/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.expression.function;

import java.sql.SQLException;
import java.util.Base64;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.phoenix.exception.SQLExceptionCode;
import org.apache.phoenix.exception.SQLExceptionInfo;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.parse.FunctionParseNode;
import org.apache.phoenix.schema.IllegalDataException;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PVarbinary;
import org.apache.phoenix.schema.types.PVarchar;

/**
 * Convert string to bytes
 */
@FunctionParseNode.BuiltInFunction(name = DecodeFunction.NAME,
    args = { @FunctionParseNode.Argument(allowedTypes = { PVarchar.class }),
      @FunctionParseNode.Argument(enumeration = "EncodeFormat") })
public class DecodeFunction extends ScalarFunction {

  public static final String NAME = "DECODE";

  public DecodeFunction() {
  }

  public DecodeFunction(List<Expression> children) throws SQLException {
    super(children);
  }

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    Expression expression = getExpression();
    if (!expression.evaluate(tuple, ptr)) {
      return false;
    }
    if (ptr.getLength() == 0) {
      return true; // expression was evaluated, but evaluated to null
    }

    String stringToDecode = (String) PVarchar.INSTANCE.toObject(ptr);

    Expression encodingExpression = getEncodingExpression();
    if (!encodingExpression.evaluate(tuple, ptr)) {
      return false;
    }

    if (ptr.getLength() == 0) {
      throw new IllegalDataException(new SQLExceptionInfo.Builder(SQLExceptionCode.ILLEGAL_DATA)
        .setMessage("Missing bytes encoding").build().buildException());
    }

    PDataType type = encodingExpression.getDataType();
    String encoding = ((String) type.toObject(ptr)).toUpperCase();

    byte out[];

    EncodeFormat format = EncodeFormat.valueOf(encoding);
    switch (format) {
      case HEX:
        out = decodeHex(stringToDecode);
        break;
      case BASE64:
        out = Base64.getDecoder().decode(stringToDecode);
        break;
      case HBASE:
        out = Bytes.toBytesBinary(stringToDecode);
        break;
      default:
        throw new IllegalDataException("Unsupported encoding \"" + encoding + "\"");
    }
    ptr.set(out);

    return true;
  }

  private byte[] decodeHex(String hexStr) {
    byte[] out = new byte[hexStr.length() / 2];
    for (int i = 0; i < hexStr.length(); i = i + 2) {
      try {
        out[i / 2] = (byte) Integer.parseInt(hexStr.substring(i, i + 2), 16);
      } catch (NumberFormatException ex) {
        throw new IllegalDataException(new SQLExceptionInfo.Builder(SQLExceptionCode.ILLEGAL_DATA)
          .setMessage("Value " + hexStr.substring(i, i + 2) + " cannot be cast to hex number")
          .build().buildException());
      } catch (StringIndexOutOfBoundsException ex) {
        throw new IllegalDataException(new SQLExceptionInfo.Builder(SQLExceptionCode.ILLEGAL_DATA)
          .setMessage("Invalid value length, cannot cast to hex number (" + hexStr + ")").build()
          .buildException());
      }
    }
    return out;
  }

  @Override
  public PDataType getDataType() {
    return PVarbinary.INSTANCE;
  }

  @Override
  public boolean isNullable() {
    return getExpression().isNullable();
  }

  private Expression getExpression() {
    return children.get(0);
  }

  private Expression getEncodingExpression() {
    return children.get(1);
  }

  @Override
  public String getName() {
    return NAME;
  }

  @Override
  public Integer getMaxLength() {
    return getExpression().getMaxLength();
  }
}
