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"""Stationary and transition entropy module."""

"""
This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <https://www.gnu.org/licenses/>.
"""

__author__ = "Théo de la Hogue"
__credits__ = []
__copyright__ = "Copyright 2023, Ecole Nationale de l'Aviation Civile (ENAC)"
__license__ = "GPLv3"

import numpy

from argaze import GazeFeatures, DataFeatures
from argaze.GazeAnalysis import TransitionMatrix


class AOIScanPathAnalyzer(GazeFeatures.AOIScanPathAnalyzer):
	"""Implementation of entropy algorithm as described in:

		**Krejtz K., Szmidt T., Duchowski A.T. (2014).**  
		*Entropy-based statistical analysis of eye movement transitions.*  
		Proceedings of the Symposium on Eye Tracking Research and Applications (ETRA'14, 159-166).  
		[https://doi.org/10.1145/2578153.2578176](https://doi.org/10.1145/2578153.2578176)
	"""

	@DataFeatures.PipelineStepInit
	def __init__(self, **kwargs):

		# Init AOIScanPathAnalyzer class
		super().__init__()

		self.__transition_matrix_analyzer = None
		self.__stationary_entropy = -1
		self.__transition_entropy = -1

	@property
	def transition_matrix_analyzer(self) -> TransitionMatrix.AOIScanPathAnalyzer:
		"""Bind to TransitionMatrix analyzer to get its transition_matrix_probabilities.

		!!! warning "Mandatory"
		    TransitionMatrix analyzer have to be loaded before.
		"""

		return self.__transition_matrix_analyzer

	@transition_matrix_analyzer.setter
	def transition_matrix_analyzer(self, transition_matrix_analyzer: TransitionMatrix.AOIScanPathAnalyzer):

		self.__transition_matrix_analyzer = transition_matrix_analyzer

	@DataFeatures.PipelineStepMethod
	def analyze(self, aoi_scan_path: GazeFeatures.AOIScanPath):

		assert(len(aoi_scan_path) > 1)

		# Count total number of fixations and how many fixations are there per aoi
		scan_fixations_count, aoi_fixations_count = aoi_scan_path.fixations_count()

		# Probability to have a fixation onto each aoi
		stationary_probabilities = {aoi: count/scan_fixations_count for aoi, count in aoi_fixations_count.items()}

		# Stationary entropy
		self.__stationary_entropy = 0

		for aoi, p in stationary_probabilities.items():

			self.__stationary_entropy += p * numpy.log(p + 1e-9)

		self.__stationary_entropy *= -1

		# Transition entropy
		self.__transition_entropy = 0

		destination_p_log_sum = self.transition_matrix_analyzer.transition_matrix_probabilities.apply(lambda row: row.apply(lambda p: p * numpy.log(p + 1e-9)).sum(), axis=1)

		for aoi, s in destination_p_log_sum.items():

			self.__transition_entropy += s * stationary_probabilities[aoi]

		self.__transition_entropy *= -1

	@property
	def stationary_entropy(self) -> float:
		"""Stationary entropy."""

		return self.__stationary_entropy

	@property
	def transition_entropy(self) -> float:
		"""Transition entropy."""

		return self.__transition_entropy