/*
    * Copyright (C) 2018, 2020 Thomas Wolf <thomas.wolf@paranor.ch> 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.junit.ssh;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertNotEquals;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertTrue;
  
  import java.io.BufferedWriter;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.security.KeyPair;
  import java.security.KeyPairGenerator;
  import java.security.PrivateKey;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Base64;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  
  import org.apache.sshd.common.config.keys.PublicKeyEntry;
  import org.eclipse.jgit.api.CloneCommand;
  import org.eclipse.jgit.api.Git;
  import org.eclipse.jgit.api.PushCommand;
  import org.eclipse.jgit.api.ResetCommand.ResetType;
  import org.eclipse.jgit.errors.UnsupportedCredentialItem;
  import org.eclipse.jgit.junit.RepositoryTestCase;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.transport.CredentialItem;
  import org.eclipse.jgit.transport.CredentialsProvider;
  import org.eclipse.jgit.transport.PushResult;
  import org.eclipse.jgit.transport.RemoteRefUpdate;
  import org.eclipse.jgit.transport.SshSessionFactory;
  import org.eclipse.jgit.transport.URIish;
  import org.eclipse.jgit.util.FS;
  import org.junit.After;
  
  /**
   * Root class for ssh tests. Sets up the ssh test server. A set of pre-computed
   * keys for testing is provided in the bundle and can be used in test cases via
   * {@link #copyTestResource(String, File)}. These test key files names have four
   * components, separated by a single underscore: "id", the algorithm, the bits
   * (if variable), and the password if the private key is encrypted. For instance
   * "{@code id_ecdsa_384_testpass}" is an encrypted ECDSA-384 key. The passphrase
   * to decrypt is "testpass". The key "{@code id_ecdsa_384}" is the same but
   * unencrypted. All keys were generated and encrypted via ssh-keygen. Note that
   * DSA and ec25519 have no "bits" component. Available keys are listed in
   * {@link SshTestBase#KEY_RESOURCES}.
   */
  public abstract class SshTestHarness extends RepositoryTestCase {
  
  	protected static final String TEST_USER = "testuser";
  
  	protected File sshDir;
  
  	protected File privateKey1;
  
  	protected File privateKey2;
  
  	protected File publicKey1;
  
  	protected File publicKey2;
  
  	protected SshTestGitServer server;
  
  	private SshSessionFactory factory;
  
  	protected int testPort;
  
  	protected File knownHosts;
  
  	private File homeDir;
  
  	@Override
  	public void setUp() throws Exception {
  		super.setUp();
  		writeTrashFile("file.txt", "something");
  		try (Git git = new Git(db)) {
  			git.add().addFilepattern("file.txt").call();
  			git.commit().setMessage("Initial commit").call();
  		}
  		mockSystemReader.setProperty("user.home",
 				getTemporaryDirectory().getAbsolutePath());
 		mockSystemReader.setProperty("HOME",
 				getTemporaryDirectory().getAbsolutePath());
 		homeDir = FS.DETECTED.userHome();
 		FS.DETECTED.setUserHome(getTemporaryDirectory().getAbsoluteFile());
 		sshDir = new File(getTemporaryDirectory(), ".ssh");
 		assertTrue(sshDir.mkdir());
 		File serverDir = new File(getTemporaryDirectory(), "srv");
 		assertTrue(serverDir.mkdir());
 		// Create two key pairs. Let's not call them "id_rsa".
 		KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
 		generator.initialize(2048);
 		privateKey1 = new File(sshDir, "first_key");
 		privateKey2 = new File(sshDir, "second_key");
 		publicKey1 = createKeyPair(generator.generateKeyPair(), privateKey1);
 		publicKey2 = createKeyPair(generator.generateKeyPair(), privateKey2);
 		// Create a host key
 		KeyPair hostKey = generator.generateKeyPair();
 		// Start a server with our test user and the first key.
 		server = new SshTestGitServer(TEST_USER, publicKey1.toPath(), db,
 				hostKey);
 		testPort = server.start();
 		assertTrue(testPort > 0);
 		knownHosts = new File(sshDir, "known_hosts");
 		StringBuilder knownHostsLine = new StringBuilder();
 		knownHostsLine.append("[localhost]:").append(testPort).append(' ');
 		PublicKeyEntry.appendPublicKeyEntry(knownHostsLine,
 				hostKey.getPublic());
 		Files.write(knownHosts.toPath(),
 				Collections.singleton(knownHostsLine.toString()));
 		factory = createSessionFactory();
 		SshSessionFactory.setInstance(factory);
 	}
 
