import datetime
import warnings
from pathlib import Path
from typing import Collection

import pandas as pd
from pyprojroot import here

import participants.query_db
from features import communication, helper, proximity

WARNING_PARTICIPANTS_LABEL = (
    "Before calculating features, please set participants label using self.set_participants_label() "
    "to be used as a filename prefix when exporting data. "
    "The filename will be of the form: %participants_label_%grouping_variable_%data_type.csv"
)


class SensorFeatures:
    """
    A class to represent all sensor (AWARE) features.

    Attributes
    ----------
    grouping_variable: str
        The name of the variable by which to group (segment) data, e.g. date_lj.
    features: dict
        A dictionary of sensors (data types) and features to calculate.
        See config/minimal_features.yaml for an example.
    participants_usernames: Collection
        A list of usernames for which to calculate features.
        If None, use all participants.

    Methods
    -------
    set_sensor_data():
        Query the database for data types defined by self.features.
    get_sensor_data(data_type): pd.DataFrame
        Returns the dataframe of sensor data for specified data_type.
    calculate_features():
        Calls appropriate functions from features/ and joins them in a single dataframe, df_features_all.
    get_features(data_type, feature_names): pd.DataFrame
        Returns the dataframe of specified features for selected sensor.

    construct_export_path():
        Construct a path for exporting the features as csv files.
    set_participants_label(label):
        Sets a label for the usernames subset. This is used to distinguish feature exports.
    """

    def __init__(
        self,
        grouping_variable: str,
        features: dict,
        participants_usernames: Collection = None,
    ):
        """
        Specifies the grouping variable and usernames for which to calculate features.
        Sets other (implicit) attributes used in other methods.
        If participants_usernames=None, this queries the usernames which belong to the main part of the study,
            i.e. from 2020-08-01 on.

        Parameters
        ----------
        grouping_variable: str
            The name of the variable by which to group (segment) data, e.g. date_lj.
        features: dict
            A dictionary of sensors (data types) and features to calculate.
            See config/minimal_features.yaml for an example.
        participants_usernames: Collection
            A list of usernames for which to calculate features.
            If None, use all participants.

        Returns
        -------
        None
        """
        self.grouping_variable_name = grouping_variable
        self.grouping_variable = [grouping_variable]

        self.data_types = features.keys()

        self.participants_label: str = ""
        if participants_usernames is None:
            participants_usernames = participants.query_db.get_usernames(
                collection_start=datetime.date.fromisoformat("2020-08-01")
            )
            self.participants_label = "all"
        self.participants_usernames = participants_usernames

        self.df_features_all = pd.DataFrame()

        self.df_proximity = pd.DataFrame()
        self.df_proximity_counts = pd.DataFrame()

        self.df_calls = pd.DataFrame()
        self.df_sms = pd.DataFrame()
        self.df_calls_sms = pd.DataFrame()

        self.folder = None
        self.filename_prefix = ""
        self.construct_export_path()
        print("SensorFeatures initialized.")

    def set_sensor_data(self):
        print("Querying database ...")
        if "proximity" in self.data_types:
            self.df_proximity = proximity.get_proximity_data(
                self.participants_usernames
            )
            print("Got proximity data from the DB.")
            self.df_proximity = helper.get_date_from_timestamp(self.df_proximity)
            self.df_proximity = proximity.recode_proximity(self.df_proximity)
        if "communication" in self.data_types:
            self.df_calls = communication.get_call_data(self.participants_usernames)
            self.df_calls = helper.get_date_from_timestamp(self.df_calls)
            print("Got calls data from the DB.")

            self.df_sms = communication.get_sms_data(self.participants_usernames)
            self.df_sms = helper.get_date_from_timestamp(self.df_sms)
            print("Got sms data from the DB.")

    def get_sensor_data(self, data_type) -> pd.DataFrame:
        if data_type == "proximity":
            return self.df_proximity
        elif data_type == "communication":
            return self.df_calls_sms
        else:
            raise KeyError("This data type has not been implemented.")

