", b.""VolumeID""
                    FROM ""Block"" b
                    WHERE b.""VolumeID"" = @SourceVolumeId
                    AND (b.""Hash"", b.""Size"") IN (
                        SELECT ""Hash"", ""Size""
                        FROM ""{m_tablename}""
                        WHERE ""Restored"" = @Restored
                    )
                "))
                    .SetParameterValue("@SourceVolumeId", sourceVolumeId)
                    .SetParameterValue("@Restored", 1);

                var moved = cmd.ExecuteNonQuery();

                // Then update the blocks table to point to the new volume
                cmd.SetCommandAndParameters(FormatInvariant($@"
                    UPDATE ""Block"" 
                    SET ""VolumeID"" = @TargetVolumeId 
                    WHERE ""VolumeID"" = @SourceVolumeId 
                    AND (""Hash"", ""Size"") IN (
                        SELECT ""Hash"", ""Size"" 
                        FROM ""{m_tablename}""
                        WHERE ""Restored"" = @Restored
                    )
                "))
                    .SetParameterValue("@TargetVolumeId", targetVolumeId)
                    .SetParameterValue("@SourceVolumeId", sourceVolumeId)
                    .SetParameterValue("@Restored", 1);

                var updated = cmd.ExecuteNonQuery();
                if (updated != moved)
                    throw new Exception($"Unexpected number of updated blocks: {updated} != {moved}");

                return updated;
            }

            public IEnumerable<IRemoteVolume> GetFilesetsUsingMissingBlocks()
            {
                var blocks = FormatInvariant($@"SELECT DISTINCT ""FileLookup"".""ID"" AS ID FROM ""{m_tablename}"", ""Block"", ""Blockset"", ""BlocksetEntry"", ""FileLookup"" WHERE ""Block"".""Hash"" = ""{m_tablename}"".""Hash"" AND ""Block"".""Size"" = ""{m_tablename}"".""Size"" AND ""BlocksetEntry"".""BlockID"" = ""Block"".""ID"" AND ""BlocksetEntry"".""BlocksetID"" = ""Blockset"".""ID"" AND ""FileLookup"".""BlocksetID"" = ""Blockset"".""ID"" ");
                var blocklists = FormatInvariant($@"SELECT DISTINCT ""FileLookup"".""ID"" AS ID FROM ""{m_tablename}"", ""Block"", ""Blockset"", ""BlocklistHash"", ""FileLookup"" WHERE ""Block"".""Hash"" = ""{m_tablename}"".""Hash"" AND ""Block"".""Size"" = ""{m_tablename}"".""Size"" AND ""BlocklistHash"".""Hash"" = ""Block"".""Hash"" AND ""BlocklistHash"".""BlocksetID"" = ""Blockset"".""ID"" AND ""FileLookup"".""BlocksetID"" = ""Blockset"".""ID"" ");
                var cmdtxt = FormatInvariant($@"SELECT DISTINCT ""RemoteVolume"".""Name"", ""RemoteVolume"".""Hash"", ""RemoteVolume"".""Size"" FROM ""RemoteVolume"", ""FilesetEntry"", ""Fileset"" WHERE ""RemoteVolume"".""ID"" = ""Fileset"".""VolumeID"" AND ""Fileset"".""ID"" = ""FilesetEntry"".""FilesetID"" AND ""RemoteVolume"".""Type"" = @Type AND ""FilesetEntry"".""FileID"" IN  (SELECT DISTINCT ""ID"" FROM ( {blocks} UNION {blocklists} ))");

                using var cmd = m_connection.CreateCommand(m_transaction.Transaction, cmdtxt)
                    .SetParameterValue("@Type", RemoteVolumeType.Files.ToString());

                foreach (var rd in cmd.ExecuteReaderEnumerable())
                    yield return new RemoteVolume(rd.ConvertValueToString(0) ?? "", rd.ConvertValueToString(1) ?? "", rd.ConvertValueToInt64(2));
            }

            public IEnumerable<IRemoteVolume> GetMissingBlockSources()
            {
                using var cmd = m_connection.CreateCommand(m_transaction.Transaction, FormatInvariant($@"SELECT DISTINCT ""RemoteVolume"".""Name"", ""RemoteVolume"".""Hash"", ""RemoteVolume"".""Size"" FROM ""RemoteVolume"", ""Block"", ""{m_tablename}"" WHERE ""{m_tablename}"".""Restored"" = @Restored AND ""Block"".""Hash"" = ""{m_tablename}"".""Hash"" AND ""Block"".""Size"" = ""{m_tablename}"".""Size"" AND ""Block"".""VolumeID"" = ""RemoteVolume"".""ID"" AND ""Remotevolume"".""Name"" != @Name "))
                    .SetParameterValue("@Restored", 0)
                    .SetParameterValue("@Name", m_volumename);

