"""Opt-in, administrator-provided licensed webfonts. Never load paths from SchDoc."""
import json
import os
from pathlib import Path

def fonts():
    directory=os.getenv('FONT_DIR')
    if not directory: return {}
    root=Path(directory).resolve()
    manifest=root/'fonts.json'
    values=json.loads(manifest.read_text())
    result={}
    for family,variants in values.items():
        if isinstance(variants,str): variants=[{'file':variants}]
        for index,variant in enumerate(variants):
            file=(root/variant['file']).resolve()
            if not file.is_relative_to(root) or not file.is_file() or file.suffix.lower() not in ('.ttf','.otf','.woff','.woff2'):
                raise ValueError('Invalid configured font path')
            weight=str(variant.get('weight','normal')); style=variant.get('style','normal')
            if weight not in {'normal','bold','100','200','300','400','500','600','700','800','900'} or style not in {'normal','italic','oblique'}:
                raise ValueError('Invalid configured font variant')
            result[f'{len(result)}{file.suffix.lower()}']={'family':family,'file':file,'weight':weight,'style':style}
    return result

def stylesheet():
    rules=[]
    for name,font in fonts().items():
        # JSON strings safely quote arbitrary family names inside CSS strings.
        family=json.dumps(font['family'],ensure_ascii=True).replace('<','\\3c ')
        rules.append(f"@font-face{{font-family:{family};src:url('/fonts/{name}');font-weight:{font['weight']};font-style:{font['style']};font-display:block}}")
    return '\n'.join(rules)