/*
    * Copyright (C) 2009, Christian Halstrick <christian.halstrick@sap.com> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  
  package org.eclipse.jgit.merge;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static org.junit.Assert.assertEquals;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  
  import org.eclipse.jgit.diff.RawText;
  import org.eclipse.jgit.diff.RawTextComparator;
  import org.eclipse.jgit.lib.Constants;
  import org.junit.Assume;
  import org.junit.Test;
  import org.junit.experimental.theories.DataPoints;
  import org.junit.experimental.theories.Theories;
  import org.junit.runner.RunWith;
  
  @RunWith(Theories.class)
  public class MergeAlgorithmTest {
  	MergeFormatter fmt=new MergeFormatter();
  
  	private final boolean newlineAtEnd;
  
  	@DataPoints
  	public static boolean[] newlineAtEndDataPoints = { false, true };
  
  	public MergeAlgorithmTest(boolean newlineAtEnd) {
  		this.newlineAtEnd = newlineAtEnd;
  	}
  
  	/**
  	 * Check for a conflict where the second text was changed similar to the
  	 * first one, but the second texts modification covers one more line.
  	 *
  	 * @throws IOException
  	 */
  	@Test
  	public void testTwoConflictingModifications() throws IOException {
  		assertEquals(t("a<b=Z>Zdefghij"),
  				merge("abcdefghij", "abZdefghij", "aZZdefghij"));
  	}
  
  	/**
  	 * Test a case where we have three consecutive chunks. The first text
  	 * modifies all three chunks. The second text modifies the first and the
  	 * last chunk. This should be reported as one conflicting region.
  	 *
  	 * @throws IOException
  	 */
  	@Test
  	public void testOneAgainstTwoConflictingModifications() throws IOException {
  		assertEquals(t("aZ<Z=c>Zefghij"),
  				merge("abcdefghij", "aZZZefghij", "aZcZefghij"));
  	}
  
  	/**
  	 * Test a merge where only the second text contains modifications. Expect as
  	 * merge result the second text.
  	 *
  	 * @throws IOException
  	 */
  	@Test
  	public void testNoAgainstOneModification() throws IOException {
  		assertEquals(t("aZcZefghij"),
  				merge("abcdefghij", "abcdefghij", "aZcZefghij"));
  	}
  
  	/**
  	 * Both texts contain modifications but not on the same chunks. Expect a
  	 * non-conflict merge result.
  	 *
  	 * @throws IOException
  	 */
  	@Test
  	public void testTwoNonConflictingModifications() throws IOException {
  		assertEquals(t("YbZdefghij"),
  				merge("abcdefghij", "abZdefghij", "Ybcdefghij"));
  	}
  
  	/**
  	 * Merge two complicated modifications. The merge algorithm has to extend
  	 * and combine conflicting regions to get to the expected merge result.
  	 *
  	 * @throws IOException
  	 */
  	@Test
  	public void testTwoComplicatedModifications() throws IOException {
  		assertEquals(t("a<ZZZZfZhZj=bYdYYYYiY>"),
  				merge("abcdefghij", "aZZZZfZhZj", "abYdYYYYiY"));
 	}
 
 	/**
 	 * Merge two modifications with a shared delete at the end. The underlying
 	 * diff algorithm has to provide consistent edit results to get the expected
 	 * merge result.
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testTwoModificationsWithSharedDelete() throws IOException {
 		assertEquals(t("Cb}n}"),
 				merge("ab}n}n}", "ab}n}", "Cb}n}"));
 	}
 
 	/**
 	 * Merge modifications with a shared insert in the middle. The
 	 * underlying diff algorithm has to provide consistent edit
 	 * results to get the expected merge result.
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testModificationsWithMiddleInsert() throws IOException {
 		assertEquals(t("aBcd123123uvwxPq"),
 				merge("abcd123uvwxpq", "aBcd123123uvwxPq", "abcd123123uvwxpq"));
 	}
 
 	/**
 	 * Merge modifications with a shared delete in the middle. The
 	 * underlying diff algorithm has to provide consistent edit
 	 * results to get the expected merge result.
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testModificationsWithMiddleDelete() throws IOException {
 		assertEquals(t("Abz}z123Q"),
 				merge("abz}z}z123q", "Abz}z123Q", "abz}z123q"));
 	}
 
 	/**
 	 * Test a conflicting region at the very start of the text.
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testConflictAtStart() throws IOException {
 		assertEquals(t("<Z=Y>bcdefghij"),
 				merge("abcdefghij", "Zbcdefghij", "Ybcdefghij"));
 	}
 
 	/**
 	 * Test a conflicting region at the very end of the text.
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testConflictAtEnd() throws IOException {
 		assertEquals(t("abcdefghi<Z=Y>"),
 				merge("abcdefghij", "abcdefghiZ", "abcdefghiY"));
 	}
 
