import importlib.util
import subprocess
import sys
import uuid
from pathlib import Path

from source.manager import ModelManager
from source.model import base


class PythonModel(base.BaseModel):
    """
    A model running a custom python model.
    """

    def __init__(self, manager: ModelManager, configuration: dict, path: Path):
        super().__init__(manager, configuration, path)

        # get the name of the file containing the model code
        file = configuration.get("file")
        if file is None:
            raise ValueError("Field 'file' is missing from the configuration")

        # install custom requirements
        requirements = configuration.get("requirements", [])
        if len(requirements) > 0:
            subprocess.run([sys.executable, "-m", "pip", "install", *requirements])

        # create the module specification
        module_spec = importlib.util.spec_from_file_location(
            f"model-{uuid.uuid4()}",
            self.path / file
        )
        # get the module
        self.module = importlib.util.module_from_spec(module_spec)
        # load the module
        module_spec.loader.exec_module(self.module)

    def _load(self) -> None:
        return self.module.load(self)

    def _unload(self) -> None:
        return self.module.unload(self)

    def _infer(self, payload: dict) -> str | bytes:
        return self.module.infer(self, payload)