//  Copyright (C) 2013, The Duplicati Team

//  http://www.duplicati.com, opensource@duplicati.com
//
//  This library is free software; you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as
//  published by the Free Software Foundation; either version 2.1 of the
//  License, or (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful, but
//  WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace Duplicati.Library.Main.ForestHash.Database
{
	public class LocalDeleteDatabase : LocalDatabase
	{
        /// <summary>
        /// An approximate size of a hash-string in memory (44 chars * 2 for unicode + 8 bytes for pointer = 104)
        /// </summary>
        private const uint HASH_GUESS_SIZE = 128;
        
        private System.Data.IDbCommand m_moveBlockToNewVolumeCommand;

		public LocalDeleteDatabase(string path)
			: this(CreateConnection(path))
		{
		}
		
		public LocalDeleteDatabase(System.Data.IDbConnection connection)
			: base(connection, "Delete")
		{
			m_moveBlockToNewVolumeCommand = m_connection.CreateCommand();
			
			m_moveBlockToNewVolumeCommand.CommandText = @"UPDATE ""Block"" SET ""VolumeID"" = ? WHERE ""Hash"" = ? AND ""Size"" = ?";
			m_moveBlockToNewVolumeCommand.AddParameters(3);
		}

		/// <summary>
		/// Deletes all but n backups from the database and remote storage.
		/// </summary>
		/// <param name="keep">The number of backups to keep</param>
		/// <param name="allowRemovingLast">If set to <c>true</c> allow removing last backup, otherwise at least one backup is kept</param>
		public IEnumerable<string> DeleteAllButN(int keep, bool allowRemovingLast, CommunicationStatistics stat, FhOptions options, System.Data.IDbTransaction transaction)
		{
			IEnumerable<string> result;

			keep = Math.Max(allowRemovingLast ? 0 : 1, keep);
						
			using(var cmd = m_connection.CreateCommand())
			{
				cmd.Transaction = transaction;
				
				//We create a table with the operationIDs that are about to be deleted
				var tmptablename = "DeletedOperations-" + Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());
				cmd.ExecuteNonQuery(string.Format(@"CREATE TEMPORARY TABLE ""{0}"" AS SELECT ""ID"" FROM ""Operation"" WHERE ""Description"" = ? AND ""ID"" NOT IN (SELECT ""ID"" FROM ""Operation"" WHERE ""Description"" = ? ORDER BY ""Timestamp"" DESC LIMIT {1})", tmptablename, keep), "Backup", "Backup");
				
				result = DropFromIDTable(cmd, tmptablename, stat);
				
				cmd.ExecuteNonQuery(string.Format(@"DROP TABLE ""{0}"" ", tmptablename));
			}
			
			return result;
		}
		
		private long GetLastBackupOperationID(System.Data.IDbCommand cmd)
		{
			long id = -1;
			var r = cmd.ExecuteScalar(@"SELECT ""ID"" FROM ""Operation"" WHERE ""Description"" = ? ORDER BY ""Timestamp"" DESC LIMIT 1", "Backup");
			if (r != null && r != DBNull.Value)
				id = Convert.ToInt64(r);
				
			return id;
		}

		/// <summary>
		/// Deletes all but n backups from the database and remote storage.
		/// </summary>
		/// <param name="keep">The number of backups to keep</param>
		/// <param name="allowRemovingLast">If set to <c>true</c> allow removing last backup, otherwise at least one backup is kept</param>
		public IEnumerable<string> DeleteOlderThan(DateTime limit, bool allowRemovingLast, CommunicationStatistics stat, FhOptions options, System.Data.IDbTransaction transaction)
		{
			IEnumerable<string> result;
			using(var cmd = m_connection.CreateCommand())
			{
				cmd.Transaction = transaction;
				long keepOperationId = -1;
				if (!allowRemovingLast)
					keepOperationId = GetLastBackupOperationID(cmd);
				
