from copy import copy, deepcopy
from random import random
from typing import Optional, Union

import numpy as np
import pandas as pd

from fedot.utilities.window_size_selector import WindowSizeSelector, WindowSizeSelectorMethodsEnum
from golem.core.log import default_log
from scipy.ndimage import gaussian_filter
from sklearn.decomposition import TruncatedSVD

from fedot.core.data.data import InputData, OutputData
from fedot.core.operations.evaluation.operation_implementations.implementation_interfaces import (
    DataOperationImplementation
)
from fedot.core.operations.operation_parameters import OperationParameters
from fedot.core.repository.dataset_types import DataTypesEnum
from fedot.preprocessing.data_types import TYPE_TO_ID


class LaggedImplementation(DataOperationImplementation):
    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)

        self.window_size_minimum = None
        self.sparse_transform = False
        self.use_svd = False
        self.features_columns = None

        # Define logger object
        self.log = default_log(self)

    @property
    def window_size(self) -> Optional[int]:
        window_size = self.params.get('window_size')
        if window_size:
            window_size = round(window_size)
        return window_size

    @property
    def n_components(self) -> Optional[int]:
        return self.params.get('n_components')

    def fit(self, input_data):
        """ Class doesn't support fit operation

        Args:
            input_data: data with features, target and ids to process
        """

        pass

    def transform(self, input_data: InputData) -> OutputData:
        """ Method for transformation of time series to lagged form for predict stage

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with transformed features table
        """

        new_input_data = copy(input_data)
        forecast_length = new_input_data.task.task_params.forecast_length

        # Correct window size parameter
        self._check_and_correct_window_size(new_input_data.features, forecast_length)

        self._apply_transformation_for_predict(new_input_data)

        output_data = self._convert_to_output(new_input_data,
                                              self.features_columns,
                                              data_type=DataTypesEnum.table)
        self._update_column_types(output_data)
        return output_data

    def transform_for_fit(self, input_data: InputData) -> OutputData:
        """Method for transformation of time series to lagged form for fit stage

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with transformed features table
        """
        new_input_data = copy(input_data)
        forecast_length = new_input_data.task.task_params.forecast_length

        # Correct window size parameter
        self._check_and_correct_window_size(new_input_data.features, forecast_length)

        target = np.array(new_input_data.target)
        features = np.array(new_input_data.features)
        old_idx = new_input_data.idx

        new_target, new_idx = self._apply_transformation_for_fit(new_input_data, features,
                                                                 target, forecast_length, old_idx)

        # Update target for Input Data
        new_input_data.target = new_target
        new_input_data.idx = new_idx
        output_data = self._convert_to_output(new_input_data,
                                              self.features_columns,
                                              data_type=DataTypesEnum.table)
        self._update_column_types(output_data)
        return output_data

    def _check_and_correct_window_size(self, time_series: np.ndarray, forecast_length: int):
        """ Method check if the length of the time series is not enough for
            lagged transformation

            Args:
                time_series: time series for transformation
                forecast_length: forecast length

            Returns:

            """
        max_allowed_window_size = max(1, len(time_series) - forecast_length - 1)

        if self.window_size == 0:
            selector = WindowSizeSelector(method=WindowSizeSelectorMethodsEnum.HAC, window_range=(5, 60))
            new = int(selector.apply(time_series) * time_series.shape[0] * 0.01)
            new = min(max_allowed_window_size, new)
            self.log.message((f"Window size of lagged transformation was changed "
                              f"by WindowSizeSelector from {self.params.get('window_size')} to {new}"))
            self.params.update(window_size=new)

        # Maximum threshold
        if self.window_size > max_allowed_window_size:
            new = int(random() * max_allowed_window_size)
            new = min(new, max_allowed_window_size)
            new = max(new, self.window_size_minimum)
            self.log.info(("Window size of lagged transformation was changed "
                           f"from {self.params.get('window_size')} to {new}"))
            self.params.update(window_size=new)

