/*
 * Copyright (C) 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.media3.exoplayer.video.spherical;

import android.content.Context;
import android.graphics.PointF;
import android.graphics.SurfaceTexture;
import android.hardware.Sensor;
import android.hardware.SensorManager;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.os.Handler;
import android.os.Looper;
import android.util.AttributeSet;
import android.view.Display;
import android.view.MotionEvent;
import android.view.Surface;
import android.view.WindowManager;
import androidx.annotation.AnyThread;
import androidx.annotation.BinderThread;
import androidx.annotation.Nullable;
import androidx.annotation.UiThread;
import androidx.annotation.VisibleForTesting;
import androidx.media3.common.C;
import androidx.media3.common.util.Assertions;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.common.util.Util;
import androidx.media3.exoplayer.video.VideoFrameMetadataListener;
import java.util.concurrent.CopyOnWriteArrayList;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

/**
 * Renders a GL scene in a non-VR Activity that is affected by phone orientation and touch input.
 *
 * <p>The two input components are the TYPE_GAME_ROTATION_VECTOR Sensor and a TouchListener. The GL
 * renderer combines these two inputs to render a scene with the appropriate camera orientation.
 *
 * <p>The primary complexity in this class is related to the various rotations. It is important to
 * apply the touch and sensor rotations in the correct order or the user's touch manipulations won't
 * match what they expect.
 */
@UnstableApi
public final class SphericalGLSurfaceView extends GLSurfaceView {

  /** Listener for the {@link Surface} to which video frames should be rendered. */
  public interface VideoSurfaceListener {

    /** Called when the {@link Surface} to which video frames should be rendered is created. */
    void onVideoSurfaceCreated(Surface surface);

    /** Called when the {@link Surface} to which video frames should be rendered is destroyed. */
    void onVideoSurfaceDestroyed(Surface surface);
  }

  // Arbitrary vertical field of view.
  private static final int FIELD_OF_VIEW_DEGREES = 90;
  private static final float Z_NEAR = 0.1f;
  private static final float Z_FAR = 100;

  // TODO Calculate this depending on surface size and field of view.
  private static final float PX_PER_DEGREES = 25;

  /* package */ static final float UPRIGHT_ROLL = (float) Math.PI;

  private final CopyOnWriteArrayList<VideoSurfaceListener> videoSurfaceListeners;
  private final SensorManager sensorManager;
  @Nullable private final Sensor orientationSensor;
  private final OrientationListener orientationListener;
  private final Handler mainHandler;
  private final TouchTracker touchTracker;
  private final SceneRenderer scene;
  @Nullable private SurfaceTexture surfaceTexture;
  @Nullable private Surface surface;
  private boolean useSensorRotation;
  private boolean isStarted;
  private boolean isOrientationListenerRegistered;

  public SphericalGLSurfaceView(Context context) {
    this(context, null);
  }

  public SphericalGLSurfaceView(Context context, @Nullable AttributeSet attributeSet) {
    super(context, attributeSet);
    videoSurfaceListeners = new CopyOnWriteArrayList<>();
    mainHandler = new Handler(Looper.getMainLooper());

    // Configure sensors and touch.
    sensorManager =
        (SensorManager) Assertions.checkNotNull(context.getSystemService(Context.SENSOR_SERVICE));
    @Nullable Sensor orientationSensor = null;
    if (Util.SDK_INT >= 18) {
      // TYPE_GAME_ROTATION_VECTOR is the easiest sensor since it handles all the complex math for
      // fusion. It's used instead of TYPE_ROTATION_VECTOR since the latter uses the magnetometer on
      // devices. When used indoors, the magnetometer can take some time to settle depending on the
      // device and amount of metal in the environment.
      orientationSensor = sensorManager.getDefaultSensor(Sensor.TYPE_GAME_ROTATION_VECTOR);
    }
    if (orientationSensor == null) {
      orientationSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR);
    }
    this.orientationSensor = orientationSensor;

    scene = new SceneRenderer();
    Renderer renderer = new Renderer(scene);

    touchTracker = new TouchTracker(context, renderer, PX_PER_DEGREES);
    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = Assertions.checkNotNull(windowManager).getDefaultDisplay();
    orientationListener = new OrientationListener(display, touchTracker, renderer);
    useSensorRotation = true;

    setEGLContextClientVersion(2);
    setRenderer(renderer);
    setOnTouchListener(touchTracker);
  }