				//We create a table with the operationIDs that are about to be deleted
				var tmptablename = "DeletedOperations-" + Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());
				cmd.ExecuteNonQuery(string.Format(@"CREATE TEMPORARY TABLE ""{0}"" AS SELECT ""ID"" FROM ""Operation"" WHERE ""Description"" = ? AND ""ID"" NOT IN (SELECT ""ID"" FROM ""Operation"" WHERE (""Description"" = ? AND ""Timestamp"" < ?) OR ""ID"" = ? ORDER BY ""Timestamp"")", tmptablename), "Backup", "Backup", limit.ToLocalTime(), keepOperationId);
				
				result = DropFromIDTable(cmd, tmptablename, stat);
				
				cmd.ExecuteNonQuery(string.Format(@"DROP TABLE ""{0}"" ", tmptablename));
			}
				
			return result;
		}
		
		/// <summary>
		/// Deletes the specified filesets from the database and remote storage.
		/// </summary>
		/// <param name="dates">The filesets to remove</param>
		/// <param name="allowRemovingLast">If set to <c>true</c> allow removing last backup, otherwise at least one backup is kept</param>
		public IEnumerable<string> DeleteFilesets(string filesets, bool allowRemovingLast, CommunicationStatistics stat, FhOptions options, System.Data.IDbTransaction transaction)
		{
			IEnumerable<string> result;
			using(var cmd = m_connection.CreateCommand())
			{
				cmd.Transaction = transaction;
				long keepOperationId = -1;
				if (!allowRemovingLast)
					keepOperationId = GetLastBackupOperationID(cmd);

				var tmptablename = "DeletedOperations-" + Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());
				cmd.ExecuteNonQuery(string.Format(@"CREATE TEMPORARY TABLE ""{0}"" (""ID"" INTEGER NOT NULL)", tmptablename));
				
				foreach(var d in filesets.Split(new char[] { Path.PathSeparator }, StringSplitOptions.RemoveEmptyEntries))
				{
					var c = cmd.ExecuteNonQuery(string.Format(@"INSERT INTO ""{0}"" (ID) VALUES (SELECT ""OperationID"" FROM ""RemoteVolume"" WHERE ""Name"" = ? AND ""Type"" = ?)", tmptablename), d, RemoteVolumeType.Files.ToString());
					if (c != 1)
						throw new Exception(string.Format("Failed to mark fileset {0}, query gave {1} volume(s)", d, c));
				}
				
				var tmp2 = tmptablename + "-2";
				cmd.ExecuteNonQuery(string.Format(@"CREATE TABLE ""{0}"" AS SELECT DISTINCT ""ID"" FROM ""{1}"" ", tmp2, tmptablename));
				cmd.ExecuteNonQuery(string.Format(@"DROP TABLE ""{0}"" ", tmptablename));

				tmptablename = tmp2;
				
				if (keepOperationId >= 0)
				{
					var c0 = Convert.ToInt64(cmd.ExecuteScalar(@"SELECT COUNT(*) FROM ""{0}"" "));
					var c1 = Convert.ToInt64(cmd.ExecuteScalar(@"SELECT COUNT(*) FROM ""RemoteVolume"" WHERE ""Type"" = ? ", RemoteVolumeType.Files.ToString()));
					if (c1 - c0 <= 0)
						cmd.ExecuteNonQuery(string.Format(@"DELETE FROM ""{0}"" WHERE ""ID"" = ?", tmptablename), keepOperationId);
				}
				
				result = DropFromIDTable(cmd, tmptablename, stat);
				
				cmd.ExecuteNonQuery(string.Format(@"DROP TABLE ""{0}"" ", tmptablename));
			}
				
			return result;
		}
		
		/// <summary>
		/// Drops all entries related to operations listed in the table.
		/// </summary>
		/// <param name="cmd">The command used to execute the queries</param>
		/// <param name="tmptablename">The name of a table with the operation IDs</param>
		/// <returns>A list of filesets to delete</returns>
		private static IEnumerable<string> DropFromIDTable(System.Data.IDbCommand cmd, string tmptablename, CommunicationStatistics stat)
		{
			//First we remove/rename the unwanted entries
			cmd.ExecuteNonQuery(string.Format(@"UPDATE ""Operation"" SET ""Description"" = ? WHERE ""ID"" IN (SELECT ""ID"" FROM ""{0}"") ", tmptablename), "DeletedBackup");
			cmd.ExecuteNonQuery(string.Format(@"DELETE FROM ""OperationFileset"" WHERE ""OperationID"" IN (SELECT ""ID"" FROM ""{0}"") ", tmptablename));
			
