RangeSpecification.java

package webdav.support;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import com.google.common.base.Preconditions;
import org.apache.commons.lang3.tuple.Pair;

public class RangeSpecification {

	private List<Pair<Long, Long>> ranges = new ArrayList<>();

	// default dimension
	private String dimension = "bytes";


	public RangeSpecification() {}


	public RangeSpecification(long position) {
		if (position < 0) {
			ranges.add(Pair.of(null, -position));
		} else {
			ranges.add(Pair.of(position, null));
		}
	}


	public RangeSpecification(long start, long end) {
		Preconditions.checkArgument(start >= 0, "start must be >=0");
		Preconditions.checkArgument(end >= 0, "end must be >=0");

		ranges.add(Pair.of(start, end));
	}


	public RangeSpecification addRange(long start, long end) {
		Preconditions.checkArgument(start >= 0, "start must be >=0");
		Preconditions.checkArgument(end >= 0, "end must be >=0");

		ranges.add(Pair.of(start, end));
		return this;
	}


	/** same as {@code addRange(0, toPosition)} */
	public RangeSpecification to(long toPosition) {
		Preconditions.checkArgument(toPosition >= 0, "toPosition must be >=0");
		ranges.add(Pair.of(0L, toPosition));
		return this;
	}


	public RangeSpecification after(long startPosition) {
		Preconditions.checkArgument(startPosition >= 0, "startPosition must be >=0");
		ranges.add(Pair.of(startPosition, null));
		return this;
	}


	public RangeSpecification last(long lastCount) {
		Preconditions.checkArgument(lastCount >= 0, "lastCount must be >=0");
		ranges.add(Pair.of(null, lastCount));
		return this;
	}


	/** Example:
	 * <pre>{@code
	 * if (rangeSpecification.hasAnyRange()
	 *   headers.add("Range, rangeSpecification.toString());
	 *  }
	 * </pre>
	 *
	 * @return
	 */
	public boolean hasAnyRange() {
		return !ranges.isEmpty();
	}


	public RangeSpecification setDimension(String dimension) {
		this.dimension = dimension;
		return this;
	}


	@Override
	public String toString() {

		StringBuilder sb = new StringBuilder();
		sb.append(dimension).append("=");
		if (ranges.isEmpty()) {
			sb.append("0-");        // if no range defined then use 'full range' from 0 to last byte.
		}
		else {
			Iterator<Pair<Long, Long>> iterator = ranges.iterator();
			while (iterator.hasNext()) {
				Pair<Long, Long> range = iterator.next();
				if (range.getLeft() != null) sb.append(range.getLeft());
				sb.append("-");
				if (range.getRight() != null) sb.append(range.getRight());

				if (iterator.hasNext()) sb.append(", ");
			}
		}
		return sb.toString();
	}
}