// Copyright (c) 2004, 2021, Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
// published by the Free Software Foundation.
//
// This program is also distributed with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation.  The authors of MySQL hereby grant you an
// additional permission to link the program and your derivative works
// with the separately licensed software that they have included with
// MySQL.
//
// Without limiting anything contained in the foregoing, this file,
// which is part of MySQL Connector/NET, is also subject to the
// Universal FOSS Exception, version 1.0, a copy of which can be found at
// http://oss.oracle.com/licenses/universal-foss-exception.
//
// This program 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 General Public License, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using MySql.Data.Common;
using MySql.Data.Types;
using System.Security;

namespace MySql.Data.MySqlClient
{
  [Flags]
  internal enum ColumnFlags : int
  {
    NOT_NULL = 1,
    PRIMARY_KEY = 2,
    UNIQUE_KEY = 4,
    MULTIPLE_KEY = 8,
    BLOB = 16,
    UNSIGNED = 32,
    ZERO_FILL = 64,
    BINARY = 128,
    ENUM = 256,
    AUTO_INCREMENT = 512,
    TIMESTAMP = 1024,
    SET = 2048,
    NUMBER = 32768
  };

  /// <summary>
  /// Summary description for Field.
  /// </summary>
  internal class MySqlField
  {
    #region Fields

    // public fields
    public string CatalogName;
    public int ColumnLength;
    public string ColumnName;
    public string OriginalColumnName;
    public string TableName;
    public string RealTableName;
    public string DatabaseName;
    public Encoding Encoding;

    // protected fields
    protected int charSetIndex;
    protected DBVersion connVersion;
    protected bool binaryOk;

    // internal fields
    internal Driver driver;

    #endregion

    [SecuritySafeCritical]
    public MySqlField(Driver driver)
    {
      this.driver = driver;
      connVersion = driver.Version;
      MaxLength = 1;
      binaryOk = true;
#if !NETFRAMEWORK
      Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
#endif
    }

    #region Properties

    public int CharacterSetIndex
    {
      get { return charSetIndex; }
      set { charSetIndex = value; SetFieldEncoding(); }
    }

    public MySqlDbType Type { get; internal set; }

    public byte Precision { get; set; }

    public byte Scale { get; set; }

    public int MaxLength { get; set; }

    public ColumnFlags Flags { get; protected set; }

    public bool IsAutoIncrement => (Flags & ColumnFlags.AUTO_INCREMENT) > 0;

    public bool IsNumeric => (Flags & ColumnFlags.NUMBER) > 0;

    public bool AllowsNull => (Flags & ColumnFlags.NOT_NULL) == 0;

    public bool IsUnique => (Flags & ColumnFlags.UNIQUE_KEY) > 0;

    public bool IsPrimaryKey => (Flags & ColumnFlags.PRIMARY_KEY) > 0;

    public bool IsBlob => (Type >= MySqlDbType.TinyBlob &&
                           Type <= MySqlDbType.Blob) ||
                          (Type >= MySqlDbType.TinyText &&
                           Type <= MySqlDbType.Text) ||
                          (Flags & ColumnFlags.BLOB) > 0;

    public bool IsBinary => binaryOk && (CharacterSetIndex == 63);

    public bool IsUnsigned => (Flags & ColumnFlags.UNSIGNED) > 0;

    public bool IsTextField
    {
      get
      {
        return Type == MySqlDbType.VarString || Type == MySqlDbType.VarChar ||
                    Type == MySqlDbType.String || (Type == MySqlDbType.Guid && !driver.Settings.OldGuids);
      }
    }

    private int CharacterLength => ColumnLength / MaxLength;

    public List<Type> TypeConversions { get; } = new List<Type>();

    #endregion

    public void SetTypeAndFlags(MySqlDbType type, ColumnFlags flags)
    {
      Flags = flags;
      Type = type;

      if (String.IsNullOrEmpty(TableName) && String.IsNullOrEmpty(RealTableName) &&
        IsBinary && driver.Settings.FunctionsReturnString)
      {
        CharacterSetIndex = driver.ConnectionCharSetIndex;
      }

      // if our type is an unsigned number, then we need
      // to bump it up into our unsigned types
      // we're trusting that the server is not going to set the UNSIGNED
      // flag unless we are a number
      if (IsUnsigned)
      {
        switch (type)
        {
          case MySqlDbType.Byte:
            Type = MySqlDbType.UByte;
            return;
          case MySqlDbType.Int16:
            Type = MySqlDbType.UInt16;
            return;
          case MySqlDbType.Int24:
            Type = MySqlDbType.UInt24;
            return;
          case MySqlDbType.Int32:
            Type = MySqlDbType.UInt32;
            return;
          case MySqlDbType.Int64:
            Flags = Flags & ColumnFlags.UNSIGNED;
            Type = MySqlDbType.UInt64;
            return;
        }
      }

      if (IsBlob)
      {
        // handle blob to UTF8 conversion if requested.  This is only activated
        // on binary blobs
        if (IsBinary && driver.Settings.TreatBlobsAsUTF8)
        {
          bool convertBlob = false;
          Regex includeRegex = driver.Settings.GetBlobAsUTF8IncludeRegex();
          Regex excludeRegex = driver.Settings.GetBlobAsUTF8ExcludeRegex();
          if (includeRegex != null && includeRegex.IsMatch(ColumnName))
            convertBlob = true;
          else if (includeRegex == null && excludeRegex != null &&
            !excludeRegex.IsMatch(ColumnName))
            convertBlob = true;

          if (convertBlob)
          {
            binaryOk = false;
            Encoding = Encoding.GetEncoding("UTF-8");
            charSetIndex = -1;  // lets driver know we are in charge of encoding
            MaxLength = 4;
          }
        }

        if (!IsBinary)
        {
          if (type == MySqlDbType.TinyBlob)
            Type = MySqlDbType.TinyText;
          else if (type == MySqlDbType.MediumBlob)
            Type = MySqlDbType.MediumText;
          else if (type == MySqlDbType.Blob)
            Type = MySqlDbType.Text;
          else if (type == MySqlDbType.LongBlob)
            Type = MySqlDbType.LongText;
        }

        if (type == MySqlDbType.JSON)
        {
          binaryOk = false;
          Encoding = Encoding.GetEncoding("UTF-8");
          charSetIndex = -1;  // lets driver know we are in charge of encoding
          MaxLength = 4;
        }
      }