                foreach (var rd in cmd.ExecuteReaderEnumerable())
                    yield return new RemoteVolume(rd.ConvertValueToString(0) ?? "", rd.ConvertValueToString(1) ?? "", rd.ConvertValueToInt64(2));
            }

            public void Dispose()
            {
                if (m_isDisposed)
                    return;

                m_isDisposed = true;
                try
                {
                    if (m_tablename != null)
                        using (var cmd = m_connection.CreateCommand(m_transaction.Transaction))
                            cmd.SetTransaction(m_transaction.Transaction).ExecuteNonQuery(FormatInvariant($@"DROP TABLE IF EXISTS ""{m_tablename}"" "));
                }
                catch { }

                try { m_insertCommand?.Dispose(); }
                catch { }
            }
        }

        public IMissingBlockList CreateBlockList(string volumename, ReusableTransaction transaction)
        {
            return new MissingBlockList(volumename, m_connection, transaction);
        }

        public void FixDuplicateMetahash()
        {
            using (var tr = m_connection.BeginTransactionSafe())
            using (var cmd = m_connection.CreateCommand(tr))
            {
                var sql_count =
                    @"SELECT COUNT(*) FROM (" +
                    @" SELECT DISTINCT c1 FROM (" +
                    @"SELECT COUNT(*) AS ""C1"" FROM (SELECT DISTINCT ""BlocksetID"" FROM ""Metadataset"") UNION SELECT COUNT(*) AS ""C1"" FROM ""Metadataset"" " +
                    @")" +
                    @")";

                var x = cmd.ExecuteScalarInt64(sql_count, 0);
                if (x > 1)
                {
                    Logging.Log.WriteInformationMessage(LOGTAG, "DuplicateMetadataHashes", "Found duplicate metadatahashes, repairing");

                    var tablename = "TmpFile-" + Guid.NewGuid().ToString("N");

                    cmd.ExecuteNonQuery(FormatInvariant($@"CREATE TEMPORARY TABLE ""{tablename}"" AS SELECT * FROM ""File"""));

                    var sql = @"SELECT ""A"".""ID"", ""B"".""BlocksetID"" FROM (SELECT MIN(""ID"") AS ""ID"", COUNT(""ID"") AS ""Duplicates"" FROM ""Metadataset"" GROUP BY ""BlocksetID"") ""A"", ""Metadataset"" ""B"" WHERE ""A"".""Duplicates"" > 1 AND ""A"".""ID"" = ""B"".""ID""";

                    using (var c2 = m_connection.CreateCommand(tr))
                    {
                        c2.SetCommandAndParameters(FormatInvariant($@"UPDATE ""{tablename}"" SET ""MetadataID"" = @MetadataId WHERE ""MetadataID"" IN (SELECT ""ID"" FROM ""Metadataset"" WHERE ""BlocksetID"" = @BlocksetId)")
                            + @"; DELETE FROM ""Metadataset"" WHERE ""BlocksetID"" = @BlocksetId AND ""ID"" != @MetadataId");
                        using (var rd = cmd.ExecuteReader(sql))
                            while (rd.Read())
                                c2.SetParameterValue("@MetadataId", rd.GetValue(0))
                                    .SetParameterValue("@BlocksetId", rd.GetValue(1))
                                    .ExecuteNonQuery();
                    }

                    sql = FormatInvariant($@"SELECT ""ID"", ""Path"", ""BlocksetID"", ""MetadataID"", ""Entries"" FROM (
                            SELECT MIN(""ID"") AS ""ID"", ""Path"", ""BlocksetID"", ""MetadataID"", COUNT(*) as ""Entries"" FROM ""{tablename}"" GROUP BY ""Path"", ""BlocksetID"", ""MetadataID"") 
                            WHERE ""Entries"" > 1 ORDER BY ""ID""");

                    using (var c2 = m_connection.CreateCommand(tr))
                    {
                        c2.SetCommandAndParameters(FormatInvariant($@"UPDATE ""FilesetEntry"" SET ""FileID"" = @FileId WHERE ""FileID"" IN (SELECT ""ID"" FROM ""{tablename}"" WHERE ""Path"" = @Path AND ""BlocksetID"" = @BlocksetId AND ""MetadataID"" = @MetadataId)")
                            + FormatInvariant($@"; DELETE FROM ""{tablename}"" WHERE ""Path"" = @Path AND ""BlocksetID"" = @BlocksetId AND ""MetadataID"" = @MetadataId AND ""ID"" != @FileId"));

