/// <summary>
/// Class to manage access to SQLite database
/// </summary>
using System;
using System.Data;
using System.Data.SQLite;
using System.Runtime.InteropServices;

internal class SQLite {
	/// Fields
	private SQLiteConnection connector;
	private SQLiteConnectionStringBuilder conString;
	private SQLiteCommand cmd = null;
	private SQLiteDataAdapter dataAdapter = null;
	private SQLiteCommandBuilder commandBuilder = null;
	private DataSet dataset = new DataSet();
	private DataTable datatable = null;
	private string last_error = string.Empty;
	/// Constructor
	public SQLite()
	{
		this.connector = new SQLiteConnection();
	}
	/// Connect to db file
	public bool connect(string strPath)
	{
		try
		{
			if (!System.IO.File.Exists(strPath))
				SQLiteConnection.CreateFile(strPath);
			conString = new SQLiteConnectionStringBuilder();
			conString.DataSource = strPath;
			this.connector.ConnectionString = conString.ToString();
			this.connector.Open();
			return true;
		}
		catch (Exception ex)
		{
			this.last_error = ex.ToString();
			return false;
		}
	}
	/// Closes connection
	public void close()
	{
		this.connector.Close();
	}
	/// Returns last error
	public string lasterror
	{
		get{ return this.last_error; }
	}
	/// Read data from db
	public DataTable read(string query)
	{
		try
		{
			dataAdapter = new SQLiteDataAdapter(query, connector);
			commandBuilder = new SQLiteCommandBuilder(dataAdapter);
			dataset.Reset();
			dataAdapter.Fill(dataset);
			datatable = dataset.Tables[0];
			return datatable;
		}
		catch (Exception ex)
		{
			this.last_error = ex.ToString();
			return null;
		}
	}
	/// Update data to db
	public bool update()
	{
		try
		{
			dataAdapter.Update(datatable);
			return true;
		}
		catch (Exception ex)
		{
			this.last_error = ex.ToString();
			return false;
		}
	}
	/// Make scalar query
	public object scalar_query(string query)
	{
		object result = null;
		try
		{
			using (cmd = new SQLiteCommand(query, connector))
			{
				result = cmd.ExecuteScalar();
			}
			return result;
		}
		catch (Exception ex)
		{
			this.last_error = ex.ToString();
			return null;
		}
	}
	/// Make execute query
	public int exec_query(string query)
	{
		int result = -1;
		try
		{
			using (cmd = new SQLiteCommand(query, connector))
			{
				result = cmd.ExecuteNonQuery();
			}
			return result;
		}
		catch (Exception ex)
		{
			this.last_error = ex.ToString();
			return -1;
		}
	}
}