"""
OpenEnv spec compliance tests — validates openv.yaml structure without
requiring the openenv package to be installed.
"""

import importlib
from pathlib import Path

import pytest
import yaml


SPEC_PATH = Path(__file__).parent.parent / "grid_env" / "openv.yaml"

REQUIRED_TOP_LEVEL = {"spec_version", "name", "entrypoint", "models", "methods", "tasks"}
REQUIRED_MODELS = {"action", "observation", "state"}
REQUIRED_TASK_FIELDS = {"id", "grader"}


@pytest.fixture(scope="module")
def spec():
    assert SPEC_PATH.exists(), f"openv.yaml not found at {SPEC_PATH}"
    with SPEC_PATH.open() as f:
        return yaml.safe_load(f)


def test_yaml_parses_successfully(spec):
    assert spec is not None
    assert isinstance(spec, dict)


def test_required_top_level_fields_present(spec):
    missing = REQUIRED_TOP_LEVEL - set(spec.keys())
    assert not missing, f"Missing top-level fields: {missing}"


def test_spec_version_is_string(spec):
    assert isinstance(spec["spec_version"], str)
    assert spec["spec_version"].strip() != ""


def test_name_is_non_empty_string(spec):
    assert isinstance(spec["name"], str)
    assert spec["name"].strip() != ""


def test_entrypoint_format(spec):
    """Entrypoint should be 'module:ClassName' style."""
    entrypoint = spec["entrypoint"]
    assert isinstance(entrypoint, str)
    assert ":" in entrypoint, "entrypoint must be 'module:ClassName'"


def test_entrypoint_module_is_importable(spec):
    module_path, _ = spec["entrypoint"].split(":", 1)
    try:
        importlib.import_module(module_path)
    except ImportError as exc:
        pytest.fail(f"Entrypoint module '{module_path}' is not importable: {exc}")


def test_models_has_required_keys(spec):
    models = spec.get("models", {})
    missing = REQUIRED_MODELS - set(models.keys())
    assert not missing, f"Missing model keys: {missing}"


def test_methods_contains_reset_step_state(spec):
    methods = set(spec.get("methods", []))
    assert {"reset", "step", "state"}.issubset(methods), \
        f"methods must include reset, step, state. Got: {methods}"


def test_tasks_list_has_at_least_three_entries(spec):
    tasks = spec.get("tasks", [])
    assert len(tasks) >= 3, f"Expected ≥3 tasks, got {len(tasks)}"


def test_each_task_has_required_fields(spec):
    for task in spec.get("tasks", []):
        missing = REQUIRED_TASK_FIELDS - set(task.keys())
        assert not missing, f"Task {task} missing fields: {missing}"


def test_task_ids_are_unique(spec):
    ids = [t["id"] for t in spec.get("tasks", [])]
    assert len(ids) == len(set(ids)), "Duplicate task IDs found in spec"


def test_grader_references_are_importable(spec):
    """Each grader in the spec should resolve to a callable."""
    for task in spec.get("tasks", []):
        grader_ref = task.get("grader", "")
        assert ":" in grader_ref, f"Grader '{grader_ref}' is not 'module:fn' format"
        mod_path, fn_name = grader_ref.split(":", 1)
        try:
            mod = importlib.import_module(mod_path)
        except ImportError as exc:
            pytest.fail(f"Cannot import grader module '{mod_path}': {exc}")
        fn = getattr(mod, fn_name, None)
        assert callable(fn), f"'{fn_name}' in '{mod_path}' is not callable"


def test_baseline_section_present(spec):
    assert "baseline" in spec
    baseline = spec["baseline"]
    assert "runner" in baseline and "seed" in baseline