			//Then we delete anything that is no longer being referenced
			cmd.ExecuteNonQuery(@"DELETE FROM ""FileEntry"" WHERE ""ID"" NOT IN (SELECT DISTINCT ""FileEntryID"" FROM ""OperationFileset"") ");
			cmd.ExecuteNonQuery(@"DELETE FROM ""Metadataset"" WHERE ""ID"" NOT IN (SELECT DISTINCT ""MetadataID"" FROM ""FileEntry"") ");
			cmd.ExecuteNonQuery(@"DELETE FROM ""Blockset"" WHERE ""ID"" NOT IN (SELECT DISTINCT ""BlocksetID"" FROM ""FileEntry"" UNION SELECT DISTINCT ""BlocksetID"" FROM ""Metadataset"") ");
			cmd.ExecuteNonQuery(@"DELETE FROM ""BlocksetEntry"" WHERE ""BlocksetID"" NOT IN (SELECT DISTINCT ""ID"" FROM ""Blockset"") ");
			
			//We save the block info for the remote files, before we delete it
			cmd.ExecuteNonQuery(@"INSERT INTO ""DeletedBlock"" (""Hash"", ""Size"", ""VolumeID"") SELECT ""Hash"", ""Size"", ""VolumeID"" FROM ""Block"" WHERE ""ID"" NOT IN (SELECT DISTINCT ""ID"" FROM ""Blockset"") ");
			cmd.ExecuteNonQuery(@"DELETE FROM ""Block"" WHERE ""ID"" NOT IN (SELECT DISTINCT ""ID"" FROM ""Blockset"") ");		
			
			//Find all remote filesets that are no longer required, and mark them as delete
			cmd.ExecuteNonQuery(string.Format(@"UPDATE ""RemoteVolume"" SET ""State"" = ? WHERE ""Type"" = ? AND ""State"" IN (?, ?) AND ""OperationID"" IN (SELECT ""ID"" FROM ""{0}"") ", tmptablename), RemoteVolumeState.Deleting.ToString(), RemoteVolumeType.Files.ToString(), RemoteVolumeState.Uploaded.ToString(), RemoteVolumeState.Verified.ToString());

			var res = new List<string>();
			using (var rd = cmd.ExecuteReader(@"SELECT ""Name"" FROM ""RemoteVolume"" WHERE ""Type"" = ? AND ""State"" = ? ", RemoteVolumeType.Files.ToString(), RemoteVolumeState.Deleting.ToString()))
			while (rd.Read())
				res.Add(rd.GetValue(0).ToString());
			
			return res;
		}

		private struct VolumeUsage
		{
			public string Name;
			public long VolumeSize;
			public long WastedSize;
			
			public VolumeUsage(string name, long volumesize, long wastedsize)
			{
				this.Name = name;
				this.VolumeSize = volumesize;
				this.WastedSize = wastedsize;
			}
		}

		/// <summary>
		/// Returns the number of bytes stored in each volume,
		/// and the number of bytes no longer needed in each volume.
		/// The sizes are the uncompressed values.
		/// </summary>
		/// <returns>A list of tuples with name, datasize, wastedbytes.</returns>
		private IEnumerable<VolumeUsage> GetWastedSpaceReport(System.Data.IDbTransaction transaction)
		{
			var tmptablename = "UsageReport-" + Utility.Utility.ByteArrayAsHexString(Guid.NewGuid().ToByteArray());
			var active = @"SELECT SUM(""Size"") AS ""ActiveSize"", 0 AS ""InactiveSize"", ""VolumeID"" AS ""VolumeID"" FROM ""Block"" GROUP BY ""VolumeID"" ";
			var inactive = @"SELECT 0 AS ""ActiveSize"", SUM(""Size"") AS ""InactiveSize"", ""VolumeID"" AS ""VolumeID"" FROM ""DeletedBlock"" GROUP BY ""VolumeID"" ";
			
