#!/usr/bin/env python3
"""Read-only invariant checks for the active Decman configuration."""

from __future__ import annotations

import os
import runpy
import subprocess
import sys
from collections import Counter
from collections.abc import Callable
from pathlib import Path
from typing import cast

ROOT = Path(__file__).resolve().parents[1]
PACKAGES = ROOT / "packages"


def lines(path: Path) -> set[str]:
    return {
        line.strip()
        for line in path.read_text(encoding="utf-8").splitlines()
        if line.strip()
    }


def actual(command: str) -> set[str]:
    return set(
        subprocess.run(
            ["pacman", command], check=True, text=True, stdout=subprocess.PIPE
        ).stdout.split()
    )


def main() -> None:
    repo_files = list(PACKAGES.glob("**/*-repo.txt"))
    aur_files = list(PACKAGES.glob("**/*-aur.txt"))
    repo = [name for path in repo_files for name in lines(path)]
    aur = [name for path in aur_files for name in lines(path)]
    duplicate = {name for name, count in Counter(repo + aur).items() if count > 1}
    if duplicate:
        raise SystemExit(f"duplicate package ownership: {sorted(duplicate)}")
    installed_repo = actual("-Qqen")
    installed_aur = actual("-Qqem")

    os.chdir(ROOT)
    sys.path.insert(0, str(ROOT))
    import decman

    runpy.run_path(str(ROOT / "source.py"))
    loaded_repo: set[str] = set()
    loaded_aur: set[str] = set()
    for module in decman.modules:
        native = getattr(module, "native_packages", None)
        foreign = getattr(module, "aur_packages", None)
        if callable(native):
            loaded_repo |= cast(Callable[[], set[str]], native)()
        if callable(foreign):
            loaded_aur |= cast(Callable[[], set[str]], foreign)()
    if loaded_repo != set(repo) or loaded_aur != set(aur):
        raise SystemExit("active profile does not compose the full laptop package set")
    expected_system = set().union(
        *(lines(path) for path in (ROOT / "manifests").glob("**/*-system.txt"))
    )
    expected_user = set().union(
        *(lines(path) for path in (ROOT / "manifests").glob("**/*-user.txt"))
    )
    loaded_system: set[str] = set()
    loaded_user: set[str] = set()
    for module in decman.modules:
        system = getattr(module, "system_units", None)
        user = getattr(module, "user_units", None)
        if callable(system):
            loaded_system |= cast(Callable[[], set[str]], system)()
        if callable(user):
            loaded_user |= cast(Callable[[], dict[str, set[str]]], user)().get(
                "alex", set()
            )
    if loaded_system != expected_system or loaded_user != expected_user:
        raise SystemExit("active profile does not compose the complete unit manifests")
    pending_remove = sorted((installed_repo - set(repo)) | (installed_aur - set(aur)))
    pending_install = sorted((set(repo) - installed_repo) | (set(aur) - installed_aur))
    print(
        f"OK: repo={len(repo)} aur={len(aur)} system={len(loaded_system)} "
        f"user={len(loaded_user)} concerns={len(repo_files)} profile=laptop"
    )
    print(f"PENDING REMOVE: {' '.join(pending_remove) or 'none'}")
    print(f"PENDING INSTALL: {' '.join(pending_install) or 'none'}")


if __name__ == "__main__":
    main()