        # Minimum threshold
        if self.window_size < self.window_size_minimum:
            self.log.info((f"Warning: window size of lagged transformation was changed "
                           f"from {self.params.get('window_size')} to {self.window_size_minimum}"))
            self.params.update(window_size=self.window_size_minimum)

    def _update_column_types(self, output_data: OutputData):
        """Update column types after lagged transformation. All features becomes ``float``
        """

        _, features_n_cols = output_data.predict.shape
        feature_type_ids = np.array([TYPE_TO_ID[float]] * features_n_cols)
        col_type_ids = {'features': feature_type_ids}

        if output_data.target is not None and len(output_data.target.shape) > 1:
            _, target_n_cols = output_data.target.shape
            target_type_ids = np.array([TYPE_TO_ID[float]] * target_n_cols)
            col_type_ids['target'] = target_type_ids
        output_data.supplementary_data.col_type_ids = col_type_ids

    def _apply_transformation_for_fit(self, input_data: InputData, features: np.array, target: np.array,
                                      forecast_length: int, old_idx: np.array):
        """Apply lagged transformation on each time series in the current dataset
        """

        # Shape of the time series
        if len(features.shape) > 1:
            # Multivariate time series
            n_elements, n_time_series = features.shape
        else:
            n_time_series = 1
        all_transformed_features = None
        for current_ts_id in range(n_time_series):
            # For each time series in the array
            if n_time_series == 1:
                current_ts = features
            else:
                current_ts = np.ravel(features[:, current_ts_id])

            # Prepare features for training
            new_idx, transformed_cols = ts_to_table(idx=old_idx,
                                                    time_series=current_ts,
                                                    window_size=self.window_size,
                                                    is_lag=True)

            # Sparsing matrix of lagged features
            if self.sparse_transform:
                transformed_cols = _sparse_matrix(self.log,
                                                  transformed_cols,
                                                  self.n_components,
                                                  self.use_svd)
            # Transform target
            current_target = self._current_target_for_each_ts(current_ts_id, target)
            new_idx, transformed_cols, new_target = prepare_target(all_idx=input_data.idx,
                                                                   idx=new_idx,
                                                                   features_columns=transformed_cols,
                                                                   target=current_target,
                                                                   forecast_length=forecast_length)
            if current_ts_id == 0:
                # Init full lagged table
                all_transformed_features = transformed_cols
                all_transformed_target = new_target
                all_transformed_idx = np.array(new_idx)
            else:
                all_transformed_features, all_transformed_target, all_transformed_idx = self.stack_by_type_fit(
                    input_data, all_transformed_features,
                    all_transformed_target, all_transformed_idx,
                    transformed_cols, new_target, new_idx)

        input_data.features = all_transformed_features
        self.features_columns = all_transformed_features
        return all_transformed_target, all_transformed_idx

    def stack_by_type_fit(self, input_data, all_features, all_target, all_idx, features, target, idx):
        """Apply stack function for multi_ts and multivariable ts types on fit step
        """

        functions_by_type = {
            DataTypesEnum.multi_ts: self._stack_multi_ts,
            DataTypesEnum.ts: self._stack_multi_variable
        }
        stack_function = functions_by_type.get(input_data.data_type)
        return stack_function(all_features, all_target, all_idx, features, target, idx)

    def _stack_multi_variable(self, all_features: np.array,
                              all_target: np.array,
                              all_idx: np.array,
                              features: np.array,
                              target: np.array,
                              idx: Union[list, np.array]):
        """Horizontally stack tables as multiple variables extends features for training

        Args:
            all_features: ``array`` with all features for adding new
            all_target:  ``array`` with all target (does not change)
            all_idx: ``array`` with all indices (does not change)
            features: ``array`` with new features for adding
            target: ``array`` with new target for adding
            idx: ``array`` with new idx for adding