                        foreach (var rd in cmd.ExecuteReaderEnumerable(sql))
                            c2.SetParameterValue("@FileId", rd.GetValue(0))
                                .SetParameterValue("@Path", rd.GetValue(1))
                                .SetParameterValue("@BlocksetId", rd.GetValue(2))
                                .SetParameterValue("@MetadataId", rd.GetValue(3))
                                .ExecuteNonQuery();
                    }

                    cmd.ExecuteNonQuery(FormatInvariant($@"DELETE FROM ""FileLookup"" WHERE ""ID"" NOT IN (SELECT ""ID"" FROM ""{tablename}"") "));
                    cmd.ExecuteNonQuery(FormatInvariant($@"CREATE INDEX ""{tablename}-Ix"" ON  ""{tablename}"" (""ID"", ""MetadataID"")"));
                    cmd.ExecuteNonQuery(FormatInvariant($@"UPDATE ""FileLookup"" SET ""MetadataID"" = (SELECT ""MetadataID"" FROM ""{tablename}"" A WHERE ""A"".""ID"" = ""FileLookup"".""ID"") "));
                    cmd.ExecuteNonQuery(FormatInvariant($@"DROP TABLE ""{tablename}"" "));

                    x = cmd.ExecuteScalarInt64(sql_count, 0);
                    if (x > 1)
                        throw new Interface.UserInformationException("Repair failed, there are still duplicate metadatahashes!", "DuplicateHashesRepairFailed");

                    Logging.Log.WriteInformationMessage(LOGTAG, "DuplicateMetadataHashesFixed", "Duplicate metadatahashes repaired succesfully");
                    tr.Commit();
                }
            }
        }

        public void FixDuplicateFileentries()
        {
            using (var tr = m_connection.BeginTransactionSafe())
            using (var cmd = m_connection.CreateCommand(tr))
            {
                var sql_count = @"SELECT COUNT(*) FROM (SELECT ""PrefixID"", ""Path"", ""BlocksetID"", ""MetadataID"", COUNT(*) as ""Duplicates"" FROM ""FileLookup"" GROUP BY ""PrefixID"", ""Path"", ""BlocksetID"", ""MetadataID"") WHERE ""Duplicates"" > 1";

                var x = cmd.ExecuteScalarInt64(sql_count, 0);
                if (x > 0)
                {
                    Logging.Log.WriteInformationMessage(LOGTAG, "DuplicateFileEntries", "Found duplicate file entries, repairing");

                    var sql = @"SELECT ""ID"", ""PrefixID"", ""Path"", ""BlocksetID"", ""MetadataID"", ""Entries"" FROM (
                            SELECT MIN(""ID"") AS ""ID"", ""PrefixID"", ""Path"", ""BlocksetID"", ""MetadataID"", COUNT(*) as ""Entries"" FROM ""FileLookup"" GROUP BY ""PrefixID"", ""Path"", ""BlocksetID"", ""MetadataID"") 
                            WHERE ""Entries"" > 1 ORDER BY ""ID""";

                    using (var c2 = m_connection.CreateCommand(tr))
                    {
                        c2.SetCommandAndParameters(@"UPDATE ""FilesetEntry"" SET ""FileID"" = @FileId WHERE ""FileID"" IN (SELECT ""ID"" FROM ""FileLookup"" WHERE ""PrefixID"" = @PrefixId AND ""Path"" = @Path AND ""BlocksetID"" = @BlocksetId AND ""MetadataID"" = @MetatadataId)"
                            + @"; DELETE FROM ""FileLookup"" WHERE ""PrefixID"" = @PrefixId AND ""Path"" = @Path AND ""BlocksetID"" = @BlocksetId AND ""MetadataID"" = @MetadataId AND ""ID"" != @FileId");

                        foreach (var rd in cmd.SetCommandAndParameters(sql).ExecuteReaderEnumerable())
                            c2.SetParameterValue("@FileId", rd.GetValue(0))
                                .SetParameterValue("@PrefixId", rd.GetValue(1))
                                .SetParameterValue("@Path", rd.GetValue(2))
                                .SetParameterValue("@BlocksetId", rd.GetValue(3))
                                .SetParameterValue("@MetadataId", rd.GetValue(4))
                                .ExecuteNonQuery();
                    }

                    x = cmd.ExecuteScalarInt64(sql_count, 0);
                    if (x > 1)
                        throw new Interface.UserInformationException("Repair failed, there are still duplicate file entries!", "DuplicateFilesRepairFailed");

