"""What the engine hashes to decide a repository's code moved.

The commit cannot answer this: an uncommitted tree stamps `-dirty` for every
run it ever produces, and the node bodies are import shims that pick up
whatever is on disk when the worker starts.
"""

from fluksio.flow import runs
from fluksio.flow.runs import code_digest, repo_digest
from fluksio.flow.schemas import FlowDef, FlowOrigin


def a_repo(tmp_path, body="x = 1\n"):
    (tmp_path / "pkg").mkdir()
    (tmp_path / "pkg" / "train.py").write_text(body)
    return str(tmp_path)


def touch(path, body, mtime):
    """Write and stamp: two writes inside one clock tick look identical."""
    path.write_text(body)
    import os

    os.utime(path, ns=(mtime, mtime))


def test_the_same_tree_hashes_the_same(tmp_path):
    repo = a_repo(tmp_path)
    assert repo_digest(repo) == repo_digest(repo)


def test_editing_a_file_changes_it(tmp_path):
    repo = a_repo(tmp_path)
    before = repo_digest(repo)
    touch(tmp_path / "pkg" / "train.py", "x = 2\n", 2_000_000_000_000_000_000)

    assert repo_digest(repo) != before


def test_a_new_file_changes_it(tmp_path):
    repo = a_repo(tmp_path)
    before = repo_digest(repo)
    (tmp_path / "pkg" / "helper.py").write_text("y = 1\n")

    assert repo_digest(repo) != before


def test_what_is_not_the_project_is_left_out(tmp_path):
    """A venv is bigger than the project and is not its code."""
    repo = a_repo(tmp_path)
    before = repo_digest(repo)

    (tmp_path / ".venv" / "lib").mkdir(parents=True)
    (tmp_path / ".venv" / "pyvenv.cfg").write_text("home = /usr\n")
    (tmp_path / ".venv" / "lib" / "numpy.py").write_text("huge = True\n")
    (tmp_path / "pkg" / "__pycache__").mkdir()
    (tmp_path / "pkg" / "__pycache__" / "train.py").write_text("compiled\n")
    (tmp_path / ".git").mkdir()
    (tmp_path / ".git" / "hook.py").write_text("hook\n")
    (tmp_path / "pkg" / "notes.md").write_text("prose\n")

    assert repo_digest(repo) == before


def test_a_repository_the_engine_cannot_see_is_empty(tmp_path):
    """Not an error: a worker elsewhere is a normal deployment."""
    assert repo_digest(str(tmp_path / "nowhere")) == ""
    assert repo_digest("") == ""


def test_only_a_code_defined_flow_has_one(tmp_path):
    """A flow drawn on the canvas has no repository, and keys as it always did."""
    repo = a_repo(tmp_path)
    declared = FlowDef(
        name="train", mode="batch", origin=FlowOrigin(repo=repo, commit="abc")
    )

    assert code_digest(declared) == repo_digest(repo)
    assert code_digest(FlowDef(name="drawn", mode="batch")) == ""


def test_unchanged_files_are_not_read_again(tmp_path, monkeypatch):
    """The warm path is a stat per file, which is what makes this per-submit."""
    repo = a_repo(tmp_path)
    repo_digest(repo)

    def refuse(*_args, **_kwargs):
        raise AssertionError("an unchanged tree must not be re-read")

    monkeypatch.setattr(runs.Path, "read_bytes", refuse)
    assert repo_digest(repo)