"""HeliosLaser: replies that span more than one line.

Regression: every status-register query answers with the value *and* a
"Bit 15..0: ..." decode line.  The driver read one line per query and threw
the rest away with reset_input_buffer(), which at 9600 baud cannot drop
bytes that are still on the wire — so from the first LER read onward every
reply was one line behind, and the panel showed a register as
"Bit 15..0: 0000 0000 0000 0010" with the reads around it timing out.
"""
import pytest

from hardware.helios_laser import HeliosLaser, PulseMode


# What the controller actually sends back, per Section 6 of the operator's
# manual and the LER/LCE/CCE tables in Section 8.
REPLIES = {
    "LDO": ["LDO = 1"],
    "LDF": ["LDF = 20000 ns"],
    "LDS": ["LDS = 1500 mA"],
    "LDG": ["LDG = 14"],
    "LRE": ["LRE = 0"],
    "LTA": ["LTA = 25400 m°C"],
    "LTT": ["LTT = 31200 m°C"],
    "EOA": ["EOA = 40100 m°C"],
    "CSR": ["CSR = 1234567"],
    "HSR": ["HSR = 7654321"],
    # The registers are the multi-line ones.
    "LER": ["LER = 0", "Bit 15..0: 0000 0000 0000 0000"],
    "LCE": ["LCE = 2", "Bit 15..0: 0000 0000 0000 0010"],
    "CCE": ["CCE = 0", "Bit 15..0: 0000 0000 0000 0000"],
}


class FakePort:
    """Serial stand-in that answers like the Helios controller.

    ``reset_input_buffer`` is deliberately a no-op: the rest of a reply is
    still in flight when the driver has read its first line, so a flush
    cannot remove it.  The driver has to stay in step by reading what it
    asked for, not by discarding what it happens to find.
    """

    def __init__(self, replies=None, timeout=1.0):
        self.replies = REPLIES if replies is None else replies
        self.timeout = timeout
        self.is_open = True
        self.written: list[str] = []
        self._buf = bytearray()

    # ── the bits of pyserial.Serial the driver uses ──────────────────────────

    def write(self, data: bytes) -> int:
        text = data.decode("ascii").strip()
        self.written.append(text)
        fields = text.split()
        for line in self.replies.get(fields[0].upper() if fields else "", []):
            self._buf += line.encode("utf-8") + b"\r\n"
        return len(data)

    @property
    def in_waiting(self) -> int:
        return len(self._buf)

    def read(self, size: int = 1) -> bytes:
        chunk = bytes(self._buf[:size])
        del self._buf[:size]
        return chunk

    def read_until(self, expected: bytes = b"\n", size=None) -> bytes:
        # No terminator in the buffer models the read timing out: pyserial
        # returns whatever it has, which is b"" when nothing is pending.
        cut = self._buf.find(expected)
        cut = len(self._buf) if cut < 0 else cut + len(expected)
        chunk = bytes(self._buf[:cut])
        del self._buf[:cut]
        return chunk

    def reset_input_buffer(self):
        """No-op — see the class docstring."""

    def close(self):
        self.is_open = False


@pytest.fixture
def laser():
    """A connected driver on a fake port, with the idle wait taken out.

    TRAILING_QUIET_S covers the ~30 ms a decode line spends on the wire at
    9600 baud; the fake answers instantly, so waiting for it only slows the
    suite down.  Zeroing it also keeps the tests honest: they pass because
    the driver reads the whole reply, not because it waited long enough.
    """
    drv = HeliosLaser(timeout=1.0)
    drv.serial = FakePort()
    drv.is_connected = True
    drv.TRAILING_QUIET_S = 0.0
    return drv


def test_status_registers_are_read_in_step(laser):
    """The regression: each register gets its own value, not the previous
    register's decode line."""
    assert laser.get_status_registers() == (0, 2, 0)


def test_reads_after_a_register_are_not_a_line_behind(laser):
    """A whole status poll, in the order HeliosWorker._poll_once issues it."""
    assert laser.get_status_registers() == (0, 2, 0)
    assert laser.is_laser_enabled() is True
    assert laser.get_current_ma() == 1500
    assert laser.get_diode_temp_c() == pytest.approx(25.4)
    assert laser.get_power_stage_temp_c() == pytest.approx(31.2)
    assert laser.get_qswitch_temp_c() == pytest.approx(40.1)


def test_decode_line_is_consumed_not_left_behind(laser):
    laser.get_status_registers()
    assert laser.serial.in_waiting == 0


def test_unit_suffix_is_stripped(laser):
    assert laser.get_frequency_hz() == 50000       # "LDF = 20000 ns"
    assert laser.get_current_ma() == 1500          # "LDS = 1500 mA"


def test_a_reply_from_an_earlier_command_is_skipped(laser):
    """An answer already in the buffer when the query goes out belongs to
    whoever asked for it, and must not be returned as this query's value."""
    laser.serial._buf += b"LER = 8\r\nBit 15..0: 0000 0000 0000 1000\r\n"
    assert laser.get_current_ma() == 1500


def test_reply_without_a_mnemonic_is_taken_as_the_value(laser):
    """The serial numbers come back as a bare string on some firmware."""
    laser.serial.replies = {"CSR": ["A1B2C3D4"]}
    assert laser.get_controller_serial() == "A1B2C3D4"


def test_silent_device_reports_a_timeout(laser):
    laser.serial.replies = {}
    assert laser.get_current_ma() is None
    assert laser._query("LTA") is None


def test_set_commands_clear_their_acknowledgement(laser):
    """A setter that leaves the controller's echo in the buffer desynchronises
    the next query just as a decode line does."""
    assert laser.set_laser_enable(True) is True
    assert laser.serial.in_waiting == 0
    assert laser.set_pulse_mode(PulseMode.CONTINUOUS_PULSING) is True
    assert laser.get_current_ma() == 1500


def test_raw_command_returns_every_line(laser):
    """The diagnostics console is where a multi-line reply should be visible."""
    assert laser.send_raw_command("LCE") == (
        "LCE = 2\nBit 15..0: 0000 0000 0000 0010"
    )