import hashlib
import importlib.machinery
import importlib.util
import json
import os
from pathlib import Path
import subprocess
import tarfile
import tempfile
import unittest
from unittest import mock


SCRIPT_DIR = Path(__file__).resolve().parent
RUNNER_PATH = SCRIPT_DIR / "nodedc-deploy"
BUILDER_PATH = SCRIPT_DIR / "build-engine-provider-target-host-policy-artifact.mjs"
ENGINE_ROOT = SCRIPT_DIR.parent.parent.parent / "NODEDC_ENGINE_INFRA"
PATCH_ID = "engine-provider-target-host-policy-20991231-999"


def load_runner():
    loader = importlib.machinery.SourceFileLoader(
        "nodedc_engine_provider_target_host_policy",
        str(RUNNER_PATH),
    )
    spec = importlib.util.spec_from_loader(loader.name, loader)
    module = importlib.util.module_from_spec(spec)
    loader.exec_module(module)
    return module


RUNNER = load_runner()


class EngineProviderTargetHostPolicyTest(unittest.TestCase):
    def require_historical_target_source(self):
        for relative_path, expected in (
            RUNNER.ENGINE_PROVIDER_TARGET_HOST_POLICY_TARGET_SHA256.items()
        ):
            path = ENGINE_ROOT / relative_path
            if (
                not path.is_file()
                or hashlib.sha256(path.read_bytes()).hexdigest() != expected
            ):
                self.skipTest(
                    "historical target-host policy source has advanced "
                    "to its exact successor"
                )

    def build(self, artifact_dir):
        environment = os.environ.copy()
        environment["NODEDC_ENGINE_SOURCE_ROOT"] = str(ENGINE_ROOT)
        environment["NODEDC_DEPLOY_ARTIFACT_DIR"] = str(artifact_dir)
        completed = subprocess.run(
            ["node", str(BUILDER_PATH), PATCH_ID],
            check=True,
            capture_output=True,
            text=True,
            env=environment,
        )
        return json.loads(completed.stdout)

    def test_builder_emits_exact_deterministic_one_file_slice(self):
        self.require_historical_target_source()
        with tempfile.TemporaryDirectory(prefix="nodedc-provider-target-host-") as directory:
            root = Path(directory)
            first = self.build(root / "first")
            second = self.build(root / "second")
            first_artifact = Path(first["artifact"])
            second_artifact = Path(second["artifact"])
            self.assertEqual(first_artifact.read_bytes(), second_artifact.read_bytes())
            self.assertEqual(first["sha256"], hashlib.sha256(first_artifact.read_bytes()).hexdigest())
            self.assertEqual(first["services"], ["nodedc-backend"])
            self.assertEqual(
                tuple(first["entries"]),
                RUNNER.ENGINE_PROVIDER_TARGET_HOST_POLICY_ARTIFACT_ENTRIES,
            )

            extract = root / "extract"
            with tarfile.open(first_artifact, "r:gz") as archive:
                archive.extractall(extract, filter="data")
            entries = tuple((extract / "files.txt").read_text(encoding="utf-8").splitlines())
            payload = extract / "payload"
            self.assertTrue(RUNNER.is_engine_provider_target_host_policy_slice("engine", entries))
            self.assertEqual(RUNNER.component_services("engine", entries), ("nodedc-backend",))
            self.assertEqual(
                RUNNER.component_healthchecks("engine", entries, ("nodedc-backend",)),
                ("http://127.0.0.1:3001/health",),
            )
            RUNNER.validate_engine_provider_target_host_policy_slice(payload, entries)

    def test_preflight_requires_the_exact_deployed_predecessor(self):
        with tempfile.TemporaryDirectory(prefix="nodedc-provider-target-host-preflight-") as directory:
            root = Path(directory)
            relative_path = RUNNER.ENGINE_PROVIDER_TARGET_HOST_POLICY_ARTIFACT_ENTRIES[0]
            path = root / relative_path
            path.parent.mkdir(parents=True, exist_ok=True)
            path.write_text("predecessor\n", encoding="utf-8")
            expected = RUNNER.ENGINE_PROVIDER_TARGET_HOST_POLICY_PREDECESSOR_SHA256[relative_path]
            with (
                mock.patch.object(RUNNER, "component_root", return_value=root),
                mock.patch.object(RUNNER, "sha256_file", return_value=expected),
                mock.patch.object(
                    RUNNER,
                    "preflight_engine_credential_backend_runtime",
                    return_value={"mode": "verified-derived-retry"},
                ),
            ):
                result = RUNNER.preflight_engine_provider_target_host_policy_predecessor()
            self.assertEqual(result["mode"], "exact-provider-literal-target-host")

            with (
                mock.patch.object(RUNNER, "component_root", return_value=root),
                mock.patch.object(RUNNER, "sha256_file", return_value="0" * 64),
            ):
                with self.assertRaises(RUNNER.DeployError):
                    RUNNER.preflight_engine_provider_target_host_policy_predecessor()

    def test_healthchecks_dispatch_target_host_policy_acceptance(self):
        entries = RUNNER.ENGINE_PROVIDER_TARGET_HOST_POLICY_ARTIFACT_ENTRIES
        root = Path("/engine")
        target_hash = next(iter(RUNNER.ENGINE_PROVIDER_TARGET_HOST_POLICY_TARGET_SHA256.values()))
        with (
            mock.patch.object(RUNNER, "component_root", return_value=root),
            mock.patch.object(RUNNER, "sha256_file", return_value=target_hash),
            mock.patch.object(RUNNER, "healthcheck_compose_service"),
            mock.patch.object(RUNNER, "component_healthchecks", return_value=()),
            mock.patch.object(
                RUNNER,
                "preflight_engine_credential_backend_runtime",
                return_value={"mode": "verified-derived-retry"},
            ),
            mock.patch.object(
                RUNNER,
                "accept_engine_provider_target_host_policy_runtime",
                return_value={"live": "accepted"},
            ) as acceptance,
            mock.patch.object(RUNNER, "healthcheck_container"),
        ):
            RUNNER.run_healthchecks("engine", entries, ("nodedc-backend",))
        acceptance.assert_called_once_with()

    def test_live_acceptance_uses_exact_literal_host_contract(self):
        self.require_historical_target_source()
        expected_live = "engine-provider-target-host-policy:exact-literal-host:v1"
        with (
            mock.patch.object(RUNNER, "component_root", return_value=ENGINE_ROOT),
            mock.patch.object(RUNNER, "engine_backend_container_id", return_value="backend"),
            mock.patch.object(
                RUNNER,
                "run_engine_backend_probe",
                return_value=expected_live,
            ) as backend_probe,
        ):
            result = RUNNER.accept_engine_provider_target_host_policy_runtime()
        self.assertEqual(result["live"], expected_live)
        self.assertEqual(backend_probe.call_args.args[1], "Engine provider target host policy")


if __name__ == "__main__":
    unittest.main(verbosity=2)
