Range.java

/*
 * Copyright (c) 2016 Cosmin Stejerean, Karl Heinz Marbaise, and contributors.
 *
 * Distributed under the MIT license: http://opensource.org/licenses/MIT
 */

package com.offbytwo.jenkins.helper;

/**
 * The range class will handle the following situations:
 * <ul>
 * <li>{M,N}: From the M-th element (inclusive) to the N-th element (exclusive).
 * </li>
 * <li>{M,}: From the M-th element (inclusive) to the end.</li>
 * <li>{,N}: From the first element (inclusive) to the N-th element (exclusive).
 * The same as {0,N}.</li>
 * <li>{N}: Just retrieve the N-th element. The same as {N,N+1}.</li>
 * </ul>
 * 
 * You can use the {@link Range} class like this:
 * 
 * <pre>
 * Range fromAndTo = Range.build().from(1).to(5);
 * Range fromOnly = Range.build().from(3).build();
 * Range toOnly = Range.build().to(5).build();
 * Range only = Range.build().only(3);
 * </pre>
 * 
 * @author Karl Heinz Marbaise
 *
 */
public final class Range {

    public static final String CURLY_BRACKET_OPEN = "%7B"; // {
    public static final String CURLY_BRACKET_CLOSE = "%7D"; // }

    private Integer from;
    private Integer to;

    private Range() {
	this.from = null;
	this.to = null;
    }

    private Range setFrom(int from) {
	if (from < 0) {
	    throw new IllegalArgumentException("from value must be greater or equal null.");
	}
	this.from = new Integer(from);
	return this;
    }

    private Range setTo(int to) {
	if (to < 0) {
	    throw new IllegalArgumentException("to must be greater or equal null.");
	}
	this.to = new Integer(to);
	return this;
    }

    public String getRangeString() {
	StringBuilder sb = new StringBuilder();
	sb.append(CURLY_BRACKET_OPEN);
	if (this.from != null) {
	    sb.append(String.format("%d", this.from));
	}

	sb.append(',');

	if (this.to != null) {
	    sb.append(String.format("%d", this.to));
	}

	sb.append(CURLY_BRACKET_CLOSE);
	return sb.toString();
    }

    public static final class FromBuilder {
	private Range range;

	public FromBuilder(Range range) {
	    this.range = range;
	}

	public Range to(int t) {
	    this.range.setTo(t);
	    if (range.to <= range.from) {
		throw new IllegalArgumentException("to must be greater than from");
	    }
	    return this.range;
	}

	public Range build() {
	    return this.range;
	}
    }

    public static final class ToBuilder {
	private Range range;

	public ToBuilder(Range range) {
	    this.range = range;
	}

	public Range build() {
	    return this.range;
	}
    }

    public static final class Builder {
	private Range range;

	protected Builder() {
	    this.range = new Range();
	}

	public FromBuilder from(int f) {
	    this.range.setFrom(f);
	    return new FromBuilder(this.range);
	}

	public ToBuilder to(int t) {
	    this.range.setTo(t);
	    return new ToBuilder(this.range);
	}

	public Range only(int only) {
	    this.range.from = new Integer(only);
	    this.range.to = new Integer(only + 1);
	    return this.range;
	}
    }

    public static Builder build() {
	return new Builder();
    }
}