/*
 * Copyright (c) 1998-2012 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source 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, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.db.sql;

import java.io.InputStream;
import java.sql.SQLException;
import java.sql.Types;
import java.util.ArrayList;

import com.caucho.db.table.Column;
import com.caucho.db.table.Table;
import com.caucho.db.table.Column.ColumnType;
import com.caucho.inject.Module;
import com.caucho.util.L10N;
import com.caucho.util.QDate;
import com.caucho.util.SQLExceptionWrapper;

@Module
abstract public class Expr {
  protected static final L10N L = new L10N(Expr.class);

  public static final int UNKNOWN = -1;
  public static final int FALSE = 0;
  public static final int TRUE = 1;

  final static long COST_INVALID  = Long.MAX_VALUE / 1000;
  final static long COST_NO_TABLE = Integer.MAX_VALUE;
  final static long COST_SCAN     = 1000000L;
  final static long COST_UNIQUE   = 10000L;
  final static long COST_INDEX    = 100L;
  final static long COST_CONSTANT = 0L;
  
  final static long INDEX_COST_INDEX = COST_SCAN * 100;

  private static QDate _gmtDate = new QDate();

  public Expr bind(Query query)
    throws SQLException
  {
    return this;
  }

  /**
   * Returns the expected result type of the expression.
   */
  public Class<?> getType()
  {
    return Object.class;
  }
  
  /**
   * Returns the java type code if known.
   */
  public ColumnType getTypeCode()
  {
    return ColumnType.NONE;
  }
  
  public int getSQLType()
  {
    return getTypeCode().getSQLType();
  }

  /**
   * Returns true if the expression returns a long.
   */
  public boolean isLong()
  {
    Class<?> type = getType();

    return (int.class.equals(type) 
            || long.class.equals(type)
            || java.sql.Date.class.equals(type));
  }

  /**
   * Returns true if the expression returns a double.
   */
  public boolean isDouble()
  {
    Class<?> type = getType();

    return isLong() || double.class.isAssignableFrom(type);
  }

  /**
   * Returns true if the expression returns a boolean.
   */
  public boolean isBoolean()
  {
    return boolean.class.equals(getType());
  }

  /**
   * Returns true if the expression returns a binary stream.
   */
  public boolean isBinaryStream(QueryContext context)
  {
    Class<?> type = getType();

    return (InputStream.class.equals(type));
  }

  /**
   * Returns true for a parameter expression.
   */
  public boolean isParam()
  {
    return false;
  }

  /**
   * Returns true if the expression can return a null value.
   */
  public boolean isNullable()
  {
    return true;
  }

  /**
   * Returns any column name.
   */
  public String getName()
  {
    return "";
  }

  /**
   * Returns the table.
   */
  public Table getTable()
  {
    return null;
  }

  /**
   * Splits the expr into and blocks.
   */
  public void splitAnd(ArrayList<Expr> andProduct)
  {
    andProduct.add(this);
  }

  /**
   * Returns the cost based on the given FromList.
   */
  public long cost(ArrayList<FromItem> fromList)
  {
    return subCost(fromList);
  }

  /**
   * Returns the cost based on the given FromList.
   */
  public long subCost(ArrayList<FromItem> fromList)
  {
    return COST_INVALID;
  }

  /**
   * Returns the cost bonus for an index.
   */
  public long indexCost(ArrayList<FromItem> costItems)
  {
    return indexSubCost(costItems);
  }

  /**
   * Returns the cost bonus for an index.
   */
  public long indexSubCost(ArrayList<FromItem> costItems)
  {
    return COST_INVALID;
  }

  /**
   * Returns an index expression if available.
   */
  public RowIterateExpr getIndexExpr(FromItem fromItem)
  {
    return null;
  }

  /**
   * Returns the order.
   */
  public Order createOrder(int index)
  {
    if (int.class.equals(getType()))
      return new IntOrder(index);
    else if (isLong())
      return new LongOrder(index);
    else if (isDouble())
      return new DoubleOrder(index);
    else
      return new StringOrder(index);
  }

  /**
   * Returns true if result is null
   *
   * @param rows the current database tuple
   *
   * @return true if null
   */
  public boolean isNull(QueryContext context)
    throws SQLException
  {
    return false;
  }

  /**
   * Returns true if the expression selects the row.
   *
   * @param rows the current database tuple
   *
   * @return the boolean value
   */
  public boolean isSelect(QueryContext context)
    throws SQLException
  {
    return evalBoolean(context) == TRUE;
  }

  /**
   * Evaluates the expression as a boolean.
   *
   * @param rows the current database tuple
   *
   * @return the boolean value
   */
  public int evalBoolean(QueryContext context)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression as a string.
   *
   * @param rows the current database tuple
   *
   * @return the string value
   */
  public String evalString(QueryContext context)
    throws SQLException
  {
      throw new UnsupportedOperationException(getClass().getName());
  }
  
  /**
   * Updates the expression as a string
   */
  public void updateString(QueryContext context, String value)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression as a long.
   *
   * @param rows the current database tuple
   *
   * @return the long value
   */
  public long evalLong(QueryContext context)
    throws SQLException
  {
    String strValue = evalString(context);

    if (strValue == null)
      return 0;
    else
      return Long.parseLong(strValue);
  }
  