 	private static File createKeyPair(KeyPair newKey, File privateKeyFile)
 			throws Exception {
 		// Write PKCS#8 PEM unencrypted. Both JSch and sshd can read that.
 		PrivateKey privateKey = newKey.getPrivate();
 		String format = privateKey.getFormat();
 		if (!"PKCS#8".equalsIgnoreCase(format)) {
 			throw new IOException("Cannot write " + privateKey.getAlgorithm()
 					+ " key in " + format + " format");
 		}
 		try (BufferedWriter writer = Files.newBufferedWriter(
 				privateKeyFile.toPath(), StandardCharsets.US_ASCII)) {
 			writer.write("-----BEGIN PRIVATE KEY-----");
 			writer.newLine();
 			write(writer, privateKey.getEncoded(), 64);
 			writer.write("-----END PRIVATE KEY-----");
 			writer.newLine();
 		}
 		File publicKeyFile = new File(privateKeyFile.getParentFile(),
 				privateKeyFile.getName() + ".pub");
 		StringBuilder builder = new StringBuilder();
 		PublicKeyEntry.appendPublicKeyEntry(builder, newKey.getPublic());
 		builder.append(' ').append(TEST_USER);
 		try (OutputStream out = new FileOutputStream(publicKeyFile)) {
 			out.write(builder.toString().getBytes(StandardCharsets.US_ASCII));
 		}
 		return publicKeyFile;
 	}
 
 	private static void write(BufferedWriter out, byte[] bytes, int lineLength)
 			throws IOException {
 		String data = Base64.getEncoder().encodeToString(bytes);
 		int last = data.length();
 		for (int i = 0; i < last; i += lineLength) {
 			if (i + lineLength <= last) {
 				out.write(data.substring(i, i + lineLength));
 			} else {
 				out.write(data.substring(i));
 			}
 			out.newLine();
 		}
 		Arrays.fill(bytes, (byte) 0);
 	}
 
 	/**
 	 * Creates a new known_hosts file with one entry for the given host and port
 	 * taken from the given public key file.
 	 *
 	 * @param file
 	 *            to write the known_hosts file to
 	 * @param host
 	 *            for the entry
 	 * @param port
 	 *            for the entry
 	 * @param publicKey
 	 *            to use
 	 * @return the public-key part of the line
 	 * @throws IOException
 	 */
 	protected static String createKnownHostsFile(File file, String host,
 			int port, File publicKey) throws IOException {
 		List<String> lines = Files.readAllLines(publicKey.toPath(),
 				StandardCharsets.UTF_8);
 		assertEquals("Public key has too many lines", 1, lines.size());
 		String pubKey = lines.get(0);
 		// Strip off the comment.
 		String[] parts = pubKey.split("\\s+");
 		assertTrue("Unexpected key content",
 				parts.length == 2 || parts.length == 3);
 		String keyPart = parts[0] + ' ' + parts[1];
 		String line = '[' + host + "]:" + port + ' ' + keyPart;
 		Files.write(file.toPath(), Collections.singletonList(line));
 		return keyPart;
 	}
 
 	/**
 	 * Checks whether there is a line for the given host and port that also
 	 * matches the given key part in the list of lines.
 	 *
 	 * @param host
 	 *            to look for
 	 * @param port
 	 *            to look for
 	 * @param keyPart
 	 *            to look for
 	 * @param lines
 	 *            to look in
 	 * @return {@code true} if found, {@code false} otherwise
 	 */
 	protected boolean hasHostKey(String host, int port, String keyPart,
 			List<String> lines) {
 		String h = '[' + host + "]:" + port;
 		return lines.stream()
 				.anyMatch(l -> l.contains(h) && l.contains(keyPart));
 	}
 
 	@After
 	public void shutdownServer() throws Exception {
 		if (server != null) {
 			server.stop();
 			server = null;
 		}
 		FS.DETECTED.setUserHome(homeDir);
 		SshSessionFactory.setInstance(null);
 		factory = null;
 	}
 
 	protected abstract SshSessionFactory createSessionFactory();
 
 	protected SshSessionFactory getSessionFactory() {
 		return factory;
 	}
 
 	protected abstract void installConfig(String... config);
 
 	/**
 	 * Copies a test data file contained in the test bundle to the given file.
 	 * Equivalent to {@link #copyTestResource(Class, String, File)} with
 	 * {@code SshTestHarness.class} as first parameter.
 	 *
 	 * @param resourceName
 	 *            of the test resource to copy
 	 * @param to
 	 *            file to copy the resource to
 	 * @throws IOException
 	 *             if the resource cannot be copied
 	 */
 	protected void copyTestResource(String resourceName, File to)
 			throws IOException {
 		copyTestResource(SshTestHarness.class, resourceName, to);
 	}
 
