/*
    * Copyright (C) 2018 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.navigation.indoor.radiosource;
  
  import com.irurueta.geometry.Point2D;
  import com.irurueta.navigation.LockedException;
  import com.irurueta.navigation.NotReadyException;
  import com.irurueta.navigation.indoor.RadioSource;
  import com.irurueta.navigation.indoor.RangingReadingLocated;
  import com.irurueta.numerical.robust.RANSACRobustEstimator;
  import com.irurueta.numerical.robust.RANSACRobustEstimatorListener;
  import com.irurueta.numerical.robust.RobustEstimator;
  import com.irurueta.numerical.robust.RobustEstimatorException;
  import com.irurueta.numerical.robust.RobustEstimatorMethod;
  
  import java.util.List;
  
  /**
   * Robustly estimated 2D position of a radio source (e.g. Wi-Fi
   * access point or bluetooth beacon), by discarding outliers using RANSAC
   * algorithm.
   *
   * @param <S> a {@link RadioSource} type.
   */
  public class RANSACRobustRangingRadioSourceEstimator2D<S extends RadioSource> extends
          RobustRangingRadioSourceEstimator2D<S> {
  
      /**
       * Constant defining default threshold on received power (RSSI) expressed in
       * dBm's.
       */
      public static final double DEFAULT_THRESHOLD = 0.1;
  
      /**
       * Minimum value that can be set as threshold.
       * Threshold must be strictly greater than 0.0.
       */
      public static final double MIN_THRESHOLD = 0.0;
  
      /**
       * Indicates that by default inliers will only be computed but not kept.
       */
      public static final boolean DEFAULT_COMPUTE_AND_KEEP_INLIERS = false;
  
      /**
       * Indicates that by default residuals will only be computed but not kept.
       */
      public static final boolean DEFAULT_COMPUTE_AND_KEEP_RESIDUALS = false;
  
      /**
       * Threshold to determine whether samples are inliers or not when testing possible solutions.
       * The threshold refers to the amount of error on received power (RSSI) expressed
       * in dBm's between received value that should have been received on estimated
       * iso-tropical model and actual measured value.
       */
      private double threshold = DEFAULT_THRESHOLD;
  
      /**
       * Indicates whether inliers must be computed and kept.
       */
      private boolean computeAndKeepInliers = DEFAULT_COMPUTE_AND_KEEP_INLIERS;
  
      /**
       * Indicates whether residuals must be computed and kept.
       */
      private boolean computeAndKeepResiduals = DEFAULT_COMPUTE_AND_KEEP_RESIDUALS;
  
      /**
       * Constructor.
       */
      public RANSACRobustRangingRadioSourceEstimator2D() {
          super();
      }
  
      /**
       * Constructor.
       * Sets radio signal ranging readings belonging to the same radio source.
       *
       * @param readings radio signal ranging readings belonging to the same
       *                 radio source.
       * @throws IllegalArgumentException if readings are not valid.
       */
      public RANSACRobustRangingRadioSourceEstimator2D(final List<? extends RangingReadingLocated<S, Point2D>> readings) {
          super(readings);
      }
  
     /**
      * Constructor.
      *
      * @param listener listener in charge of attending events raised by this instance.
      */
     public RANSACRobustRangingRadioSourceEstimator2D(
             final RobustRangingRadioSourceEstimatorListener<S, Point2D> listener) {
         super(listener);
     }
 
     /**
      * Constructor.
      * Sets radio signal readings belonging to the same radio source.
      *
      * @param readings radio signal readings belonging to the same radio source.
      * @param listener listener in charge of attending events raised by this instance.
      * @throws IllegalArgumentException if readings are not valid.
      */
     public RANSACRobustRangingRadioSourceEstimator2D(
             final List<? extends RangingReadingLocated<S, Point2D>> readings,
             final RobustRangingRadioSourceEstimatorListener<S, Point2D> listener) {
         super(readings, listener);
     }
 
     /**
      * Constructor.
      *
      * @param initialPosition initial position to start the estimation or radio
      *                        source position.
      */
     public RANSACRobustRangingRadioSourceEstimator2D(final Point2D initialPosition) {
         super(initialPosition);
     }
 
     /**
      * Constructor.
      * Sets radio signal readings belonging to the same radio source.
      *
      * @param readings        radio signal readings belonging to the same radio source.
      * @param initialPosition initial position to start the estimation of radio
      *                        source position.
      * @throws IllegalArgumentException if readings are not valid.
      */
     public RANSACRobustRangingRadioSourceEstimator2D(
             final List<? extends RangingReadingLocated<S, Point2D>> readings, final Point2D initialPosition) {
         super(readings, initialPosition);
     }
 
     /**
      * Constructor.
      *
      * @param initialPosition initial position to start the estimation of radio
      *                        source position.
      * @param listener        listener in charge of attending events raised by this instance.
      */
     public RANSACRobustRangingRadioSourceEstimator2D(
             final Point2D initialPosition, final RobustRangingRadioSourceEstimatorListener<S, Point2D> listener) {
         super(initialPosition, listener);
     }
 
     /**
      * Constructor.
      * Sets radio signal ranging readings belonging to the same radio source.
      *
      * @param readings        radio signal ranging readings belonging to the same radio source.
      * @param initialPosition initial position to start the estimation of radio source
      *                        position.
      * @param listener        listener in charge of attending events raised by this instance.
      * @throws IllegalArgumentException if readings are not valid.
      */
     public RANSACRobustRangingRadioSourceEstimator2D(
             final List<? extends RangingReadingLocated<S, Point2D>> readings, final Point2D initialPosition,
             final RobustRangingRadioSourceEstimatorListener<S, Point2D> listener) {
         super(readings, initialPosition, listener);
     }
 