			var combined = active + " UNION " + inactive;
			var collected = @"SELECT ""VolumeID"" AS ""VolumeID"", SUM(""ActiveSize"") AS ""ActiveSize"", SUM(""InactiveSize"") AS ""InactiveSize"" FROM (" + combined + @") GROUP BY ""VolumeID"" ";
			var createtable = @"CREATE TEMPORARY TABLE """ + tmptablename + @""" AS " + collected;
						
			using (var cmd = m_connection.CreateCommand())
			{
				cmd.Transaction = transaction;
				try
				{
					cmd.ExecuteNonQuery(createtable);
					var res = new List<VolumeUsage>();
					using (var rd = cmd.ExecuteReader(string.Format(@"SELECT ""Remotevolume"".""Name"", ""{0}"".""ActiveSize"", ""{0}"".""InactiveSize"" FROM ""Remotevolume"", ""{0}"" WHERE ""Remotevolume"".""ID"" = ""{0}"".""VolumeID"" ", tmptablename)))
						while (rd.Read())
							res.Add(new VolumeUsage(rd.GetValue(0).ToString(), Convert.ToInt64(rd.GetValue(1)) + Convert.ToInt64(rd.GetValue(2)), Convert.ToInt64(rd.GetValue(2))));
							
					return res;
				}
				finally 
				{
					try { cmd.ExecuteNonQuery(string.Format(@"DROP TABLE ""{0}"" ", tmptablename)); }
					catch { }
				}
			}
		}
		
		public interface ICompactReport
		{
			IEnumerable<string> DeleteableVolumes { get; }
			IEnumerable<string> CompactableVolumes { get; }
			bool ShouldCompact { get; }
			void ReportCompactData(CommunicationStatistics stat); 
		}
		
		private class CompactReport : ICompactReport
		{
			private IEnumerable<VolumeUsage> m_report;
			private IEnumerable<VolumeUsage> m_cleandelete;
			private IEnumerable<VolumeUsage> m_wastevolumes;
			private IEnumerable<VolumeUsage> m_smallvolumes;
			
			private long m_deletablevolumes;
			private long m_wastedspace;
			private long m_smallspace;
			
			private long m_maxwastesize;
			private long m_volsize;
			
			public CompactReport(long volsize, long maxwastesize, long volsizetolerance, IEnumerable<VolumeUsage> report)
			{
				m_report = report;
				
				m_cleandelete = from n in m_report where n.VolumeSize <= n.WastedSize select n;
				m_wastevolumes = from n in m_report where n.WastedSize > volsizetolerance && !m_cleandelete.Contains(n) select n;
				m_smallvolumes = from n in m_report where n.VolumeSize - volsizetolerance < volsize && !m_cleandelete.Contains(n) select n;

				m_maxwastesize = maxwastesize;
				m_volsize = volsize;

				m_deletablevolumes = m_cleandelete.Count();
				m_wastedspace = m_wastevolumes.Aggregate(0L, (a,x) => a + x.WastedSize);
				m_smallspace = m_smallvolumes.Aggregate(0L, (a,x) => a + x.VolumeSize);
			}
			
			public void ReportCompactData(CommunicationStatistics stat)
			{
				stat.LogMessage("Found {0} fully deletable volume(s)", m_deletablevolumes);
				stat.LogMessage("Found {0} small volumes(s) with a total size of {1}", m_smallvolumes.Count(), Utility.Utility.FormatSizeString(m_smallspace));
				stat.LogMessage("Found {0} volume(s) with a total of {1} wasted space", m_wastevolumes.Count(), Utility.Utility.FormatSizeString(m_wastedspace));
				
				if (m_deletablevolumes > 0)
					stat.LogMessage("Compacting because there are {0} fully deletable volume(s)", m_deletablevolumes);
				else if (m_wastedspace > m_maxwastesize && m_wastevolumes.Count() >= 2)
					stat.LogMessage("Compacting because there are {0} wasted space and the limit is {1}", Utility.Utility.FormatSizeString(m_wastedspace), Utility.Utility.FormatSizeString(m_maxwastesize));
				else if (m_smallspace > m_volsize)
					stat.LogMessage("Compacting because there are {0} in small volumes and the volume size is {1}", Utility.Utility.FormatSizeString(m_smallspace), Utility.Utility.FormatSizeString(m_volsize));
				else
					stat.LogMessage("Not compacting");
			}
			