    def calculate_features(self, cached=True):
        print("Calculating features ...")
        if not self.participants_label:
            raise ValueError(WARNING_PARTICIPANTS_LABEL)
        self.df_features_all = pd.DataFrame()

        if "proximity" in self.data_types:
            try:
                if not cached:  # Do not use the file, even if it exists.
                    raise FileNotFoundError
                self.df_proximity_counts = read_csv_with_settings(
                    self.folder,
                    self.filename_prefix,
                    data_type="prox",
                    grouping_variable=self.grouping_variable,
                )
                print("Read proximity features from the file.")
            except FileNotFoundError:
                # We need to recalculate the features in this case.
                self.df_proximity_counts = proximity.count_proximity(
                    self.df_proximity, self.grouping_variable
                )
                print("Calculated proximity features.")
                to_csv_with_settings(
                    self.df_proximity_counts,
                    self.folder,
                    self.filename_prefix,
                    data_type="prox",
                )
            finally:
                self.df_features_all = safe_outer_merge_on_index(
                    self.df_features_all, self.df_proximity_counts
                )

        if "communication" in self.data_types:
            try:
                if not cached:  # Do not use the file, even if it exists.
                    raise FileNotFoundError
                self.df_calls_sms = read_csv_with_settings(
                    self.folder,
                    self.filename_prefix,
                    data_type="comm",
                    grouping_variable=self.grouping_variable,
                )
                print("Read communication features from the file.")
            except FileNotFoundError:
                # We need to recalculate the features in this case.
                self.df_calls_sms = communication.calls_sms_features(
                    df_calls=self.df_calls,
                    df_sms=self.df_sms,
                    group_by=self.grouping_variable,
                )
                print("Calculated communication features.")
                to_csv_with_settings(
                    self.df_calls_sms,
                    self.folder,
                    self.filename_prefix,
                    data_type="comm",
                )
            finally:
                self.df_features_all = safe_outer_merge_on_index(
                    self.df_features_all, self.df_calls_sms
                )

        self.df_features_all.fillna(
            value=proximity.FILL_NA_PROXIMITY, inplace=True, downcast="infer",
        )
        self.df_features_all.fillna(
            value=communication.FILL_NA_CALLS_SMS_ALL, inplace=True, downcast="infer",
        )

    def get_features(self, data_type, feature_names) -> pd.DataFrame:
        if data_type == "proximity":
            if feature_names == "all":
                feature_names = proximity.FEATURES_PROXIMITY
            return self.df_proximity_counts[feature_names]
        elif data_type == "communication":
            if feature_names == "all":
                feature_names = communication.FEATURES_CALLS_SMS_ALL
            return self.df_calls_sms[feature_names]
        elif data_type == "all":
            return self.df_features_all
        else:
            raise KeyError("This data type has not been implemented.")

    def construct_export_path(self):
        if not self.participants_label:
            warnings.warn(WARNING_PARTICIPANTS_LABEL, UserWarning)
        self.folder = here("machine_learning/intermediate_results/features", warn=True)
        self.filename_prefix = (
            self.participants_label + "_" + self.grouping_variable_name
        )

    def set_participants_label(self, label: str):
        self.participants_label = label
        self.construct_export_path()


def safe_outer_merge_on_index(left, right):
    if left.empty:
        return right
    elif right.empty:
        return left
    else:
        return pd.merge(
            left,
            right,
            how="outer",
            left_index=True,
            right_index=True,
            validate="one_to_one",
        )


def to_csv_with_settings(
    df: pd.DataFrame, folder: Path, filename_prefix: str, data_type: str
) -> None:
    full_path = construct_full_path(folder, filename_prefix, data_type)
    df.to_csv(
        path_or_buf=full_path,
        sep=",",
        na_rep="NA",
        header=True,
        index=True,
        encoding="utf-8",
    )
    print("Exported the dataframe to " + str(full_path))


def read_csv_with_settings(
    folder: Path, filename_prefix: str, data_type: str, grouping_variable: list
) -> pd.DataFrame:
    full_path = construct_full_path(folder, filename_prefix, data_type)
    return pd.read_csv(
        filepath_or_buffer=full_path,
        sep=",",
        header=0,
        na_values="NA",
        encoding="utf-8",
        index_col=(["participant_id"] + grouping_variable),
        parse_dates=True,
        infer_datetime_format=True,
    )


def construct_full_path(folder: Path, filename_prefix: str, data_type: str) -> Path:
    export_filename = filename_prefix + "_" + data_type + ".csv"
    full_path = folder / export_filename
    return full_path