/**
 * Licensed 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.aurora.common.args.constraints;

import java.lang.annotation.Annotation;
import java.math.BigDecimal;

import com.google.common.base.Function;
import com.google.common.base.Functions;

import org.apache.aurora.common.args.Verifier;
import org.apache.aurora.common.args.VerifierFor;

import static com.google.common.base.Preconditions.checkArgument;

/**
 * Verifies that a number (inclusively) lies within a range.
 *
 * @author William Farner
 */
@VerifierFor(Range.class)
public class RangeNumberVerifier implements Verifier<Number> {
  @Override
  public void verify(Number value, Annotation annotation) {
    Range range = getRange(annotation);

    checkArgument(range.lower() < range.upper(),
        "Range lower bound must be greater than upper bound.");

    double dblValue = value.doubleValue();
    checkArgument(dblValue >= range.lower() && dblValue <= range.upper(),
        String.format("Value must be in range [%f, %f]", range.lower(), range.upper()));
  }

  @Override
  public String toString(Class<? extends Number> argType, Annotation annotation) {
    Range range = getRange(annotation);

    Function<Number, Number> converter;
    if (Float.class.isAssignableFrom(argType)
        || Double.class.isAssignableFrom(argType)
        || BigDecimal.class.isAssignableFrom(argType)) {

      converter = Functions.identity();
    } else {
      converter = Number::longValue;
    }

    return String.format("must be >= %s and <= %s",
                         converter.apply(range.lower()),
                         converter.apply(range.upper()));
  }

  private Range getRange(Annotation annotation) {
    checkArgument(annotation instanceof Range, "Annotation is not a range: " + annotation);

    return (Range) annotation;
  }
}