/*
    * Copyright (C) 2016, Christian Halstrick <christian.halstrick@sap.com>
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
    *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package org.eclipse.jgit.lfs;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  import java.io.PrintStream;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.UnsupportedCharsetException;
  import java.util.Locale;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
  import org.eclipse.jgit.lfs.lib.Constants;
  import org.eclipse.jgit.lfs.lib.LongObjectId;
  
  /**
   * Represents an LFS pointer file
   *
   * @since 4.6
   */
  public class LfsPointer implements Comparable<LfsPointer> {
  	/**
  	 * The version of the LfsPointer file format
  	 */
  	public static final String VERSION = "https://git-lfs.github.com/spec/v1"; //$NON-NLS-1$
  
  	/**
  	 * The version of the LfsPointer file format using legacy URL
  	 * @since 4.7
  	 */
  	public static final String VERSION_LEGACY = "https://hawser.github.com/spec/v1"; //$NON-NLS-1$
  
  	/**
  	 * Don't inspect files that are larger than this threshold to avoid
  	 * excessive reading. No pointer file should be larger than this.
  	 * @since 4.11
  	 */
  	public static final int SIZE_THRESHOLD = 200;
  
  	/**
  	 * The name of the hash function as used in the pointer files. This will
  	 * evaluate to "sha256"
  	 */
  	public static final String HASH_FUNCTION_NAME = Constants.LONG_HASH_FUNCTION
  			.toLowerCase(Locale.ROOT).replace("-", ""); //$NON-NLS-1$ //$NON-NLS-2$
  
  	private AnyLongObjectId oid;
  
  	private long size;
  
  	/**
  	 * <p>Constructor for LfsPointer.</p>
  	 *
 	 * @param oid
 	 *            the id of the content
 	 * @param size
 	 *            the size of the content
 	 */
 	public LfsPointer(AnyLongObjectId oid, long size) {
 		this.oid = oid;
 		this.size = size;
 	}
 
 	/**
 	 * <p>Getter for the field <code>oid</code>.</p>
 	 *
 	 * @return the id of the content
 	 */
 	public AnyLongObjectId getOid() {
 		return oid;
 	}
 
 	/**
 	 * <p>Getter for the field <code>size</code>.</p>
 	 *
 	 * @return the size of the content
 	 */
 	public long getSize() {
 		return size;
 	}
 
 	/**
 	 * Encode this object into the LFS format defined by {@link #VERSION}
 	 *
 	 * @param out
 	 *            the {@link java.io.OutputStream} into which the encoded data should be
 	 *            written
 	 */
 	public void encode(OutputStream out) {
 		try (PrintStream ps = new PrintStream(out, false,
 				UTF_8.name())) {
 			ps.print("version "); //$NON-NLS-1$
 			ps.print(VERSION + "\n"); //$NON-NLS-1$
 			ps.print("oid " + HASH_FUNCTION_NAME + ":"); //$NON-NLS-1$ //$NON-NLS-2$
 			ps.print(oid.name() + "\n"); //$NON-NLS-1$
 			ps.print("size "); //$NON-NLS-1$
 			ps.print(size + "\n"); //$NON-NLS-1$
 		} catch (UnsupportedEncodingException e) {
 			// should not happen, we are using a standard charset
 			throw new UnsupportedCharsetException(UTF_8.name());
 		}
 	}
 
 	/**
 	 * Try to parse the data provided by an InputStream to the format defined by
 	 * {@link #VERSION}
 	 *
 	 * @param in
 	 *            the {@link java.io.InputStream} from where to read the data
 	 * @return an {@link org.eclipse.jgit.lfs.LfsPointer} or <code>null</code>
 	 *         if the stream was not parseable as LfsPointer
 	 * @throws java.io.IOException
 	 */
 	@Nullable
 	public static LfsPointer parseLfsPointer(InputStream in)
 			throws IOException {
 		boolean versionLine = false;
 		LongObjectId id = null;
 		long sz = -1;
 
 		try (BufferedReader br = new BufferedReader(
 				new InputStreamReader(in, UTF_8))) {
 			for (String s = br.readLine(); s != null; s = br.readLine()) {
 				if (s.startsWith("#") || s.length() == 0) { //$NON-NLS-1$
 					continue;
 				} else if (s.startsWith("version") && s.length() > 8 //$NON-NLS-1$
 						&& (s.substring(8).trim().equals(VERSION) ||
 								s.substring(8).trim().equals(VERSION_LEGACY))) {
 					versionLine = true;
 				} else if (s.startsWith("oid sha256:")) { //$NON-NLS-1$
 					id = LongObjectId.fromString(s.substring(11).trim());
 				} else if (s.startsWith("size") && s.length() > 5) { //$NON-NLS-1$
 					sz = Long.parseLong(s.substring(5).trim());
 				}
 			}
 			if (versionLine && id != null && sz > -1) {
 				return new LfsPointer(id, sz);
 			}
 		}
 		return null;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public String toString() {
 		return "LfsPointer: oid=" + oid.name() + ", size=" //$NON-NLS-1$ //$NON-NLS-2$
 				+ size;
 	}
 
 	/**
 	 * @since 4.11
 	 */
 	@Override
 	public int compareTo(LfsPointer o) {
 		int x = getOid().compareTo(o.getOid());
 		if (x != 0) {
 			return x;
 		}
 
 		return (int) (getSize() - o.getSize());
 	}
 }