			public bool ShouldCompact
			{
				get 
				{
					return m_deletablevolumes > 0 || (m_wastedspace > m_maxwastesize && m_wastevolumes.Count() >= 2) || m_smallspace > m_volsize;
				}
			}
			
			public IEnumerable<string> DeleteableVolumes 
			{ 
				get { return from n in m_cleandelete select n.Name; } 
			}
			
			public IEnumerable<string> CompactableVolumes 
			{ 
				get 
				{ 
					//The order matters, we compact old volumes together first,
					// as we anticipate old data will stay around, where never data
					// is more likely to be discarded again
					return m_wastevolumes.Union(m_smallvolumes).Select(x => x.Name).Distinct();
				} 
			}
		}
		
		public ICompactReport GetCompactReport(long volsize, long maxwastesize, long volsizetolerance, System.Data.IDbTransaction transaction)
		{
			return new CompactReport(volsize, maxwastesize, volsizetolerance, GetWastedSpaceReport(transaction).ToList());
		}
		
				
		public interface IBlockQuery : IDisposable
		{
			bool UseBlock(string hash, long size);
		}
		
		private class BlockQuery : IBlockQuery
		{
			private System.Data.IDbCommand m_command;
			private HashDatabaseProtector<string, long> m_lookup;
			
			public BlockQuery(System.Data.IDbConnection con, FhOptions options, System.Data.IDbTransaction transaction)
			{
				m_command = con.CreateCommand();
				m_command.Transaction = transaction;
				
				if (options.FhBlockHashLookupSize > 0)
				{
					m_lookup = new HashDatabaseProtector<string, long>(HASH_GUESS_SIZE, (ulong)options.FhBlockHashLookupSize);
					using(var reader = m_command.ExecuteReader(@"SELECT ""Hash"", ""Size"" FROM ""Block"" "))
					while (reader.Read())
					{
						var hash = reader.GetValue(0).ToString();
						var size = Convert.ToInt64(reader.GetValue(1));
						m_lookup.Add(HashPrefixLookup.DecodeBase64Hash(hash), hash, size);
					}
				}
				
				m_command.Parameters.Clear();
				m_command.CommandText = @"SELECT ""VolumeID"" FROM ""Block"" WHERE ""Hash"" = ? AND ""Size"" = ? ";
				m_command.AddParameters(2);
			}
			
			public bool UseBlock(string hash, long size)
			{
				if (m_lookup != null)
				{
					long nsize;
					switch(m_lookup.HasValue(HashPrefixLookup.DecodeBase64Hash(hash), hash, out nsize))
					{
						case HashLookupResult.Found:
							if (nsize == size)
								return true;
							break;
						case HashLookupResult.NotFound:
							return false;
					}
				}
				
				m_command.SetParameterValue(0, hash);	
				m_command.SetParameterValue(1, size);
				var r = m_command.ExecuteScalar();
				return r != null && r != DBNull.Value;
			}
			
			public void Dispose()
			{
				if (m_lookup != null)
					try { m_lookup.Dispose(); } 
					finally { m_lookup = null; }
					
				if (m_command != null)
					try { m_command.Dispose(); }
					finally { m_command = null; }
			}
		}
		
		/// <summary>
		/// Builds a lookup table to enable faster response to block queries
		/// </summary>
		/// <param name="volumename">The name of the volume to prepare for</param>
		public IBlockQuery CreateBlockQueryHelper(FhOptions options, System.Data.IDbTransaction transaction)
		{
			return new BlockQuery(m_connection, options, transaction);
		}

		public void MoveBlockToNewVolume(string hash, long size, long volumeID, System.Data.IDbTransaction tr)
		{
			m_moveBlockToNewVolumeCommand.SetParameterValue(0, volumeID);
			m_moveBlockToNewVolumeCommand.SetParameterValue(1, hash);
			m_moveBlockToNewVolumeCommand.SetParameterValue(2, size);
			m_moveBlockToNewVolumeCommand.Transaction = tr;
			var c = m_moveBlockToNewVolumeCommand.ExecuteNonQuery();
			if (c != 1)
				throw new Exception("Unexpected update result");
		}

	}
}