/*
    * Copyright (C) 2017, Google Inc.
    * 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
    *
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   * without modification, are permitted provided that the following
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   *   names of its contributors may be used to endorse or promote
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  package org.eclipse.jgit.pgm.debug;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static org.eclipse.jgit.lib.Constants.HEAD;
  import static org.eclipse.jgit.lib.Constants.MASTER;
  import static org.eclipse.jgit.lib.Constants.R_HEADS;
  import static org.eclipse.jgit.lib.Ref.Storage.NEW;
  import static org.eclipse.jgit.lib.Ref.Storage.PACKED;
  
  import java.io.BufferedReader;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStreamReader;
  
  import org.eclipse.jgit.internal.storage.io.BlockSource;
  import org.eclipse.jgit.internal.storage.reftable.RefCursor;
  import org.eclipse.jgit.internal.storage.reftable.ReftableReader;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectIdRef;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.SymbolicRef;
  import org.eclipse.jgit.pgm.Command;
  import org.eclipse.jgit.pgm.TextBuiltin;
  import org.eclipse.jgit.util.RefList;
  import org.kohsuke.args4j.Argument;
  import org.kohsuke.args4j.Option;
  
  @Command
  class BenchmarkReftable extends TextBuiltin {
  	enum Test {
  		SCAN,
  		SEEK_COLD, SEEK_HOT,
  		BY_ID_COLD, BY_ID_HOT;
  	}
  
  	@Option(name = "--tries")
  	private int tries = 10;
  
  	@Option(name = "--test")
  	private Test test = Test.SCAN;
  
  	@Option(name = "--ref")
  	private String ref;
  
  	@Option(name = "--object-id")
  	private String objectId;
  
  	@Argument(index = 0)
  	private String lsRemotePath;
  
  	@Argument(index = 1)
  	private String reftablePath;
  
  	/** {@inheritDoc} */
  	@Override
 	protected void run() throws Exception {
 		switch (test) {
 		case SCAN:
 			scan();
 			break;
 
 		case SEEK_COLD:
 			seekCold(ref);
 			break;
 		case SEEK_HOT:
 			seekHot(ref);
 			break;
 
 		case BY_ID_COLD:
 			byIdCold(ObjectId.fromString(objectId));
 			break;
 		case BY_ID_HOT:
 			byIdHot(ObjectId.fromString(objectId));
 			break;
 		}
 	}
 
 	private void printf(String fmt, Object... args) throws IOException {
 		errw.println(String.format(fmt, args));
 	}
 
 	@SuppressWarnings({ "nls", "boxing" })
 	private void scan() throws Exception {
 		long start, tot;
 
 		start = System.currentTimeMillis();
 		for (int i = 0; i < tries; i++) {
 			readLsRemote();
 		}
 		tot = System.currentTimeMillis() - start;
 		printf("%12s %10d ms  %6d ms/run", "packed-refs", tot, tot / tries);
 
 		start = System.currentTimeMillis();
 		for (int i = 0; i < tries; i++) {
 			try (FileInputStream in = new FileInputStream(reftablePath);
 					BlockSource src = BlockSource.from(in);
 					ReftableReader reader = new ReftableReader(src)) {
 				try (RefCursor rc = reader.allRefs()) {
 					while (rc.next()) {
 						rc.getRef();
 					}
 				}
 			}
 		}
 		tot = System.currentTimeMillis() - start;
 		printf("%12s %10d ms  %6d ms/run", "reftable", tot, tot / tries);
 	}
 
 	private RefList<Ref> readLsRemote()
 			throws IOException, FileNotFoundException {
 		RefList.Builder<Ref> list = new RefList.Builder<>();
 		try (BufferedReader br = new BufferedReader(new InputStreamReader(
 				new FileInputStream(lsRemotePath), UTF_8))) {
 			Ref last = null;
 			String line;
 			while ((line = br.readLine()) != null) {
 				ObjectId id = ObjectId.fromString(line.substring(0, 40));
 				String name = line.substring(41, line.length());
 				if (last != null && name.endsWith("^{}")) { //$NON-NLS-1$
 					last = new ObjectIdRef.PeeledTag(PACKED, last.getName(),
 							last.getObjectId(), id);
 					list.set(list.size() - 1, last);
 					continue;
 				}
 
 				if (name.equals(HEAD)) {
 					last = new SymbolicRef(name, new ObjectIdRef.Unpeeled(NEW,
 							R_HEADS + MASTER, null));
 				} else {
 					last = new ObjectIdRef.PeeledNonTag(PACKED, name, id);
 				}
 				list.add(last);
 			}
 		}
 		list.sort();
 		return list.toRefList();
 	}
 
