package com.notsocomplex.regex;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.junit.Assert;
import org.junit.Test;

public class RegexReplaceGroupTest {

	@Test
	public void testReplacementWithGroupsSingleMatch() {

		String text = "Frank Castle is Spider-Man. No Really!";

		// Group 1: (.+\\Wis\\W)
		//			-Match any character 1 or more time
		//			-Followed by 'is'
		//			-Followed by non-word boundary
		// Group 2: (.+)
		//			-Match any character 1 or more time
		// Group 3: (\\..+)
		//			-Match the dot character followed by 1 or more character
		String regex = "(.+is\\W)(.+)(\\..+)";

		Pattern pattern = Pattern.compile(regex);
		Matcher matcher = pattern.matcher(text);

		// Make sure we have a match. This matches the entire input.
		Assert.assertTrue(matcher.find());

		// 3 groups are created
		Assert.assertEquals("Frank Castle is ", matcher.group(1));
		Assert.assertEquals("Spider-Man", matcher.group(2));
		Assert.assertEquals(". No Really!", matcher.group(3));

		// Replace the match (which is the entire input!) by the group at position 1, the literal
		// string 'The Punisher' and the group at position 3
		String replaced = matcher.replaceAll("$1The Punisher$3");
		Assert.assertEquals("Frank Castle is The Punisher. No Really!", replaced);

		// Also works with replaceFirst, since we have a single match
		replaced = matcher.replaceFirst("$1The Punisher$3");
		Assert.assertEquals("Frank Castle is The Punisher. No Really!", replaced);

		// Lets reset the matcher and use appendReplacement instead to replace the individual groups
		matcher.reset();
		matcher.matches();

		// Replace the match, which is everything, by group 1, 'The Punisher' and group 3
		StringBuffer buffer = new StringBuffer();
		matcher.appendReplacement(buffer, "$1The Punisher$3");
		Assert.assertEquals("Frank Castle is The Punisher. No Really!", buffer.toString());

	}

}
}