                    Logging.Log.WriteInformationMessage(LOGTAG, "DuplicateFileEntriesFixed", "Duplicate file entries repaired succesfully");
                    tr.Commit();
                }
            }

        }

        public void FixMissingBlocklistHashes(string blockhashalgorithm, long blocksize)
        {
            var blocklistbuffer = new byte[blocksize];

            using (var tr = m_connection.BeginTransactionSafe())
            using (var cmd = m_connection.CreateCommand(tr))
            using (var blockhasher = HashFactory.CreateHasher(blockhashalgorithm))
            {
                var hashsize = blockhasher.HashSize / 8;

                var sql = FormatInvariant($@"SELECT * FROM (SELECT ""N"".""BlocksetID"", ((""N"".""BlockCount"" + {blocksize / hashsize} - 1) / {blocksize / hashsize}) AS ""BlocklistHashCountExpected"", CASE WHEN ""G"".""BlocklistHashCount"" IS NULL THEN 0 ELSE ""G"".""BlocklistHashCount"" END AS ""BlocklistHashCountActual"" FROM (SELECT ""BlocksetID"", COUNT(*) AS ""BlockCount"" FROM ""BlocksetEntry"" GROUP BY ""BlocksetID"") ""N"" LEFT OUTER JOIN (SELECT ""BlocksetID"", COUNT(*) AS ""BlocklistHashCount"" FROM ""BlocklistHash"" GROUP BY ""BlocksetID"") ""G"" ON ""N"".""BlocksetID"" = ""G"".""BlocksetID"" WHERE ""N"".""BlockCount"" > 1) WHERE ""BlocklistHashCountExpected"" != ""BlocklistHashCountActual""");
                var countsql = @"SELECT COUNT(*) FROM (" + sql + @")";

                var itemswithnoblocklisthash = cmd.ExecuteScalarInt64(countsql, 0);
                if (itemswithnoblocklisthash != 0)
                {
                    Logging.Log.WriteInformationMessage(LOGTAG, "MissingBlocklistHashes", "Found {0} missing blocklisthash entries, repairing", itemswithnoblocklisthash);
                    using (var c2 = m_connection.CreateCommand(tr))
                    using (var c3 = m_connection.CreateCommand(tr))
                    using (var c4 = m_connection.CreateCommand(tr))
                    using (var c5 = m_connection.CreateCommand(tr))
                    using (var c6 = m_connection.CreateCommand(tr))
                    {
                        c3.SetCommandAndParameters(@"INSERT INTO ""BlocklistHash"" (""BlocksetID"", ""Index"", ""Hash"") VALUES (@BlocksetId, @Index, @Hash) ");
                        c4.SetCommandAndParameters(@"SELECT ""ID"" FROM ""Block"" WHERE ""Hash"" = @Hash AND ""Size"" = @Size");
                        c5.SetCommandAndParameters(@"SELECT ""ID"" FROM ""DeletedBlock"" WHERE ""Hash"" = @Hash AND ""Size"" = @Size AND ""VolumeID"" IN (SELECT ""ID"" FROM ""RemoteVolume"" WHERE ""Type"" = @Type AND (""State"" IN (@State1, @State2)))");
                        c6.SetCommandAndParameters(@"INSERT INTO ""Block"" (""Hash"", ""Size"", ""VolumeID"") SELECT ""Hash"", ""Size"", ""VolumeID"" FROM ""DeletedBlock"" WHERE ""ID"" = @DeletedBlockId LIMIT 1; DELETE FROM ""DeletedBlock"" WHERE ""ID"" = @DeletedBlockId;");

                        foreach (var e in cmd.ExecuteReaderEnumerable(sql))
                        {
                            var blocksetid = e.ConvertValueToInt64(0);
                            var ix = 0L;
                            int blocklistoffset = 0;

                            c2.SetCommandAndParameters(@"DELETE FROM ""BlocklistHash"" WHERE ""BlocksetID"" = @BlocksetId")
                                .SetParameterValue("@BlocksetId", blocksetid)
                                .ExecuteNonQuery();

                            c2.SetCommandAndParameters(@"SELECT ""A"".""Hash"" FROM ""Block"" ""A"", ""BlocksetEntry"" ""B"" WHERE ""A"".""ID"" = ""B"".""BlockID"" AND ""B"".""BlocksetID"" = @BlocksetId ORDER BY ""B"".""Index""")
                                .SetParameterValue("@BlocksetId", blocksetid);

