/*
 * Copyright (C) 2009-2010, Google Inc.
 * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com>
 * Copyright (C) 2007, Shawn O. Pearce <spearce@spearce.org>
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.junit;

import static org.junit.Assert.assertFalse;
import static org.junit.Assert.fail;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.PersonIdent;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.lib.RepositoryCache;
import org.eclipse.jgit.storage.file.FileBasedConfig;
import org.eclipse.jgit.storage.file.FileRepository;
import org.eclipse.jgit.storage.file.WindowCache;
import org.eclipse.jgit.storage.file.WindowCacheConfig;
import org.eclipse.jgit.util.FS;
import org.eclipse.jgit.util.FileUtils;
import org.eclipse.jgit.util.IO;
import org.eclipse.jgit.util.SystemReader;
import org.junit.After;
import org.junit.Before;

/**
 * JUnit TestCase with specialized support for temporary local repository.
 * <p>
 * A temporary directory is created for each test, allowing each test to use a
 * fresh environment. The temporary directory is cleaned up after the test ends.
 * <p>
 * Callers should not use {@link RepositoryCache} from within these tests as it
 * may wedge file descriptors open past the end of the test.
 * <p>
 * A system property {@code jgit.junit.usemmap} defines whether memory mapping
 * is used. Memory mapping has an effect on the file system, in that memory
 * mapped files in Java cannot be deleted as long as the mapped arrays have not
 * been reclaimed by the garbage collector. The programmer cannot control this
 * with precision, so temporary files may hang around longer than desired during
 * a test, or tests may fail altogether if there is insufficient file
 * descriptors or address space for the test process.
 */
public abstract class LocalDiskRepositoryTestCase {
	private static Thread shutdownHook;

	private static int testCount;

	private static final boolean useMMAP = "true".equals(System
			.getProperty("jgit.junit.usemmap"));

	/** A fake (but stable) identity for author fields in the test. */
	protected PersonIdent author;

	/** A fake (but stable) identity for committer fields in the test. */
	protected PersonIdent committer;

	private final File trash = new File(new File("target"), "trash");

	private final List<Repository> toClose = new ArrayList<Repository>();

	private MockSystemReader mockSystemReader;

	@Before
	public void setUp() throws Exception {

		synchronized(this) {
			if (shutdownHook == null) {
				shutdownHook = new Thread() {
					@Override
					public void run() {
						// On windows accidentally open files or memory
						// mapped regions may prevent files from being deleted.
						// Suggesting a GC increases the likelihood that our
						// test repositories actually get removed after the
						// tests, even in the case of failure.
						System.gc();
						recursiveDelete("SHUTDOWN", trash, false, false);
					}
				};
				Runtime.getRuntime().addShutdownHook(shutdownHook);
			}
		}
		recursiveDelete(testId(), trash, true, false);

		mockSystemReader = new MockSystemReader();
		mockSystemReader.userGitConfig = new FileBasedConfig(new File(trash,
				"usergitconfig"), FS.DETECTED);
		ceilTestDirectories(getCeilings());
		SystemReader.setInstance(mockSystemReader);

		final long now = mockSystemReader.getCurrentTime();
		final int tz = mockSystemReader.getTimezone(now);
		author = new PersonIdent("J. Author", "jauthor@example.com");
		author = new PersonIdent(author, now, tz);

		committer = new PersonIdent("J. Committer", "jcommitter@example.com");
		committer = new PersonIdent(committer, now, tz);

		final WindowCacheConfig c = new WindowCacheConfig();
		c.setPackedGitLimit(128 * WindowCacheConfig.KB);
		c.setPackedGitWindowSize(8 * WindowCacheConfig.KB);
		c.setPackedGitMMAP(useMMAP);
		c.setDeltaBaseCacheLimit(8 * WindowCacheConfig.KB);
		WindowCache.reconfigure(c);
	}


	protected List<File> getCeilings() {
		return Collections.singletonList(trash.getParentFile().getAbsoluteFile());
	}

	private void ceilTestDirectories(List<File> ceilings) {
		mockSystemReader.setProperty(Constants.GIT_CEILING_DIRECTORIES_KEY, makePath(ceilings));
	}

	private String makePath(List<?> objects) {
		final StringBuilder stringBuilder = new StringBuilder();
		for (Object object : objects) {
			if (stringBuilder.length() > 0)
				stringBuilder.append(File.pathSeparatorChar);
			stringBuilder.append(object.toString());
		}
		return stringBuilder.toString();
	}

