def long_to_matrix_format(csv_path):
    """
    Convert a long format CSV with 'datetime' and 'value' columns
    to a matrix format with 'Year', 'Day', and hourly columns.

    Parameters:
    - csv_path: str, path to the long format CSV

    Returns:
    - matrix_df: DataFrame in matrix format
    """

    # Read the CSV
    df = pl.read_csv(csv_path, try_parse_dates=True).to_pandas(())
    
# Convert the 'datetime' column to a pandas datetime format
    df["date"] = pd.to_datetime(df["date"])
    
# Set the DateTime column as the index
    df.set_index("date", inplace=True)
    df = df.resample("60min").sum()
    df["date"] = df.index.to_series()


    # Extract year, day of year, and hour
    df["Year"] = df["date"].dt.year
    df["Day"] = df["date"].dt.dayofyear
    df["Hour"] = (
        df["date"].dt.hour + 1
    )  # +1 to start hours from 1 to 24 instead of 0 to 23

    # Pivot the DataFrame to the desired matrix format
    matrix_df = df.pivot_table(
        index=["Year", "Day"], columns="Hour", values="value", aggfunc="sum"
    ).reset_index()

    # Rearrange columns to the desired order
    matrix_df = matrix_df[["Year", "Day"] + [i for i in range(1, 25)]]
    matrix_df.columns = ["Year", "Day"] + [f"Hour {i}" for i in range(1, 25)]

    # Fill NaN values with 0
    matrix_df.fillna(0, inplace=True)

    matrix_df["Year"] = matrix_df["Year"] - matrix_df["Year"].min() + 1

    return matrix_df.to_numpy().astype(float).copy()#this is important to make use of the numba code.

@numba.njit('float64[:,::1](float64[:,::1])')
@cc.export('nb_get_idf_rolling_sum', 'float64[:,::1](float64[:,::1])')
def get_idf_rolling_sum(df_array):
    rows = np.unique(df_array[:, 0]).size
    data = np.zeros((rows, 24))

    for i in range(rows):
        # Filter by year and drop the 'Year' and 'Day' columns
        df1_array = df_array[df_array[:, 0] == i + 1][:, 2:].T

        # Loop through 0 to 23 to calculate the max rolling sum for each window size
        for j in range(24):
            max_rolling_sum = np.NINF

            # Loop through each column
            for col in range(df1_array.shape[1]):
                # Loop through each possible window in the current column
                for row in range(df1_array.shape[0] - j):
                    rolling_sum = np.sum(df1_array[row : row + j + 1, col])

                    # Update max rolling sum if this sum is greater
                    if rolling_sum > max_rolling_sum:
                        max_rolling_sum = rolling_sum

            # Store the max rolling sum in the data array
            data[i, j] = max_rolling_sum

    return data