/*
    * Copyright (C) 2016, Google Inc. 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.internal.ketch;
  
  import static java.util.concurrent.TimeUnit.MILLISECONDS;
  import static java.util.concurrent.TimeUnit.SECONDS;
  import static org.eclipse.jgit.internal.ketch.Proposal.State.EXECUTED;
  import static org.eclipse.jgit.internal.ketch.Proposal.State.QUEUED;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_REASON;
  
  import java.io.IOException;
  import java.util.Collection;
  
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.transport.PreReceiveHook;
  import org.eclipse.jgit.transport.ProgressSpinner;
  import org.eclipse.jgit.transport.ReceiveCommand;
  import org.eclipse.jgit.transport.ReceivePack;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * PreReceiveHook for handling push traffic in a Ketch system.
   * <p>
   * Install an instance on {@link org.eclipse.jgit.transport.ReceivePack} to
   * capture the commands and other connection state and relay them through the
   * {@link org.eclipse.jgit.internal.ketch.KetchLeader}, allowing the leader to
   * gain consensus about the new reference state.
   */
  public class KetchPreReceive implements PreReceiveHook {
  	private static final Logger log = LoggerFactory.getLogger(KetchPreReceive.class);
  
  	private final KetchLeader leader;
  
  	/**
  	 * Construct a hook executing updates through a
  	 * {@link org.eclipse.jgit.internal.ketch.KetchLeader}.
  	 *
  	 * @param leader
  	 *            leader for this repository.
  	 */
  	public KetchPreReceive(KetchLeader leader) {
  		this.leader = leader;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public void onPreReceive(ReceivePack rp, Collection<ReceiveCommand> cmds) {
  		cmds = ReceiveCommand.filter(cmds, NOT_ATTEMPTED);
  		if (cmds.isEmpty()) {
  			return;
  		}
  
  		try {
  			Proposal proposal = new Proposal(rp.getRevWalk(), cmds)
  				.setPushCertificate(rp.getPushCertificate())
  				.setAuthor(rp.getRefLogIdent())
  				.setMessage("push"); //$NON-NLS-1$
  			leader.queueProposal(proposal);
  			if (proposal.isDone()) {
  				// This failed fast, e.g. conflict or bad precondition.
  				return;
  			}
  
  			ProgressSpinner spinner = new ProgressSpinner(
  					rp.getMessageOutputStream());
  			if (proposal.getState() == QUEUED) {
  				waitForQueue(proposal, spinner);
  			}
  			if (!proposal.isDone()) {
  				waitForPropose(proposal, spinner);
  			}
  		} catch (IOException | InterruptedException e) {
  			String msg = JGitText.get().transactionAborted;
  			for (ReceiveCommand cmd : cmds) {
  				if (cmd.getResult() == NOT_ATTEMPTED) {
  					cmd.setResult(REJECTED_OTHER_REASON, msg);
  				}
  			}
  			log.error(msg, e);
  		}
  	}
  
  	private void waitForQueue(Proposal proposal, ProgressSpinner spinner)
  			throws InterruptedException {
  		spinner.beginTask(KetchText.get().waitingForQueue, 1, SECONDS);
  		while (!proposal.awaitStateChange(QUEUED, 250, MILLISECONDS)) {
  			spinner.update();
  		}
  		switch (proposal.getState()) {
 		case RUNNING:
 		default:
 			spinner.endTask(KetchText.get().starting);
 			break;
 
 		case EXECUTED:
 			spinner.endTask(KetchText.get().accepted);
 			break;
 
 		case ABORTED:
 			spinner.endTask(KetchText.get().failed);
 			break;
 		}
 	}
 
 	private void waitForPropose(Proposal proposal, ProgressSpinner spinner)
 			throws InterruptedException {
 		spinner.beginTask(KetchText.get().proposingUpdates, 2, SECONDS);
 		while (!proposal.await(250, MILLISECONDS)) {
 			spinner.update();
 		}
 		spinner.endTask(proposal.getState() == EXECUTED
 				? KetchText.get().accepted
 				: KetchText.get().failed);
 	}
 }