import functools
import pathlib

import attr
import click


@attr.s
class CommandSpec:
    module = attr.ib()
    function = attr.ib()
    input_files = attr.ib()
    output_files = attr.ib()


class ScriptsCLI(click.MultiCommand):
    @functools.lru_cache(None)
    def _collect_commands(commands_path):
        command_dicts = toml.load(pathlib.Path(commands_path).read_text())["commands"]
        command_specs = [CommandSpec(d) for d in command_dicts]
        return {spec.name: spec for spec in command_specs}

    def list_commands(self, ctx):
        specs = self._collect_commands(ctx.obj.config_dir / "commands.toml")
        return sorted(specs.keys())

    def get_command(self, ctx, name):
        specs = self._collect_commands(ctx.obj.config_dir / "commands.toml")
        spec = specs[name]
        module = importlib.import_module(spec.module)
        command = getattr(module, spec.function)
        return command


@click.group()
@click.pass_context
def cli(ctx):
    ctx.obj.config_dir = 'THE_DIR'
    pass


@cli.command(cls=ScriptsCLI)
@click.pass_context
def hello(ctx):
    pass


if __name__ == "__main__":
    cli()



#   File "cli3.py", line 38, in cli
#     ctx.obj.config_dir = 'THE_DIR'
# AttributeError: 'NoneType' object has no attribute 'config_dir'