import json
from pathlib import Path


def get_book_list() -> str:
    """
    Get list of available books.

    Returns:
        str: JSON string containing the list of book names.
    """
    books_dir = Path("./books")
    if not books_dir.exists():
        return json.dumps("Error: Books directory not found.")

    text_files = []
    for file in books_dir.iterdir():
        if file.is_file() and file.suffix.lower() == ".txt":
            text_files.append(file.stem)

    return json.dumps(sorted(text_files))


def get_book_content(book_name: str, max_length: int = 0) -> str:
    """
    Get the content of a book.

    Args:
        book_name (str): The name of the book (without .txt extension).
        max_length (int): The maximum length of the content to return. If 0, return the full content.
    Returns:
        str: The content of the book, or an error message if the book is not found.
    """
    books_dir = Path("./books")
    book_file = books_dir / f"{book_name}.txt"
    if not book_file.exists():
        return f"Error: Book '{book_name}' not found."

    with open(book_file, "r", encoding="utf-8") as f:
        lines = f.readlines()

    content = _remove_header_footer(lines)

    if not max_length:
        return content
    else:
        return content[:max_length]


def _remove_header_footer(lines: list[str]) -> str:
    """
    Remove the header and footer from the book content.

    Args:
        lines (list[str]): List of lines from the book content.

    Returns:
        str: The content without the header and footer.
    """
    # Find start index
    start_index = 0
    for i, line in enumerate(lines):
        if line.startswith("*** START OF THE PROJECT GUTENBERG EBOOK"):
            start_index = i + 1
            break

    # Find end index
    end_index = len(lines)
    for i in range(len(lines) - 1, -1, -1):
        if lines[i].startswith("*** END OF THE PROJECT GUTENBERG EBOOK"):
            end_index = i
            break

    return '\n'.join(lines[start_index:end_index])



if __name__ == "__main__":
    print("Available books:", get_book_list())

    book_name = "Winnie_the_Pooh_by_A_A_Milne_9255"
    book_content = get_book_content(book_name)
    print(f"Start of '{book_name}':\n{book_content[:500]}...\n")
    print(f"End of '{book_name}':\n{book_content[-500:]}\n")