/*
    * Copyright (C) 2015 Alberto Irurueta Carro (alberto@irurueta.com)
    *
    * 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.irurueta.ar.sfm;
  
  import com.irurueta.geometry.CoordinatesType;
  import com.irurueta.geometry.PinholeCamera;
  import com.irurueta.geometry.Point2D;
  import com.irurueta.geometry.Point3D;
  import com.irurueta.geometry.estimators.LockedException;
  import com.irurueta.geometry.estimators.NotReadyException;
  import com.irurueta.numerical.robust.MSACRobustEstimator;
  import com.irurueta.numerical.robust.MSACRobustEstimatorListener;
  import com.irurueta.numerical.robust.RobustEstimator;
  import com.irurueta.numerical.robust.RobustEstimatorException;
  import com.irurueta.numerical.robust.RobustEstimatorMethod;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Robustly triangulates 3D points from matched 2D points and their
   * corresponding cameras on several views using MSAC algorithm.
   */
  public class MSACRobustSinglePoint3DTriangulator extends RobustSinglePoint3DTriangulator {
  
      /**
       * Constant defining default threshold to determine whether samples are
       * inliers or not.
       * By default, 1.0 is considered a good value for cases where 2D point
       * measures are done on pixels, since typically the minimum resolution is 1
       * pixel.
       */
      public static final double DEFAULT_THRESHOLD = 1.0;
  
      /**
       * Minimum value that can be set as threshold.
       * Threshold must be strictly greater than 0.0.
       */
      public static final double MIN_THRESHOLD = 0.0;
  
      /**
       * Threshold to determine whether samples are inliers or not when testing
       * possible estimation solutions.
       * The threshold refers to the amount of projection error (i.e. distance of
       * projected solution using each camera).
       */
      private double threshold;
  
      /**
       * Constructor.
       */
      public MSACRobustSinglePoint3DTriangulator() {
          super();
          threshold = DEFAULT_THRESHOLD;
      }
  
      /**
       * Constructor.
       *
       * @param listener listener to be notified of events such as when estimation
       *                 starts, ends or its progress significantly changes.
       */
      public MSACRobustSinglePoint3DTriangulator(final RobustSinglePoint3DTriangulatorListener listener) {
          super(listener);
          threshold = DEFAULT_THRESHOLD;
      }
  
      /**
       * Constructor.
       *
       * @param points  Matched 2D points. Each point in the list is assumed to be
       *                projected by the corresponding camera in the list.
       * @param cameras List of cameras associated to the matched 2D point on the
       *                same position as the camera on the list.
       * @throws IllegalArgumentException if provided lists don't have the same
       *                                  length or their length is less than 2 views, which is the minimum
       *                                  required to compute triangulation.
       */
      public MSACRobustSinglePoint3DTriangulator(final List<Point2D> points, final List<PinholeCamera> cameras) {
          super(points, cameras);
          threshold = DEFAULT_THRESHOLD;
      }
  
      /**
       * Constructor.
       *
      * @param points   Matched 2D points. Each point in the list is assumed to be
      *                 projected by the corresponding camera in the list.
      * @param cameras  List of cameras associated to the matched 2D point on the
      *                 same position as the camera on the list.
      * @param listener listener to be notified of events such as when estimation
      *                 starts, ends or its progress significantly changes.
      * @throws IllegalArgumentException if provided lists don't have the same
      *                                  length or their length is less than 2 views, which is the minimum
      *                                  required to compute triangulation.
      */
     public MSACRobustSinglePoint3DTriangulator(
             final List<Point2D> points, final List<PinholeCamera> cameras,
             final RobustSinglePoint3DTriangulatorListener listener) {
         super(points, cameras, listener);
         threshold = DEFAULT_THRESHOLD;
     }
 
     /**
      * Returns threshold to determine whether points are inliers or not when
      * testing possible estimation solutions.
      * The threshold refers to the amount of error (i.e. Euclidean distance) a
      * possible solution has on projected 2D points.
      *
      * @return threshold to determine whether points are inliers or not when
      * testing possible estimation solutions.
      */
     public double getThreshold() {
         return threshold;
     }
 
     /**
      * Sets threshold to determine whether points are inliers or not when
      * testing possible estimation solutions.
      * The threshold refers to the amount of error (i.e. Euclidean distance) a
      * possible solution has on projected 2D points.
      *
      * @param threshold threshold to be set.
      * @throws IllegalArgumentException if provided value is equal or less than
      *                                  zero.
      * @throws LockedException          if robust estimator is locked because an
      *                                  estimation is already in progress.
      */
     public void setThreshold(final double threshold) throws LockedException {
         if (isLocked()) {
             throw new LockedException();
         }
         if (threshold <= MIN_THRESHOLD) {
             throw new IllegalArgumentException();
         }
         this.threshold = threshold;
     }
 
