/*
    * Copyright (C) 2015, Matthias Sohn <matthias.sohn@sap.com> 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.lfs.server.fs;
  
  import static org.eclipse.jgit.util.HttpSupport.HDR_AUTHORIZATION;
  
  import java.io.IOException;
  import java.nio.channels.FileChannel;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.StandardOpenOption;
  import java.util.Collections;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.lfs.internal.AtomicObjectOutputStream;
  import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
  import org.eclipse.jgit.lfs.lib.Constants;
  import org.eclipse.jgit.lfs.server.LargeFileRepository;
  import org.eclipse.jgit.lfs.server.Response;
  import org.eclipse.jgit.lfs.server.Response.Action;
  
  /**
   * Repository storing large objects in the file system
   *
   * @since 4.3
   */
  public class FileLfsRepository implements LargeFileRepository {
  
  	private String url;
  	private final Path dir;
  
  	/**
  	 * <p>Constructor for FileLfsRepository.</p>
  	 *
  	 * @param url
  	 *            external URL of this repository
  	 * @param dir
  	 *            storage directory
  	 * @throws java.io.IOException
  	 */
  	public FileLfsRepository(String url, Path dir) throws IOException {
  		this.url = url;
  		this.dir = dir;
  		Files.createDirectories(dir);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public Response.Action getDownloadAction(AnyLongObjectId id) {
  		return getAction(id);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public Action getUploadAction(AnyLongObjectId id, long size) {
  		return getAction(id);
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	@Nullable
  	public Action getVerifyAction(AnyLongObjectId id) {
  		return null;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public long getSize(AnyLongObjectId id) throws IOException {
  		Path p = getPath(id);
  		if (Files.exists(p)) {
  			return Files.size(p);
  		}
  		return -1;
  	}
  
  	/**
  	 * Get the storage directory
  	 *
  	 * @return the path of the storage directory
  	 */
  	public Path getDir() {
  		return dir;
  	}
  
  	/**
  	 * Get the path where the given object is stored
  	 *
  	 * @param id
  	 *            id of a large object
  	 * @return path the object's storage path
  	 */
 	protected Path getPath(AnyLongObjectId id) {
 		StringBuilder s = new StringBuilder(
 				Constants.LONG_OBJECT_ID_STRING_LENGTH + 6);
 		s.append(toHexCharArray(id.getFirstByte())).append('/');
 		s.append(toHexCharArray(id.getSecondByte())).append('/');
 		s.append(id.name());
 		return dir.resolve(s.toString());
 	}
 
 	private Response.Action getAction(AnyLongObjectId id) {
 		Response.Action a = new Response.Action();
 		a.href = url + id.getName();
 		a.header = Collections.singletonMap(HDR_AUTHORIZATION, "not:required"); //$NON-NLS-1$
 		return a;
 	}
 
 	ReadableByteChannel getReadChannel(AnyLongObjectId id)
 			throws IOException {
 		return FileChannel.open(getPath(id), StandardOpenOption.READ);
 	}
 
 	AtomicObjectOutputStream getOutputStream(AnyLongObjectId id)
 			throws IOException {
 		Path path = getPath(id);
 		Path parent = path.getParent();
 		if (parent != null) {
 			Files.createDirectories(parent);
 		}
 		return new AtomicObjectOutputStream(path, id);
 	}
 
 	private static char[] toHexCharArray(int b) {
 		final char[] dst = new char[2];
 		formatHexChar(dst, 0, b);
 		return dst;
 	}
 
 	private static final char[] hexchar = { '0', '1', '2', '3', '4', '5', '6',
 			'7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
 
 	private static void formatHexChar(char[] dst, int p, int b) {
 		int o = p + 1;
 		while (o >= p && b != 0) {
 			dst[o--] = hexchar[b & 0xf];
 			b >>>= 4;
 		}
 		while (o >= p)
 			dst[o--] = '0';
 	}
 
 	/**
 	 * @return the url of the content server
 	 * @since 4.11
 	 */
 	public String getUrl() {
 		return url;
 	}
 
 	/**
 	 * @param url
 	 *            the url of the content server
 	 * @since 4.11
 	 */
 	public void setUrl(String url) {
 		this.url = url;
 	}
 }