 	/**
 	 * Check for a conflict where the second text was changed similar to the
 	 * first one, but the second texts modification covers one more line.
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testSameModification() throws IOException {
 		assertEquals(t("abZdefghij"),
 				merge("abcdefghij", "abZdefghij", "abZdefghij"));
 	}
 
 	/**
 	 * Check that a deleted vs. a modified line shows up as conflict (see Bug
 	 * 328551)
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testDeleteVsModify() throws IOException {
 		assertEquals(t("ab<=Z>defghij"),
 				merge("abcdefghij", "abdefghij", "abZdefghij"));
 	}
 
 	@Test
 	public void testInsertVsModify() throws IOException {
 		assertEquals(t("a<bZ=XY>"), merge("ab", "abZ", "aXY"));
 	}
 
 	@Test
 	public void testAdjacentModifications() throws IOException {
 		assertEquals(t("a<Zc=bY>d"), merge("abcd", "aZcd", "abYd"));
 	}
 
 	@Test
 	public void testSeparateModifications() throws IOException {
 		assertEquals(t("aZcYe"), merge("abcde", "aZcde", "abcYe"));
 	}
 
 	@Test
 	public void testBlankLines() throws IOException {
 		assertEquals(t("aZc\nYe"), merge("abc\nde", "aZc\nde", "abc\nYe"));
 	}
 
 	/**
 	 * Test merging two contents which do one similar modification and one
 	 * insertion is only done by one side, in the middle. Between modification
 	 * and insertion is a block which is common between the two contents and the
 	 * common base
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testTwoSimilarModsAndOneInsert() throws IOException {
 		assertEquals(t("aBcDde"), merge("abcde", "aBcde", "aBcDde"));
 		assertEquals(t("IAAAJCAB"), merge("iACAB", "IACAB", "IAAAJCAB"));
 		assertEquals(t("HIAAAJCAB"), merge("HiACAB", "HIACAB", "HIAAAJCAB"));
 		assertEquals(t("AGADEFHIAAAJCAB"),
 				merge("AGADEFHiACAB", "AGADEFHIACAB", "AGADEFHIAAAJCAB"));
 	}
 
 	/**
 	 * Test merging two contents which do one similar modification and one
 	 * insertion is only done by one side, at the end. Between modification and
 	 * insertion is a block which is common between the two contents and the
 	 * common base
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testTwoSimilarModsAndOneInsertAtEnd() throws IOException {
 		Assume.assumeTrue(newlineAtEnd);
 		assertEquals(t("IAAJ"), merge("iA", "IA", "IAAJ"));
 		assertEquals(t("IAJ"), merge("iA", "IA", "IAJ"));
 		assertEquals(t("IAAAJ"), merge("iA", "IA", "IAAAJ"));
 	}
 
 	@Test
 	public void testTwoSimilarModsAndOneInsertAtEndNoNewlineAtEnd()
 			throws IOException {
 		Assume.assumeFalse(newlineAtEnd);
 		assertEquals(t("I<A=AAJ>"), merge("iA", "IA", "IAAJ"));
 		assertEquals(t("I<A=AJ>"), merge("iA", "IA", "IAJ"));
 		assertEquals(t("I<A=AAAJ>"), merge("iA", "IA", "IAAAJ"));
 	}
 
 	/**
 	 * Test situations where (at least) one input value is the empty text
 	 *
 	 * @throws IOException
 	 */
 	@Test
 	public void testEmptyTexts() throws IOException {
 		// test modification against deletion
 		assertEquals(t("<AB=>"), merge("A", "AB", ""));
 		assertEquals(t("<=AB>"), merge("A", "", "AB"));
 
 		// test unmodified against deletion
 		assertEquals(t(""), merge("AB", "AB", ""));
 		assertEquals(t(""), merge("AB", "", "AB"));
 
 		// test deletion against deletion
 		assertEquals(t(""), merge("AB", "", ""));
 	}
 
 	private String merge(String commonBase, String ours, String theirs) throws IOException {
 		MergeResult r = new MergeAlgorithm().merge(RawTextComparator.DEFAULT,
 				T(commonBase), T(ours), T(theirs));
 		ByteArrayOutputStream bo=new ByteArrayOutputStream(50);
 		fmt.formatMerge(bo, r, "B", "O", "T", UTF_8);
 		return new String(bo.toByteArray(), UTF_8);
 	}
 
 	public String t(String text) {
 		StringBuilder r = new StringBuilder();
 		for (int i = 0; i < text.length(); i++) {
 			char c = text.charAt(i);
 			switch (c) {
 			case '<':
 				r.append("<<<<<<< O\n");
 				break;
 			case '=':
 				r.append("=======\n");
 				break;
 			case '>':
 				r.append(">>>>>>> T\n");
 				break;
 			default:
 				r.append(c);
 				if (newlineAtEnd || i < text.length() - 1)
 					r.append('\n');
 			}
 		}
 		return r.toString();
 	}
 
 	public RawText T(String text) {
 		return new RawText(Constants.encode(t(text)));
 	}
 }