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/*
 * Copyright 2015 Stanley Shyiko
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.wicp.tams.commons.binlog;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * GTIDGTID set as described
 * https://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html
 * 
 * @author Administrator
 *
 */
public class GtidSet {

	private final Map map = new LinkedHashMap();

	/**
	 * @param isSimple
	 *            是否支持简写
	 * @param gtidSet
	 *            gtid set comprised of closed intervals (like MySQL's
	 *            executed_gtid_set).
	 */
	public GtidSet(String gtidSet, boolean isSimple) {
		gtidSet = gtidSet.replace("\n", "");
		String[] uuidSets = gtidSet.isEmpty() ? new String[0] : gtidSet.split(",");
		for (String uuidSet : uuidSets) {
			int uuidSeparatorIndex = uuidSet.indexOf(":");
			String sourceId = uuidSet.substring(0, uuidSeparatorIndex);
			List intervals = new ArrayList();
			String[] rawIntervals = uuidSet.substring(uuidSeparatorIndex + 1).split(":");
			for (String interval : rawIntervals) {
				String[] is = interval.split("-");
				long[] split = new long[is.length];
				for (int i = 0, e = is.length; i < e; i++) {
					split[i] = Long.parseLong(is[i]);
				}
				if (split.length == 1) {
					if (isSimple) {
						split = new long[] { 1L, split[0] };
					} else {
						split = new long[] { split[0], split[0] };
					}
				}
				intervals.add(new Interval(split[0], split[1]));
			}
			map.put(sourceId, new UUIDSet(sourceId, intervals));
		}
	}

	public GtidSet(String gtidSet) {
		this(gtidSet, true);
	}

	public Collection getUUIDSets() {
		return map.values();
	}

	/**
	 * @param gtid
	 *            GTID ("source_id:transaction_id")
	 * @return whether or not gtid was added to the set (false if it was already
	 *         there)
	 */
	public boolean add(String gtid) {
		String[] split = gtid.split(":");
		String sourceId = split[0];
		long transactionId = Long.parseLong(split[1]);
		UUIDSet uuidSet = map.get(sourceId);
		if (uuidSet == null) {
			map.put(sourceId, uuidSet = new UUIDSet(sourceId, new ArrayList()));
		}
		List intervals = (List) uuidSet.intervals;
		int index = findInterval(intervals, transactionId);
		boolean addedToExisting = false;
		if (index < intervals.size()) {
			Interval interval = intervals.get(index);
			if (interval.start == transactionId + 1) {
				interval.start = transactionId;
				addedToExisting = true;
			} else if (interval.end + 1 == transactionId) {
				interval.end = transactionId;
				addedToExisting = true;
			} else if (interval.start <= transactionId && transactionId <= interval.end) {
				return false;
			}
		}
		if (!addedToExisting) {
			intervals.add(index, new Interval(transactionId, transactionId));
		}
		if (intervals.size() > 1) {
			joinAdjacentIntervals(intervals, index);
		}
		return true;
	}

	/**
	 * Collapses intervals like a-(b-1):b-c into a-c (only in index+-1 range).
	 */
	private void joinAdjacentIntervals(List intervals, int index) {
		for (int i = Math.min(index + 1, intervals.size() - 1), e = Math.max(index - 1, 0); i > e; i--) {
			Interval a = intervals.get(i - 1), b = intervals.get(i);
			if (a.end + 1 == b.start) {
				a.end = b.end;
				intervals.remove(i);
			}
		}
	}

	@Override
	public String toString() {
		List gtids = new ArrayList();
		for (UUIDSet uuidSet : map.values()) {
			gtids.add(uuidSet.getUUID() + ":" + join(uuidSet.intervals, ":"));
		}
		return join(gtids, ",");
	}

	/**
	 * @return index which is either a pointer to the interval containing v or a
	 *         position at which v can be added
	 */
	private static int findInterval(List ii, long v) {
		int l = 0, p = 0, r = ii.size();
		while (l < r) {
			p = (l + r) / 2;
			Interval i = ii.get(p);
			if (i.end < v) {
				l = p + 1;
			} else if (v < i.start) {
				r = p;
			} else {
				return p;
			}
		}
		if (!ii.isEmpty() && ii.get(p).end < v) {
			p++;
		}
		return p;
	}

	private String join(Collection o, String delimiter) {
		if (o.isEmpty()) {
			return "";
		}
		StringBuilder sb = new StringBuilder();
		for (Object o1 : o) {
			sb.append(o1).append(delimiter);
		}
		return sb.substring(0, sb.length() - delimiter.length());
	}

	/**
	 * @see GtidSet
	 */
	public static final class UUIDSet {

		private String uuid;
		private Collection intervals;

		private UUIDSet(String uuid, Collection intervals) {
			this.uuid = uuid;
			this.intervals = intervals;
		}

		public String getUUID() {
			return uuid;
		}

		public Collection getIntervals() {
			return intervals;
		}
	}

	/**
	 * @see GtidSet
	 */
	public static final class Interval implements Comparable {

		private long start;
		private long end;

		private Interval(long start, long end) {
			this.start = start;
			this.end = end;
		}

		public long getStart() {
			return start;
		}

		public long getEnd() {
			return end;
		}

		@Override
		public String toString() {
			return start + "-" + end;
		}

		@Override
		public int compareTo(Interval o) {
			return saturatedCast(this.start - o.start);
		}

		private static int saturatedCast(long value) {
			if (value > Integer.MAX_VALUE) {
				return Integer.MAX_VALUE;
			}
			if (value < Integer.MIN_VALUE) {
				return Integer.MIN_VALUE;
			}
			return (int) value;
		}
	}

}