//	Spludlow Software
//	Copyright © Samuel P. Ludlow 2020 All Rights Reserved
//	Distributed under the terms of the GNU General Public License version 3
//	Distributed WITHOUT ANY WARRANTY; without implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
//	https://www.spludlow.co.uk/LICENCE.TXT
//	The Spludlow logo is a registered trademark of Samuel P. Ludlow and may not be used without permission
//	v1.14

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.IO;
using System.Data;

using Microsoft.Isam.Esent.Interop;
using Microsoft.Isam.Esent.Interop.Vista;
using Microsoft.Isam.Esent.Interop.Windows10;

namespace Spludlow.Data
{
	/// <summary>
	/// ExtensibleStorageEngine ESE Read only methods (not a DAL Implimentaion)
	/// 
	/// Wrapper for ManagedEsent
	/// 
	/// ListTables() uses ESENTUTL.EXE
	/// 
	/// Only used it so far for reading MS Edge Browser favorites, but there are a few places in Windows where this may come in handy
	/// 
	/// Edge needs to be closed for these methods to work.
	/// dataSet = Spludlow.Data.ExtensibleStorageEngine.ReadDatabase(@"C:\Users\Fred\AppData\Local\Packages\Microsoft.MicrosoftEdge_8wekyb3d8bbwe\AC\MicrosoftEdge\User\Default\DataStore\Data\nouser1\120712-0049\DBStore\spartan.edb", "Favorites");
	/// good one Microsoft
	/// 
	/// ManagedEsent/Esent.Interop (ONLY),	Esent.Isam (NOT USED)
	/// </summary>
	public class ExtensibleStorageEngine
	{
		private static Dictionary<JET_coltyp, Type> dataTypeLookup;
		static ExtensibleStorageEngine()
		{
			dataTypeLookup = new Dictionary<JET_coltyp, Type>();

			dataTypeLookup.Add(JET_coltyp.Binary, typeof(Byte[]));
			dataTypeLookup.Add(JET_coltyp.Bit, typeof(Boolean));
			dataTypeLookup.Add(JET_coltyp.Currency, typeof(Int64));
			dataTypeLookup.Add(JET_coltyp.DateTime, typeof(DateTime));
			dataTypeLookup.Add(JET_coltyp.IEEEDouble, typeof(Double));
			dataTypeLookup.Add(JET_coltyp.IEEESingle, typeof(Single));
			dataTypeLookup.Add(JET_coltyp.Long, typeof(Int32));
			dataTypeLookup.Add(JET_coltyp.LongBinary, typeof(Byte[]));
			dataTypeLookup.Add(JET_coltyp.LongText, typeof(String));
			dataTypeLookup.Add(JET_coltyp.Short, typeof(Int16));
			dataTypeLookup.Add(JET_coltyp.Text, typeof(String));
			dataTypeLookup.Add(JET_coltyp.UnsignedByte, typeof(Byte));

			dataTypeLookup.Add(VistaColtyp.GUID, typeof(Guid));
			dataTypeLookup.Add(VistaColtyp.LongLong, typeof(Int64));
			dataTypeLookup.Add(VistaColtyp.UnsignedLong, typeof(UInt32));
			dataTypeLookup.Add(VistaColtyp.UnsignedShort, typeof(UInt16));

			dataTypeLookup.Add(Windows10Coltyp.UnsignedLongLong, typeof(UInt64));
		}

		public static string[] ListTables(string edbFilename)
		{
			string programPath = Spludlow.SpawnProcess.FindPath(@"ESENTUTL.EXE");

			Spludlow.SpawnProcess.ProcessExitInfo info = Spludlow.SpawnProcess.Run(programPath, "/mm " + edbFilename, 0);

			if (info.ExitCode != 0)
				throw new ApplicationException("ESE ListTables: ESENTUTL.EXE Exit Code: " + info.ExitCode + ", stderr:" + info.StandardError);

			List<string> tableNames = new List<string>();

			bool inBody = false;

			foreach (string line in Spludlow.Text.SplitLines(info.StandardOutput))
			{
				if (line.StartsWith("====") == true)
				{
					inBody = true;
					continue;
				}

				if (inBody == false)
					continue;

				if (line.StartsWith("****") == true)
					break;

				string[] words = Spludlow.Text.Split(line, ' ', true, false);

				if (words.Length != 4)
					continue;

				if (words[1] == "Tbl")
					tableNames.Add(words[0]);
			}

			return tableNames.ToArray();
		}

		/// <summary>
		/// Clean shutdown state
		/// </summary>
		public static void Recover(string edbFilename)
		{
			string programPath = Spludlow.SpawnProcess.FindPath(@"ESENTUTL.EXE");

			string logDirectory = Path.GetDirectoryName(edbFilename) + @"\LogFiles";

			Spludlow.SpawnProcess.ProcessExitInfo info = Spludlow.SpawnProcess.Run(programPath, "/r edb", logDirectory, null, 0, false);

			if (info.ExitCode != 0)
				throw new ApplicationException("ESE Repair: ESENTUTL.EXE Exit Code: " + info.ExitCode + ", stderr:" + info.StandardError);
		}

		public static void Repair(string edbFilename)
		{
			string programPath = Spludlow.SpawnProcess.FindPath(@"ESENTUTL.EXE");

			Spludlow.SpawnProcess.ProcessExitInfo info = Spludlow.SpawnProcess.Run(programPath, "/p /o " + edbFilename, 0);

			if (info.ExitCode != 0)
				throw new ApplicationException("ESE Repair: ESENTUTL.EXE Exit Code: " + info.ExitCode + ", stderr:" + info.StandardError);
		}

		public static DataSet ReadDatabase(string edbFilename)
		{
			string[] tableNames = ListTables(edbFilename);
			return ReadDatabase(edbFilename, tableNames);

