"""N-Gram 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"

from argaze import GazeFeatures, DataFeatures

class AOIScanPathAnalyzer(GazeFeatures.AOIScanPathAnalyzer):
    """Implementation of N-Gram algorithm as proposed in:

        **Lounis C., Peysakhovich V., Causse M. (2021).**  
        *Visual scanning strategies in the cockpit are modulated by pilots’ expertise: A flight simulator study.*  
        PLoS ONE (16(2), 6).  
        [https://doi.org/10.1371/journal.pone.0247061](https://doi.org/10.1371/journal.pone.0247061)
    """

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

        # Init AOIScanPathAnalyzer class
        super().__init__()

        self.__n_min = 2
        self.__n_max = 2
        self.__ngrams_count = {}

    @property
    def n_min(self) -> int:
        """Minimal grams length to search."""
        return self.__n_min

    @n_min.setter
    def n_min(self, n_min: int):

        self.__n_min = n_min

    @property
    def n_max(self) -> int:
        """Maximal grams length to search."""
        return self.__n_max
    
    @n_max.setter
    def n_max(self, n_max: int):

        self.__n_max = n_max    

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

        assert(len(aoi_scan_path) > 1)

        sequence = aoi_scan_path.letter_sequence

        self.__ngrams_count = {}

        for n in range(self.n_min, self.n_max + 1):

            ngrams = zip(*[sequence[i:] for i in range(n)])
            ngrams = [ngram for ngram in ngrams]

            self.__ngrams_count[n] = {tuple([aoi_scan_path.get_letter_aoi(l) for l in ngram]) : ngrams.count(ngram) for ngram in ngrams}

    @property
    def ngrams_count(self) -> dict:
        """N-Grams count."""
        
        return self.__ngrams_count