/*
    * Copyright (C) 2018, 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 static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_DEEPEN_RELATIVE;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_FILTER;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_AGENT;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_INCLUDE_TAG;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_NO_PROGRESS;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_OFS_DELTA;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SERVER_OPTION;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDEBAND_ALL;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDE_BAND_64K;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_THIN_PACK;
  import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_WANT_REF;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.function.Consumer;
  
  import org.eclipse.jgit.errors.PackProtocolException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.ObjectId;
  
  /**
   * Parse the incoming git protocol lines from the wire and translate them into a
   * Request object.
   *
   * It requires a transferConfig object to know what the server supports (e.g.
   * ref-in-want and/or filters).
   */
  final class ProtocolV2Parser {
  
  	private final TransferConfig transferConfig;
  
  	ProtocolV2Parser(TransferConfig transferConfig) {
  		this.transferConfig = transferConfig;
  	}
  
  	/*
  	 * Read lines until DELIM or END, calling the appropiate consumer.
  	 *
  	 * Returns the last read line (so caller can check if there is more to read
  	 * in the line).
  	 */
  	private static String consumeCapabilities(PacketLineIn pckIn,
  			Consumer<String> serverOptionConsumer,
  			Consumer<String> agentConsumer) throws IOException {
  
  		String serverOptionPrefix = OPTION_SERVER_OPTION + '=';
  		String agentPrefix = OPTION_AGENT + '=';
  
  		String line = pckIn.readString();
  		while (!PacketLineIn.isDelimiter(line) && !PacketLineIn.isEnd(line)) {
  			if (line.startsWith(serverOptionPrefix)) {
  				serverOptionConsumer
  						.accept(line.substring(serverOptionPrefix.length()));
  			} else if (line.startsWith(agentPrefix)) {
  				agentConsumer.accept(line.substring(agentPrefix.length()));
  			} else {
  				// Unrecognized capability. Ignore it.
  			}
  			line = pckIn.readString();
  		}
  
  		return line;
  	}
  
  	/**
  	 * Parse the incoming fetch request arguments from the wire. The caller must
  	 * be sure that what is comings is a fetch request before coming here.
  	 *
  	 * @param pckIn
  	 *            incoming lines
  	 * @return A FetchV2Request populated with information received from the
  	 *         wire.
  	 * @throws PackProtocolException
  	 *             incompatible options, wrong type of arguments or other issues
  	 *             where the request breaks the protocol.
  	 * @throws IOException
  	 *             an IO error prevented reading the incoming message.
  	 */
  	FetchV2Request parseFetchRequest(PacketLineIn pckIn)
  			throws PackProtocolException, IOException {
  		FetchV2Request.Builder reqBuilder = FetchV2Request.builder();
  
  		// Packs are always sent multiplexed and using full 64K
  		// lengths.
  		reqBuilder.addClientCapability(OPTION_SIDE_BAND_64K);
  
 		String line = consumeCapabilities(pckIn,
 				serverOption -> reqBuilder.addServerOption(serverOption),
 				agent -> reqBuilder.setAgent(agent));
 
 		if (PacketLineIn.isEnd(line)) {
 			return reqBuilder.build();
 		}
 
 		if (!PacketLineIn.isDelimiter(line)) {
 			throw new PackProtocolException(
 					MessageFormat.format(JGitText.get().unexpectedPacketLine,
 							line));
 		}
 
