/*
 * Moonlight|3D
 * Copyright (C) 2006 The Moonlight|3D team
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Created on May 2, 2006
 */
package ml.backend.anim;

import java.util.ArrayList;

import ml.backend.anim.KeyframeAnimationTrack.KeyValuePair;
import ml.core.exceptions.Exception;
import ml.core.helper.Value;
import ml.core.helper.Value.Type;
import ml.math.Vector3D;

public class LinearValueInterpolator implements KeyframeInterpolator {

	public boolean isAppliciable(Type valueType) {
		if(valueType==Type.Boolean || valueType==Type.Integer || valueType==Type.Float ||
		   valueType==Type.Vector3D) {
			return true;
		}
		return false;
	}

	private boolean interpolateBoolean(boolean start, boolean end, double fraction) {
		if(fraction<0.5) {
			return start;
		}
		return end;
	}
	
	private int interpolateInteger(int start, int end, double fraction) {
		return (int)(start+(end-start)*fraction);
	}
	
	private double interpolateFloat(double start, double end, double fraction) {
		return start+(end-start)*fraction;
	}
	
	private Vector3D interpolateVector3D(Vector3D start, Vector3D end, double fraction) {
		Vector3D result=new Vector3D();
		
		result.X1=start.X1+(end.X1-start.X1)*fraction;
		result.X2=start.X2+(end.X2-start.X2)*fraction;
		result.X3=start.X3+(end.X3-start.X3)*fraction;
		
		return result;
	}
	
	private Value interpolateValue(Value start, Value end, double fraction) {
		Value result=new Value();
		result.setType(start.getType());
		if(start.getType()==Type.Boolean) {
			try {
				result.setValue(interpolateBoolean(start.getBooleanValue(),end.getBooleanValue(),fraction));
			} catch (Exception e) {
				// this exception cannot happen here - this is typesafe
				e.printStackTrace();
			}
		} else if(start.getType()==Type.Integer) {
			try {
				result.setValue(interpolateInteger(start.getIntegerValue(),end.getIntegerValue(),fraction));
			} catch (Exception e) {
				// this exception cannot happen here - this is typesafe
				e.printStackTrace();
			}			
		} else if(start.getType()==Type.Float) {
			try {
				result.setValue(interpolateFloat(start.getFloatValue(),end.getFloatValue(),fraction));
			} catch (Exception e) {
				// this exception cannot happen here - this is typesafe
				e.printStackTrace();
			}
		} else if(start.getType()==Type.Vector3D) {
			try {
				result.setValue(interpolateVector3D(start.getVectorValue(),end.getVectorValue(),fraction));
			} catch (Exception e) {
				// this exception cannot happen here - this is typesafe
				e.printStackTrace();
			}			
		}
		return result;
	}

	public Value interpolate(KeyframeAnimationTrack track, double time) {
		ArrayList<KeyValuePair> keys=track.getKeyList();
		
		if(keys.size()==0) {
			return track.getDefaultValue();
		} else if(keys.size()==1) {
			return keys.get(0).value;
		}
		if(keys.get(0).time>time) {
			double fraction=(time-keys.get(0).time)/(keys.get(1).time-keys.get(0).time);
			return interpolateValue(keys.get(0).value,keys.get(1).value,fraction);
		}
		if(time>keys.get(keys.size()-2).time) {
			double fraction=(time-keys.get(keys.size()-2).time)/(keys.get(keys.size()-1).time-keys.get(keys.size()-2).time);
			return interpolateValue(keys.get(keys.size()-2).value,keys.get(keys.size()-1).value,fraction);
		}
		for(int i=0;i<keys.size()-1;i++) {
			if(time>keys.get(i).time) {
				double fraction=(time-keys.get(i).time)/(keys.get(i+1).time-keys.get(i).time);
				return interpolateValue(keys.get(i).value,keys.get(i+1).value,fraction);
			}
		}
		
		return null; // this line should never be reached
	}

	public String getType() {
		return "LinearInterpolator";
	}

}