'''
Bookbot reads a book from a text file and prints out a simple report about it
to the standard output.
'''
import argparse


def main() -> None:
    '''The entrypoint to the bookbot code.'''
    parser = argparse.ArgumentParser(
        prog='Bookbot',
        description='Bookbot produces a simple book report.',
    )
    parser.add_argument(
        'filename',
        type=str,
        help='the path to the text file.'
    )
    args = parser.parse_args()
    text = read_file(args.filename)
    report(args.filename, number_of_words(text), character_map(text))


def read_file(path: str) -> str:
    '''
    Opens a file from a given file path and returns the contents of the file.

        Parameters:
            path (str): The path to the text file.

        Returns:
            text (str): The contents of the text file.
    '''
    with open(path, mode='r', encoding='utf-8') as file:
        text = file.read()
        return text


def number_of_words(text: str) -> int:
    '''
    Returns the number of words in a given text string.

        Parameters:
            text (str): The string of text.

        Returns:
            num_words (int): The number of words in the text.
    '''
    num_words = len(text.split())
    return num_words


def character_map(text: str) -> dict[str, int]:
    '''
    Returns a dictionary with the amount of times
    a character appears in a given text.

    Non-letter characters are ignored.

        Parameters:
            text (str): The string of text.

        Returns:
            output (dict[str, int]): A dictionary with the amount of times each
                                     character appears in the text.
    '''
    output = {
        'a': 0,
        'b': 0,
        'c': 0,
        'd': 0,
        'e': 0,
        'f': 0,
        'g': 0,
        'h': 0,
        'i': 0,
        'j': 0,
        'k': 0,
        'l': 0,
        'm': 0,
        'n': 0,
        'o': 0,
        'p': 0,
        'q': 0,
        'r': 0,
        's': 0,
        't': 0,
        'u': 0,
        'v': 0,
        'w': 0,
        'x': 0,
        'y': 0,
        'z': 0,
    }

    for character in text:
        lowercase_character = character.lower()
        if lowercase_character in output:
            output[lowercase_character] += 1

    return output


def report(path: str, total_words: int, characters: dict[str, int]) -> None:
    '''
    Prints a report about the given text.

        Parameters:
            path (str): The path to the text file.
            total_words (int): The total amount of words found in the
                               text file.
            characters: The dictionary with the amount of times
                           each character appears in the text.

        Returns:
            None
    '''
    print(f"--- Begin report of {path} ---")
    print(f"{total_words} words found in the document\n")
    for key, value in characters.items():
        print(f"The character '{key}' was found {value} times")
    print("--- End report ---")


if __name__ == "__main__":
    main()