"""Tests for scripts/modbus_cli.py.

Acceptance criteria covered
----------------------------
1. ``modbus_cli read`` (via mock) prints decoded engineering values for all
   profile metrics; columns are present for each metric key.
2. ``modbus_cli read`` exits non-zero on connection failure.
3. ``modbus_cli probe --fc 4`` prints raw register values in hex; optionally
   decodes float32 pairs.
4. ``modbus_cli probe`` exits non-zero on connection failure.
5. CLI has NO write-register sub-command (only ``read`` and ``probe`` exist).
"""

from __future__ import annotations

import sys
from pathlib import Path
from unittest.mock import MagicMock, patch

import pytest

# Ensure project root is available when tests are run from the repo root.
PROJECT_ROOT = Path(__file__).resolve().parents[1]
if str(PROJECT_ROOT) not in sys.path:
    sys.path.insert(0, str(PROJECT_ROOT))

import scripts.modbus_cli as cli  # noqa: E402


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _make_ok_response(registers: list[int]) -> MagicMock:
    resp = MagicMock()
    resp.isError.return_value = False
    resp.registers = registers
    return resp


def _make_error_response() -> MagicMock:
    resp = MagicMock()
    resp.isError.return_value = True
    resp.__str__ = lambda self: "ExceptionResponse(2)"
    return resp


# ---------------------------------------------------------------------------
# CLI: read sub-command
# ---------------------------------------------------------------------------


class TestReadCommand:
    """``python -m scripts.modbus_cli read ...`` with mocked driver."""

    def _make_sdm120_registers(self) -> dict[int, int]:
        """Return a minimal register map covering all 8 sdm120 core metrics."""
        import struct

        def pack(value: float) -> tuple[int, int]:
            raw = struct.pack(">f", value)
            hi = (raw[0] << 8) | raw[1]
            lo = (raw[2] << 8) | raw[3]
            return hi, lo

        pairs: dict[int, tuple[int, int]] = {
            0x0000: pack(230.2),   # voltage
            0x0006: pack(1.3),     # current
            0x000C: pack(295.0),   # active_power
            0x001E: pack(0.98),    # power_factor
            0x0046: pack(50.0),    # frequency
            0x0048: pack(123.4),   # import_energy
            0x004A: pack(0.0),     # export_energy
            0x0156: pack(123.4),   # total_energy
        }
        regs: dict[int, int] = {}
        for addr, (hi, lo) in pairs.items():
            regs[addr] = hi
            regs[addr + 1] = lo
        return regs

    @patch("app.integrations.modbus.driver.ModbusTcpClient")
    def test_read_prints_decoded_values(self, mock_client_cls: MagicMock, capsys) -> None:
        """``read`` prints all profile metric keys with values."""
        mock_client = MagicMock()
        mock_client_cls.return_value = mock_client
        mock_client.connect.return_value = True

        regs = self._make_sdm120_registers()
        # sdm120 has 2 blocks; simulate both responses.
        # Block 1: 0x0000, count=0x0060 → we need 0x60=96 registers
        block1 = [regs.get(i, 0) for i in range(0x0000, 0x0060)]
        # Block 2: 0x0156, count=0x0004 → 4 registers
        block2 = [regs.get(i, 0) for i in range(0x0156, 0x015A)]
        mock_client.read_input_registers.side_effect = [
            _make_ok_response(block1),
            _make_ok_response(block2),
        ]

        # Run the CLI.
        cli.main(["read", "--host", "10.0.0.1", "--port", "502", "--unit", "1",
                  "--profile", "sdm120"])

        captured = capsys.readouterr()
        output = captured.out

        # All eight core metric keys must appear in the output.
        for key in ("voltage", "current", "active_power", "power_factor",
                    "frequency", "import_energy", "export_energy", "total_energy"):
            assert key in output, f"Missing metric key '{key}' in output:\n{output}"

        # The decoded voltage should be close to 230.2.
        assert "230." in output, f"Expected voltage ~230.2 in output:\n{output}"

    @patch("app.integrations.modbus.driver.ModbusTcpClient")
    def test_read_exits_nonzero_on_connection_failure(
        self, mock_client_cls: MagicMock
    ) -> None:
        """Connection failure causes ``sys.exit(1)``."""
        mock_client = MagicMock()
        mock_client_cls.return_value = mock_client
        mock_client.connect.return_value = False  # Cannot connect.

        with pytest.raises(SystemExit) as exc_info:
            cli.main(["read", "--host", "10.0.0.1", "--port", "502", "--unit", "1",
                      "--profile", "sdm120"])
        assert exc_info.value.code != 0

    def test_read_exits_nonzero_for_missing_profile(self, capsys) -> None:
        """Unknown profile name causes sys.exit(1)."""
        with pytest.raises(SystemExit) as exc_info:
            cli.main(["read", "--host", "10.0.0.1", "--port", "502", "--unit", "1",
                      "--profile", "nonexistent_profile_xyz"])
        assert exc_info.value.code != 0


# ---------------------------------------------------------------------------
# CLI: probe sub-command
# ---------------------------------------------------------------------------


class TestProbeCommand:
    """``python -m scripts.modbus_cli probe ...`` with mocked pymodbus."""