                            foreach (var h in c2.ExecuteReaderEnumerable())
                            {
                                var tmp = Convert.FromBase64String(h.ConvertValueToString(0) ?? throw new Exception("Hash value was null"));
                                if (blocklistbuffer.Length - blocklistoffset < tmp.Length)
                                {
                                    var blkey = Convert.ToBase64String(blockhasher.ComputeHash(blocklistbuffer, 0, blocklistoffset));

                                    // Check if the block exists in "blocks"
                                    var existingBlockId = c4.SetParameterValue("@Hash", blkey)
                                        .SetParameterValue("@Size", blocklistoffset)
                                        .ExecuteScalarInt64(-1);

                                    if (existingBlockId <= 0)
                                    {
                                        var deletedBlockId = c5.SetParameterValue("@Hash", blkey)
                                            .SetParameterValue("@Size", blocklistoffset)
                                            .SetParameterValue("@Type", RemoteVolumeType.Blocks.ToString())
                                            .SetParameterValue("@State1", RemoteVolumeState.Uploaded.ToString())
                                            .SetParameterValue("@State2", RemoteVolumeState.Verified.ToString())
                                            .ExecuteScalarInt64(-1);

                                        if (deletedBlockId <= 0)
                                            throw new Exception($"Missing block for blocklisthash: {blkey}");
                                        else
                                        {
                                            var rc = c6.SetParameterValue("@DeletedBlockId", deletedBlockId)
                                                .ExecuteNonQuery();

                                            if (rc != 2)
                                                throw new Exception($"Unexpected update count: {rc}");
                                        }
                                    }

                                    // Add to table
                                    c3.SetParameterValue("@BlocksetId", blocksetid)
                                        .SetParameterValue("@Index", ix)
                                        .SetParameterValue("@Hash", blkey)
                                        .ExecuteNonQuery();

                                    ix++;
                                    blocklistoffset = 0;
                                }

                                Array.Copy(tmp, 0, blocklistbuffer, blocklistoffset, tmp.Length);
                                blocklistoffset += tmp.Length;

                            }

                            if (blocklistoffset != 0)
                            {
                                var blkeyfinal = Convert.ToBase64String(blockhasher.ComputeHash(blocklistbuffer, 0, blocklistoffset));

                                // Ensure that the block exists in "blocks"
                                var existingBlockId = c4.SetParameterValue("@Hash", blkeyfinal)
                                        .SetParameterValue("@Size", blocklistoffset)
                                        .ExecuteScalarInt64(-1);

                                if (existingBlockId <= 0)
                                {
                                    var deletedBlockId = c5.SetParameterValue("@Hash", blkeyfinal)
                                            .SetParameterValue("@Size", blocklistoffset)
                                            .SetParameterValue("@Type", RemoteVolumeType.Blocks.ToString())
                                            .SetParameterValue("@State1", RemoteVolumeState.Uploaded.ToString())
                                            .SetParameterValue("@State2", RemoteVolumeState.Verified.ToString())
                                            .ExecuteScalarInt64(-1);

                                    if (deletedBlockId == 0)
                                        throw new Exception($"Missing block for blocklisthash: {blkeyfinal}");
                                    else
                                    {
                                        var rc = c6.SetParameterValue("@DeletedBlockId", deletedBlockId)
                                                .ExecuteNonQuery();
                                        if (rc != 2)
                                            throw new Exception($"Unexpected update count: {rc}");
                                    }
                                }

                                // Add to table
                                c3.SetParameterValue("@BlocksetId", blocksetid)
                                    .SetParameterValue("@Index", ix)
                                    .SetParameterValue("@Hash", blkeyfinal)
                                    .ExecuteNonQuery();
                            }
                        }
                    }


                    itemswithnoblocklisthash = cmd.ExecuteScalarInt64(countsql, 0);
                    if (itemswithnoblocklisthash != 0)
                        throw new Interface.UserInformationException($"Failed to repair, after repair {itemswithnoblocklisthash} blocklisthashes were missing", "MissingBlocklistHashesRepairFailed");

                    Logging.Log.WriteInformationMessage(LOGTAG, "MissingBlocklisthashesRepaired", "Missing blocklisthashes repaired succesfully");
                    tr.Commit();
                }
            }

