/*
    * Copyright (C) 2019, Google LLC. 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.transport;
  
  import java.text.MessageFormat;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.errors.PackProtocolException;
  import org.eclipse.jgit.internal.JGitText;
  
  /**
   * Represents either a filter specified in a protocol "filter" line, or a
   * placeholder to indicate no filtering.
   *
   * @since 5.4
   */
  public final class FilterSpec {
  
  	private final long blobLimit;
  
  	private final long treeDepthLimit;
  
  	private FilterSpec(long blobLimit, long treeDepthLimit) {
  		this.blobLimit = blobLimit;
  		this.treeDepthLimit = treeDepthLimit;
  	}
  
  	/**
  	 * Process the content of "filter" line from the protocol. It has a shape
  	 * like:
  	 *
  	 * <ul>
  	 *   <li>"blob:none"
  	 *   <li>"blob:limit=N", with N &gt;= 0
  	 *   <li>"tree:DEPTH", with DEPTH &gt;= 0
  	 * </ul>
  	 *
  	 * @param filterLine
  	 *            the content of the "filter" line in the protocol
  	 * @return a FilterSpec representing the given filter
  	 * @throws PackProtocolException
  	 *             invalid filter because due to unrecognized format or
  	 *             negative/non-numeric filter.
  	 */
  	public static FilterSpec fromFilterLine(String filterLine)
  			throws PackProtocolException {
  		if (filterLine.equals("blob:none")) { //$NON-NLS-1$
  			return FilterSpec.withBlobLimit(0);
  		} else if (filterLine.startsWith("blob:limit=")) { //$NON-NLS-1$
  			long blobLimit = -1;
  			try {
  				blobLimit = Long
  						.parseLong(filterLine.substring("blob:limit=".length())); //$NON-NLS-1$
  			} catch (NumberFormatException e) {
  				// Do not change blobLimit so that we throw a
  				// PackProtocolException later.
  			}
  			if (blobLimit >= 0) {
  				return FilterSpec.withBlobLimit(blobLimit);
  			}
  		} else if (filterLine.startsWith("tree:")) { //$NON-NLS-1$
  			long treeDepthLimit = -1;
  			try {
  				treeDepthLimit = Long
  						.parseLong(filterLine.substring("tree:".length())); //$NON-NLS-1$
  			} catch (NumberFormatException e) {
  				// Do not change blobLimit so that we throw a
  				// PackProtocolException later.
  			}
  			if (treeDepthLimit >= 0) {
  				return FilterSpec.withTreeDepthLimit(treeDepthLimit);
  			}
  		}
  
  		// Did not match any known filter format.
  		throw new PackProtocolException(
  				MessageFormat.format(JGitText.get().invalidFilter, filterLine));
  	}
  
  	/**
  	 * @param blobLimit
  	 *            the blob limit in a "blob:[limit]" or "blob:none" filter line
  	 * @return a filter spec which filters blobs above a certain size
  	 */
  	static FilterSpec withBlobLimit(long blobLimit) {
  		if (blobLimit < 0) {
  			throw new IllegalArgumentException(
  					"blobLimit cannot be negative: " + blobLimit); //$NON-NLS-1$
  		}
  		return new FilterSpec(blobLimit, -1);
  	}
 
 	/**
 	 * @param treeDepthLimit
 	 *            the tree depth limit in a "tree:[depth]" filter line
 	 * @return a filter spec which filters blobs and trees beyond a certain tree
 	 *         depth
 	 */
 	static FilterSpec withTreeDepthLimit(long treeDepthLimit) {
 		if (treeDepthLimit < 0) {
 			throw new IllegalArgumentException(
 					"treeDepthLimit cannot be negative: " + treeDepthLimit); //$NON-NLS-1$
 		}
 		return new FilterSpec(-1, treeDepthLimit);
 	}
 
 	/**
 	 * A placeholder that indicates no filtering.
 	 */
 	public static final FilterSpecec.html#FilterSpec">FilterSpec NO_FILTER = new FilterSpec(-1, -1);
 
 	/**
 	 * @return -1 if this filter does not filter blobs based on size, or a
 	 *         non-negative integer representing the max size of blobs to allow
 	 */
 	public long getBlobLimit() {
 		return blobLimit;
 	}
 
 	/**
 	 * @return -1 if this filter does not filter blobs and trees based on depth,
 	 *         or a non-negative integer representing the max tree depth of
 	 *         blobs and trees to fetch
 	 */
 	public long getTreeDepthLimit() {
 		return treeDepthLimit;
 	}
 
 	/**
 	 * @return true if this filter doesn't filter out anything
 	 */
 	public boolean isNoOp() {
 		return blobLimit == -1 && treeDepthLimit == -1;
 	}
 
 	/**
 	 * @return the filter line which describes this spec, e.g. "filter blob:limit=42"
 	 */
 	@Nullable
 	public String filterLine() {
 		if (blobLimit == 0) {
 			return GitProtocolConstants.OPTION_FILTER + " blob:none"; //$NON-NLS-1$
 		}
 
 		if (blobLimit > 0) {
 			return GitProtocolConstants.OPTION_FILTER + " blob:limit=" + blobLimit; //$NON-NLS-1$
 		}
 
 		return null;
 	}
 }