import io
import os
from typing import IO, Type

from services.io import add_fast_api_root, get_filename, get_or_create_dir, remove_fastapi_root


class FileFieldMeta(type):
    def __getitem__(self, upload_root: str,) -> Type['FileField']:
        return type('MyFieldValue', (FileField,), {'upload_root': upload_root})


class FileField(str, metaclass=FileFieldMeta):
    upload_root: str

    @classmethod
    def __get_validators__(cls):
        yield cls.validate
    
    @classmethod
    def validate(cls, value: str | IO, values):
        
        upload_root = get_or_create_dir(
            add_fast_api_root(cls.upload_root))
        if not isinstance(value, str):
            value.seek(0)

            is_binary = isinstance(value, io.BytesIO)

            name = get_filename(value, 'exo_source.py')

            parent = get_or_create_dir(os.path.join(
                upload_root, values['id_code']))

            mode = 'w+' if not is_binary else 'wb+'

            path = os.path.join(parent, name)
            with open(path, mode) as f:
                f.write(value.read())

            return remove_fastapi_root(path)

        else:
            if not os.path.exists(add_fast_api_root(value)):
                raise ValueError('File does not exist')
            return value