        }

        public void FixDuplicateBlocklistHashes(long blocksize, long hashsize)
        {
            using (var tr = m_connection.BeginTransactionSafe())
            using (var cmd = m_connection.CreateCommand(tr))
            {
                var dup_sql = @"SELECT * FROM (SELECT ""BlocksetID"", ""Index"", COUNT(*) AS ""EC"" FROM ""BlocklistHash"" GROUP BY ""BlocksetID"", ""Index"") WHERE ""EC"" > 1";

                var sql_count = @"SELECT COUNT(*) FROM (" + dup_sql + ")";

                var x = cmd.ExecuteScalarInt64(sql_count, 0);
                if (x > 0)
                {
                    Logging.Log.WriteInformationMessage(LOGTAG, "DuplicateBlocklistHashes", "Found duplicate blocklisthash entries, repairing");

                    var unique_count = cmd.ExecuteScalarInt64(@"SELECT COUNT(*) FROM (SELECT DISTINCT ""BlocksetID"", ""Index"" FROM ""BlocklistHash"")", 0);

                    using (var c2 = m_connection.CreateCommand(tr))
                    {
                        c2.SetCommandAndParameters(@"DELETE FROM ""BlocklistHash"" WHERE rowid IN (SELECT rowid FROM ""BlocklistHash"" WHERE ""BlocksetID"" = @BlocksetId AND ""Index"" = @Index LIMIT @Limit)");
                        foreach (var rd in cmd.ExecuteReaderEnumerable(dup_sql))
                        {
                            var expected = rd.GetInt32(2) - 1;
                            var actual = c2.SetParameterValue("@BlocksetId", rd.GetValue(0))
                                .SetParameterValue("@Index", rd.GetValue(1))
                                .SetParameterValue("@Limit", expected)
                                .ExecuteNonQuery();

                            if (actual != expected)
                                throw new Exception($"Unexpected number of results after fix, got: {actual}, expected: {expected}");
                        }
                    }

                    x = cmd.ExecuteScalarInt64(sql_count);
                    if (x > 1)
                        throw new Exception("Repair failed, there are still duplicate file entries!");

                    var real_count = cmd.ExecuteScalarInt64(@"SELECT Count(*) FROM ""BlocklistHash""", 0);

                    if (real_count != unique_count)
                        throw new Interface.UserInformationException($"Failed to repair, result should have been {unique_count} blocklist hashes, but result was {real_count} blocklist hashes", "DuplicateBlocklistHashesRepairFailed");

                    try
                    {
                        VerifyConsistency(blocksize, hashsize, true, tr);
                    }
                    catch (Exception ex)
                    {
                        throw new Interface.UserInformationException("Repaired blocklisthashes, but the database was broken afterwards, rolled back changes", "DuplicateBlocklistHashesRepairFailed", ex);
                    }

                    Logging.Log.WriteInformationMessage(LOGTAG, "DuplicateBlocklistHashesRepaired", "Duplicate blocklisthashes repaired succesfully");
                    tr.Commit();
                }
            }
        }

        public void CheckAllBlocksAreInVolume(string filename, IEnumerable<KeyValuePair<string, long>> blocks, IDbTransaction transaction)
        {
            using var cmd = m_connection.CreateCommand(transaction);
            var tablename = "ProbeBlocks-" + Library.Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());
            try
            {
                cmd.ExecuteNonQuery(FormatInvariant($@"CREATE TEMPORARY TABLE ""{tablename}"" (""Hash"" TEXT NOT NULL, ""Size"" INTEGER NOT NULL)"));
                cmd.SetCommandAndParameters(FormatInvariant($@"INSERT INTO ""{tablename}"" (""Hash"", ""Size"") VALUES (@Hash, @Size)"));

                foreach (var kp in blocks)
                {
                    cmd.SetParameterValue("@Hash", kp.Key);
                    cmd.SetParameterValue("@Size", kp.Value);
                    cmd.ExecuteNonQuery();
                }

                var id = cmd.SetCommandAndParameters(@"SELECT ""ID"" FROM ""RemoteVolume"" WHERE ""Name"" = @Name")
                    .SetParameterValue("@Name", filename)
                    .ExecuteScalarInt64(-1);

                var aliens = cmd.SetCommandAndParameters(FormatInvariant($@"SELECT COUNT(*) FROM (SELECT ""A"".""VolumeID"" FROM ""{tablename}"" B LEFT OUTER JOIN ""Block"" A ON ""A"".""Hash"" = ""B"".""Hash"" AND ""A"".""Size"" = ""B"".""Size"") WHERE ""VolumeID"" != @VolumeId "))
                    .SetParameterValue("@VolumeId", id)
                    .ExecuteScalarInt64(0);

                if (aliens != 0)
                    throw new Exception($"Not all blocks were found in {filename}");
            }
            finally
            {
                cmd.ExecuteNonQuery(FormatInvariant($@"DROP TABLE IF EXISTS ""{tablename}"" "));
            }
        }