	@After
	public void tearDown() throws Exception {
		RepositoryCache.clear();
		for (Repository r : toClose)
			r.close();
		toClose.clear();

		// Since memory mapping is controlled by the GC we need to
		// tell it this is a good time to clean up and unlock
		// memory mapped files.
		//
		if (useMMAP)
			System.gc();

		recursiveDelete(testId(), trash, false, true);
	}

	/** Increment the {@link #author} and {@link #committer} times. */
	protected void tick() {
		final long delta = TimeUnit.MILLISECONDS.convert(5 * 60,
				TimeUnit.SECONDS);
		final long now = author.getWhen().getTime() + delta;
		final int tz = mockSystemReader.getTimezone(now);

		author = new PersonIdent(author, now, tz);
		committer = new PersonIdent(committer, now, tz);
	}

	/**
	 * Recursively delete a directory, failing the test if the delete fails.
	 *
	 * @param dir
	 *            the recursively directory to delete, if present.
	 */
	protected void recursiveDelete(final File dir) {
		recursiveDelete(testId(), dir, false, true);
	}

	private static boolean recursiveDelete(final String testName,
			final File dir, boolean silent, boolean failOnError) {
		assert !(silent && failOnError);
		if (!dir.exists())
			return silent;
		final File[] ls = dir.listFiles();
		if (ls != null)
			for (int k = 0; k < ls.length; k++) {
				final File e = ls[k];
				if (e.isDirectory())
					silent = recursiveDelete(testName, e, silent, failOnError);
				else if (!e.delete()) {
					if (!silent)
						reportDeleteFailure(testName, failOnError, e);
					silent = !failOnError;
				}
			}
		if (!dir.delete()) {
			if (!silent)
				reportDeleteFailure(testName, failOnError, dir);
			silent = !failOnError;
		}
		return silent;
	}

	private static void reportDeleteFailure(final String testName,
			final boolean failOnError, final File e) {
		final String severity;
		if (failOnError)
			severity = "ERROR";
		else
			severity = "WARNING";

		final String msg = severity + ": Failed to delete " + e + " in "
				+ testName;
		if (failOnError)
			fail(msg);
		else
			System.err.println(msg);
	}

	/**
	 * Creates a new empty bare repository.
	 *
	 * @return the newly created repository, opened for access
	 * @throws IOException
	 *             the repository could not be created in the temporary area
	 */
	protected FileRepository createBareRepository() throws IOException {
		return createRepository(true /* bare */);
	}

	/**
	 * Creates a new empty repository within a new empty working directory.
	 *
	 * @return the newly created repository, opened for access
	 * @throws IOException
	 *             the repository could not be created in the temporary area
	 */
	protected FileRepository createWorkRepository() throws IOException {
		return createRepository(false /* not bare */);
	}

	/**
	 * Creates a new empty repository.
	 *
	 * @param bare
	 *            true to create a bare repository; false to make a repository
	 *            within its working directory
	 * @return the newly created repository, opened for access
	 * @throws IOException
	 *             the repository could not be created in the temporary area
	 */
	private FileRepository createRepository(boolean bare) throws IOException {
		File gitdir = createUniqueTestGitDir(bare);
		FileRepository db = new FileRepository(gitdir);
		assertFalse(gitdir.exists());
		db.create();
		toClose.add(db);
		return db;
	}

	/**
	 * Adds a repository to the list of repositories which is closed at the end
	 * of the tests
	 *
	 * @param r
	 *            the repository to be closed
	 */
	public void addRepoToClose(Repository r) {
		toClose.add(r);
	}

	private String createUniqueTestFolderPrefix() {
		return "test" + (System.currentTimeMillis() + "_" + (testCount++));
	}

	/**
	 * Creates a unique directory for a test
	 *
	 * @param name
	 *            a subdirectory
	 * @return a unique directory for a test
	 * @throws IOException
	 */
	protected File createTempDirectory(String name) throws IOException {
		String gitdirName = createUniqueTestFolderPrefix();
		File parent = new File(trash, gitdirName);
		File directory = new File(parent, name);
		FileUtils.mkdirs(directory);
		return directory.getCanonicalFile();
	}