		}
		public static DataSet ReadDatabase(string edbFilename, string tableName)
		{
			return ReadDatabase(edbFilename, new string[] { tableName });
		}

		public static DataSet ReadDatabase(string edbFilename, string[] tableNames)
		{
			DataSet dataSet = new DataSet();

			int pageSize = 0;
			Api.JetGetDatabaseFileInfo(edbFilename, out pageSize, JET_DbInfo.PageSize);
			Api.JetSetSystemParameter(JET_INSTANCE.Nil, JET_SESID.Nil, JET_param.DatabasePageSize, pageSize, null);
			
			string instanceName = Guid.NewGuid().ToString();

			JET_INSTANCE jetInstance = JET_INSTANCE.Nil;
			Api.JetCreateInstance(out jetInstance, instanceName);
			Api.JetInit(ref jetInstance);
			try
			{
				JET_SESID jetSession = JET_SESID.Nil;
				Api.JetBeginSession(jetInstance, out jetSession, null, null);
				try
				{
					JET_DBID jetDatabaseId = JET_DBID.Nil;
					Api.JetAttachDatabase(jetSession, edbFilename, AttachDatabaseGrbit.ReadOnly);
					Api.JetOpenDatabase(jetSession, edbFilename, null, out jetDatabaseId, OpenDatabaseGrbit.ReadOnly);
					try
					{
						foreach (string tableName in tableNames)
							ReadTable(dataSet, tableName, jetSession, jetDatabaseId);
					}
					finally
					{
						Api.JetCloseDatabase(jetSession, jetDatabaseId, CloseDatabaseGrbit.None);
						Api.JetDetachDatabase(jetSession, edbFilename);
					}
				}
				finally
				{
					Api.JetEndSession(jetSession, EndSessionGrbit.None);
				}
			}
			finally
			{
				Api.JetTerm(jetInstance);
			}

			return dataSet;
		}

		private static void ReadTable(DataSet dataSet, string tableName, JET_SESID jetSession, JET_DBID jetDatabaseId)
		{
			DataTable table = new DataTable(tableName);

			JET_TABLEID tableId = JET_TABLEID.Nil;
			Api.JetOpenTable(jetSession, jetDatabaseId, tableName, null, 0, OpenTableGrbit.ReadOnly, out tableId);
			try
			{
				List<ColumnInfo> tableColumns = new List<ColumnInfo>(Api.GetTableColumns(jetSession, tableId));

				foreach (ColumnInfo columnInfo in tableColumns)
				{
					if (dataTypeLookup.ContainsKey(columnInfo.Coltyp) == false)
						throw new ApplicationException("ExtensibleStorageEngine ReadTable; Type not found: " + columnInfo.Coltyp);

					table.Columns.Add(columnInfo.Name, dataTypeLookup[columnInfo.Coltyp]);
				}

				for (JET_Move move = JET_Move.First; Api.TryMove(jetSession, tableId, move, MoveGrbit.None); move = JET_Move.Next)
				{
					DataRow row = table.NewRow();

					foreach (ColumnInfo columnInfo in tableColumns)
					{
						object data = null;

						switch (columnInfo.Coltyp)
						{
							case JET_coltyp.Binary:
								data = Api.RetrieveColumn(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.Bit:
								data = Api.RetrieveColumnAsBoolean(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.Currency:
								data = Api.RetrieveColumnAsInt64(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.DateTime:
								data = Api.RetrieveColumnAsDateTime(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.IEEEDouble:
								data = Api.RetrieveColumnAsDouble(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.IEEESingle:
								data = Api.RetrieveColumnAsFloat(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.Long:
								data = Api.RetrieveColumnAsInt32(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.LongBinary:
								data = Api.RetrieveColumn(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.LongText:
								data = Api.RetrieveColumnAsString(jetSession, tableId, columnInfo.Columnid, (columnInfo.Cp == JET_CP.Unicode ? Encoding.Unicode : Encoding.ASCII));
								break;
							case JET_coltyp.Short:
								data = Api.RetrieveColumnAsInt16(jetSession, tableId, columnInfo.Columnid);
								break;
							case JET_coltyp.Text:
								data = Api.RetrieveColumnAsString(jetSession, tableId, columnInfo.Columnid, (columnInfo.Cp == JET_CP.Unicode ? Encoding.Unicode : Encoding.ASCII));
								break;
							case JET_coltyp.UnsignedByte:
								data = Api.RetrieveColumnAsByte(jetSession, tableId, columnInfo.Columnid);
								break;

							case VistaColtyp.GUID:
								data = Api.RetrieveColumnAsGuid(jetSession, tableId, columnInfo.Columnid);
								break;
							case VistaColtyp.LongLong:
								data = Api.RetrieveColumnAsInt64(jetSession, tableId, columnInfo.Columnid);
								break;
							case VistaColtyp.UnsignedLong:
								data = Api.RetrieveColumnAsUInt32(jetSession, tableId, columnInfo.Columnid);
								break;
							case VistaColtyp.UnsignedShort:
								data = Api.RetrieveColumnAsUInt16(jetSession, tableId, columnInfo.Columnid);
								break;

							case Windows10Coltyp.UnsignedLongLong:
								data = Api.RetrieveColumnAsUInt64(jetSession, tableId, columnInfo.Columnid);
								break;
						}

						if (data == null)
							data = DBNull.Value;

						row[columnInfo.Name] = data;
					}
					table.Rows.Add(row);
				}

				dataSet.Tables.Add(table);
			}
			finally
			{
				Api.JetCloseTable(jetSession, tableId);
			}
		}

	}
}