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/*
 * SCIE -- Spinal Cord Injury Information Extraction
 * Copyright (C) 2013, 2014
 * Raphael Dickfelder, Jan Göpfert, Benjamin Paaßen, Andreas Stöckel
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see .
 */

package de.citec.scie.util;

import java.io.File;
import java.io.IOException;

/**
 * The ResourceFinder class is responsible for finding certain resources. This
 * class is mainly needed because we want the scie-core subproject to run from
 * its own sub folder yet allow to store the data in the top-level project. To
 * do so, the ResourceFinder traverses upwards the complete directory tree. If
 * you run in an environment where this might be a security threat or you don't
 * want this application to search for files in locations it shouldn't simply
 * provide the scie.noascend property to true, e.g. via the
 * -Dscie.noascend="true" Java CLI switch.
 *
 * @author Andreas Stöckel -- [email protected]
 */
public class ResourceFinder {

	/**
	 * If true, ascends the complete directory tree upwards to search for the
	 * specified files.
	 */
	private static final boolean ASCEND
			= !System.getProperty("scie.noascend", "false").equalsIgnoreCase("true");

	/**
	 * Exception thrown whenever a requested file is not found.
	 */
	public static class ResourceFinderException extends RuntimeException {

		/**
		 * Constructor of the ResourceFinderException class.
		 *
		 * @param msg message describing the exception.
		 * @param cause cause of the exception or null.
		 */
		public ResourceFinderException(String msg, Throwable cause) {
			super(msg, cause);
		}

	}

	/**
	 * Tries to find a file with the given filename. Throws a
	 * ResourceFinderException if the file is not found. This function ascends
	 * the directory tree until the file is found (unless -Dscie.noascend="true"
	 * is set).
	 *
	 * @param name is the name of the file to find. The filename should not
	 * start with a "/".
	 * @param path is an array of subdirectories/prefixes in which the given
	 * file should be searched. The paths should end with a "/". If null or an
	 * empty array is given, the prefix "./" is used. Paths and filename are
	 * joined using the "parent", "child" version of the File constructor.
	 * @return a File instance pointing at the found file.
	 */
	public static File find(String name, String[] path) {
		// Search at least in the current directory
		if (path == null || path.length == 0) {
			path = new String[]{"./"};
		}

		try {
			final String wd = (new File(".")).getCanonicalPath();
			File curDir = new File(wd);
			do {
				for (String p : path) {
					final File f = new File(curDir, (new File(p, name)).getPath());
					if (f.exists()) {
						final String fp = f.getCanonicalPath();
						//System.err.println("Found " + name + " at " + fp);
						return new File(fp);
					}
				}
				curDir = curDir.getParentFile();
			} while (ASCEND && curDir != null && !curDir.getPath().equals("/"));
		} catch (IOException ex) {
			throw new ResourceFinderException(ex.getMessage(), ex);
		}
		throw new RuntimeException("File " + name
				+ " not found in this or the parent directories!", null);
	}

	/**
	 * Tries to find a file with the given filename. Throws a
	 * ResourceFinderException if the file is not found. This function ascends
	 * the directory tree until the file is found (unless -Dscie.noascend="true"
	 * is set).
	 *
	 * @param name is the name of the file to find. The filename should not
	 * start with a "/".
	 * @return a file
	 */
	public static File find(String name) {
		return find(name, null);
	}

}