# Copyright 2019 Huawei Technologies Co., Ltd
#
# 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.
"""
Model-Test Coverage Metrics.
"""

import numpy as np

from mindspore import Tensor
from mindspore import Model

from mindarmour.utils._check_param import check_model, check_numpy_param, \
    check_int_positive
from mindarmour.utils.logger import LogUtil

LOGGER = LogUtil.get_instance()
TAG = 'ModelCoverageMetrics'


class ModelCoverageMetrics:
    """
    As we all known, each neuron output of a network will have a output range
    after training (we call it original range), and test dataset is used to
    estimate the accuracy of the trained network. However, neurons' output
    distribution would be different with different test datasets. Therefore,
    similar to function fuzz, model fuzz means testing those neurons' outputs
    and estimating the proportion of original range that has emerged with test
    datasets.

    Reference: `DeepGauge: Multi-Granularity Testing Criteria for Deep
    Learning Systems <https://arxiv.org/abs/1803.07519>`_

    Args:
        model (Model): The pre-trained model which waiting for testing.
        segmented_num (int): The number of segmented sections of neurons' output intervals.
        neuron_num (int): The number of testing neurons.
        train_dataset (numpy.ndarray): Training dataset used for determine
            the neurons' output boundaries.

    Raises:
        ValueError: If neuron_num is too big (for example, bigger than 1e+9).

    Examples:
        >>> train_images = np.random.random((10000, 128)).astype(np.float32)
        >>> test_images = np.random.random((5000, 128)).astype(np.float32)
        >>> model = Model(net)
        >>> model_fuzz_test = ModelCoverageMetrics(model, 10000, 10, train_images)
        >>> model_fuzz_test.test_adequacy_coverage_calculate(test_images)
        >>> print('KMNC of this test is : %s', model_fuzz_test.get_kmnc())
        >>> print('NBC of this test is : %s', model_fuzz_test.get_nbc())
        >>> print('SNAC of this test is : %s', model_fuzz_test.get_snac())
    """

    def __init__(self, model, segmented_num, neuron_num, train_dataset):
        self._model = check_model('model', model, Model)
        self._segmented_num = check_int_positive('segmented_num', segmented_num)
        self._neuron_num = check_int_positive('neuron_num', neuron_num)
        if self._neuron_num > 1e+9:
            msg = 'neuron_num should be less than 1e+10, otherwise a MemoryError' \
                  'would occur'
            LOGGER.error(TAG, msg)
            raise ValueError(msg)
        train_dataset = check_numpy_param('train_dataset', train_dataset)
        self._lower_bounds = [np.inf]*self._neuron_num
        self._upper_bounds = [-np.inf]*self._neuron_num
        self._var = [0]*self._neuron_num
        self._main_section_hits = [[0 for _ in range(self._segmented_num)] for _ in
                                   range(self._neuron_num)]
        self._lower_corner_hits = [0]*self._neuron_num
        self._upper_corner_hits = [0]*self._neuron_num
        self._bounds_get(train_dataset)

    def _bounds_get(self, train_dataset, batch_size=32):
        """
        Update the lower and upper boundaries of neurons' outputs.

        Args:
            train_dataset (numpy.ndarray): Training dataset used for
                determine the neurons' output boundaries.
            batch_size (int): The number of samples in a predict batch.
                Default: 32.
        """
        batch_size = check_int_positive('batch_size', batch_size)
        output_mat = []
        batches = train_dataset.shape[0] // batch_size
        for i in range(batches):
            inputs = train_dataset[i*batch_size: (i + 1)*batch_size]
            output = self._model.predict(Tensor(inputs)).asnumpy()
            output_mat.append(output)
            lower_compare_array = np.concatenate(
                [output, np.array([self._lower_bounds])], axis=0)
            self._lower_bounds = np.min(lower_compare_array, axis=0)
            upper_compare_array = np.concatenate(
                [output, np.array([self._upper_bounds])], axis=0)
            self._upper_bounds = np.max(upper_compare_array, axis=0)
        if batches == 0:
            output = self._model.predict(Tensor(train_dataset)).asnumpy()
            self._lower_bounds = np.min(output, axis=0)
            self._upper_bounds = np.max(output, axis=0)
            output_mat.append(output)
        self._var = np.std(np.concatenate(np.array(output_mat), axis=0),
                           axis=0)

    def _sections_hits_count(self, dataset, intervals):
        """
        Update the coverage matrix of neurons' output subsections.

        Args:
            dataset (numpy.ndarray): Testing data.
            intervals (list[float]): Segmentation intervals of neurons'
                outputs.
        """
        dataset = check_numpy_param('dataset', dataset)
        batch_output = self._model.predict(Tensor(dataset)).asnumpy()
        batch_section_indexes = (batch_output - self._lower_bounds) // intervals
        for section_indexes in batch_section_indexes:
            for i in range(self._neuron_num):
                if section_indexes[i] < 0:
                    self._lower_corner_hits[i] = 1
                elif section_indexes[i] >= self._segmented_num:
                    self._upper_corner_hits[i] = 1
                else:
                    self._main_section_hits[i][int(section_indexes[i])] = 1

    def calculate_coverage(self, dataset, bias_coefficient=0, batch_size=32):
        """
        Calculate the testing adequacy of the given dataset.

        Args:
            dataset (numpy.ndarray): Data for fuzz test.
            bias_coefficient (float): The coefficient used for changing the
                neurons' output boundaries. Default: 0.
            batch_size (int): The number of samples in a predict batch.
                Default: 32.

        Examples:
            >>> model_fuzz_test = ModelCoverageMetrics(model, 10000, 10, train_images)
            >>> model_fuzz_test.calculate_coverage(test_images)
        """
        dataset = check_numpy_param('dataset', dataset)
        batch_size = check_int_positive('batch_size', batch_size)
        self._lower_bounds -= bias_coefficient*self._var
        self._upper_bounds += bias_coefficient*self._var
        intervals = (self._upper_bounds - self._lower_bounds) / self._segmented_num
        batches = dataset.shape[0] // batch_size
        for i in range(batches):
            self._sections_hits_count(
                dataset[i*batch_size: (i + 1)*batch_size], intervals)

    def get_kmnc(self):
        """
        Get the metric of 'k-multisection neuron coverage'.

        Returns:
            float, the metric of 'k-multisection neuron coverage'.

        Examples:
            >>> model_fuzz_test.get_kmnc()
        """
        kmnc = np.sum(self._main_section_hits) / (self._neuron_num*self._segmented_num)
        return kmnc

    def get_nbc(self):
        """
        Get the metric of 'neuron boundary coverage'.

        Returns:
            float, the metric of 'neuron boundary coverage'.

        Examples:
            >>> model_fuzz_test.get_nbc()
        """
        nbc = (np.sum(self._lower_corner_hits) + np.sum(
            self._upper_corner_hits)) / (2*self._neuron_num)
        return nbc

    def get_snac(self):
        """
        Get the metric of 'strong neuron activation coverage'.

        Returns:
            float, the metric of 'strong neuron activation coverage'.

        Examples:
            >>> model_fuzz_test.get_snac()
        """
        snac = np.sum(self._upper_corner_hits) / self._neuron_num
        return snac