 	@SuppressWarnings({ "nls", "boxing" })
 	private void seekCold(String refName) throws Exception {
 		long start, tot;
 
 		int lsTries = Math.min(tries, 64);
 		start = System.nanoTime();
 		for (int i = 0; i < lsTries; i++) {
 			readLsRemote().get(refName);
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "packed-refs",
 				tot / 1000,
 				(((double) tot) / lsTries) / 1000,
 				lsTries);
 
 		start = System.nanoTime();
 		for (int i = 0; i < tries; i++) {
 			try (FileInputStream in = new FileInputStream(reftablePath);
 					BlockSource src = BlockSource.from(in);
 					ReftableReader reader = new ReftableReader(src)) {
 				try (RefCursor rc = reader.seekRef(refName)) {
 					while (rc.next()) {
 						rc.getRef();
 					}
 				}
 			}
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "reftable",
 				tot / 1000,
 				(((double) tot) / tries) / 1000,
 				tries);
 	}
 
 	@SuppressWarnings({ "nls", "boxing" })
 	private void seekHot(String refName) throws Exception {
 		long start, tot;
 
 		int lsTries = Math.min(tries, 64);
 		start = System.nanoTime();
 		RefList<Ref> lsRemote = readLsRemote();
 		for (int i = 0; i < lsTries; i++) {
 			lsRemote.get(refName);
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "packed-refs",
 				tot / 1000, (((double) tot) / lsTries) / 1000, lsTries);
 
 		start = System.nanoTime();
 		try (FileInputStream in = new FileInputStream(reftablePath);
 				BlockSource src = BlockSource.from(in);
 				ReftableReader reader = new ReftableReader(src)) {
 			for (int i = 0; i < tries; i++) {
 				try (RefCursor rc = reader.seekRef(refName)) {
 					while (rc.next()) {
 						rc.getRef();
 					}
 				}
 			}
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "reftable",
 				tot / 1000, (((double) tot) / tries) / 1000, tries);
 	}
 
 	@SuppressWarnings({ "nls", "boxing" })
 	private void byIdCold(ObjectId id) throws Exception {
 		long start, tot;
 
 		int lsTries = Math.min(tries, 64);
 		start = System.nanoTime();
 		for (int i = 0; i < lsTries; i++) {
 			for (Ref r : readLsRemote()) {
 				if (id.equals(r.getObjectId())) {
 					continue;
 				}
 			}
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "packed-refs",
 				tot / 1000, (((double) tot) / lsTries) / 1000, lsTries);
 
 		start = System.nanoTime();
 		for (int i = 0; i < tries; i++) {
 			try (FileInputStream in = new FileInputStream(reftablePath);
 					BlockSource src = BlockSource.from(in);
 					ReftableReader reader = new ReftableReader(src)) {
 				try (RefCursor rc = reader.byObjectId(id)) {
 					while (rc.next()) {
 						rc.getRef();
 					}
 				}
 			}
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "reftable",
 				tot / 1000, (((double) tot) / tries) / 1000, tries);
 	}
 
 	@SuppressWarnings({ "nls", "boxing" })
 	private void byIdHot(ObjectId id) throws Exception {
 		long start, tot;
 
 		int lsTries = Math.min(tries, 64);
 		start = System.nanoTime();
 		RefList<Ref> lsRemote = readLsRemote();
 		for (int i = 0; i < lsTries; i++) {
 			for (Ref r : lsRemote) {
 				if (id.equals(r.getObjectId())) {
 					continue;
 				}
 			}
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "packed-refs",
 				tot / 1000, (((double) tot) / lsTries) / 1000, lsTries);
 
 		start = System.nanoTime();
 		try (FileInputStream in = new FileInputStream(reftablePath);
 				BlockSource src = BlockSource.from(in);
 				ReftableReader reader = new ReftableReader(src)) {
 			for (int i = 0; i < tries; i++) {
 				try (RefCursor rc = reader.byObjectId(id)) {
 					while (rc.next()) {
 						rc.getRef();
 					}
 				}
 			}
 		}
 		tot = System.nanoTime() - start;
 		printf("%12s %10d usec  %9.1f usec/run  %5d runs", "reftable",
 				tot / 1000, (((double) tot) / tries) / 1000, tries);
 	}
 }