  /**
   * Adds a {@link VideoSurfaceListener}.
   *
   * @param listener The listener to add.
   */
  public void addVideoSurfaceListener(VideoSurfaceListener listener) {
    videoSurfaceListeners.add(listener);
  }

  /**
   * Removes a {@link VideoSurfaceListener}.
   *
   * @param listener The listener to remove.
   */
  public void removeVideoSurfaceListener(VideoSurfaceListener listener) {
    videoSurfaceListeners.remove(listener);
  }

  /**
   * Returns the {@link Surface} to which video frames should be rendered, or {@code null} if it has
   * not been created.
   */
  @Nullable
  public Surface getVideoSurface() {
    return surface;
  }

  /** Returns the {@link VideoFrameMetadataListener} that should be registered during playback. */
  public VideoFrameMetadataListener getVideoFrameMetadataListener() {
    return scene;
  }

  /** Returns the {@link CameraMotionListener} that should be registered during playback. */
  public CameraMotionListener getCameraMotionListener() {
    return scene;
  }

  /**
   * Sets the default stereo mode. If the played video doesn't contain a stereo mode the default one
   * is used.
   *
   * @param stereoMode A {@link C.StereoMode} value.
   */
  public void setDefaultStereoMode(@C.StereoMode int stereoMode) {
    scene.setDefaultStereoMode(stereoMode);
  }

  /** Sets whether to use the orientation sensor for rotation (if available). */
  public void setUseSensorRotation(boolean useSensorRotation) {
    this.useSensorRotation = useSensorRotation;
    updateOrientationListenerRegistration();
  }

  @Override
  public void onResume() {
    super.onResume();
    isStarted = true;
    updateOrientationListenerRegistration();
  }

  @Override
  public void onPause() {
    isStarted = false;
    updateOrientationListenerRegistration();
    super.onPause();
  }

  @Override
  protected void onDetachedFromWindow() {
    // This call stops GL thread.
    super.onDetachedFromWindow();

    // Post to make sure we occur in order with any onSurfaceTextureAvailable calls.
    mainHandler.post(
        () -> {
          @Nullable Surface oldSurface = surface;
          if (oldSurface != null) {
            for (VideoSurfaceListener videoSurfaceListener : videoSurfaceListeners) {
              videoSurfaceListener.onVideoSurfaceDestroyed(oldSurface);
            }
          }
          releaseSurface(surfaceTexture, oldSurface);
          surfaceTexture = null;
          surface = null;
        });
  }

  private void updateOrientationListenerRegistration() {
    boolean enabled = useSensorRotation && isStarted;
    if (orientationSensor == null || enabled == isOrientationListenerRegistered) {
      return;
    }
    if (enabled) {
      sensorManager.registerListener(
          orientationListener, orientationSensor, SensorManager.SENSOR_DELAY_FASTEST);
    } else {
      sensorManager.unregisterListener(orientationListener);
    }
    isOrientationListenerRegistered = enabled;
  }

  // Called on GL thread.
  private void onSurfaceTextureAvailable(SurfaceTexture newSurfaceTexture) {
    mainHandler.post(
        () -> {
          @Nullable SurfaceTexture oldSurfaceTexture = surfaceTexture;
          @Nullable Surface oldSurface = surface;
          Surface newSurface = new Surface(newSurfaceTexture);
          surfaceTexture = newSurfaceTexture;
          surface = newSurface;
          for (VideoSurfaceListener videoSurfaceListener : videoSurfaceListeners) {
            videoSurfaceListener.onVideoSurfaceCreated(newSurface);
          }
          releaseSurface(oldSurfaceTexture, oldSurface);
        });
  }

  private static void releaseSurface(
      @Nullable SurfaceTexture oldSurfaceTexture, @Nullable Surface oldSurface) {
    if (oldSurfaceTexture != null) {
      oldSurfaceTexture.release();
    }
    if (oldSurface != null) {
      oldSurface.release();
    }
  }

  /**
   * Standard GL Renderer implementation. The notable code is the matrix multiplication in
   * onDrawFrame and updatePitchMatrix.
   */
  @VisibleForTesting
  /* package */ final class Renderer
      implements GLSurfaceView.Renderer, TouchTracker.Listener, OrientationListener.Listener {
    private final SceneRenderer scene;
    private final float[] projectionMatrix = new float[16];