 	/**
 	 * Copies a test data file contained in the test bundle to the given file,
 	 * using {@link Class#getResourceAsStream(String)} to get the test resource.
 	 *
 	 * @param loader
 	 *            {@link Class} to use to load the resource
 	 * @param resourceName
 	 *            of the test resource to copy
 	 * @param to
 	 *            file to copy the resource to
 	 * @throws IOException
 	 *             if the resource cannot be copied
 	 */
 	protected void copyTestResource(Class<?> loader, String resourceName,
 			File to) throws IOException {
 		try (InputStream in = loader.getResourceAsStream(resourceName)) {
 			Files.copy(in, to.toPath());
 		}
 	}
 
 	protected File cloneWith(String uri, File to, CredentialsProvider provider,
 			String... config) throws Exception {
 		installConfig(config);
 		CloneCommand clone = Git.cloneRepository().setCloneAllBranches(true)
 				.setDirectory(to).setURI(uri);
 		if (provider != null) {
 			clone.setCredentialsProvider(provider);
 		}
 		try (Git git = clone.call()) {
 			Repository repo = git.getRepository();
 			assertNotNull(repo.resolve("master"));
 			assertNotEquals(db.getWorkTree(),
 					git.getRepository().getWorkTree());
 			assertTrue(new File(git.getRepository().getWorkTree(), "file.txt")
 					.exists());
 			return repo.getWorkTree();
 		}
 	}
 
 	protected void pushTo(File localClone) throws Exception {
 		pushTo(null, localClone);
 	}
 
 	protected void pushTo(CredentialsProvider provider, File localClone)
 			throws Exception {
 		RevCommit commit;
 		File newFile = null;
 		try (Git git = Git.open(localClone)) {
 			// Write a new file and modify a file.
 			Repository local = git.getRepository();
 			newFile = File.createTempFile("new", "sshtest",
 					local.getWorkTree());
 			write(newFile, "something new");
 			File existingFile = new File(local.getWorkTree(), "file.txt");
 			write(existingFile, "something else");
 			git.add().addFilepattern("file.txt")
 					.addFilepattern(newFile.getName())
 					.call();
 			commit = git.commit().setMessage("Local commit").call();
 			// Push
 			PushCommand push = git.push().setPushAll();
 			if (provider != null) {
 				push.setCredentialsProvider(provider);
 			}
 			Iterable<PushResult> results = push.call();
 			for (PushResult result : results) {
 				for (RemoteRefUpdate u : result.getRemoteUpdates()) {
 					assertEquals(
 							"Could not update " + u.getRemoteName() + ' '
 									+ u.getMessage(),
 							RemoteRefUpdate.Status.OK, u.getStatus());
 				}
 			}
 		}
 		// Now check "master" in the remote repo directly:
 		assertEquals("Unexpected remote commit", commit, db.resolve("master"));
 		assertEquals("Unexpected remote commit", commit,
 				db.resolve(Constants.HEAD));
 		File remoteFile = new File(db.getWorkTree(), newFile.getName());
 		assertFalse("File should not exist on remote", remoteFile.exists());
 		try (Git git = new Git(db)) {
 			git.reset().setMode(ResetType.HARD).setRef(Constants.HEAD).call();
 		}
 		assertTrue("File does not exist on remote", remoteFile.exists());
 		checkFile(remoteFile, "something new");
 	}
 
 	protected static class TestCredentialsProvider extends CredentialsProvider {
 
 		private final List<String> stringStore;
 
 		private final Iterator<String> strings;
 
 		public TestCredentialsProvider(String... strings) {
 			if (strings == null || strings.length == 0) {
 				stringStore = Collections.emptyList();
 			} else {
 				stringStore = Arrays.asList(strings);
 			}
 			this.strings = stringStore.iterator();
 		}
 
 		@Override
 		public boolean isInteractive() {
 			return true;
 		}
 
 		@Override
 		public boolean supports(CredentialItem... items) {
 			return true;
 		}
 
 		@Override
 		public boolean get(URIish uri, CredentialItem... items)
 				throws UnsupportedCredentialItem {
 			System.out.println("URI: " + uri);
 			for (CredentialItem item : items) {
 				System.out.println(item.getClass().getSimpleName() + ' '
 						+ item.getPromptText());
 			}
 			logItems(uri, items);
 			for (CredentialItem item : items) {
 				if (item instanceof CredentialItem.InformationalMessage) {
 					continue;
 				}
 				if (item instanceof CredentialItem.YesNoType) {
 					((CredentialItem.YesNoType) item).setValue(true);
 				} else if (item instanceof CredentialItem.CharArrayType) {
 					if (strings.hasNext()) {
 						((CredentialItem.CharArrayType) item)
 								.setValue(strings.next().toCharArray());
 					} else {
 						return false;
 					}
 				} else if (item instanceof CredentialItem.StringType) {
 					if (strings.hasNext()) {
 						((CredentialItem.StringType) item)
 								.setValue(strings.next());
 					} else {
 						return false;
 					}
 				} else {
 					return false;
 				}
 			}
 			return true;
 		}
 
 		private List<LogEntry> log = new ArrayList<>();
 
 		private void logItems(URIish uri, CredentialItem... items) {
 			log.add(new LogEntry(uri, Arrays.asList(items)));
 		}
 
 		public List<LogEntry> getLog() {
 			return log;
 		}
 	}
 
 	protected static class LogEntry {
 
 		private URIish uri;
 
 		private List<CredentialItem> items;
 
 		public LogEntry(URIish uri, List<CredentialItem> items) {
 			this.uri = uri;
 			this.items = items;
 		}
 
 		public URIish getURIish() {
 			return uri;
 		}
 
 		public List<CredentialItem> getItems() {
 			return items;
 		}
 	}
 }