        Returns:
            table
        """

        all_features = np.hstack((all_features, features))
        return all_features, all_target, all_idx

    def _stack_multi_ts(self, all_features: np.array,
                        all_target: np.array,
                        all_idx: np.array,
                        features: np.array,
                        target: np.array,
                        idx: Union[list, np.array]):
        """Vertically stack tables as multi_ts data extends training set as combination of train and target

        Args:
            all_features: ``array`` with all features for adding new
            all_target:  ``array`` with all target
            all_idx: ``array`` with all indices
            features: ``array`` with new features for adding
            target: ``array`` with new target for adding
            idx: ``array`` with new idx for adding

        Returns:
            table
        """

        all_features = np.vstack((all_features, features))
        all_target = np.vstack((all_target, target))
        all_idx = np.hstack((all_idx, np.array(idx)))
        return all_features, all_target, all_idx

    def _current_target_for_each_ts(self, current_ts_id, target):
        """Returns target for each time-series
        """

        if len(target.shape) > 1:
            # if multi_ts case
            if current_ts_id >= target.shape[1]:
                while current_ts_id >= target.shape[1]:
                    current_ts_id = current_ts_id - target.shape[1]
            return target[:, current_ts_id]
        else:
            # if multivariable case
            return target

    def _apply_transformation_for_predict(self, input_data: InputData):
        """Apply lagged transformation for every column (time series) in the dataset
        """
        old_idx = copy(input_data.idx)

        if len(input_data.features.shape) > 1:
            # Multivariate time series
            n_elements, n_time_series = input_data.features.shape
        else:
            n_time_series = 1

        all_transformed_features = None
        for current_ts_id in range(n_time_series):
            # For each time series
            if n_time_series == 1:
                current_ts = input_data.features
            else:
                current_ts = np.ravel(input_data.features[:, current_ts_id])

            if self.sparse_transform:
                self.log.debug('Sparse lagged transformation applied. If new data were used. Call fit method')
                transformed_cols = self._update_features_for_sparse(current_ts, old_idx)
                # Take last row in the lagged table and reshape into array with 1 row and n columns
                current_ts = transformed_cols[-1].reshape(1, -1)

            # Take last window_size elements for current ts
            last_part_of_ts = current_ts[-self.window_size:].reshape(1, -1)
            if current_ts_id == 0:
                all_transformed_features = last_part_of_ts
            else:
                all_transformed_features = self.stack_by_type_predict(input_data,
                                                                      all_transformed_features,
                                                                      last_part_of_ts)

        if input_data.data_type == DataTypesEnum.multi_ts:
            all_transformed_features = np.expand_dims(all_transformed_features[0], axis=0)
        self.features_columns = all_transformed_features
        return all_transformed_features

    def stack_by_type_predict(self, input_data, all_features, part_to_add):
        """Apply stack function for multi_ts and multivariable ts types on predict step
        """

        if input_data.data_type == DataTypesEnum.multi_ts:
            # for mutli_ts
            all_features = np.vstack((all_features, part_to_add))
        if input_data.data_type == DataTypesEnum.ts:
            # for multivariable
            all_features = np.hstack((all_features, part_to_add))
        return all_features

    def _update_features_for_sparse(self, time_series: np.array, idx: np.array):
        """Make sparse matrix which will be used during forecasting
        """

        # Prepare features for training
        new_idx, transformed_cols = ts_to_table(idx=idx,
                                                time_series=time_series,
                                                window_size=self.window_size,
                                                is_lag=True)
        # Sparsing
        transformed_cols = _sparse_matrix(self.log,
                                          transformed_cols,
                                          self.n_components,
                                          self.use_svd)
        return transformed_cols


class SparseLaggedTransformationImplementation(LaggedImplementation):
    """Implementation of sparse lagged transformation for time series forecasting
    """

    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)
        self.sparse_transform = True
        self.window_size_minimum = 4


class LaggedTransformationImplementation(LaggedImplementation):
    """Implementation of lagged transformation for time series forecasting
    """

    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)
        self.window_size_minimum = 1


class TsSmoothingImplementation(DataOperationImplementation):

