#!/usr/bin/env python3

import hswro
import os
from pathlib import PurePosixPath
from typing import List
from os import environ

LIBRARY_DIR = "/home/reticulum/library"

library_contents = [""]


def get_from_list(l: List[str], i: int) -> str:
    try:
        return l[i]
    except IndexError:
        return ""


with os.scandir(LIBRARY_DIR) as it:
    for entry in it:
        if not entry.name.startswith('.') and entry.is_file():
            library_contents.append(PurePosixPath(entry.path).stem)

content_lines = ["", "Select a file to begin reading."]

if "var_view" in environ:
    document_name = environ["var_view"]                                                                                                                                
    if len(document_name) > 20:
        raise ValueError("Document name is too long, rejecting")
    if not all(map(lambda c: c.isalnum(), document_name)):
        raise ValueError("Document name contains not allowed characters, rejecting")
    content_lines = []
    with open(f"{LIBRARY_DIR}/{document_name}.txt") as file:
        content_lines = [line.rstrip() for line in file]

page_len = max(len(library_contents), len(content_lines)) + 2

hswro.header("Library")
for i in range(page_len):
    menuitem = " "*23
    item_name = get_from_list(library_contents, i)
    if item_name != "":
        menuitem = f"  `[{item_name:<20}`:/page/library.mu`view={item_name}] "
    content = get_from_list(content_lines, i)
    print(f"{hswro.MENUBGCOLOR}{menuitem}{hswro.BGCOLOR} {content}")
print("-.")
hswro.footer()