      // now determine if we really should be binary
      if (driver.Settings.RespectBinaryFlags)
        CheckForExceptions();

      if (Type == MySqlDbType.String && CharacterLength == 36 && !driver.Settings.OldGuids)
        Type = MySqlDbType.Guid;

      if (!IsBinary) return;

      if (driver.Settings.RespectBinaryFlags)
      {
        if (type == MySqlDbType.String)
          Type = MySqlDbType.Binary;
        else if (type == MySqlDbType.VarChar ||
             type == MySqlDbType.VarString)
          Type = MySqlDbType.VarBinary;
      }

      if (CharacterSetIndex == 63)
        CharacterSetIndex = driver.ConnectionCharSetIndex;

      if (Type == MySqlDbType.Binary && ColumnLength == 16 && driver.Settings.OldGuids)
        Type = MySqlDbType.Guid;
    }

    public void AddTypeConversion(Type t)
    {
      if (TypeConversions.Contains(t)) return;
      TypeConversions.Add(t);
    }

    private void CheckForExceptions()
    {
      string colName = String.Empty;
      if (OriginalColumnName != null)
        colName = StringUtility.ToUpperInvariant(OriginalColumnName);
      if (colName.StartsWith("CHAR(", StringComparison.Ordinal))
        binaryOk = false;
    }

    public IMySqlValue GetValueObject()
    {
      IMySqlValue v = GetIMySqlValue(Type);
      if (v is MySqlByte && ColumnLength == 1 && driver.Settings.TreatTinyAsBoolean)
      {
        MySqlByte b = (MySqlByte)v;
        b.TreatAsBoolean = true;
        v = b;
      }
      else if (v is MySqlGuid)
      {
        MySqlGuid g = (MySqlGuid)v;
        g.OldGuids = driver.Settings.OldGuids;
        v = g;
      }
      return v;
    }

    public static IMySqlValue GetIMySqlValue(MySqlDbType type)
    {
      switch (type)
      {
        case MySqlDbType.Byte:
          return new MySqlByte();
        case MySqlDbType.UByte:
          return new MySqlUByte();
        case MySqlDbType.Year:
        case MySqlDbType.Int16:
          return new MySqlInt16();
        case MySqlDbType.UInt16:
          return new MySqlUInt16();
        case MySqlDbType.Int24:
        case MySqlDbType.Int32:
          return new MySqlInt32(type, true);
        case MySqlDbType.UInt24:
        case MySqlDbType.UInt32:
          return new MySqlUInt32(type, true);
        case MySqlDbType.Bit:
          return new MySqlBit();
        case MySqlDbType.Int64:
          return new MySqlInt64();
        case MySqlDbType.UInt64:
          return new MySqlUInt64();
        case MySqlDbType.Time:
          return new MySqlTimeSpan();
        case MySqlDbType.Date:
        case MySqlDbType.DateTime:
        case MySqlDbType.Newdate:
        case MySqlDbType.Timestamp:
          return new MySqlDateTime(type, true);
        case MySqlDbType.Decimal:
        case MySqlDbType.NewDecimal:
          return new MySqlDecimal();
        case MySqlDbType.Float:
          return new MySqlSingle();
        case MySqlDbType.Double:
          return new MySqlDouble();
        case MySqlDbType.Set:
        case MySqlDbType.Enum:
        case MySqlDbType.String:
        case MySqlDbType.VarString:
        case MySqlDbType.VarChar:
        case MySqlDbType.Text:
        case MySqlDbType.TinyText:
        case MySqlDbType.MediumText:
        case MySqlDbType.LongText:
        case MySqlDbType.JSON:
        case (MySqlDbType)Field_Type.NULL:
          return new MySqlString(type, true);
        case MySqlDbType.Geometry:
          return new MySqlGeometry(type, true);
        case MySqlDbType.Blob:
        case MySqlDbType.MediumBlob:
        case MySqlDbType.LongBlob:
        case MySqlDbType.TinyBlob:
        case MySqlDbType.Binary:
        case MySqlDbType.VarBinary:
          return new MySqlBinary(type, true);
        case MySqlDbType.Guid:
          return new MySqlGuid();
        default:
          throw new MySqlException("Unknown data type");
      }
    }

    private void SetFieldEncoding()
    {
      Dictionary<int, string> charSets = driver.CharacterSets;
      DBVersion version = driver.Version;

      if (charSets == null || charSets.Count == 0 || CharacterSetIndex == -1) return;
      if (charSets[CharacterSetIndex] == null) return;

      CharacterSet cs = CharSetMap.GetCharacterSet(version, (string)charSets[CharacterSetIndex]);
      MaxLength = cs.byteCount;
      Encoding = CharSetMap.GetEncoding(version, (string)charSets[CharacterSetIndex]);
    }
  }
}
