from pathlib import Path

import pandas as pd


def safe_outer_merge_on_index(left: pd.DataFrame, right: pd.DataFrame) -> pd.DataFrame:
    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,
        cache_dates=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