    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)

    @property
    def window_size(self) -> int:
        return round(self.params.setdefault('window_size', 10))

    def fit(self, input_data: InputData):
        """Class doesn't support fit operation

        Args:
            input_data: data with features, target and ids to process
        """

        pass

    def transform(self, input_data: InputData) -> OutputData:
        """Method for smoothing time series

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with smoothed time series
        """

        source_ts = input_data.features
        if input_data.data_type == DataTypesEnum.multi_ts:
            full_smoothed_ts = []
            for ts_n in range(source_ts.shape[1]):
                ts = pd.Series(source_ts[:, ts_n])
                smoothed_ts = self._apply_smoothing_to_series(ts)
                full_smoothed_ts.append(smoothed_ts)
            output_data = self._convert_to_output(input_data,
                                                  np.array(full_smoothed_ts).T,
                                                  data_type=input_data.data_type)
        else:
            source_ts = pd.Series(input_data.features)
            smoothed_ts = np.ravel(self._apply_smoothing_to_series(source_ts))
            output_data = self._convert_to_output(input_data,
                                                  smoothed_ts,
                                                  data_type=input_data.data_type)

        return output_data

    def _apply_smoothing_to_series(self, ts):
        smoothed_ts = ts.rolling(window=self.window_size).mean()
        smoothed_ts = np.array(smoothed_ts)

        # Filling first nans with source values
        smoothed_ts[:self.window_size] = ts[:self.window_size]
        return smoothed_ts


class ExogDataTransformationImplementation(DataOperationImplementation):

    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)

    def fit(self, input_data: InputData):
        """ Class doesn't support fit operation

        Args:
            input_data: data with features, target and ids to process
        """

        pass

    def transform(self, input_data: InputData) -> OutputData:
        """ Method for representing time series as column

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with features as columns
        """
        copied_data = copy(input_data)
        parameters = copied_data.task.task_params
        forecast_length = parameters.forecast_length

        features_columns = np.array(copied_data.features)[-forecast_length:]
        copied_data.idx = copied_data.idx[-forecast_length:]
        features_columns = features_columns.reshape(1, -1)

        output_data = self._convert_to_output(copied_data,
                                              features_columns,
                                              data_type=DataTypesEnum.table)

        return output_data

    def transform_for_fit(self, input_data: InputData) -> OutputData:
        """Method for representing time series as column for fit stage

        Args:
            input_data: data with features, target and ids to process
        Returns:
            output data with features as columns
        """

        copied_data = copy(input_data)
        parameters = copied_data.task.task_params
        old_idx = copied_data.idx
        forecast_length = parameters.forecast_length

        # Transform features in "target-like way"
        _, _, features_columns = prepare_target(all_idx=input_data.idx,
                                                idx=old_idx,
                                                features_columns=copied_data.features,
                                                target=copied_data.features,
                                                forecast_length=forecast_length)

        # Transform target
        new_idx, _, new_target = prepare_target(all_idx=input_data.idx,
                                                idx=old_idx,
                                                features_columns=copied_data.features,
                                                target=copied_data.target,
                                                forecast_length=forecast_length)
        copied_data.target = new_target
        copied_data.idx = new_idx

        output_data = self._convert_to_output(copied_data,
                                              features_columns,
                                              data_type=DataTypesEnum.table)

        return output_data


class GaussianFilterImplementation(DataOperationImplementation):
    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)

    def fit(self, input_data: InputData):
        """ Class doesn't support fit operation

        Args:
            input_data: data with features, target and ids to process
        """

        pass

    def transform(self, input_data: InputData) -> OutputData:
        """ Method for smoothing time series for predict stage

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with smoothed time series
        """

        source_ts = np.array(input_data.features)