 		boolean filterReceived = false;
 		for (String line2 : pckIn.readStrings()) {
 			if (line2.startsWith("want ")) { //$NON-NLS-1$
 				reqBuilder.addWantId(ObjectId.fromString(line2.substring(5)));
 			} else if (transferConfig.isAllowRefInWant()
 					&& line2.startsWith(OPTION_WANT_REF + " ")) { //$NON-NLS-1$
 				reqBuilder.addWantedRef(
 						line2.substring(OPTION_WANT_REF.length() + 1));
 			} else if (line2.startsWith("have ")) { //$NON-NLS-1$
 				reqBuilder.addPeerHas(ObjectId.fromString(line2.substring(5)));
 			} else if (line2.equals("done")) { //$NON-NLS-1$
 				reqBuilder.setDoneReceived();
 			} else if (line2.equals(OPTION_THIN_PACK)) {
 				reqBuilder.addClientCapability(OPTION_THIN_PACK);
 			} else if (line2.equals(OPTION_NO_PROGRESS)) {
 				reqBuilder.addClientCapability(OPTION_NO_PROGRESS);
 			} else if (line2.equals(OPTION_INCLUDE_TAG)) {
 				reqBuilder.addClientCapability(OPTION_INCLUDE_TAG);
 			} else if (line2.equals(OPTION_OFS_DELTA)) {
 				reqBuilder.addClientCapability(OPTION_OFS_DELTA);
 			} else if (line2.startsWith("shallow ")) { //$NON-NLS-1$
 				reqBuilder.addClientShallowCommit(
 						ObjectId.fromString(line2.substring(8)));
 			} else if (line2.startsWith("deepen ")) { //$NON-NLS-1$
 				int parsedDepth = Integer.parseInt(line2.substring(7));
 				if (parsedDepth <= 0) {
 					throw new PackProtocolException(
 							MessageFormat.format(JGitText.get().invalidDepth,
 									Integer.valueOf(parsedDepth)));
 				}
 				if (reqBuilder.getDeepenSince() != 0) {
 					throw new PackProtocolException(
 							JGitText.get().deepenSinceWithDeepen);
 				}
 				if (reqBuilder.hasDeepenNotRefs()) {
 					throw new PackProtocolException(
 							JGitText.get().deepenNotWithDeepen);
 				}
 				reqBuilder.setDepth(parsedDepth);
 			} else if (line2.startsWith("deepen-not ")) { //$NON-NLS-1$
 				reqBuilder.addDeepenNotRef(line2.substring(11));
 				if (reqBuilder.getDepth() != 0) {
 					throw new PackProtocolException(
 							JGitText.get().deepenNotWithDeepen);
 				}
 			} else if (line2.equals(OPTION_DEEPEN_RELATIVE)) {
 				reqBuilder.addClientCapability(OPTION_DEEPEN_RELATIVE);
 			} else if (line2.startsWith("deepen-since ")) { //$NON-NLS-1$
 				int ts = Integer.parseInt(line2.substring(13));
 				if (ts <= 0) {
 					throw new PackProtocolException(MessageFormat
 							.format(JGitText.get().invalidTimestamp, line2));
 				}
 				if (reqBuilder.getDepth() != 0) {
 					throw new PackProtocolException(
 							JGitText.get().deepenSinceWithDeepen);
 				}
 				reqBuilder.setDeepenSince(ts);
 			} else if (transferConfig.isAllowFilter()
 					&& line2.startsWith(OPTION_FILTER + ' ')) {
 				if (filterReceived) {
 					throw new PackProtocolException(
 							JGitText.get().tooManyFilters);
 				}
 				filterReceived = true;
 				reqBuilder.setFilterSpec(FilterSpec.fromFilterLine(
 						line2.substring(OPTION_FILTER.length() + 1)));
 			} else if (transferConfig.isAllowSidebandAll()
 					&& line2.equals(OPTION_SIDEBAND_ALL)) {
 				reqBuilder.setSidebandAll(true);
 			} else if (line2.startsWith("packfile-uris ")) { //$NON-NLS-1$
 				for (String s : line2.substring(14).split(",")) { //$NON-NLS-1$
 					reqBuilder.addPackfileUriProtocol(s);
 				}
 			} else {
 				throw new PackProtocolException(MessageFormat
 						.format(JGitText.get().unexpectedPacketLine, line2));
 			}
 		}
 
 		return reqBuilder.build();
 	}
 
 	/**
 	 * Parse the incoming ls-refs request arguments from the wire. This is meant
 	 * for calling immediately after the caller has consumed a "command=ls-refs"
 	 * line indicating the beginning of a ls-refs request.
 	 *
 	 * The incoming PacketLineIn is consumed until an END line, but the caller
 	 * is responsible for closing it (if needed)
 	 *
 	 * @param pckIn
 	 *            incoming lines. This method will read until an END line.
 	 * @return a LsRefsV2Request object with the data received in the wire.
 	 * @throws PackProtocolException
 	 *             for inconsistencies in the protocol (e.g. unexpected lines)
 	 * @throws IOException
 	 *             reporting problems reading the incoming messages from the
 	 *             wire
 	 */
 	LsRefsV2Request parseLsRefsRequest(PacketLineIn pckIn)
 			throws PackProtocolException, IOException {
 		LsRefsV2Request.Builder builder = LsRefsV2Request.builder();
 		List<String> prefixes = new ArrayList<>();
 
 		String line = consumeCapabilities(pckIn,
 				serverOption -> builder.addServerOption(serverOption),
 				agent -> builder.setAgent(agent));
 
 		if (PacketLineIn.isEnd(line)) {
 			return builder.build();
 		}
 
 		if (!PacketLineIn.isDelimiter(line)) {
 			throw new PackProtocolException(MessageFormat
 					.format(JGitText.get().unexpectedPacketLine, line));
 		}
 
 		for (String line2 : pckIn.readStrings()) {
 			if (line2.equals("peel")) { //$NON-NLS-1$
 				builder.setPeel(true);
 			} else if (line2.equals("symrefs")) { //$NON-NLS-1$
 				builder.setSymrefs(true);
 			} else if (line2.startsWith("ref-prefix ")) { //$NON-NLS-1$
 				prefixes.add(line2.substring("ref-prefix ".length())); //$NON-NLS-1$
 			} else {
 				throw new PackProtocolException(MessageFormat
 						.format(JGitText.get().unexpectedPacketLine, line2));
 			}
 		}
 
 		return builder.setRefPrefixes(prefixes).build();
 	}
 
 }