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/*
 * Copyright © 2009 HotPads ([email protected])
 *
 * 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 io.datarouter.instrumentation.trace;

import java.util.Optional;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class W3TraceContext{

	public static final Pattern TRACESTATE_PATTERN = Pattern.compile(
			"^([a-z0-9_\\-*/@]*=[a-zA-Z0-9]*)(,[a-z0-9_\\-*/@]*=[a-zA-Z0-9]*)*$");

	private Traceparent traceparent;
	private Tracestate tracestate;
	private long createdTimestamp;
	private boolean hasValidTraceparent = false;

	/**
	 * @param traceparentStr the traceparent passed in the request header
	 * @param tracestateStr the tracestate passed in the request header
	 * @param createdTimestampEpochNanos the timestamp used when existing traceparent is invalid or missing to create
	 * 			a parentId
	 */
	public W3TraceContext(String traceparentStr, String tracestateStr, long createdTimestampEpochNanos){
		// If either trace-id, parent-id or trace-flags are invalid, we create a new traceparent and tracestate headers
		if(!validateAndSetTraceparent(traceparentStr)){
			traceparent = Traceparent.generateNew(createdTimestampEpochNanos);
			tracestate = Tracestate.generateNew(traceparent.parentId);
		}
		parseOrCreateNewTracestate(tracestateStr);
		this.createdTimestamp = createdTimestampEpochNanos;
	}

	public W3TraceContext(Traceparent traceparent, Tracestate tracestate, long createdTimestampEpochNanos){
		this.traceparent = traceparent;
		this.tracestate = tracestate;
		this.createdTimestamp = createdTimestampEpochNanos;
	}

	public W3TraceContext(long createdTimestampEpochNanos){
		this.traceparent = Traceparent.generateNew(createdTimestampEpochNanos);
		this.tracestate = Tracestate.generateNew(traceparent.parentId);
		this.createdTimestamp = createdTimestampEpochNanos;
	}

	public W3TraceContext copy(){
		return new W3TraceContext(traceparent, tracestate, createdTimestamp);
	}

	public Traceparent getTraceparent(){
		return traceparent;
	}

	public Tracestate getTracestate(){
		return tracestate;
	}

	public String getTraceId(){
		return traceparent.traceId;
	}

	public String getParentId(){
		return traceparent.parentId;
	}

	public void updateParentIdAndAddTracestateMember(){
		traceparent = traceparent.copyWithNewParentId();
		tracestate.addDatarouterListMember(traceparent.parentId);
	}

	public long getTimestampMs(){
		return traceparent.getInstantTruncatedToMillis().toEpochMilli();
	}

	private boolean validateAndSetTraceparent(String traceparentStr){
		Optional parsedTraceparentOpt = Traceparent.parseIfValid(traceparentStr);
		parsedTraceparentOpt.ifPresent(traceparent -> this.traceparent = traceparent);
		return hasValidTraceparent = parsedTraceparentOpt.isPresent();
	}

	private void parseOrCreateNewTracestate(String tracestateStr){
		if(!hasValidTraceparent){
			tracestate = Tracestate.generateNew(traceparent.parentId);
			return;
		}
		if(tracestateStr == null || tracestateStr.isEmpty()){
			tracestate = Tracestate.generateNew(traceparent.parentId);
			return;
		}
		Matcher matcher = TRACESTATE_PATTERN.matcher(tracestateStr);
		if(!matcher.matches()){
			tracestate = Tracestate.generateNew(traceparent.parentId);
			return;
		}

		tracestate = new Tracestate();
		String[] members = tracestateStr.split(Tracestate.TRACESTATE_MEMBER_DELIMITER);
		for(String member : members){
			String[] tokens = member.split(Tracestate.TRACESTATE_KEYVALUE_DELIMITER);
			if(tokens.length > 1){
				tracestate.addListMember(tokens[0], tokens[1]);
			}
		}
	}

	@Override
	public String toString(){
		return "traceparent=\"" + traceparent + "\", tracestate=\"" + tracestate + "\"";
	}

}