        public void CheckBlocklistCorrect(string hash, long length, IEnumerable<string> blocklist, long blocksize, long blockhashlength, IDbTransaction? transaction)
        {
            using (var cmd = m_connection.CreateCommand(transaction))
            {
                var query = FormatInvariant($@"
SELECT 
    ""C"".""Hash"", 
    ""C"".""Size""
FROM 
    ""BlocksetEntry"" A, 
    (
        SELECT 
            ""Y"".""BlocksetID"",
            ""Y"".""Hash"" AS ""BlocklistHash"",
            ""Y"".""Index"" AS ""BlocklistHashIndex"",
            ""Z"".""Size"" AS ""BlocklistSize"",
            ""Z"".""ID"" AS ""BlocklistHashBlockID"" 
        FROM 
            ""BlocklistHash"" Y,
            ""Block"" Z 
        WHERE 
            ""Y"".""Hash"" = ""Z"".""Hash"" AND ""Y"".""Hash"" = @Hash AND ""Z"".""Size"" = @Size
        LIMIT 1
    ) B,
    ""Block"" C
WHERE 
    ""A"".""BlocksetID"" = ""B"".""BlocksetID"" 
    AND 
    ""A"".""BlockID"" = ""C"".""ID""
    AND
    ""A"".""Index"" >= ""B"".""BlocklistHashIndex"" * ({blocksize} / {blockhashlength})
    AND
    ""A"".""Index"" < (""B"".""BlocklistHashIndex"" + 1) * ({blocksize} / {blockhashlength})
ORDER BY 
    ""A"".""Index""

");

                using (var en = blocklist.GetEnumerator())
                {
                    cmd.SetCommandAndParameters(query)
                        .SetParameterValue("@Hash", hash)
                        .SetParameterValue("@Size", length);
                    foreach (var r in cmd.ExecuteReaderEnumerable())
                    {
                        if (!en.MoveNext())
                            throw new Exception($"Too few entries in source blocklist with hash {hash}");
                        if (en.Current != r.ConvertValueToString(0))
                            throw new Exception($"Mismatch in blocklist with hash {hash}");
                    }

                    if (en.MoveNext())
                        throw new Exception($"Too many source blocklist entries in {hash}");
                }
            }
        }

        public IEnumerable<string> MissingLocalFilesets()
        {
            using var cmd = m_connection.CreateCommand(@"SELECT ""Name"" FROM ""RemoteVolume"" WHERE ""Type"" = @Type AND ""State"" NOT IN (@States) AND ""ID"" NOT IN (SELECT ""VolumeID"" FROM ""Fileset"")")
                .SetParameterValue("@Type", RemoteVolumeType.Files.ToString())
                .ExpandInClauseParameter("@States", [RemoteVolumeState.Deleting.ToString(), RemoteVolumeState.Deleted.ToString()]);

            foreach (var rd in cmd.ExecuteReaderEnumerable())
                yield return rd.ConvertValueToString(0) ?? "";
        }

        public IEnumerable<(long FilesetID, DateTime Timestamp, bool IsFull)> MissingRemoteFilesets()
        {
            using var cmd = m_connection.CreateCommand(@"SELECT ""ID"", ""Timestamp"", ""IsFullBackup"" FROM ""Fileset"" WHERE ""VolumeID"" NOT IN (SELECT ""ID"" FROM ""RemoteVolume"" WHERE ""Type"" = @Type AND ""State"" NOT IN (@States))")
                .SetParameterValue("@Type", RemoteVolumeType.Files.ToString())
                .ExpandInClauseParameter("@States", [RemoteVolumeState.Deleting.ToString(), RemoteVolumeState.Deleted.ToString()]);

            foreach (var rd in cmd.ExecuteReaderEnumerable())
                yield return (rd.ConvertValueToInt64(0), ParseFromEpochSeconds(rd.ConvertValueToInt64(1)), rd.ConvertValueToInt64(2) == BackupType.FULL_BACKUP);
        }

        public IEnumerable<IRemoteVolume> EmptyIndexFiles()
        {
            using var cmd = m_connection.CreateCommand(@"SELECT ""Name"", ""Hash"", ""Size"" FROM ""RemoteVolume"" WHERE ""Type"" = @Type AND ""State"" IN (@States) AND ""ID"" NOT IN (SELECT ""IndexVolumeId"" FROM ""IndexBlockLink"")")
                .SetParameterValue("@Type", RemoteVolumeType.Index.ToString())
                .ExpandInClauseParameter("@States", [RemoteVolumeState.Uploaded.ToString(), RemoteVolumeState.Verified.ToString()]);