    @patch("scripts.modbus_cli.ModbusTcpClient" if False else "pymodbus.client.ModbusTcpClient")
    def _run_probe(self, mock_cls, args: list[str], regs: list[int]):
        """Helper: runs probe with a mocked client returning *regs*."""

    @patch("app.integrations.modbus.driver.ModbusTcpClient")
    def test_probe_prints_raw_registers(self, mock_driver_cls, capsys) -> None:
        # probe uses its own client import, not the driver's — patch it there.
        pass  # see next test for the direct approach

    def _setup_mock_client(self, regs: list[int]) -> MagicMock:
        """Return a mock ModbusTcpClient that returns *regs* for both FC03 and FC04."""
        mock_cls = MagicMock()
        mock_client = MagicMock()
        mock_cls.return_value = mock_client
        mock_client.connect.return_value = True
        ok_response = _make_ok_response(regs)
        mock_client.read_input_registers.return_value = ok_response
        mock_client.read_holding_registers.return_value = ok_response
        return mock_cls

    def test_probe_fc4_prints_hex_values(self, capsys) -> None:
        """FC04 probe prints at least two hex addresses and values."""
        mock_cls = self._setup_mock_client([0x4366, 0x3334])

        with patch("pymodbus.client.ModbusTcpClient", mock_cls):
            cli.main([
                "probe",
                "--host", "10.0.0.1",
                "--port", "502",
                "--unit", "1",
                "--fc", "4",
                "--address", "0x0000",
                "--count", "2",
            ])

        captured = capsys.readouterr()
        output = captured.out
        # Expect hex addresses and values in the output.
        assert "0x0000" in output.lower() or "0000" in output
        assert "4366" in output.upper()
        assert "3334" in output.upper()

    def test_probe_fc4_with_float32_decode(self, capsys) -> None:
        """--decode float32 adds a float32 decode section to output."""
        mock_cls = self._setup_mock_client([0x4366, 0x3334])

        with patch("pymodbus.client.ModbusTcpClient", mock_cls):
            cli.main([
                "probe",
                "--host", "10.0.0.1",
                "--port", "502",
                "--unit", "1",
                "--fc", "4",
                "--address", "0x0000",
                "--count", "2",
                "--decode", "float32",
            ])

        captured = capsys.readouterr()
        output = captured.out
        # The float decode section should show ~230.2.
        assert "230." in output, f"Expected ~230.2 in float decode output:\n{output}"

    def test_probe_exits_nonzero_on_connection_failure(self, capsys) -> None:
        """Connection failure causes non-zero exit."""
        mock_cls = MagicMock()
        mock_client = MagicMock()
        mock_cls.return_value = mock_client
        mock_client.connect.return_value = False

        with patch("pymodbus.client.ModbusTcpClient", mock_cls):
            with pytest.raises(SystemExit) as exc_info:
                cli.main([
                    "probe",
                    "--host", "10.0.0.1",
                    "--port", "502",
                    "--unit", "1",
                    "--fc", "4",
                    "--address", "0x0000",
                    "--count", "2",
                ])
        assert exc_info.value.code != 0

    def test_probe_fc3_also_works(self, capsys) -> None:
        """FC03 (holding registers) is supported by probe."""
        mock_cls = self._setup_mock_client([0x0001, 0x0002])

        with patch("pymodbus.client.ModbusTcpClient", mock_cls):
            cli.main([
                "probe",
                "--host", "10.0.0.1",
                "--port", "502",
                "--unit", "1",
                "--fc", "3",
                "--address", "0x0014",
                "--count", "2",
            ])

        # Verify holding-register read was called (not input-register read).
        mock_client = mock_cls.return_value
        mock_client.read_holding_registers.assert_called_once()
        mock_client.read_input_registers.assert_not_called()


# ---------------------------------------------------------------------------
# CLI: no write sub-commands
# ---------------------------------------------------------------------------


class TestNoWriteSubcommands:
    """The CLI must not expose any write-register sub-commands."""

    def test_no_write_subcommand_in_parser(self) -> None:
        """The argument parser has no 'write', 'set', or 'force' sub-commands."""
        parser = cli.build_parser()
        # Access the subparsers group.
        subparsers_actions = [
            action
            for action in parser._actions
            if hasattr(action, "_name_parser_map")
        ]
        assert len(subparsers_actions) == 1
        available_commands = set(subparsers_actions[0]._name_parser_map.keys())
        # Only read-only commands must exist.
        assert "read" in available_commands
        assert "probe" in available_commands
        # No write-related commands.
        for name in available_commands:
            assert name not in {"write", "set", "force", "write-register", "set-register"}, (
                f"Write sub-command '{name}' found in CLI — it must not exist"
            )

    def test_only_read_and_probe_subcommands(self) -> None:
        """Exactly two sub-commands are available: read and probe."""
        parser = cli.build_parser()
        subparsers_actions = [
            action
            for action in parser._actions
            if hasattr(action, "_name_parser_map")
        ]
        available = set(subparsers_actions[0]._name_parser_map.keys())
        assert available == {"read", "probe"}, (
            f"Expected only {{read, probe}}, got {available}"
        )