import jm.music.data.*;
import jm.JMC;
import jm.util.*;
import jm.music.tools.*;

/**
 * Class that holds an element in a song
 * @author Mark Guzdial
 * @author Barb Ericson
 */
public class SongElement {
  
  /** the next song element */
  private SongElement next;
  
  /** a part (notes) in the song */
  private Part myPart;
  
  /**
   * Constructor that takes no arguments.
   * The next part is empty, and ours is a blank new part
   */
  public SongElement(){
    this.next = null;
    this.myPart = new Part();
  }
  
  /** This method takes a phrase and makes it the one for this element 
    * at the desired start time with the given instrument
    * @param myPhrase the phrase to use
    * @param startTime the time to start this phrase
    * @param instrument the instrument to use to play this
    */
  public void setPhrase(Phrase myPhrase, double startTime, 
                        int instrument) {
    myPhrase.setStartTime(startTime);
    this.myPart.addPhrase(myPhrase);
    this.myPart.setInstrument(instrument);
  }
  
  
  /** 
   * Method to set the next element in the song
   * @param nextOne the element that should be next
   */
  public void setNext(SongElement nextOne) {
    this.next = nextOne;
  }
  
  /**
   * Method to get the next element in the song
   * @return the next element or null if none
   */
  public SongElement getNext() {
    return this.next;
  }
  
  /**
   * Method to get the part associated with this element
   * @return the part
   */
  private Part getPart() {
    return this.myPart;
  }
  
  /**
   * Method to get the end time for this element.
   * @return the time this element ends
   */
  public double getEndTime(){
    return this.myPart.getPhrase(0).getEndTime();
  }
  
  /**
   * We need setChannel because each part has to be in its
   * own channel if it has different start times.
   * So, we'll set the channel when we assemble the score.
   * @param channel the channel to use
   */
  private void setChannel(int channel) {
    myPart.setChannel(channel);
  }
  
  /**
   * Method to show the song from this element
   */
  public void showFromMeOn() {
    
    // Make the score that we'll assemble the elements into
    // We'll set it up with a default time signature and tempo we like
    // (Should probably make it possible to change these -- 
    // maybe with inputs?)
    Score myScore = new Score("My Song");
    myScore.setTimeSignature(3,4);
    myScore.setTempo(120.0);
    
    // Each element will be in its own channel
    int channelCount = 1;
    
    // Start from this element (this)
    SongElement current = this;
    // While we're not through...
    while (current != null) {
      
      // Set the channel, increment the channel, then add it in.
      current.setChannel(channelCount);
      channelCount = channelCount + 1;
      myScore.addPart(current.getPart());
      
      // Now, move on to the next element
      // which we already know isn't null
      current = current.getNext();
    }
    
    // At the end, let's see it!
    View.notate(myScore);
  }
  
}