/*
 * Copyright (C) 2010 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 com.android.gallery3d.photoeditor.filters;

import android.media.effect.Effect;
import android.media.effect.EffectContext;
import android.os.Parcel;
import android.os.Parcelable;

import com.android.gallery3d.photoeditor.Photo;

import java.util.HashMap;

/**
 * Image filter for photo editing; most of its methods must be called from a single GL thread except
 * validate()/isValid() that are called from UI thread.
 */
public abstract class Filter implements Parcelable {

    // TODO: This should be set in MFF instead.
    private static final int DEFAULT_TILE_SIZE = 640;

    private static final HashMap<Filter, Effect> effects = new HashMap<Filter, Effect>();
    private static EffectContext context;

    private boolean isValid;

    /**
     * Filter context should be released before the current GL context is lost.
     */
    public static void releaseContext() {
        if (context != null) {
            // Release all effects created with the releasing context.
            for (Effect effect : effects.values()) {
                effect.release();
            }
            effects.clear();
            context.release();
            context = null;
        }
    }

    public void release() {
        Effect effect = effects.remove(this);
        if (effect != null) {
            effect.release();
        }
    }

    protected Effect getEffect(String name) {
        Effect effect = effects.get(this);
        if (effect == null) {
            if (context == null) {
                context = EffectContext.createWithCurrentGlContext();
            }
            effect = context.getFactory().createEffect(name);
            effect.setParameter("tile_size", DEFAULT_TILE_SIZE);
            effects.put(this, effect);
        }
        return effect;
    }

    protected void validate() {
        isValid = true;
    }

    /**
     * Some filters, e.g. lighting filters, are initially invalid until set up with parameters while
     * others, e.g. Sepia or Posterize filters, are initially valid without parameters.
     */
    public boolean isValid() {
        return isValid;
    }

    /**
     * Processes the source bitmap and matrix and output the destination bitmap and matrix.
     *
     * @param src source photo as the input.
     * @param dst destination photo having the same dimension as source photo as the output.
     */
    public abstract void process(Photo src, Photo dst);

    /**
     * Instantiates CREATOR of subclasses for Parcelable implementations.
     */
    protected static <T extends Filter> Parcelable.Creator<T> creatorOf(Class<T> filterClass) {
        return new FilterCreator<T>(filterClass);
    }

    /**
     * Saves states for restoring filter later; subclasses can override this to persist states.
     */
    protected void writeToParcel(Parcel out) {
    }

    /**
     * Restores filter from the saved states; subclasses can override this to persist states.
     */
    protected void readFromParcel(Parcel in) {
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        writeToParcel(dest);
    }
}