"""TDD — MPack schema must contain only pack fields.

A pack carries commits + snapshots + objects + summary + meta + tags.
Nothing else. The fields that were historically embedded in a "bundle"
but belong in the HTTP layer must not appear in MPack:

  branch_heads          → POST /push request body  (which branch, what tip)
  pusher_id             → Authorization header      (MSign identity)
  declared_objects_count → POST /push request body  (advisory integrity hint)

These fields cannot live in the pack because the pack is content-addressed:
  pack_id = sha256(pack_bytes)
Any push-specific metadata embedded in the bytes would make two identical
content pushes produce different pack IDs — defeating content-addressing.

Tests in this file are schema-level (TypedDict annotation checks) plus
a round-trip assertion that build_mpack never emits the forbidden fields.
"""
from __future__ import annotations

import json
import pathlib

import pytest

from muse.core.mpack import MPack, build_mpack
from muse.core.object_store import write_object
from muse.core.paths import muse_dir
from muse.core.ids import hash_commit as compute_commit_id, hash_snapshot as compute_snapshot_id
from muse.core.refs import write_branch_ref
from muse.core.commits import (
    CommitRecord,
    write_commit,
)
from muse.core.snapshots import (
    SnapshotRecord,
    write_snapshot,
)
from muse.core.types import blob_id


# ---------------------------------------------------------------------------
# Minimal repo fixture
# ---------------------------------------------------------------------------

@pytest.fixture()
def repo(tmp_path: pathlib.Path) -> tuple[pathlib.Path, str]:
    """One-commit repo. Returns (root, commit_id)."""
    dot = muse_dir(tmp_path)
    dot.mkdir()
    (dot / "repo.json").write_text(json.dumps({"repo_id": "schema-test"}))
    for d in ("commits", "snapshots", "objects"):
        (dot / d).mkdir()
    (dot / "refs" / "heads").mkdir(parents=True)
    (dot / "HEAD").write_text("ref: refs/heads/main\n")
    (dot / "config.toml").write_text("")

    content = b"hello schema test"
    oid = blob_id(content)
    write_object(tmp_path, oid, content)

    manifest = {"src/hello.py": oid}
    sid = compute_snapshot_id(manifest)
    write_snapshot(tmp_path, SnapshotRecord(snapshot_id=sid, manifest=manifest))

    import datetime
    ts = datetime.datetime(2026, 1, 1, tzinfo=datetime.timezone.utc)
    cid = compute_commit_id(
        parent_ids=[],
        snapshot_id=sid,
        message="init",
        committed_at_iso=ts.isoformat(),
        author="gabriel",
    )
    write_commit(tmp_path, CommitRecord(
        commit_id=cid, branch="main",
        snapshot_id=sid, message="init", committed_at=ts,
        parent_commit_id=None, parent2_commit_id=None,
        author="gabriel", metadata={}, structured_delta=None,
        sem_ver_bump="none", breaking_changes=[],
        agent_id="", model_id="", toolchain_id="",
        prompt_hash="", signature="", signer_key_id="",
    ))
    write_branch_ref(tmp_path, "main", cid)
    return tmp_path, cid


# ---------------------------------------------------------------------------
# Schema-level: forbidden fields must not be declared on MPack
# ---------------------------------------------------------------------------

_FORBIDDEN = {"branch_heads", "pusher_id", "declared_objects_count"}


@pytest.mark.parametrize("field", sorted(_FORBIDDEN))
def test_mpack_bundle_type_does_not_declare_push_metadata(field: str) -> None:
    """MPack.__annotations__ must not contain push-layer metadata fields.

    These fields belong in the HTTP request body or Authorization header,
    not in the content-addressed pack bytes.
    """
    assert field not in MPack.__annotations__, (
        f"MPack declares '{field}' but that field belongs in the HTTP "
        f"layer, not the pack. Remove it from the TypedDict."
    )


# ---------------------------------------------------------------------------
# Naming: BundleMeta must not exist — it is MPackMeta
# ---------------------------------------------------------------------------

def test_bundle_meta_name_does_not_exist() -> None:
    """BundleMeta is the old bundle-era name — it must not exist in muse.core.mpack."""
    import importlib, muse.core.mpack as _mod
    assert not hasattr(_mod, "BundleMeta"), (
        "BundleMeta still exists in muse.core.mpack — rename it to MPackMeta."
    )

def test_mpack_meta_name_exists() -> None:
    """MPackMeta is the canonical name for the pack metadata TypedDict."""
    from muse.core.mpack import MPackMeta  # noqa: F401


# ---------------------------------------------------------------------------
# Naming: MPack must not exist — the type is MPack
# ---------------------------------------------------------------------------

def test_mpack_type_exists() -> None:
    """MPack is the canonical TypedDict for the wire artifact."""
    from muse.core.mpack import MPack  # noqa: F401


# ---------------------------------------------------------------------------
# Runtime: build_mpack must never emit the forbidden fields
# ---------------------------------------------------------------------------

def test_build_mpack_does_not_emit_push_metadata(
    repo: tuple[pathlib.Path, str],
) -> None:
    """build_mpack() must return a dict free of push-layer metadata fields."""
    root, head = repo
    pack = build_mpack(root, [head], have=[])
    for field in _FORBIDDEN:
        assert field not in pack, (
            f"build_mpack() emitted '{field}' — that field belongs in the "
            f"HTTP layer, not in the pack bytes."
        )


# ---------------------------------------------------------------------------
# Positive: expected fields are present
# ---------------------------------------------------------------------------

def test_build_mpack_contains_required_fields(
    repo: tuple[pathlib.Path, str],
) -> None:
    """build_mpack() must emit exactly the core pack fields."""
    root, head = repo
    pack = build_mpack(root, [head], have=[])
    for field in ("commits", "snapshots", "blobs", "summary", "meta"):
        assert field in pack, f"build_mpack() missing required field '{field}'"