import logging
import os
import shlex
import signal
import subprocess

from django.conf import settings


class SingleFileError(Exception):
    pass


logger = logging.getLogger(__name__)


def create_snapshot(url: str, filepath: str):
    singlefile_path = settings.LD_SINGLEFILE_PATH

    # parse options to list of arguments
    ublock_options = shlex.split(settings.LD_SINGLEFILE_UBLOCK_OPTIONS)
    custom_options = shlex.split(settings.LD_SINGLEFILE_OPTIONS)
    # concat lists
    args = [singlefile_path] + ublock_options + custom_options + [url, filepath]
    try:
        # Use start_new_session=True to create a new process group
        process = subprocess.Popen(args, start_new_session=True)
        process.wait(timeout=settings.LD_SINGLEFILE_TIMEOUT_SEC)

        # check if the file was created
        if not os.path.exists(filepath):
            raise SingleFileError("Failed to create snapshot")
    except subprocess.TimeoutExpired:
        # First try to terminate properly
        try:
            logger.error(
                "Timeout expired while creating snapshot. Terminating process..."
            )
            process.terminate()
            process.wait(timeout=20)
            raise SingleFileError("Timeout expired while creating snapshot")
        except subprocess.TimeoutExpired:
            # Kill the whole process group, which should also clean up any chromium
            # processes spawned by single-file
            logger.error("Timeout expired while terminating. Killing process...")
            os.killpg(os.getpgid(process.pid), signal.SIGTERM)
            raise SingleFileError("Timeout expired while creating snapshot")
    except subprocess.CalledProcessError as error:
        raise SingleFileError(f"Failed to create snapshot: {error.stderr}")