        # Apply smoothing operation
        sigma = round(self.params.setdefault('sigma', 1))
        smoothed_ts = gaussian_filter(source_ts, sigma=sigma)
        smoothed_ts = np.array(smoothed_ts)

        if input_data.data_type != DataTypesEnum.multi_ts:
            smoothed_ts = np.ravel(smoothed_ts)
        output_data = self._convert_to_output(input_data,
                                              smoothed_ts,
                                              data_type=input_data.data_type)

        return output_data


class NumericalDerivativeFilterImplementation(DataOperationImplementation):
    def __init__(self, params: OperationParameters):
        super().__init__(params)
        self.max_poly_degree = 5
        self.default_poly_degree = 2
        self.default_order = 1

        self.log = default_log(self)

        self._correct_params()

    @property
    def poly_degree(self) -> int:
        return int(self.params.get('poly_degree'))

    @property
    def order(self) -> int:
        return int(self.params.get('order'))

    @property
    def window_size(self) -> int:
        return int(self.params.get('window_size'))

    def fit(self, input_data: InputData):
        """ Class doesn't support fit operation

        Args:
            input_data: data with features, target and ids to process
        """

        pass

    def transform(self, input_data: InputData) -> OutputData:
        """ Method for finding numerical derivative of time series for predict stage

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with smoothed time series
        """

        source_ts = np.array(input_data.features)
        # Apply differential operation
        if input_data.data_type == DataTypesEnum.multi_ts:
            full_differential_ts = []
            for ts_n in range(source_ts.shape[1]):
                ts = source_ts[:, ts_n]
                differential_ts = self._differential_filter(ts)
                full_differential_ts.append(differential_ts)
            output_data = self._convert_to_output(input_data,
                                                  np.array(full_differential_ts).T,
                                                  data_type=input_data.data_type)
        else:
            differential_ts = np.ravel(self._differential_filter(source_ts))
            output_data = self._convert_to_output(input_data,
                                                  differential_ts,
                                                  data_type=input_data.data_type)

        return output_data

    def _differential_filter(self, ts):
        """:obj:`NumericalDerivative` filter
        """

        if self.window_size > ts.shape[0]:
            self.log.info(f'NumericalDerivativeFilter: invalid parameter window_size ({self.window_size}) changed to '
                          f'{self.poly_degree + 1}')
            self.params.update(window_size=self.poly_degree + 1)
        x = np.arange(ts.shape[0])

        ts_len = x.shape[0]
        der_f = np.zeros(ts_len)

        # Take the differentials in the center of the domain
        for center_window in range(self.window_size, ts_len - self.window_size):
            points = np.arange(center_window - self.window_size, center_window + self.window_size)
            # Fit to a Chebyshev polynomial
            # this is the same as any polynomial since we're on a fixed grid but it's better conditioned :)
            poly = np.polynomial.chebyshev.Chebyshev.fit(x[points], ts[points], self.poly_degree,
                                                         window=[np.min(points), np.max(points)])
            der_f[center_window] = poly.deriv(m=self.order)(x[center_window])

        supp_1 = ts[0:self.window_size]
        coordsupp_1 = x[0:self.window_size]
        supp_2 = ts[-self.window_size:]
        coordsupp_2 = x[-self.window_size:]
        poly = np.polynomial.chebyshev.Chebyshev.fit(coordsupp_1, supp_1, self.window_size - 1)
        der_f[0:self.window_size] = poly.deriv(m=self.order)(coordsupp_1)
        poly = np.polynomial.chebyshev.Chebyshev.fit(coordsupp_2, supp_2, self.window_size - 1)
        der_f[-self.window_size:] = poly.deriv(m=self.order)(coordsupp_2)
        for _ in range(self.order):
            supp_1 = np.gradient(supp_1, coordsupp_1, edge_order=2)
            supp_2 = np.gradient(supp_2, coordsupp_2, edge_order=2)
        der_f[0:self.window_size] = supp_1
        der_f[-self.window_size:] = supp_2
        return np.transpose(der_f)

