from giant import config as gconfig


def _write_config(path, git_hash):
    path.write_text(
        f"""
[train]
epochs = 5

[model]
hidden_dim = 64

[meta]
git_hash = "{git_hash}"
"""
    )


def test_merge_cli_overrides_applies_file_then_cli(tmp_path, monkeypatch):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "abc123")
    path = tmp_path / "config.toml"
    _write_config(path, "abc123")

    cfg = gconfig.merge_cli_overrides(
        gconfig.DEFAULT_CONFIG,
        path,
        train_overrides={},
        model_overrides={"hidden_dim": 128},
    )
    assert cfg["train"]["epochs"] == 5  # from file
    assert cfg["model"]["hidden_dim"] == 128  # CLI override wins over file


def test_merge_cli_overrides_warns_on_git_hash_mismatch(tmp_path, monkeypatch, capsys):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "current999")
    path = tmp_path / "config.toml"
    _write_config(path, "old111")

    cfg = gconfig.merge_cli_overrides(gconfig.DEFAULT_CONFIG, path, {}, {})

    assert cfg["train"]["epochs"] == 5  # does not fail, config still applied
    captured = capsys.readouterr()
    assert "warning" in captured.err
    assert "old111" in captured.err
    assert "current999" in captured.err


def test_merge_cli_overrides_no_warning_on_matching_git_hash(
    tmp_path, monkeypatch, capsys
):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "same123")
    path = tmp_path / "config.toml"
    _write_config(path, "same123")

    gconfig.merge_cli_overrides(gconfig.DEFAULT_CONFIG, path, {}, {})
    assert capsys.readouterr().err == ""


def test_merge_cli_overrides_no_warning_when_git_hash_unknown(
    tmp_path, monkeypatch, capsys
):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "unknown")
    path = tmp_path / "config.toml"
    _write_config(path, "abc123")

    gconfig.merge_cli_overrides(gconfig.DEFAULT_CONFIG, path, {}, {})
    assert capsys.readouterr().err == ""


def test_merge_cli_overrides_no_warning_when_meta_section_absent(
    tmp_path, monkeypatch, capsys
):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "current999")
    path = tmp_path / "config.toml"
    path.write_text("[train]\nepochs = 5\n")

    gconfig.merge_cli_overrides(gconfig.DEFAULT_CONFIG, path, {}, {})
    assert capsys.readouterr().err == ""


def test_warn_if_checkpoint_config_mismatch_finds_sibling_toml(
    tmp_path, monkeypatch, capsys
):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "current999")
    ckpt_path = tmp_path / "best.pt"
    ckpt_path.write_bytes(b"")  # contents irrelevant, only its directory is used
    _write_config(tmp_path / "config.toml", "old111")

    gconfig.warn_if_checkpoint_config_mismatch(ckpt_path)

    captured = capsys.readouterr()
    assert "warning" in captured.err
    assert "old111" in captured.err
    assert "current999" in captured.err


def test_warn_if_checkpoint_config_mismatch_no_warning_when_toml_absent(
    tmp_path, monkeypatch, capsys
):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "current999")
    ckpt_path = tmp_path / "best.pt"
    ckpt_path.write_bytes(b"")

    gconfig.warn_if_checkpoint_config_mismatch(ckpt_path)
    assert capsys.readouterr().err == ""


def test_warn_if_checkpoint_config_mismatch_no_warning_when_hashes_match(
    tmp_path, monkeypatch, capsys
):
    monkeypatch.setattr(gconfig, "git_hash", lambda: "same123")
    ckpt_path = tmp_path / "best.pt"
    ckpt_path.write_bytes(b"")
    _write_config(tmp_path / "config.toml", "same123")

    gconfig.warn_if_checkpoint_config_mismatch(ckpt_path)
    assert capsys.readouterr().err == ""


def test_resolve_expert_dims_default_config_inherits_hidden_dim_and_n_blocks():
    # The unset sentinel (expert_hidden_dim/n_blocks == 0 in DEFAULT_CONFIG)
    # is exactly the bug fixed by resolve_expert_dims: it must not silently
    # fall back to some other hardcoded default, only to the monolith's own
    # hidden_dim/n_blocks, so --hidden-dim/--n-blocks reach the experts too.
    router_cfg = dict(gconfig.DEFAULT_CONFIG["model"]["router"])
    assert router_cfg["expert_hidden_dim"] == 0
    assert router_cfg["expert_n_blocks"] == 0

    hidden_dim, n_blocks = gconfig.resolve_expert_dims(router_cfg, 512, 6)
    assert (hidden_dim, n_blocks) == (512, 6)


def test_resolve_expert_dims_missing_keys_also_inherit():
    hidden_dim, n_blocks = gconfig.resolve_expert_dims({}, 512, 6)
    assert (hidden_dim, n_blocks) == (512, 6)


def test_resolve_expert_dims_explicit_override_wins():
    router_cfg = {"expert_hidden_dim": 128, "expert_n_blocks": 3}
    hidden_dim, n_blocks = gconfig.resolve_expert_dims(router_cfg, 512, 6)
    assert (hidden_dim, n_blocks) == (128, 3)


def test_resolve_expert_dims_partial_override_mixes_explicit_and_inherited():
    router_cfg = {"expert_hidden_dim": 128, "expert_n_blocks": 0}
    hidden_dim, n_blocks = gconfig.resolve_expert_dims(router_cfg, 512, 6)
    assert (hidden_dim, n_blocks) == (128, 6)  # n_blocks inherited, hidden_dim not