            foreach (var rd in cmd.ExecuteReaderEnumerable())
                yield return new RemoteVolume(rd.ConvertValueToString(0) ?? "", rd.ConvertValueToString(1) ?? "", rd.ConvertValueToInt64(2));
        }

        public void FixEmptyMetadatasets(Options options)
        {
            using var tr = m_connection.BeginTransactionSafe();
            using var cmd = m_connection.CreateCommand(tr,
                @"SELECT COUNT(*) 
                FROM Metadataset 
                JOIN Blockset ON Metadataset.BlocksetID = Blockset.ID 
                WHERE Blockset.Length = 0");
            var emptyMetaCount = cmd.ExecuteScalarInt64(0);
            if (emptyMetaCount <= 0)
                return;

            Logging.Log.WriteInformationMessage(LOGTAG, "ZeroLengthMetadata", "Found {0} zero-length metadata entries", emptyMetaCount);

            // Create replacement metadata
            var emptyMeta = Utility.WrapMetadata(new Dictionary<string, string>(), options);
            var emptyBlocksetId = GetEmptyMetadataBlocksetId(Array.Empty<long>(), emptyMeta.FileHash, emptyMeta.Blob.Length, tr);
            if (emptyBlocksetId < 0)
                throw new Interface.UserInformationException(
                    "Failed to locate an empty metadata blockset to replace missing metadata. Set the option --disable-replace-missing-metadata=true to ignore this and drop files with missing metadata.",
                    "FailedToLocateEmptyMetadataBlockset");

            // Step 1: Create temp table with Metadataset IDs referencing empty blocksets (excluding the one to keep)
            var tablename = "FixMetadatasets-" + Library.Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());

            try
            {
                cmd.SetCommandAndParameters(
                    @$"CREATE TEMP TABLE ""{tablename}"" AS
                SELECT m.ID AS MetadataID, m.BlocksetID
                FROM Metadataset m
                JOIN Blockset b ON m.BlocksetID = b.ID
                WHERE b.Length = 0
                    AND m.BlocksetID != @KeepBlockset")
                    .SetParameterValue("@KeepBlockset", emptyBlocksetId)
                    .ExecuteNonQuery();

                // Step 2: Update FileLookup to use a valid metadata ID
                cmd.SetCommandAndParameters(
                    @$"UPDATE FileLookup
                SET MetadataID = (
                    SELECT ID FROM Metadataset 
                    WHERE BlocksetID = @KeepBlockset 
                    LIMIT 1
                )
                WHERE MetadataID IN (SELECT MetadataID FROM ""{tablename}"")")
                    .SetParameterValue("@KeepBlockset", emptyBlocksetId)
                    .ExecuteNonQuery();

                // Step 3: Delete obsolete Metadataset entries
                cmd.SetCommandAndParameters(
                    @$"DELETE FROM Metadataset 
                WHERE ID IN (SELECT MetadataID FROM ""{tablename}"")")
                    .ExecuteNonQuery();

                // Step 4: Delete orphaned blocksets (affected only)
                cmd.SetCommandAndParameters(
                    @$"DELETE FROM Blockset
                WHERE ID IN (SELECT BlocksetID FROM ""{tablename}"")
                    AND NOT EXISTS (SELECT 1 FROM Metadataset WHERE BlocksetID = Blockset.ID)
                    AND NOT EXISTS (SELECT 1 FROM File WHERE BlocksetID = Blockset.ID)")
                    .ExecuteNonQuery();

                // Step 5: Confirm all broken metadata entries are resolved
                cmd.SetCommandAndParameters(
                    @"SELECT COUNT(*) 
                FROM Metadataset 
                JOIN Blockset ON Metadataset.BlocksetID = Blockset.ID 
                WHERE Blockset.Length = 0");

                var remaining = cmd.ExecuteScalarInt64(0);
                if (remaining > 0)
                    throw new Interface.UserInformationException(
                        "Some zero-length metadata entries could not be repaired.",
                        "MetadataRepairFailed");

                Logging.Log.WriteInformationMessage(LOGTAG, "ZeroLengthMetadataRepaired", "Zero length metadata entries repaired successfully");
                tr.Commit();
            }
            finally
            {
                try
                {
                    cmd.SetCommandAndParameters(FormatInvariant($@"DROP TABLE IF EXISTS ""{tablename}"" "))
                        .ExecuteNonQuery();
                }
                catch (Exception ex)
                {
                    Logging.Log.WriteVerboseMessage(LOGTAG, "ErrorDroppingTempTable", ex, "Failed to drop temporary table {0}: {1}", tablename, ex.Message);
                }
            }
        }
    }
}