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 * Institute of Molecular Cell Biology and Genetics, University of
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package org.scijava.test;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.AbstractMap;
import java.util.Map;

import org.scijava.util.FileUtils;
import org.scijava.util.Types;

/**
 * A bunch of helpful functions for unit tests.
 * 
 * @author Johannes Schindelin
 * @author Curtis Rueden
 */
public class TestUtils {

	/**
	 * Creates an empty file at the given path, creating intermediate directories
	 * as necessary.
	 * 
	 * @param parent The parent directory of the relative path.
	 * @param path The forward-slash-separated path to create.
	 * @return a {@link File} pointing at the newly created empty path.
	 * @throws IOException if the file cannot be created.
	 */
	public static File createPath(final File parent, final String path)
		throws IOException
	{
		File file = parent;
		final String[] elements = path.split("/");
		for (int i=0; i<elements.length; i++) {
			file = new File(file, elements[i]);
			if (i == elements.length - 1) file.createNewFile();
			else file.mkdir();
		}
		return file;
	}

	/**
	 * Makes a temporary directory for use with unit tests.
	 * <p>
	 * When the unit test runs in a Maven context, the temporary directory will be
	 * created in the {@code target/} directory corresponding to the calling class
	 * instead of {@code /tmp/}.
	 * </p>
	 * 
	 * @param prefix the prefix for the directory's name
	 * @return the reference to the newly-created temporary directory
	 * @throws IOException
	 */
	public static File createTemporaryDirectory(final String prefix) throws IOException {
		final Map.Entry<Class<?>, String> calling = getCallingCodeLocation(null);
		return createTemporaryDirectory(prefix, calling.getKey(), calling.getValue());
	}

	/**
	 * Makes a temporary directory for use with unit tests.
	 * <p>
	 * When the unit test runs in a Maven context, the temporary directory will be
	 * created in the corresponding {@code target/} directory instead of
	 * {@code /tmp/}.
	 * </p>
	 * 
	 * @param prefix the prefix for the directory's name
	 * @param forClass the class for context (to determine whether there's a
	 *          {@code target/} directory)
	 * @return the reference to the newly-created temporary directory
	 * @throws IOException
	 */
	public static File createTemporaryDirectory(final String prefix,
		final Class<?> forClass) throws IOException
	{
		return createTemporaryDirectory(prefix, forClass, "" + temporaryDirectoryCounter++);
	}

	private static int temporaryDirectoryCounter = 1;

	/**
	 * Makes a temporary directory for use with unit tests.
	 * <p>
	 * When the unit test runs in a Maven context, the temporary directory will be
	 * created in the corresponding {@code target/} directory instead of
	 * {@code /tmp/}.
	 * </p>
	 * 
	 * @param prefix the prefix for the directory's name
	 * @param forClass the class for context (to determine whether there's a
	 *          {@code target/} directory)
	 * @param suffix the suffix for the directory's name
	 * @return the reference to the newly-created temporary directory
	 * @throws IOException
	 */
	public static File createTemporaryDirectory(final String prefix,
		final Class<?> forClass, final String suffix) throws IOException
	{
		final URL directory = Types.location(forClass);
		if (directory == null) {
			throw new IllegalArgumentException("No location for class " + forClass);
		}
		if (!"file".equals(directory.getProtocol())) {
			throw new IllegalArgumentException("Invalid directory: " + directory);
		}
		final String path = directory.getPath();
		if (path == null) throw new IllegalArgumentException("Directory has null path");
		final File baseDirectory;
		if (path.endsWith("/target/test-classes/")) {
			baseDirectory = new File(path).getParentFile();
		} else {
			baseDirectory = new File(path);
		}

		File file = new File(baseDirectory, prefix + suffix);
		if (file.isDirectory()) {
			if (!FileUtils.deleteRecursively(file)) {
				// Oh, how I *love* Windows. Love, love, love.
				for (int i = -1; file.isDirectory(); i--) {
					file = new File(baseDirectory, prefix + i + suffix);
				}
			}
		}
		else if (file.exists() && !file.delete()) {
			throw new IOException("Could not remove " + file);
		}
		if (!file.mkdir()) throw new IOException("Could not make directory " + file);
		return file;
	}

	/**
	 * Returns the class of the caller (excluding the specified class).
	 * <p>
	 * Sometimes it is convenient to determine the caller's context, e.g. to
	 * determine whether running in a maven-surefire-plugin context (in which case
	 * the location of the caller's class would end in
	 * {@code target/test-classes/}).
	 * </p>
	 * 
	 * @param excluding the class to exclude (or null)
	 * @return the class of the caller
	 */
	public static Class<?> getCallingClass(final Class<?> excluding) {
		return getCallingCodeLocation(excluding).getKey();
	}

	/**
	 * Returns the class and the method/line number of the caller (excluding the specified class).
	 * <p>
	 * Sometimes it is convenient to determine the caller's context, e.g. to
	 * determine whether running in a maven-surefire-plugin context (in which case
	 * the location of the caller's class would end in
	 * {@code target/test-classes/}).
	 * </p>
	 * 
	 * @param excluding the class to exclude (or null)
	 * @return the class of the caller and the method and line number
	 */
	public static Map.Entry<Class<?>, String> getCallingCodeLocation(final Class<?> excluding) {
		final String thisClassName = TestUtils.class.getName();
		final String thisClassName2 = excluding == null ? null : excluding.getName();
		final Thread currentThread = Thread.currentThread();
		for (final StackTraceElement element : currentThread.getStackTrace()) {
			final String thatClassName = element.getClassName();
			if (thatClassName == null || thatClassName.equals(thisClassName) ||
				thatClassName.equals(thisClassName2) ||
				thatClassName.endsWith("TestUtils") ||
				thatClassName.startsWith("java.lang.")) {
				continue;
			}
			final ClassLoader loader = currentThread.getContextClassLoader();
			final Class<?> clazz;
			try {
				clazz = loader.loadClass(element.getClassName());
				final URL url = clazz.getResource("/" + clazz.getName().replace('.', '/') + ".class");
				if (url == null || !"file".equals(url.getProtocol())) {
					// the calling code location must be unpacked; Maven artifacts in $HOME/.m2/ are excluded
					continue;
				}
			}
			catch (ClassNotFoundException e) {
				throw new UnsupportedOperationException("Could not load " +
					element.getClassName() + " with the current context class loader (" +
					loader + ")!");
			}
			final String suffix = element.getMethodName() + "-L" + element.getLineNumber();
			return new AbstractMap.SimpleEntry<>(clazz, suffix);
		}
		throw new UnsupportedOperationException("No calling class outside " + thisClassName + " found!");
	}

}
