# deck-it - the module contract and registry
# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

"""The module contract and the registry that dispatches to modules.

A module is a data source plus an allow-listed set of actions. The client sends
a module name and an action id; it never sends a command. The registry is the
single place that maps ids to code, so adding a module never touches the server.
"""

from dataclasses import dataclass, field
from typing import Callable


class ModuleError(Exception):
    """A bad module/action id, or a module that cannot serve the request."""


@dataclass
class Module:
    name: str
    title: str
    state: Callable[[], dict]
    actions: dict[str, Callable[[dict], dict | None]] = field(default_factory=dict)
    start: Callable[[], None] | None = None
    stop: Callable[[], None] | None = None


class Registry:
    def __init__(self, modules):
        self._modules = {m.name: m for m in modules}

    def names(self) -> list[dict]:
        return [{"name": m.name, "title": m.title} for m in self._modules.values()]

    def get(self, name: str) -> Module:
        if name not in self._modules:
            raise ModuleError(f"unknown module: {name}")
        return self._modules[name]

    _get = get

    def start_all(self) -> None:
        for m in self._modules.values():
            if m.start:
                try:
                    m.start()
                except Exception:
                    pass

    def stop_all(self) -> None:
        for m in self._modules.values():
            if m.stop:
                try:
                    m.stop()
                except Exception:
                    pass

    def state(self, name: str) -> dict:
        return self._get(name).state()

    def run_action(self, name: str, action: str, body: dict) -> dict | None:
        module = self._get(name)
        if action not in module.actions:
            raise ModuleError(f"unknown action: {name}/{action}")
        return module.actions[action](body)