    def _correct_params(self):
        if self.poly_degree > 5:
            self.log.info(f'NumericalDerivativeFilter: invalid parameter poly_degree ({self.poly_degree}) '
                          f'changed to {self.max_poly_degree}')
            self.params.update(poly_degree=self.max_poly_degree)
        if self.order < 1:
            self.log.info(f'NumericalDerivativeFilter: invalid parameter order ({self.order}) '
                          f'changed to {self.default_order}')
            self.params.update(degree=self.default_order)
        if self.order >= self.poly_degree:
            self.log.info(f'NumericalDerivativeFilter: invalid parameter poly_degree ({self.poly_degree}) '
                          f'changed to {self.order + 1}')
            self.params.update(poly_degree=self.order + 1)
        if self.window_size < self.poly_degree:
            self.log.info(f'NumericalDerivativeFilter: invalid parameter window_size ({self.window_size}) changed to '
                          f'{self.poly_degree + 1}')
            self.params.update(window_size=self.poly_degree + 1)


class CutImplementation(DataOperationImplementation):
    def __init__(self, params: Optional[OperationParameters]):
        super().__init__(params)
        self._correct_cut_part()
        # Define logger object
        self.log = default_log(self)

    @property
    def cut_part(self):
        return self.params.get('cut_part')

    def _correct_cut_part(self):
        if not 0 < self.cut_part <= 0.9:
            # Default parameter
            self.log.info(f"Change invalid parameter cut_part ({self.cut_part}) on default value (0.5)")
            self.params.update(cut_part=0.5)

    def fit(self, input_data: InputData):
        """Class doesn't support fit operation

        Args:
            input_data: data with features, target and ids to process
        """

        pass

    def transform(self, input_data: InputData) -> OutputData:
        """ Cut first cut_part from time series\n
            ``new_len = len - int(self.cut_part * (input_values.shape[0]-horizon))``

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with cutted time series
        """
        old_target = deepcopy(input_data.target)
        input_data = self._cut_input_data(input_data)
        input_data.target = old_target

        output_data = self._convert_to_output(input_data,
                                              input_data.features,
                                              data_type=input_data.data_type)
        return output_data

    def transform_for_fit(self, input_data: InputData) -> OutputData:
        """ Cut first cut_part from time series for fit stage
            ``new_len = len - int(self.cut_part * (input_values.shape[0]-horizon))``

        Args:
            input_data: data with features, target and ids to process

        Returns:
            output data with cutted time series
        """

        input_data = self._cut_input_data(input_data, reset_idx=True)

        output_data = self._convert_to_output(input_data,
                                              input_data.features,
                                              data_type=input_data.data_type)
        return output_data

    def _cut_input_data(self, input_data: InputData, reset_idx: bool = False) -> InputData:
        horizon = input_data.task.task_params.forecast_length
        input_copy = copy(input_data)
        input_values = input_copy.features

        cut_len = int(self.cut_part * (input_values.shape[0] - horizon))
        output_values = input_values[cut_len::]

        input_copy.features = output_values
        input_copy.target = output_values

        if reset_idx:
            input_copy.idx = np.arange(cut_len, input_values.shape[0])
        return input_copy


def ts_to_table(idx, time_series: np.array, window_size: int, is_lag: bool = False):
    """Method convert time series to lagged form.

    Args:
        idx: the indices of the time series to convert
        time_series: source time series
        window_size: size of sliding window, which defines lag
        is_lag: is function used for lagged transformation.
            ``False`` needs to convert one dimensional output to lagged form.

