using System;
using System.Data;
using System.Data.OleDb;
using System.Globalization;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace ThinkGeo.MapSuite.MapSuiteGeocoderExtension
{
    internal class DbfManager
    {
        private string dbfPahtFileName;

        public DbfManager(string dbfPahtFileName)
        {
            this.dbfPahtFileName = dbfPahtFileName;
        }

        public DataTable ExecuteQuery(string sqlStatement)
        {
            DataTable dataTable = new DataTable();
            dataTable.Locale = CultureInfo.InvariantCulture;
            OleDbCommand oleDbCommand = null;
            OleDbDataAdapter adapter = null;
            try
            {
                sqlStatement = ReplaceTableName(sqlStatement);
                oleDbCommand = GetOleDbCommand(sqlStatement);

                adapter = new OleDbDataAdapter(oleDbCommand);
                adapter.Fill(dataTable);
            }
            finally
            {
                if (oleDbCommand != null)
                {
                    oleDbCommand.Dispose();
                }
                if (adapter != null)
                {
                    adapter.Dispose();
                }
            }

            return dataTable;
        }

        private OleDbCommand GetOleDbCommand(string sqlStatement)
        {
            OleDbConnection connection;
            if (Environment.Is64BitProcess)
            {
                connection = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Path.GetDirectoryName(dbfPahtFileName) + "\\;Extended Properties=dBASE IV;User ID=Admin;Password=");
            }
            else
            {
                connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Path.GetDirectoryName(dbfPahtFileName) + "\\;Extended Properties=dBASE IV;User ID=Admin;Password=");
            }

            if (connection.State != ConnectionState.Open)
            {
                connection.Open();
            }

            return new OleDbCommand(sqlStatement, connection);
        }

        private string ReplaceTableName(string sqlStatement)
        {
            sqlStatement += " ";
            string shortName = GetShortFileName(dbfPahtFileName);

            string sourceFileNameWithoutExtension = Path.GetFileNameWithoutExtension(dbfPahtFileName).ToUpperInvariant();
            string shortNameWithoutExtension = Path.GetFileNameWithoutExtension(shortName);
            int position = sqlStatement.IndexOf(sourceFileNameWithoutExtension, StringComparison.OrdinalIgnoreCase);
            string tableName = sqlStatement.Substring(position, sourceFileNameWithoutExtension.Length);

            string substringIncludeTableName = sqlStatement.Substring(0, position + tableName.Length);
            sqlStatement = sqlStatement.Replace(substringIncludeTableName, substringIncludeTableName.Replace(tableName, shortNameWithoutExtension));

            if (!sqlStatement.Contains(" [" + shortNameWithoutExtension + "] "))
            {
                sqlStatement = sqlStatement.Replace(" " + shortNameWithoutExtension + " ", " [" + shortNameWithoutExtension + "] ");
            }

            return sqlStatement;
        }

        private static string GetShortFileName(string pathFileName)
        {
            StringBuilder sb = new StringBuilder(1024);
            UnsafeNativeMethods.GetShortPathName(pathFileName, sb, sb.Capacity);

            string shortPath = sb.ToString();
            //TODO: whether throw exception if short path is empty

            return shortPath;
        }
    }

    internal static class UnsafeNativeMethods
    {
        //TODo check this method works fine in chinese string.
        [DllImport("kernel32", EntryPoint = "GetShortPathNameA", ExactSpelling = true, CharSet = CharSet.Ansi, SetLastError = true)]
        internal static extern int GetShortPathName(string lpszLongPath, StringBuilder lpszShortPath, int cchBuffer);
    } 
}