/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.geckoview;

import android.graphics.Color;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.UiThread;
import java.util.ArrayList;
import java.util.List;
import org.mozilla.gecko.annotation.RobocopTarget;
import org.mozilla.gecko.util.ThreadUtils;

@UiThread
public final class CompositorController {
  private final GeckoSession.Compositor mCompositor;

  private List<Runnable> mDrawCallbacks;
  private int mDefaultClearColor = Color.WHITE;
  private Runnable mFirstPaintCallback;

  /* package */ CompositorController(final GeckoSession session) {
    mCompositor = session.mCompositor;
  }

  /* package */ void onCompositorReady() {
    mCompositor.setDefaultClearColor(mDefaultClearColor);
    mCompositor.enableLayerUpdateNotifications(mDrawCallbacks != null && !mDrawCallbacks.isEmpty());
  }

  /* package */ void onCompositorDetached() {
    if (mDrawCallbacks != null) {
      mDrawCallbacks.clear();
    }
  }

  /* package */ void notifyDrawCallbacks() {
    if (mDrawCallbacks != null) {
      for (final Runnable callback : mDrawCallbacks) {
        callback.run();
      }
    }
  }

  /**
   * Add a callback to run when drawing (layer update) occurs.
   *
   * @param callback Callback to add.
   */
  @RobocopTarget
  public void addDrawCallback(final @NonNull Runnable callback) {
    ThreadUtils.assertOnUiThread();

    if (mDrawCallbacks == null) {
      mDrawCallbacks = new ArrayList<Runnable>(2);
    }

    if (mDrawCallbacks.add(callback) && mDrawCallbacks.size() == 1 && mCompositor.isReady()) {
      mCompositor.enableLayerUpdateNotifications(true);
    }
  }

  /**
   * Remove a previous draw callback.
   *
   * @param callback Callback to remove.
   */
  @RobocopTarget
  public void removeDrawCallback(final @NonNull Runnable callback) {
    ThreadUtils.assertOnUiThread();

    if (mDrawCallbacks == null) {
      return;
    }

    if (mDrawCallbacks.remove(callback) && mDrawCallbacks.isEmpty() && mCompositor.isReady()) {
      mCompositor.enableLayerUpdateNotifications(false);
    }
  }

  /**
   * Get the current clear color when drawing.
   *
   * @return Curent clear color.
   */
  public int getClearColor() {
    ThreadUtils.assertOnUiThread();
    return mDefaultClearColor;
  }

  /**
   * Set the clear color when drawing. Default is Color.WHITE.
   *
   * @param color Clear color.
   */
  public void setClearColor(final int color) {
    ThreadUtils.assertOnUiThread();

    mDefaultClearColor = color;
    if (mCompositor.isReady()) {
      mCompositor.setDefaultClearColor(mDefaultClearColor);
    }
  }

  /**
   * Get the current first paint callback.
   *
   * @return Current first paint callback or null if not set.
   */
  public @Nullable Runnable getFirstPaintCallback() {
    ThreadUtils.assertOnUiThread();
    return mFirstPaintCallback;
  }

  /**
   * Set a callback to run when a document is first drawn.
   *
   * @param callback First paint callback.
   */
  public void setFirstPaintCallback(final @Nullable Runnable callback) {
    ThreadUtils.assertOnUiThread();
    mFirstPaintCallback = callback;
  }

  /* package */ void onFirstPaint() {
    if (mFirstPaintCallback != null) {
      mFirstPaintCallback.run();
    }
  }
}