    // There is no model matrix for this scene so viewProjectionMatrix is used for the mvpMatrix.
    private final float[] viewProjectionMatrix = new float[16];

    // Device orientation is derived from sensor data. This is accessed in the sensor's thread and
    // the GL thread.
    private final float[] deviceOrientationMatrix = new float[16];

    // Optional pitch and yaw rotations are applied to the sensor orientation. These are accessed on
    // the UI, sensor and GL Threads.
    private final float[] touchPitchMatrix = new float[16];
    private final float[] touchYawMatrix = new float[16];
    private float touchPitch;
    private float deviceRoll;

    // viewMatrix = touchPitch * deviceOrientation * touchYaw.
    private final float[] viewMatrix = new float[16];
    private final float[] tempMatrix = new float[16];

    public Renderer(SceneRenderer scene) {
      this.scene = scene;
      Matrix.setIdentityM(deviceOrientationMatrix, 0);
      Matrix.setIdentityM(touchPitchMatrix, 0);
      Matrix.setIdentityM(touchYawMatrix, 0);
      deviceRoll = UPRIGHT_ROLL;
    }

    @Override
    public synchronized void onSurfaceCreated(GL10 gl, EGLConfig config) {
      onSurfaceTextureAvailable(scene.init());
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
      GLES20.glViewport(0, 0, width, height);
      float aspect = (float) width / height;
      float fovY = calculateFieldOfViewInYDirection(aspect);
      Matrix.perspectiveM(projectionMatrix, 0, fovY, aspect, Z_NEAR, Z_FAR);
    }

    @Override
    public void onDrawFrame(GL10 gl) {
      // Combine touch & sensor data.
      // Orientation = pitch * sensor * yaw since that is closest to what most users expect the
      // behavior to be.
      synchronized (this) {
        Matrix.multiplyMM(tempMatrix, 0, deviceOrientationMatrix, 0, touchYawMatrix, 0);
        Matrix.multiplyMM(viewMatrix, 0, touchPitchMatrix, 0, tempMatrix, 0);
      }

      Matrix.multiplyMM(viewProjectionMatrix, 0, projectionMatrix, 0, viewMatrix, 0);
      scene.drawFrame(viewProjectionMatrix, /* rightEye= */ false);
    }

    /** Adjusts the GL camera's rotation based on device rotation. Runs on the sensor thread. */
    @Override
    @BinderThread
    public synchronized void onOrientationChange(float[] matrix, float deviceRoll) {
      System.arraycopy(matrix, 0, deviceOrientationMatrix, 0, deviceOrientationMatrix.length);
      this.deviceRoll = -deviceRoll;
      updatePitchMatrix();
    }

    /**
     * Updates the pitch matrix after a physical rotation or touch input. The pitch matrix rotation
     * is applied on an axis that is dependent on device rotation so this must be called after
     * either touch or sensor update.
     */
    @AnyThread
    private void updatePitchMatrix() {
      // The camera's pitch needs to be rotated along an axis that is parallel to the real world's
      // horizon. This is the <1, 0, 0> axis after compensating for the device's roll.
      Matrix.setRotateM(
          touchPitchMatrix,
          0,
          -touchPitch,
          (float) Math.cos(deviceRoll),
          (float) Math.sin(deviceRoll),
          0);
    }

    @Override
    @UiThread
    public synchronized void onScrollChange(PointF scrollOffsetDegrees) {
      touchPitch = scrollOffsetDegrees.y;
      updatePitchMatrix();
      Matrix.setRotateM(touchYawMatrix, 0, -scrollOffsetDegrees.x, 0, 1, 0);
    }

    @Override
    @UiThread
    public boolean onSingleTapUp(MotionEvent event) {
      return performClick();
    }

    private float calculateFieldOfViewInYDirection(float aspect) {
      boolean landscapeMode = aspect > 1;
      if (landscapeMode) {
        double halfFovX = FIELD_OF_VIEW_DEGREES / 2f;
        double tanY = Math.tan(Math.toRadians(halfFovX)) / aspect;
        double halfFovY = Math.toDegrees(Math.atan(tanY));
        return (float) (halfFovY * 2);
      } else {
        return FIELD_OF_VIEW_DEGREES;
      }
    }
  }
}