package net.sourceforge.tuned;


import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.ibm.icu.text.CharsetDetector;
import com.ibm.icu.text.CharsetMatch;


public final class FileUtilities {
	
	public static File renameFile(File source, File destination) throws IOException {
		// resolve destination
		if (!destination.isAbsolute()) {
			// same folder, different name
			destination = new File(source.getParentFile(), destination.getPath());
		}
		
		// make sure we that we can create the destination folder structure
		File destinationFolder = destination.getParentFile();
		
		// create parent folder if necessary
		if (!destinationFolder.isDirectory() && !destinationFolder.mkdirs()) {
			throw new IOException("Failed to create folder: " + destinationFolder);
		}
		
		try {
			renameFileNIO2(source, destination);
		} catch (LinkageError e) {
			renameFileIO(source, destination);
		}
		
		return destination;
	}
	

	private static void renameFileNIO2(File source, File destination) throws IOException {
		Files.move(source.toPath(), destination.toPath());
	}
	

	private static void renameFileIO(File source, File destination) throws IOException {
		if (!source.renameTo(destination)) {
			throw new IOException("Failed to rename file: " + source.getName());
		}
	}
	

	public static byte[] readFile(File source) throws IOException {
		InputStream in = new FileInputStream(source);
		
		try {
			byte[] data = new byte[(int) source.length()];
			
			int position = 0;
			int read = 0;
			
			while (position < data.length && (read = in.read(data, position, data.length - position)) >= 0) {
				position += read;
			}
			
			return data;
		} finally {
			in.close();
		}
	}
	

	public static String readAll(Reader source) throws IOException {
		StringBuilder text = new StringBuilder();
		char[] buffer = new char[2048];
		
		int read = 0;
		while ((read = source.read(buffer)) >= 0) {
			text.append(buffer, 0, read);
		}
		
		return text.toString();
	}
	

	public static void writeFile(ByteBuffer data, File destination) throws IOException {
		FileChannel fileChannel = new FileOutputStream(destination).getChannel();
		
		try {
			fileChannel.write(data);
		} finally {
			fileChannel.close();
		}
	}
	

	public static Reader createTextReader(File file) throws IOException {
		CharsetDetector detector = new CharsetDetector();
		detector.setDeclaredEncoding("UTF-8"); // small boost for UTF-8 as default encoding
		detector.setText(new BufferedInputStream(new FileInputStream(file)));
		
		CharsetMatch charset = detector.detect();
		if (charset != null)
			return charset.getReader();
		
		// assume UTF-8 by default
		return new InputStreamReader(new FileInputStream(file), "UTF-8");
	}
	

	public static String getText(ByteBuffer data) throws IOException {
		CharsetDetector detector = new CharsetDetector();
		detector.setDeclaredEncoding("UTF-8"); // small boost for UTF-8 as default encoding
		detector.setText(new ByteBufferInputStream(data));
		
		CharsetMatch charset = detector.detect();
		if (charset != null) {
			try {
				return charset.getString();
			} catch (RuntimeException e) {
				throw new IOException("Failed to read text", e);
			}
		}
		
		// assume UTF-8 by default
		return Charset.forName("UTF-8").decode(data).toString();
	}
	

	/**
	 * Pattern used for matching file extensions.
	 * 
	 * e.g. "file.txt" -> match "txt", ".hidden" -> no match
	 */
	public static final Pattern EXTENSION = Pattern.compile("(?<=.[.])\\p{Alnum}+$");
	

	public static String getExtension(File file) {
		if (file.isDirectory())
			return null;
		
		return getExtension(file.getName());
	}
	

	public static String getExtension(String name) {
		Matcher matcher = EXTENSION.matcher(name);
		
		if (matcher.find()) {
			// extension without leading '.'
			return matcher.group();
		}
		
