/*
 * Copyright 2018 The Android Open Source Project
 *
 * 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 androidx.core.animation;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.Resources.Theme;
import android.content.res.TypedArray;
import android.util.AttributeSet;

import androidx.annotation.FloatRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

/**
 * An interpolator where the change starts backward then flings forward and overshoots
 * the target value and finally goes back to the final value.
 */
public class AnticipateOvershootInterpolator implements Interpolator {
    private final float mTension;

    /**
     * Creates a new instance of {@link AnticipateOvershootInterpolator} with slight anticipate and
     * overshoot.
     */
    public AnticipateOvershootInterpolator() {
        mTension = 2.0f * 1.5f;
    }

    /**
     * Creates a new instance of {@link AnticipateOvershootInterpolator}.
     *
     * @param tension Amount of anticipation/overshoot. When tension equals 0.0f,
     *                there is no anticipation/overshoot and the interpolator becomes
     *                a simple acceleration/deceleration interpolator.
     */
    public AnticipateOvershootInterpolator(float tension) {
        mTension = tension * 1.5f;
    }

    /**
     * Creates a new instance of {@link AnticipateOvershootInterpolator}.
     *
     * @param tension Amount of anticipation/overshoot. When tension equals 0.0f,
     *                there is no anticipation/overshoot and the interpolator becomes
     *                a simple acceleration/deceleration interpolator.
     * @param extraTension Amount by which to multiply the tension. For instance,
     *                     to get the same overshoot as an OvershootInterpolator with
     *                     a tension of 2.0f, you would use an extraTension of 1.5f.
     */
    public AnticipateOvershootInterpolator(float tension, float extraTension) {
        mTension = tension * extraTension;
    }

    public AnticipateOvershootInterpolator(@NonNull Context context, @Nullable AttributeSet attrs) {
        this(context.getResources(), context.getTheme(), attrs);
    }

    AnticipateOvershootInterpolator(Resources res, Theme theme, AttributeSet attrs) {
        TypedArray a;
        if (theme != null) {
            a = theme.obtainStyledAttributes(attrs,
                    AndroidResources.STYLEABLE_ANTICIPATEOVERSHOOT_INTERPOLATOR, 0, 0);
        } else {
            a = res.obtainAttributes(attrs,
                    AndroidResources.STYLEABLE_ANTICIPATEOVERSHOOT_INTERPOLATOR);
        }

        mTension = a.getFloat(AndroidResources.STYLEABLE_ANTICIPATEOVERSHOOT_INTERPOLATOR_TENSION,
                2.0f) * a.getFloat(
                        AndroidResources.STYLEABLE_ANTICIPATEOVERSHOOT_INTERPOLATOR_EXTRA_TENSION,
                1.5f);
        a.recycle();
    }

    private static float a(float t, float s) {
        return t * t * ((s + 1) * t - s);
    }

    private static float o(float t, float s) {
        return t * t * ((s + 1) * t + s);
    }

    @Override
    @FloatRange(to = 1)
    public float getInterpolation(@FloatRange(from = 0, to = 1) float input) {
        // a(t, s) = t * t * ((s + 1) * t - s)
        // o(t, s) = t * t * ((s + 1) * t + s)
        // f(t) = 0.5 * a(t * 2, tension * extraTension), when t < 0.5
        // f(t) = 0.5 * (o(t * 2 - 2, tension * extraTension) + 2), when t <= 1.0
        if (input < 0.5f) return 0.5f * a(input * 2.0f, mTension);
        else return 0.5f * (o(input * 2.0f - 2.0f, mTension) + 2.0f);
    }

}