    Returns:
        ``updated_idx`` -> clipped indices of time series\n
        ``features_columns`` -> lagged time series feature table
    """
    features_columns = np.array([time_series[i:window_size + i]
                                 for i in range(time_series.shape[0] - window_size + 1)])

    if is_lag:
        updated_idx = np.concatenate([idx[window_size:], idx[-1:]])
    else:
        updated_idx = idx[:len(idx) - window_size + 1]

    return updated_idx, features_columns


def _sparse_matrix(logger, features_columns: np.array, n_components_perc=0.5, use_svd=False):
    """Method converts the matrix to sparse form

        Args:
            features_columns: matrix to sparse
            n_components_perc: initial approximation of percent of components to keep
            use_svd: is there need to use :obj:`SVD` method for sparse or use naive method

        Returns:
            reduced dimension matrix

        Notes:
            shape of returned matrix depends on the number of components which includes
            the threshold of explained variance gain
        """

    if not n_components_perc:
        n_components_perc = 0.5

    if use_svd:
        n_components = int(features_columns.shape[1] * n_components_perc)
        # Getting the initial approximation of number of components
        if not n_components:
            n_components = int(features_columns.shape[1] * n_components_perc)
        if n_components >= features_columns.shape[0]:
            n_components = features_columns.shape[0] - 1
        logger.info(f'Initial approximation of number of components set as {n_components}')

        # Forming the first value of explained variance
        components = _get_svd(features_columns, n_components)
    else:
        step = int(1 / n_components_perc)
        indeces_to_stay = np.arange(1, features_columns.shape[1], step)
        components = np.take(features_columns, indeces_to_stay, 1)

    return components


def _get_svd(features_columns: np.array, n_components: int):
    """Method converts the matrix to svd sparse form

    Args:
        features_columns: matrix to sparse
        n_components: number of components to keep

    Returns:
        transformed sparse matrix
    """

    svd = TruncatedSVD(n_components=n_components, n_iter=5, random_state=42)
    svd.fit(features_columns.T)
    components = svd.components_.T
    return components


def prepare_target(all_idx, idx, features_columns: np.array, target, forecast_length: int):
    """Method convert time series to lagged form. Transformation applied
    only for generating target table (time series considering as multi-target
    regression task)

    Args:
        all_idx: all indices in data
        idx: remaining indices after lagged feature table generation
        features_columns: lagged feature table
        target: source time series
        forecast_length: forecast length

    Returns:
        ``updated_idx``, ``updated_features``, ``updated_target``

        .. details:: more information:

            - ``updated_idx`` -> clipped indices of time series
            - ``updated_features`` -> clipped lagged feature table
            - ``updated_target`` -> lagged target table

    """
    # Remove last repeated element
    idx = idx[: -1]

    # Update target (clip first "window size" values)
    # be careful, some implementation may be dramatically slow
    index_hash_table = {val: i for i, val in enumerate(all_idx)}
    row_nums = [index_hash_table[i] for i in idx]
    ts_target = target[row_nums]

    # Multi-target transformation
    if forecast_length > 1:
        updated_target = np.array([ts_target[i:forecast_length + i]
                                   for i in range(ts_target.shape[0] - forecast_length + 1)])

        updated_idx = idx[: -forecast_length + 1]
        updated_features = features_columns[: -forecast_length]
    else:
        # Forecast horizon equals to 1
        updated_idx = idx
        updated_features = features_columns[: -1]
        updated_target = np.reshape(ts_target, (-1, 1))

    return updated_idx, updated_features, updated_target


def transform_features_and_target_into_lagged(input_data: InputData, forecast_length: int,
                                              window_size: int):
    """Perform lagged transformation firstly on features and secondly on target array

    Args:
        input_data: dataclass with features
        forecast_length: forecast horizon
        window_size: window size for features transformation

    Returns:
        ``new_idx``, ``transformed_cols``, ``new_target``

        .. details:: more information:

            - ``new_idx`` ->
            - ``transformed_cols`` ->
            - ``new_target`` ->

    """

    new_idx, transformed_cols = ts_to_table(idx=input_data.idx,
                                            time_series=input_data.features,
                                            window_size=window_size,
                                            is_lag=True)
    new_idx, transformed_cols, new_target = prepare_target(all_idx=input_data.idx,
                                                           idx=new_idx,
                                                           features_columns=transformed_cols,
                                                           target=input_data.target,
                                                           forecast_length=forecast_length)
    return new_idx, transformed_cols, new_target