		// no extension
		return null;
	}
	

	public static boolean hasExtension(File file, String... extensions) {
		// avoid native call for speed, if possible
		return hasExtension(file.getName(), extensions) && !file.isDirectory();
	}
	

	public static boolean hasExtension(String filename, String... extensions) {
		String extension = getExtension(filename);
		
		for (String value : extensions) {
			if ((extension == null && value == null) || (extension != null && extension.equalsIgnoreCase(value)))
				return true;
		}
		
		return false;
	}
	

	public static String getNameWithoutExtension(String name) {
		Matcher matcher = EXTENSION.matcher(name);
		
		if (matcher.find()) {
			return name.substring(0, matcher.start() - 1);
		}
		
		// no extension, return given name
		return name;
	}
	

	public static String getName(File file) {
		if (file.isDirectory())
			return getFolderName(file);
		
		return getNameWithoutExtension(file.getName());
	}
	

	public static String getFolderName(File file) {
		String name = file.getName();
		
		if (!name.isEmpty())
			return name;
		
		// file might be a drive (only has a path, but no name)
		return file.toString();
	}
	

	public static boolean isDerived(File derivate, File prime) {
		return isDerived(getName(derivate), prime);
	}
	

	public static boolean isDerived(String derivate, File prime) {
		String base = getName(prime).trim().toLowerCase();
		derivate = derivate.trim().toLowerCase();
		return derivate.startsWith(base);
	}
	

	public static boolean isDerivedByExtension(File derivate, File prime) {
		return isDerivedByExtension(getName(derivate), prime);
	}
	

	public static boolean isDerivedByExtension(String derivate, File prime) {
		String base = getName(prime).trim().toLowerCase();
		derivate = derivate.trim().toLowerCase();
		
		if (derivate.equals(base))
			return true;
		
		while (derivate.length() > base.length() && getExtension(derivate) != null) {
			derivate = getNameWithoutExtension(derivate);
			
			if (derivate.equals(base))
				return true;
		}
		
		return false;
	}
	

	public static boolean containsOnly(Iterable<File> files, FileFilter filter) {
		for (File file : files) {
			if (!filter.accept(file))
				return false;
		}
		
		return true;
	}
	

	public static List<File> filter(Iterable<File> files, FileFilter... filters) {
		List<File> accepted = new ArrayList<File>();
		
		for (File file : files) {
			for (FileFilter filter : filters) {
				if (filter.accept(file)) {
					accepted.add(file);
					break;
				}
			}
		}
		
		return accepted;
	}
	

	public static List<File> flatten(Iterable<File> roots, int maxDepth, boolean listHiddenFiles) {
		List<File> files = new ArrayList<File>();
		
		// unfold/flatten file tree
		for (File root : roots) {
			if (root.isDirectory()) {
				listFiles(root, 0, files, maxDepth, listHiddenFiles);
			} else {
				files.add(root);
			}
		}
		
		return files;
	}
	

	public static List<File> listPath(File file) {
		LinkedList<File> nodes = new LinkedList<File>();
		
		for (File node = file; node != null; node = node.getParentFile()) {
			nodes.addFirst(node);
		}
		
		return nodes;
	}
	

	public static List<File> listFiles(Iterable<File> folders, int maxDepth, boolean listHiddenFiles) {
		List<File> files = new ArrayList<File>();
		
		// collect files from directory tree
		for (File folder : folders) {
			listFiles(folder, 0, files, maxDepth, listHiddenFiles);
		}
		
		return files;
	}
	

	private static void listFiles(File folder, int depth, List<File> files, int maxDepth, boolean listHiddenFiles) {
		if (depth > maxDepth)
			return;
		
		for (File file : folder.listFiles()) {
			if (!listHiddenFiles && file.isHidden()) // ignore hidden files
				continue;
			
			if (file.isDirectory()) {
				listFiles(file, depth + 1, files, maxDepth, listHiddenFiles);
			} else {
				files.add(file);
			}
		}
	}
	

	public static SortedMap<File, List<File>> mapByFolder(Iterable<File> files) {
		SortedMap<File, List<File>> map = new TreeMap<File, List<File>>();
		
		for (File file : files) {
			File key = file.getParentFile();
			if (key == null) {
				throw new IllegalArgumentException("Parent is null: " + file);
			}
			
			List<File> valueList = map.get(key);
			if (valueList == null) {
				valueList = new ArrayList<File>();
				map.put(key, valueList);
			}
			
			valueList.add(file);
		}
		
		return map;
	}
	

	public static Map<String, List<File>> mapByExtension(Iterable<File> files) {
		Map<String, List<File>> map = new HashMap<String, List<File>>();
		
		for (File file : files) {
			String key = getExtension(file);
			if (key != null) {
				key = key.toLowerCase();
			}
			