  /**
   * Updates the expression as a long
   */
  public void updateLong(QueryContext context, long value)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression as a double.
   *
   * @param rows the current database tuple
   *
   * @return the double value
   */
  public double evalDouble(QueryContext context)
    throws SQLException
  {
    String strValue = evalString(context);

    if (strValue == null)
      return 0;
    else
      return Double.parseDouble(strValue);
  }
  
  /**
   * Updates the expression as a double
   */
  public void updateDouble(QueryContext context, double value)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression as a date.
   *
   * @param rows the current database tuple
   *
   * @return the double value
   */
  public long evalDate(QueryContext context)
    throws SQLException
  {
    String dateString = evalString(context);

    try {
      synchronized (_gmtDate) {
        return _gmtDate.parseDate(dateString);
      }
    } catch (Exception e) {
      throw new SQLExceptionWrapper(e);
    }
  }

  /**
   * Evaluates the expression, writing to the result stream.
   *
   * @param result the output result
   */
  public void evalToResult(QueryContext context, SelectResult result)
    throws SQLException
  {
    String s = evalString(context);

    if (s == null) {
      result.writeNull();
      return;
    }

    result.writeString(s);
  }

  /**
   * Evaluates the expression as a stream.
   *
   * @param rows the current database tuple
   *
   * @return the string value
   */
  public InputStream evalStream(QueryContext context)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression as a stream.
   *
   * @param rows the current database tuple
   *
   * @return the string value
   */
  public byte []evalBytes(QueryContext context)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression to a buffer
   *
   * @param result the result buffer
   *
   * @return the length of the result
   */
  public int evalToBuffer(QueryContext context,
                          byte []buffer,
                          int offset)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  /**
   * Evaluates the expression to a buffer
   *
   * @param result the result buffer
   *
   * @return the length of the result
   */
  public int evalToBuffer(QueryContext context,
                          byte []buffer,
                          int off,
                          Column.ColumnType columnType)
    throws SQLException
  {
    switch (columnType) {
    case INT:
      {
        int v = (int) evalLong(context);

        buffer[0] = (byte) (v >> 24);
        buffer[1] = (byte) (v >> 16);
        buffer[2] = (byte) (v >> 8);
        buffer[3] = (byte) (v);

        return 4;
      }

    case LONG:
    case DATE:
      {
        long v = evalLong(context);

        buffer[0] = (byte) (v >> 56);
        buffer[1] = (byte) (v >> 48);
        buffer[2] = (byte) (v >> 40);
        buffer[3] = (byte) (v >> 32);

        buffer[4] = (byte) (v >> 24);
        buffer[5] = (byte) (v >> 16);
        buffer[6] = (byte) (v >> 8);
        buffer[7] = (byte) (v);

        return 8;
      }

    case VARCHAR:
      {
        String v = evalString(context);
        
        if (v == null)
          return -1;

        int length = v.length();

        int offset = 0;
        buffer[offset++] = (byte) length;
        for (int i = 0; i < length; i++) {
          int ch = v.charAt(i);

          buffer[offset++] = (byte) (ch >> 8);
          buffer[offset++] = (byte) (ch);
        }

        return offset;
      }

    case VARBINARY:
      {
        String v = evalString(context);

        if (v == null)
          return -1;

        int length = v.length();
        int offset = 1;

        for (int i = 0; i < length; i++) {
          int ch = v.charAt(i);

          if (ch < 0x80)
            buffer[offset++] = (byte) (ch & 0xff);
          else if (ch < 0x800) {
            buffer[offset++] = (byte) (0xc0 + ((ch >> 6) & 0x1f));
            buffer[offset++] = (byte) (0x80 + (ch & 0x3f));
          }
          else {
            buffer[offset++] = (byte) (0xe0 + ((ch >> 12) & 0x0f));
            buffer[offset++] = (byte) (0x80 + ((ch >> 6) & 0x3f));
            buffer[offset++] = (byte) (0x80 + (ch & 0x3f));
          }
        }
        buffer[0] = (byte) (offset - 1);

        return offset;
      }

      /*
    case BINARY:
      {
        byte []bytes = evalBytes(context);
        
        if (bytes != null) {
          System.arraycopy(bytes, 0, buffer, off, bytes.length);
        
          return bytes.length;
        }
        else
          return 0;
      }
      */
      
    case BINARY:
    {
      return evalToBuffer(context, buffer, off);
    }

    default:
      throw new UnsupportedOperationException(getClass().getName() + " unknown column: " + columnType);
    }
  }

  /**
   * Initializes aggregate functions during the group phase.
   *
   * @param context the current database tuple
   */
  public void initGroup(QueryContext context)
    throws SQLException
  {
  }

  /**
   * Evaluates aggregate functions during the group phase.
   *
   * @param context the current database tuple
   */
  public void evalGroup(QueryContext context)
    throws SQLException
  {
  }

  public boolean evalEqual(QueryContext context, String evalString)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }

  public boolean evalEqual(QueryContext context, byte []data)
    throws SQLException
  {
    throw new UnsupportedOperationException(getClass().getName());
  }
}