     /**
      * Gets threshold to determine whether samples are inliers or not when testing possible solutions.
      * The threshold refers to the amount of error on ranging distances.
      *
      * @return threshold to determine whether samples are inliers or not.
      */
     public double getThreshold() {
         return threshold;
     }
 
     /**
      * Sets threshold to determine whether samples are inliers or not when testing possible solutions.
      * The threshold refers to the amount of error on ranging distances.
      *
      * @param threshold threshold to determine whether samples are inliers or not.
      * @throws IllegalArgumentException if provided value is equal or less than zero.
      * @throws LockedException          if this estimator is locked.
      */
     public void setThreshold(final double threshold) throws LockedException {
         if (isLocked()) {
             throw new LockedException();
         }
         if (threshold <= MIN_THRESHOLD) {
             throw new IllegalArgumentException();
         }
         this.threshold = threshold;
     }
 
 
     /**
      * Indicates whether inliers must be computed and kept.
      *
      * @return true if inliers must be computed and kept, false if inliers
      * only need to be computed but not kept.
      */
     public boolean isComputeAndKeepInliersEnabled() {
         return computeAndKeepInliers;
     }
 
     /**
      * Specifies whether inliers must be computed and kept.
      *
      * @param computeAndKeepInliers true if inliers must be computed and kept,
      *                              false if inliers only need to be computed but not kept.
      * @throws LockedException if this solver is locked.
      */
     public void setComputeAndKeepInliersEnabled(final boolean computeAndKeepInliers) throws LockedException {
         if (isLocked()) {
             throw new LockedException();
         }
         this.computeAndKeepInliers = computeAndKeepInliers;
     }
 
     /**
      * Indicates whether residuals must be computed and kept.
      *
      * @return true if residuals must be computed and kept, false if residuals
      * only need to be computed but not kept.
      */
     public boolean isComputeAndKeepResidualsEnabled() {
         return computeAndKeepResiduals;
     }
 
     /**
      * Specifies whether residuals must be computed and kept.
      *
      * @param computeAndKeepResiduals true if residuals must be computed and kept,
      *                                false if residuals only need to be computed but not kept.
      * @throws LockedException if this solver is locked.
      */
     public void setComputeAndKeepResidualsEnabled(final boolean computeAndKeepResiduals) throws LockedException {
         if (isLocked()) {
             throw new LockedException();
         }
         this.computeAndKeepResiduals = computeAndKeepResiduals;
     }
 
     /**
      * Robustly estimates position for a radio source.
      *
      * @throws LockedException          if instance is busy during estimation.
      * @throws NotReadyException        if estimator is not ready.
      * @throws RobustEstimatorException if estimation fails for any reason
      *                                  (i.e. numerical instability, no solution available, etc).
      */
     @SuppressWarnings("DuplicatedCode")
     @Override
     public void estimate() throws LockedException, NotReadyException, RobustEstimatorException {
         if (isLocked()) {
             throw new LockedException();
         }
         if (!isReady()) {
             throw new NotReadyException();
         }
 
         final var innerEstimator = new RANSACRobustEstimator<>(new RANSACRobustEstimatorListener<Solution<Point2D>>() {
             @Override
             public double getThreshold() {
                 return threshold;
             }
 
             @Override
             public int getTotalSamples() {
                 return readings.size();
             }
 
             @Override
             public int getSubsetSize() {
                 return Math.max(preliminarySubsetSize, getMinReadings());
             }
 
             @Override
             public void estimatePreliminarSolutions(
                     final int[] samplesIndices, final List<Solution<Point2D>> solutions) {
                 solvePreliminarySolutions(samplesIndices, solutions);
             }
 
             @Override
             public double computeResidual(final Solution<Point2D> currentEstimation, final int i) {
                 return residual(currentEstimation, i);
             }
 
             @Override
             public boolean isReady() {
                 return RANSACRobustRangingRadioSourceEstimator2D.this.isReady();
             }
 
             @Override
             public void onEstimateStart(final RobustEstimator<Solution<Point2D>> estimator) {
                 // no action needed
             }
 
             @Override
             public void onEstimateEnd(final RobustEstimator<Solution<Point2D>> estimator) {
                 // no action needed
             }
 
             @Override
             public void onEstimateNextIteration(
                     final RobustEstimator<Solution<Point2D>> estimator, final int iteration) {
                 if (listener != null) {
                     listener.onEstimateNextIteration(
                             RANSACRobustRangingRadioSourceEstimator2D.this, iteration);
                 }
             }
 
             @Override
             public void onEstimateProgressChange(
                     final RobustEstimator<Solution<Point2D>> estimator, final float progress) {
                 if (listener != null) {
                     listener.onEstimateProgressChange(
                             RANSACRobustRangingRadioSourceEstimator2D.this, progress);
                 }
             }
         });
 
         try {
             locked = true;
 
             if (listener != null) {
                 listener.onEstimateStart(this);
             }
 
             inliersData = null;
             innerEstimator.setComputeAndKeepInliersEnabled(computeAndKeepInliers || refineResult);
             innerEstimator.setComputeAndKeepResidualsEnabled(computeAndKeepResiduals || refineResult);
             innerEstimator.setConfidence(confidence);
             innerEstimator.setMaxIterations(maxIterations);
             innerEstimator.setProgressDelta(progressDelta);
             final var result = innerEstimator.estimate();
             inliersData = innerEstimator.getInliersData();
             attemptRefine(result);
 
             if (listener != null) {
                 listener.onEstimateEnd(this);
             }
 
         } 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.RANSAC;
     }
 }