			List<File> valueList = map.get(key);
			if (valueList == null) {
				valueList = new ArrayList<File>();
				map.put(key, valueList);
			}
			
			valueList.add(file);
		}
		
		return map;
	}
	

	/**
	 * Invalid file name characters: \, /, :, *, ?, ", <, >, |, \r and \n
	 */
	public static final Pattern ILLEGAL_CHARACTERS = Pattern.compile("[\\\\/:*?\"<>|\\r\\n]");
	

	/**
	 * Strip file name of invalid characters
	 * 
	 * @param filename original filename
	 * @return valid file name stripped of invalid characters
	 */
	public static String validateFileName(CharSequence filename) {
		// strip invalid characters from file name
		return ILLEGAL_CHARACTERS.matcher(filename).replaceAll("");
	}
	

	public static boolean isInvalidFileName(CharSequence filename) {
		// check if file name contains any illegal characters
		return ILLEGAL_CHARACTERS.matcher(filename).find();
	}
	

	public static File validateFileName(File file) {
		// windows drives (e.g. c:, d:, etc.) are never invalid because name will be an empty string
		if (!isInvalidFileName(file.getName()))
			return file;
		
		// validate file name only
		return new File(file.getParentFile(), validateFileName(file.getName()));
	}
	

	public static File validateFilePath(File path) {
		Iterator<File> nodes = listPath(path).iterator();
		
		// initialize with root node, keep original root object if possible (so we don't loose the drive on windows)
		File validatedPath = validateFileName(nodes.next());
		
		// validate the rest of the path
		while (nodes.hasNext()) {
			validatedPath = new File(validatedPath, validateFileName(nodes.next().getName()));
		}
		
		return validatedPath;
	}
	

	public static boolean isInvalidFilePath(File path) {
		// check if file name contains any illegal characters
		for (File node = path; node != null; node = node.getParentFile()) {
			if (isInvalidFileName(node.getName()))
				return true;
		}
		
		return false;
	}
	

	public static String normalizePathSeparators(String path) {
		return path.replace('\\', '/');
	}
	

	public static String replacePathSeparators(CharSequence path) {
		return Pattern.compile("\\s*[\\\\/]+\\s*").matcher(path).replaceAll(" ");
	}
	

	public static final long KILO = 1024;
	public static final long MEGA = KILO * 1024;
	public static final long GIGA = MEGA * 1024;
	

	public static String formatSize(long size) {
		if (size >= MEGA)
			return String.format("%,d MB", size / MEGA);
		else if (size >= KILO)
			return String.format("%,d KB", size / KILO);
		else
			return String.format("%,d Byte", size);
	}
	

	public static final FileFilter FOLDERS = new FileFilter() {
		
		@Override
		public boolean accept(File file) {
			return file.isDirectory();
		}
	};
	
	public static final FileFilter FILES = new FileFilter() {
		
		@Override
		public boolean accept(File file) {
			return file.isFile();
		}
	};
	
	public static final FileFilter TEMPORARY = new FileFilter() {
		
		private final File TEMP_DIR = new File(System.getProperty("java.io.tmpdir"));
		

		@Override
		public boolean accept(File file) {
			return file.getAbsolutePath().startsWith(TEMP_DIR.getAbsolutePath());
		}
	};
	

	public static class ExtensionFileFilter implements FileFilter {
		
		private final String[] extensions;
		

		public ExtensionFileFilter(String... extensions) {
			this.extensions = extensions;
		}
		

		public ExtensionFileFilter(Collection<String> extensions) {
			this.extensions = extensions.toArray(new String[0]);
		}
		

		@Override
		public boolean accept(File file) {
			return hasExtension(file, extensions);
		}
		

		public boolean accept(String name) {
			return hasExtension(name, extensions);
		}
		

		public boolean acceptExtension(String extension) {
			for (String other : extensions) {
				if (other.equalsIgnoreCase(extension))
					return true;
			}
			
			return false;
		}
		

		public String extension() {
			return extensions[0];
		}
		

		public String[] extensions() {
			return extensions.clone();
		}
	}
	

	/**
	 * Dummy constructor to prevent instantiation.
	 */
	private FileUtilities() {
		throw new UnsupportedOperationException();
	}
	
}