#!/usr/bin/env python3
"""Installer ↔ templates/downstream SoT parity (flake check `template-sot`).

Usage:
    check-template-sot.py <install-share-template> <templates/downstream>

Asserts the files nomarchy-install ships under
$out/share/nomarchy-install/template/ are byte-identical to the same
names in templates/downstream — the single source of truth for machine
flake seed files (see pkgs/nomarchy-install/default.nix installPhase).

The package copies a fixed file list (not a recursive tree copy):

    flake.nix  system.nix  home.nix  state.json

README.md and hardware-configuration.nix stay repo-only (docs /
nixos-generate-config at install time) and are intentionally absent
from the share.

Wired as `checks.template-sot` in flake.nix; also runnable after a local
package build:

    share=$(nix build --no-link --print-out-paths .#nomarchy-install)
    python3 tools/check-template-sot.py \
      "$share/share/nomarchy-install/template" templates/downstream
"""

from __future__ import annotations

import sys
from pathlib import Path

# Must match the cp list in pkgs/nomarchy-install/default.nix installPhase.
SHIPPED = ("flake.nix", "system.nix", "home.nix", "state.json")


def fail(msg: str) -> None:
    print(f"template-sot: {msg}", file=sys.stderr)
    sys.exit(1)


def main() -> int:
    if len(sys.argv) != 3:
        print(
            f"usage: {sys.argv[0]} <install-share-template> <templates/downstream>",
            file=sys.stderr,
        )
        return 2

    share = Path(sys.argv[1])
    sot = Path(sys.argv[2])

    if not share.is_dir():
        fail(f"install share template dir missing: {share}")
    if not sot.is_dir():
        fail(f"templates/downstream dir missing: {sot}")

    share_names = sorted(p.name for p in share.iterdir() if p.is_file())
    expected = sorted(SHIPPED)

    if share_names != expected:
        fail(
            "install share template file set drifted from default.nix copy list:\n"
            f"  share:    {share_names}\n"
            f"  expected: {expected}\n"
            "  (update SHIPPED here and the cp in pkgs/nomarchy-install/default.nix together)"
        )

    mismatches = []
    for name in SHIPPED:
        src = sot / name
        dst = share / name
        if not src.is_file():
            fail(f"SoT missing shipped file: {src}")
        a = src.read_bytes()
        b = dst.read_bytes()
        if a != b:
            mismatches.append(
                f"{name}: share ({len(b)} bytes) != SoT ({len(a)} bytes)"
            )

    if mismatches:
        print("template-sot: content mismatch(es):", file=sys.stderr)
        for m in mismatches:
            print(f"  {m}", file=sys.stderr)
        return 1

    print(
        f"template-sot: {len(SHIPPED)} files match "
        f"{sot} ↔ {share}"
    )
    return 0


if __name__ == "__main__":
    sys.exit(main())