	/**
	 * Creates a new unique directory for a test repository
	 *
	 * @param bare
	 *            true for a bare repository; false for a repository with a
	 *            working directory
	 * @return a unique directory for a test repository
	 * @throws IOException
	 */
	protected File createUniqueTestGitDir(boolean bare) throws IOException {
		String gitdirName = createUniqueTestFolderPrefix();
		if (!bare)
			gitdirName += "/";
		gitdirName += Constants.DOT_GIT;
		File gitdir = new File(trash, gitdirName);
		return gitdir.getCanonicalFile();
	}

	protected File createTempFile() throws IOException {
		return new File(trash, "tmp-" + UUID.randomUUID()).getCanonicalFile();
	}

	/**
	 * Run a hook script in the repository, returning the exit status.
	 *
	 * @param db
	 *            repository the script should see in GIT_DIR environment
	 * @param hook
	 *            path of the hook script to execute, must be executable file
	 *            type on this platform
	 * @param args
	 *            arguments to pass to the hook script
	 * @return exit status code of the invoked hook
	 * @throws IOException
	 *             the hook could not be executed
	 * @throws InterruptedException
	 *             the caller was interrupted before the hook completed
	 */
	protected int runHook(final Repository db, final File hook,
			final String... args) throws IOException, InterruptedException {
		final String[] argv = new String[1 + args.length];
		argv[0] = hook.getAbsolutePath();
		System.arraycopy(args, 0, argv, 1, args.length);

		final Map<String, String> env = cloneEnv();
		env.put("GIT_DIR", db.getDirectory().getAbsolutePath());
		putPersonIdent(env, "AUTHOR", author);
		putPersonIdent(env, "COMMITTER", committer);

		final File cwd = db.getWorkTree();
		final Process p = Runtime.getRuntime().exec(argv, toEnvArray(env), cwd);
		p.getOutputStream().close();
		p.getErrorStream().close();
		p.getInputStream().close();
		return p.waitFor();
	}

	private static void putPersonIdent(final Map<String, String> env,
			final String type, final PersonIdent who) {
		final String ident = who.toExternalString();
		final String date = ident.substring(ident.indexOf("> ") + 2);
		env.put("GIT_" + type + "_NAME", who.getName());
		env.put("GIT_" + type + "_EMAIL", who.getEmailAddress());
		env.put("GIT_" + type + "_DATE", date);
	}

	/**
	 * Create a string to a UTF-8 temporary file and return the path.
	 *
	 * @param body
	 *            complete content to write to the file. If the file should end
	 *            with a trailing LF, the string should end with an LF.
	 * @return path of the temporary file created within the trash area.
	 * @throws IOException
	 *             the file could not be written.
	 */
	protected File write(final String body) throws IOException {
		final File f = File.createTempFile("temp", "txt", trash);
		try {
			write(f, body);
			return f;
		} catch (Error e) {
			f.delete();
			throw e;
		} catch (RuntimeException e) {
			f.delete();
			throw e;
		} catch (IOException e) {
			f.delete();
			throw e;
		}
	}

	/**
	 * Write a string as a UTF-8 file.
	 *
	 * @param f
	 *            file to write the string to. Caller is responsible for making
	 *            sure it is in the trash directory or will otherwise be cleaned
	 *            up at the end of the test. If the parent directory does not
	 *            exist, the missing parent directories are automatically
	 *            created.
	 * @param body
	 *            content to write to the file.
	 * @throws IOException
	 *             the file could not be written.
	 */
	protected void write(final File f, final String body) throws IOException {
		FileUtils.mkdirs(f.getParentFile(), true);
		Writer w = new OutputStreamWriter(new FileOutputStream(f), "UTF-8");
		try {
			w.write(body);
		} finally {
			w.close();
		}
	}

	/**
	 * Fully read a UTF-8 file and return as a string.
	 *
	 * @param f
	 *            file to read the content of.
	 * @return UTF-8 decoded content of the file, empty string if the file
	 *         exists but has no content.
	 * @throws IOException
	 *             the file does not exist, or could not be read.
	 */
	protected String read(final File f) throws IOException {
		final byte[] body = IO.readFully(f);
		return new String(body, 0, body.length, "UTF-8");
	}

	private static String[] toEnvArray(final Map<String, String> env) {
		final String[] envp = new String[env.size()];
		int i = 0;
		for (Map.Entry<String, String> e : env.entrySet())
			envp[i++] = e.getKey() + "=" + e.getValue();
		return envp;
	}

	private static HashMap<String, String> cloneEnv() {
		return new HashMap<String, String>(System.getenv());
	}

	private String testId() {
		return getClass().getName() + "." + testCount;
	}

}