package edu.washington.escience.myria.expression;

import java.nio.ByteBuffer;
import java.util.Objects;

import org.apache.commons.lang.StringEscapeUtils;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

import edu.washington.escience.myria.Type;
import edu.washington.escience.myria.expression.evaluate.ExpressionOperatorParameter;

/**
 * An expression that returns a constant value.
 */
public class ConstantExpression extends ZeroaryExpression {

  /***/
  private static final long serialVersionUID = 1L;

  /** The type of this object. */
  @JsonProperty private final Type valueType;

  /** The value of this object. */
  @JsonProperty private final String value;

  /**
   * @param type the type of this object.
   * @param value the value of this constant.
   */
  @JsonCreator
  public ConstantExpression(
      @JsonProperty("valueType") final Type type, @JsonProperty("value") final String value) {
    valueType = type;
    if (type == Type.LONG_TYPE && value.toUpperCase().indexOf('L') == -1) {
      this.value = value + 'L';
    } else if (type == Type.FLOAT_TYPE && value.toUpperCase().indexOf('F') == -1) {
      this.value = value + 'F';
    } else {
      this.value = value;
    }
  }

  /**
   * Construct integer constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final int value) {
    this(Type.INT_TYPE, String.valueOf(value));
  }

  /**
   * Construct long constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final long value) {
    this(Type.LONG_TYPE, String.valueOf(value) + 'L');
  }

  /**
   * Construct float constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final float value) {
    this(Type.FLOAT_TYPE, String.valueOf(value) + 'f');
  }

  /**
   * Construct double constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final double value) {
    this(Type.DOUBLE_TYPE, String.valueOf(value));
  }

  /**
   * Construct boolean constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final boolean value) {
    this(Type.BOOLEAN_TYPE, String.valueOf(value));
  }

  /**
   * Construct string constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final String value) {
    this(Type.STRING_TYPE, value);
  }

  /**
   * Construct Blob constant.
   *
   * @param value the value of this constant.
   */
  public ConstantExpression(final ByteBuffer value) {
    throw new UnsupportedOperationException();
  }

  @Override
  public Type getOutputType(final ExpressionOperatorParameter parameters) {
    return valueType;
  }

  @Override
  public String getJavaString(final ExpressionOperatorParameter parameters) {
    switch (valueType) {
      case BOOLEAN_TYPE:
      case DOUBLE_TYPE:
      case FLOAT_TYPE:
      case INT_TYPE:
      case LONG_TYPE:
        return value;
      case DATETIME_TYPE:
        throw new UnsupportedOperationException("using constant value of type DateTime");
      case BLOB_TYPE:
        return value;
      case STRING_TYPE:
        return '\"' + StringEscapeUtils.escapeJava(value) + '\"';
    }
    throw new UnsupportedOperationException("using constant value of type " + valueType);
  }

  @Override
  public int hashCode() {
    return Objects.hash(getClass().getCanonicalName(), valueType, value);
  }

  @Override
  public boolean equals(final Object other) {
    if (other == null || !(other instanceof ConstantExpression)) {
      return false;
    }
    ConstantExpression otherExp = (ConstantExpression) other;
    return Objects.equals(valueType, otherExp.valueType) && Objects.equals(value, otherExp.value);
  }

  /**
   * @return the value
   */
  public String getValue() {
    return value;
  }
}