"""Tests for dry-run parsing and DAG restriction in :mod:`nix_estimator.graph`."""

from nix_estimator import graph

# --- captured `nix build --dry-run` text (issue #5) ------------------------

WARM = """\
this path will be fetched (0.02 MiB download, 0.10 MiB unpacked):
  /nix/store/aaa-hello-2.12.1
"""

PARTIAL = """\
these 2 derivations will be built:
  /nix/store/bbb-foo-1.0.drv
  /nix/store/ccc-bar-2.0.drv
these 3 paths will be fetched (1.0 MiB download):
  /nix/store/ddd-baz-3.0
"""

GARBAGE = """\
error: some totally unrelated failure with no dry-run structure
traceback blah blah
"""


def test_warm_cache_only_fetched_is_empty_set():
    # dry-run succeeded, nothing to build: distinct from a parse failure
    result = graph.parse_dry_run_text(WARM, returncode=0)
    assert result == set()


def test_partial_returns_only_built_drvs():
    result = graph.parse_dry_run_text(PARTIAL, returncode=0)
    assert result == {"bbb-foo-1.0.drv", "ccc-bar-2.0.drv"}


def test_garbage_without_header_and_failure_is_none():
    assert graph.parse_dry_run_text(GARBAGE, returncode=1) is None


def test_clean_exit_without_header_is_empty_not_none():
    # exit 0 but no recognizable header still counts as "nothing to build"
    assert graph.parse_dry_run_text("", returncode=0) == set()


# --- structured `nix build --dry-run --json` output (issue #8) -------------

JSON_PARTIAL = """\
[
  {"drvPath": "/nix/store/bbb-foo-1.0.drv", "outputs": {"out": "/nix/store/e-foo"}},
  {"drvPath": "/nix/store/ccc-bar-2.0.drv", "outputs": {"out": "/nix/store/f-bar"}}
]
"""

JSON_WARM = "[]"

JSON_ALT_KEY = '[{"drv": "/nix/store/ggg-qux-9.drv"}]'


def test_json_partial_returns_built_drvs():
    assert graph.parse_dry_run_json(JSON_PARTIAL) == {
        "bbb-foo-1.0.drv",
        "ccc-bar-2.0.drv",
    }


def test_json_warm_cache_is_empty_set():
    assert graph.parse_dry_run_json(JSON_WARM) == set()


def test_json_alternate_drv_key():
    assert graph.parse_dry_run_json(JSON_ALT_KEY) == {"ggg-qux-9.drv"}


def test_json_non_structured_is_none():
    # human text or an unexpected shape must fall back (None), not crash
    assert graph.parse_dry_run_json(WARM) is None
    assert graph.parse_dry_run_json('{"not": "a list"}') is None
    assert graph.parse_dry_run_json("not json at all") is None


def test_build_dag_empty_set_yields_no_nodes():
    closure = {"a.drv": {"inputDrvs": {}}, "b.drv": {"inputDrvs": {"a.drv": {}}}}
    preds, nodes = graph.build_dag(closure, set())
    assert nodes == set()
    assert preds == {}


def test_build_dag_none_costs_whole_closure():
    closure = {
        "a.drv": {"inputDrvs": {}},
        "b.drv": {"inputDrvs": {"/nix/store/x-a.drv": {}}},
    }
    _, nodes = graph.build_dag(closure, None)
    assert nodes == {"a.drv", "b.drv"}