"""TDD — log._collect_all_commits must use iter_ancestors, not inline deque BFS.

LC1  Structural — _collect_all_commits uses iter_ancestors; no inline deque BFS
LC2  Behavioural — collects all commits reachable from start_ids
LC3  Behavioural — truncated flag fires at max_commits cap
"""
from __future__ import annotations

import datetime
import inspect
import json
import pathlib

import pytest

from muse._version import __version__
from muse.core.object_store import write_object
from muse.core.ids import hash_commit as compute_commit_id, hash_snapshot as compute_snapshot_id
from muse.core.commits import (
    CommitRecord,
    write_commit,
)
from muse.core.snapshots import (
    SnapshotRecord,
    write_snapshot,
)
from muse.core.types import blob_id
from muse.core.paths import muse_dir


def _repo(tmp_path: pathlib.Path, monkeypatch: pytest.MonkeyPatch) -> pathlib.Path:
    dot_muse = muse_dir(tmp_path)
    for d in ("commits", "snapshots", "objects", "refs/heads", "remotes"):
        (dot_muse / d).mkdir(parents=True, exist_ok=True)
    (dot_muse / "HEAD").write_text("ref: refs/heads/main\n")
    (dot_muse / "repo.json").write_text(
        json.dumps({"repo_id": "test-repo", "schema_version": __version__, "domain": "code"})
    )
    monkeypatch.setenv("MUSE_REPO_ROOT", str(tmp_path))
    monkeypatch.chdir(tmp_path)
    return tmp_path


def _make_commit(
    root: pathlib.Path,
    parent_id: str | None = None,
    *,
    message: str = "test",
) -> CommitRecord:
    oid = blob_id(b"data-" + message.encode())
    write_object(root, oid, b"data-" + message.encode())
    manifest = {"f.py": oid}
    snap_id = compute_snapshot_id(manifest)
    write_snapshot(root, SnapshotRecord(snapshot_id=snap_id, manifest=manifest))
    ts = datetime.datetime(2026, 1, 1, tzinfo=datetime.timezone.utc)
    cid = compute_commit_id(
        parent_ids=[parent_id] if parent_id else [],
        snapshot_id=snap_id,
        message=message,
        committed_at_iso=ts.isoformat(),
    )
    rec = CommitRecord(
        commit_id=cid,
        branch="main",
        snapshot_id=snap_id,
        message=message,
        committed_at=ts,
        parent_commit_id=parent_id,
    )
    write_commit(root, rec)
    return rec


# ---------------------------------------------------------------------------
# LC1  Structural
# ---------------------------------------------------------------------------

def test_lc1_collect_all_commits_uses_iter_ancestors() -> None:
    """_collect_all_commits must delegate to iter_ancestors; no inline deque."""
    from muse.cli.commands import log as log_mod

    src = inspect.getsource(log_mod._collect_all_commits)

    assert "iter_ancestors" in src, (
        "_collect_all_commits must delegate to iter_ancestors. "
        "Replace the inline deque BFS."
    )
    assert "deque" not in src, (
        "_collect_all_commits still has an inline deque. Replace with iter_ancestors."
    )


# ---------------------------------------------------------------------------
# LC2  Behavioural — collects all reachable commits
# ---------------------------------------------------------------------------

def test_lc2_collect_all_commits_returns_all(
    tmp_path: pathlib.Path,
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    """Returns a CommitIndex containing every reachable commit."""
    from muse.cli.commands.log import _collect_all_commits  # type: ignore[attr-defined]

    root = _repo(tmp_path, monkeypatch)
    c1 = _make_commit(root, message="c1")
    c2 = _make_commit(root, c1.commit_id, message="c2")
    c3 = _make_commit(root, c2.commit_id, message="c3")

    index, truncated = _collect_all_commits(root, [c3.commit_id])

    assert truncated is False
    assert c1.commit_id in index
    assert c2.commit_id in index
    assert c3.commit_id in index


# ---------------------------------------------------------------------------
# LC3  Behavioural — truncated flag
# ---------------------------------------------------------------------------

def test_lc3_collect_all_commits_truncated_flag(
    tmp_path: pathlib.Path,
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    """truncated=True when max_commits is reached before exhausting the DAG."""
    from muse.cli.commands.log import _collect_all_commits  # type: ignore[attr-defined]

    root = _repo(tmp_path, monkeypatch)
    parent_id: str | None = None
    for i in range(5):
        c = _make_commit(root, parent_id, message=f"c{i}")
        parent_id = c.commit_id

    index, truncated = _collect_all_commits(root, [parent_id], max_commits=2)  # type: ignore[arg-type]

    assert truncated is True
    assert len(index) == 2