     /**
      * Triangulates provided matched 2D points being projected by each
      * corresponding camera into a single 3D point.
      * At least 2 matched 2D points and their corresponding 2 cameras are
      * required to compute triangulation. If more views are provided, an
      * averaged solution can be found.
      *
      * @return computed triangulated 3D point.
      * @throws LockedException          if this instance is locked.
      * @throws NotReadyException        if lists of points and cameras don't have the
      *                                  same length or less than 2 views are provided.
      * @throws RobustEstimatorException if estimation fails for any reason
      *                                  (i.e. numerical instability, no solution available, etc).
      */
     @SuppressWarnings("DuplicatedCode")
     @Override
     public Point3D triangulate() throws LockedException, NotReadyException, RobustEstimatorException {
         if (isLocked()) {
             throw new LockedException();
         }
         if (!isReady()) {
             throw new NotReadyException();
         }
 
         final var innerEstimator = new MSACRobustEstimator<Point3D>(new MSACRobustEstimatorListener<>() {
 
             // point to be reused when computing residuals
             private final Point2D testPoint = Point2D.create(CoordinatesType.HOMOGENEOUS_COORDINATES);
 
             // non-robust 3D point triangulator
             private final SinglePoint3DTriangulator triangulator = SinglePoint3DTriangulator.create(
                     useHomogeneousSolution ? Point3DTriangulatorType.LMSE_HOMOGENEOUS_TRIANGULATOR
                             : Point3DTriangulatorType.LMSE_INHOMOGENEOUS_TRIANGULATOR);
 
             // subset of 2D points
             private final List<Point2D> subsetPoints = new ArrayList<>();
 
             // subst of cameras
             private final List<PinholeCamera> subsetCameras = new ArrayList<>();
 
             @Override
             public double getThreshold() {
                 return threshold;
             }
 
             @Override
             public int getTotalSamples() {
                 return points2D.size();
             }
 
             @Override
             public int getSubsetSize() {
                 return MIN_REQUIRED_VIEWS;
             }
 
             @Override
             public void estimatePreliminarSolutions(final int[] samplesIndices, final List<Point3D> solutions) {
                 subsetPoints.clear();
                 subsetPoints.add(points2D.get(samplesIndices[0]));
                 subsetPoints.add(points2D.get(samplesIndices[1]));
 
                 subsetCameras.clear();
                 subsetCameras.add(cameras.get(samplesIndices[0]));
                 subsetCameras.add(cameras.get(samplesIndices[1]));
 
                 try {
                     triangulator.setPointsAndCameras(subsetPoints, subsetCameras);
                     final var triangulated = triangulator.triangulate();
                     solutions.add(triangulated);
                 } catch (final Exception e) {
                     // if anything fails, no solution is added
                 }
             }
 
             @Override
             public double computeResidual(final Point3D currentEstimation, final int i) {
                 final var point2D = points2D.get(i);
                 final var camera = cameras.get(i);
 
                 // project estimated point with camera
                 camera.project(currentEstimation, testPoint);
 
                 // return distance of projected point respect to the original one
                 // as a residual
                 return testPoint.distanceTo(point2D);
             }
 
             @Override
             public boolean isReady() {
                 return MSACRobustSinglePoint3DTriangulator.this.isReady();
             }
 
             @Override
             public void onEstimateStart(final RobustEstimator<Point3D> estimator) {
                 if (listener != null) {
                     listener.onTriangulateStart(MSACRobustSinglePoint3DTriangulator.this);
                 }
             }
 
             @Override
             public void onEstimateEnd(final RobustEstimator<Point3D> estimator) {
                 if (listener != null) {
                     listener.onTriangulateEnd(MSACRobustSinglePoint3DTriangulator.this);
                 }
             }
 
             @Override
             public void onEstimateNextIteration(final RobustEstimator<Point3D> estimator, final int iteration) {
                 if (listener != null) {
                     listener.onTriangulateNextIteration(MSACRobustSinglePoint3DTriangulator.this, iteration);
                 }
             }
 
             @Override
             public void onEstimateProgressChange(final RobustEstimator<Point3D> estimator, final float progress) {
                 if (listener != null) {
                     listener.onTriangulateProgressChange(MSACRobustSinglePoint3DTriangulator.this, progress);
                 }
             }
         });
 
         try {
             locked = true;
             innerEstimator.setConfidence(confidence);
             innerEstimator.setMaxIterations(maxIterations);
             innerEstimator.setProgressDelta(progressDelta);
             return innerEstimator.estimate();
         } catch (final com.irurueta.numerical.LockedException e) {
             throw new LockedException(e);
         } catch (final com.irurueta.numerical.NotReadyException e) {
             throw new NotReadyException(e);
         } finally {
             locked = false;
         }
     }
 
     /**
      * Returns method being used for robust estimation.
      *
      * @return method being used for robust estimation.
      */
     @Override
     public RobustEstimatorMethod getMethod() {
         return RobustEstimatorMethod.MSAC;
     }
 }