import csv
import importlib.util
import tempfile
import unittest
from pathlib import Path


MODULE_PATH = Path(__file__).with_name("unified_simulator.py")


def load_simulator_module():
    spec = importlib.util.spec_from_file_location("unified_simulator_contract", MODULE_PATH)
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    return module


class UnifiedSimulatorContractTests(unittest.TestCase):
    def setUp(self):
        self.simulator = load_simulator_module()

    def test_modbus_contract_constants_are_explicit(self):
        self.assertEqual(self.simulator.MODBUS_PORT, 5020)
        self.assertEqual(self.simulator.HTTP_PORT, 8085)
        self.assertEqual(self.simulator.REQUIRED_PYMODBUS_VERSION, "3.6.9")
        self.assertEqual(sorted(self.simulator.BANKS), [1, 2, 3, 4, 5])

    def test_pymodbus_version_guard_accepts_only_supported_version(self):
        compatible = self.simulator.validate_pymodbus_version("3.6.9")
        incompatible = self.simulator.validate_pymodbus_version("3.11.1")

        self.assertTrue(compatible.is_compatible)
        self.assertFalse(incompatible.is_compatible)
        self.assertIn("pymodbus==3.6.9", incompatible.install_hint)
        self.assertIn("live register updates", incompatible.reason)

    def test_generated_csv_matches_backend_import_contract(self):
        expected_headers = [
            "WellCode", "DeviceName", "Host", "Port", "UnitId",
            "VariableAlias", "Address", "DataType",
            "LastCalibrationDate", "NextCalibrationDate", "CalibrationCertificateUrl",
        ]

        with tempfile.TemporaryDirectory() as temp_dir:
            original_path = self.simulator.CSV_PATH
            self.simulator.CSV_PATH = str(Path(temp_dir) / "variables_import.csv")
            try:
                csv_path = self.simulator.write_import_csv()
            finally:
                self.simulator.CSV_PATH = original_path

            with open(csv_path, newline="", encoding="utf-8") as csv_file:
                reader = csv.DictReader(csv_file)
                rows = list(reader)

        self.assertEqual(reader.fieldnames, expected_headers)
        self.assertEqual(len(rows), 1000)
        self.assertEqual({int(row["UnitId"]) for row in rows}, {1, 2, 3, 4, 5})
        self.assertIn("HR:0", {row["Address"] for row in rows})
        self.assertIn("IR:0", {row["Address"] for row in rows})
        self.assertEqual({row["DataType"] for row in rows}, {"uint16"})

    def test_api_payload_exposes_documented_shape(self):
        payload = self.simulator.build_api_payload()

        self.assertEqual(set(payload), {"timestamp", "summary", "wells", "sample"})
        self.assertEqual(payload["summary"]["total"], 1000)
        self.assertEqual(payload["summary"]["wells"], 5)
        self.assertEqual(len(payload["wells"]), 5)
        self.assertGreater(len(payload["sample"]), 0)
        self.assertIn("address", payload["sample"][0])


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