"""TDD — Phase 7: msgpack confined to wire-protocol files only.

Phase 7 requirements (issue #12):
- `import msgpack` must appear ONLY in wire-protocol files (transport, object
  store, gc, migration, bundle, pack/unpack commands).
- Every file in the allowlist must exist (guard against stale allowlist).
- No file under muse/core/, muse/plugins/, or muse/cli/commands/ outside the
  allowlist may import the msgpack library.
"""

from __future__ import annotations

import ast
import pathlib

# ---------------------------------------------------------------------------
# Wire-only allowlist — files that legitimately import msgpack
# ---------------------------------------------------------------------------

_REPO_ROOT = pathlib.Path(__file__).parent.parent

_WIRE_ALLOWLIST: frozenset[pathlib.Path] = frozenset({
    _REPO_ROOT / "muse" / "core" / "io.py",
    _REPO_ROOT / "muse" / "core" / "gc.py",
    _REPO_ROOT / "muse" / "core" / "transport.py",
    _REPO_ROOT / "muse" / "core" / "migrate.py",
    _REPO_ROOT / "muse" / "core" / "mpack.py",
    _REPO_ROOT / "muse" / "cli" / "commands" / "bundle.py",
    _REPO_ROOT / "muse" / "cli" / "commands" / "pack_objects.py",
    _REPO_ROOT / "muse" / "cli" / "commands" / "unpack_objects.py",
    _REPO_ROOT / "muse" / "cli" / "commands" / "verify_pack.py",
})


def _imports_msgpack(path: pathlib.Path) -> bool:
    """Return True if *path* contains any import of the msgpack library."""
    try:
        tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
    except SyntaxError:
        return False
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            for alias in node.names:
                if alias.name == "msgpack" or alias.name.startswith("msgpack."):
                    return True
        elif isinstance(node, ast.ImportFrom):
            if node.module and (
                node.module == "msgpack" or node.module.startswith("msgpack.")
            ):
                return True
    return False


# ---------------------------------------------------------------------------
# Test: allowlist files all exist
# ---------------------------------------------------------------------------


class TestWireAllowlistFilesExist:
    def test_all_allowlist_files_exist(self) -> None:
        """Every file in the wire allowlist must actually exist on disk."""
        missing = [p for p in _WIRE_ALLOWLIST if not p.is_file()]
        assert missing == [], (
            f"Stale allowlist — these files no longer exist: "
            + ", ".join(str(p.relative_to(_REPO_ROOT)) for p in missing)
        )


# ---------------------------------------------------------------------------
# Test: no msgpack in muse/core/ (except allowlist)
# ---------------------------------------------------------------------------


class TestNoMsgpackInCore:
    def test_no_msgpack_import_in_core_storage(self) -> None:
        """No file in muse/core/ outside the allowlist may import msgpack."""
        violations: list[str] = []
        for path in (_REPO_ROOT / "muse" / "core").rglob("*.py"):
            if path in _WIRE_ALLOWLIST:
                continue
            if _imports_msgpack(path):
                violations.append(str(path.relative_to(_REPO_ROOT)))
        assert violations == [], (
            "Non-wire muse/core/ files import msgpack:\n  "
            + "\n  ".join(sorted(violations))
        )

    def test_no_msgpack_import_in_plugins(self) -> None:
        """No file in muse/plugins/ may import msgpack."""
        violations: list[str] = []
        for path in (_REPO_ROOT / "muse" / "plugins").rglob("*.py"):
            if path in _WIRE_ALLOWLIST:
                continue
            if _imports_msgpack(path):
                violations.append(str(path.relative_to(_REPO_ROOT)))
        assert violations == [], (
            "Plugin files import msgpack:\n  "
            + "\n  ".join(sorted(violations))
        )


# ---------------------------------------------------------------------------
# Test: no msgpack in muse/cli/commands/ (except allowlist)
# ---------------------------------------------------------------------------


class TestNoMsgpackInCliCommands:
    def test_no_msgpack_import_in_cli_storage(self) -> None:
        """No cli/commands/ file outside the wire allowlist may import msgpack."""
        violations: list[str] = []
        for path in (_REPO_ROOT / "muse" / "cli" / "commands").rglob("*.py"):
            if path in _WIRE_ALLOWLIST:
                continue
            if _imports_msgpack(path):
                violations.append(str(path.relative_to(_REPO_ROOT)))
        assert violations == [], (
            "Non-wire cli/commands/ files import msgpack:\n  "
            + "\n  ".join(sorted(violations))
        )