/**
 * Copyright (c) 2006, Sun Microsystems, Inc
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
 *     copyright notice, this list of conditions and the following 
 *     disclaimer in the documentation and/or other materials provided 
 *     with the distribution.
 *   * Neither the name of the TimingFramework project nor the names of its
 *     contributors may be used to endorse or promote products derived 
 *     from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.pushingpixels.trident.interpolator;

import org.pushingpixels.trident.ease.TimelineEase;

/**
 * 
 * KeyFrames holds information about the times at which values are sampled
 * (KeyTimes) and the values at those times (KeyValues). It also holds
 * information about how to interpolate between these values for times that lie
 * between the sampling points.
 * 
 * @author Chet
 */
public class KeyFrames<T> {

	private KeyValues<T> keyValues;
	private KeyTimes keyTimes;
	private KeyInterpolators interpolators;

	/**
	 * Simplest variation; determine keyTimes based on even division of 0-1
	 * range based on number of keyValues. This constructor assumes LINEAR
	 * interpolation.
	 * 
	 * @param keyValues
	 *            values that will be assumed at each time in keyTimes
	 */
	public KeyFrames(KeyValues<T> keyValues) {
		init(keyValues, null, (TimelineEase) null);
	}

	/**
	 * This variant takes both keyValues (values at each point in time) and
	 * keyTimes (times at which values are sampled).
	 * 
	 * @param keyValues
	 *            values that the animation will assume at each of the
	 *            corresponding times in keyTimes
	 * @param keyTimes
	 *            times at which the animation will assume the corresponding
	 *            values in keyValues
	 * @throws IllegalArgumentException
	 *             keyTimes and keySizes must have the same number of elements
	 *             since these structures are meant to have corresponding
	 *             entries; an exception is thrown otherwise.
	 */
	public KeyFrames(KeyValues<T> keyValues, KeyTimes keyTimes) {
		init(keyValues, keyTimes, (TimelineEase) null);
	}

	/**
	 * Full constructor: caller provides an instance of all key* structures
	 * which will be used to calculate between all times in the keyTimes list. A
	 * null interpolator parameter is equivalent to calling
	 * {@link KeyFrames#KeyFrames(KeyValues, KeyTimes)}.
	 * 
	 * @param keyValues
	 *            values that the animation will assume at each of the
	 *            corresponding times in keyTimes
	 * @param keyTimes
	 *            times at which the animation will assume the corresponding
	 *            values in keyValues
	 * @param interpolators
	 *            collection of Interpolators that control the calculation of
	 *            values in each of the intervals defined by keyFrames. If this
	 *            value is null, a {@link LinearInterpolator} will be used for
	 *            all intervals. If there is only one interpolator, that
	 *            interpolator will be used for all intervals. Otherwise, there
	 *            must be a number of interpolators equal to the number of
	 *            intervals (which is one less than the number of keyTimes).
	 * @throws IllegalArgumentException
	 *             keyTimes and keyValues must have the same number of elements
	 *             since these structures are meant to have corresponding
	 *             entries; an exception is thrown otherwise.
	 * @throws IllegalArgumentException
	 *             The number of interpolators must either be zero
	 *             (interpolators == null), one, or one less than the size of
	 *             keyTimes.
	 */
	public KeyFrames(KeyValues<T> keyValues, KeyTimes keyTimes,
			TimelineEase... interpolators) {
		init(keyValues, keyTimes, interpolators);
	}

	/**
	 * Utility constructor that assumes even division of times according to size
	 * of keyValues and interpolation according to interpolators parameter.
	 * 
	 * @param keyValues
	 *            values that the animation will assume at each of the
	 *            corresponding times in keyTimes
	 * @param interpolators
	 *            collection of Interpolators that control the calculation of
	 *            values in each of the intervals defined by keyFrames. If this
	 *            value is null, a {@link LinearInterpolator} will be used for
	 *            all intervals. If there is only one interpolator, that
	 *            interpolator will be used for all intervals. Otherwise, there
	 *            must be a number of interpolators equal to the number of
	 *            intervals (which is one less than the number of keyTimes).
	 * @throws IllegalArgumentException
	 *             The number of interpolators must either be zero
	 *             (interpolators == null), one, or one less than the size of
	 *             keyTimes.
	 */
	public KeyFrames(KeyValues<T> keyValues, TimelineEase... interpolators) {
		init(keyValues, null, interpolators);
	}

	/**
	 * Utility function called by constructors to perform common initialization
	 * chores
	 */
	private void init(KeyValues<T> keyValues, KeyTimes keyTimes,
			TimelineEase... interpolators) {
		int numFrames = keyValues.getSize();
		// If keyTimes null, create our own
		if (keyTimes == null) {
			float keyTimesArray[] = new float[numFrames];
			float timeVal = 0.0f;
			keyTimesArray[0] = timeVal;
			for (int i = 1; i < (numFrames - 1); ++i) {
				timeVal += (1.0f / (numFrames - 1));
				keyTimesArray[i] = timeVal;
			}
			keyTimesArray[numFrames - 1] = 1.0f;
			this.keyTimes = new KeyTimes(keyTimesArray);
		} else {
			this.keyTimes = keyTimes;
		}
		this.keyValues = keyValues;
		if (numFrames != this.keyTimes.getSize()) {
			throw new IllegalArgumentException("keyValues and keyTimes"
					+ " must be of equal size");
		}
		if (interpolators != null && (interpolators.length != (numFrames - 1))
				&& (interpolators.length != 1)) {
			throw new IllegalArgumentException(
					"interpolators must be "
							+ "either null (implying interpolation for all intervals), "
							+ "a single interpolator (which will be used for all "
							+ "intervals), or a number of interpolators equal to "
							+ "one less than the number of times.");
		}
		this.interpolators = new KeyInterpolators(numFrames - 1, interpolators);
	}

	public Class getType() {
		return keyValues.getType();
	}

	KeyValues getKeyValues() {
		return keyValues;
	}

	KeyTimes getKeyTimes() {
		return keyTimes;
	}

	/**
	 * Returns time interval that contains this time fraction
	 */
	public int getInterval(float fraction) {
		return keyTimes.getInterval(fraction);
	}

	/**
	 * Returns a value for the given fraction elapsed of the animation cycle.
	 * Given the fraction, this method will determine what interval the fraction
	 * lies within, how much of that interval has elapsed, what the boundary
	 * values are (from KeyValues), what the interpolated fraction is (from the
	 * Interpolator for the interval), and what the final interpolated
	 * intermediate value is (using the appropriate Evaluator). This method will
	 * call into the Interpolator for the time interval to get the interpolated
	 * method. To ensure that future operations succeed, the value received from
	 * the interpolation will be clamped to the interval [0,1].
	 */
	public Object getValue(float fraction) {
		// First, figure out the real fraction to use, given the
		// interpolation type and keyTimes
		int interval = getInterval(fraction);
		float t0 = keyTimes.getTime(interval);
		float t1 = keyTimes.getTime(interval + 1);
		float t = (fraction - t0) / (t1 - t0);
		float interpolatedT = interpolators.interpolate(interval, t);
		// clamp to avoid problems with buggy Interpolators
		if (interpolatedT < 0f) {
			interpolatedT = 0f;
		} else if (interpolatedT > 1f) {
			interpolatedT = 1f;
		}
		return keyValues.getValue(interval, (interval + 1), interpolatedT);
	}

}
