package org.daisy.pipeline.tts.calabash.impl;
   
   import java.net.URI;
   import java.time.Duration;
   import java.util.concurrent.atomic.AtomicReference;
   
   import org.daisy.pipeline.audio.AudioClip;
   import org.daisy.pipeline.tts.TTSLog;
   
  /**
   * Mapping between a fragment in the XML document and a fragment in an audio file.
   */
  class SoundFileLink {
  
  	/** Reference to fragment in XML document */
  	private final URI textRef;
  	/** Time position where the audio fragment starts within <code>clipBase</code> */
  	private final Duration clipBegin;
  	/** Time position where the audio fragment ends within <code>clipBase</code> */
  	private final Duration clipEnd;
  
  	/**
  	 * Audio clip that is used as the base for <code>clipBegin</code> and <code>clipEnd</code>. The
  	 * purpose of the reference is so that it can be easily shared between {@link TextToPcmThread}
  	 * and {@link EncodingThread} (via {@link ContiguousPCM}), because {@link AudioClip} is
  	 * immutable.
  	 */
  	public AtomicReference<AudioClip> clipBase;
  
  	public SoundFileLink(URI textRef, Duration clipBegin, Duration clipEnd) {
  		if (clipBegin == null || clipEnd == null || textRef == null)
  			throw new NullPointerException();
  		if (clipBegin.compareTo(Duration.ZERO) < 0)
  			throw new IllegalArgumentException("Clip begin can not be negative: " + clipBegin);
  		if (clipEnd.compareTo(clipBegin) < 0)
  			throw new IllegalArgumentException("Clip end can not come before clip begin: " + clipEnd + " < " + clipBegin);
  		this.textRef = textRef;
  		this.clipBegin = clipBegin;
  		this.clipEnd = clipEnd;
  	}
  
  	public URI getTextFragment() {
  		return textRef;
  	}
  
  	private AudioClip clip;
  
  	public AudioClip getAudioFragment(TTSLog log) {
  		if (clip == null) {
  			if (clipBase == null)
  				throw new IllegalStateException(); // should not happen
  			AudioClip base = clipBase.get();
  			if (base == null)
  				return null; // was not set in EncodingThread due to an error
  			Duration begin = base.clipBegin.plus(clipBegin);
  			Duration end = base.clipBegin.plus(clipEnd);
  			if (begin.compareTo(base.clipEnd) > 0) {
  				if (begin.minus(base.clipEnd).toMillis() > 1)
  					// this can not be a rounding error due to sampling
  					log.getOrCreateEntry(getTextFragment().toString()).addError(
  						new TTSLog.Error(TTSLog.ErrorCode.AUDIO_MISSING, "clip not encoded"));
  				begin = base.clipEnd;
  				end = base.clipEnd;
  			} else if (end.compareTo(base.clipEnd) > 0) {
  				if (end.minus(base.clipEnd).toMillis() > 1)
  					// this can not be a rounding error due to sampling
  					log.getOrCreateEntry(getTextFragment().toString()).addError(
  						new TTSLog.Error(TTSLog.ErrorCode.AUDIO_MISSING, "part of clip not encoded"));
  				end = base.clipEnd;
  			}
  			clip = new AudioClip(base.src, begin, end);
  		}
  		return clip;
  	}
  }