"""Tests for DualInterfaceSession coordinator."""
import time
import pytest
from pm3py.sim.dual_session import DualInterfaceSession
from pm3py.sim.mcu_bridge import McuBridge
from pm3py.sim.mcu_protocol import MsgType, build_frame, cobs_decode, parse_frame
from pm3py.sim.ntag5_link import Ntag5LinkTag


class MockSimSession:
    """Mock SimSession for testing — no real PM3 hardware."""
    def __init__(self):
        self.on_field_strength = None
        self._started = False
        self._stopped = False
        self._tag = None
        self._trace = False

    def start_15693(self, tag, trace=False):
        self._started = True
        self._tag = tag
        self._trace = trace

    def stop(self):
        self._stopped = True


class MockSerial:
    """Mock serial port for McuBridge."""
    def __init__(self):
        self._rx_buf = bytearray()
        self._tx_buf = bytearray()
        self.is_open = True
        self.timeout = 0.1

    def read(self, size=1):
        if not self._rx_buf:
            time.sleep(0.01)
            return b""
        data = bytes(self._rx_buf[:size])
        self._rx_buf = self._rx_buf[size:]
        return data

    def write(self, data):
        self._tx_buf.extend(data)
        return len(data)

    def inject(self, data: bytes):
        self._rx_buf.extend(data)

    def get_sent(self) -> bytes:
        data = bytes(self._tx_buf)
        self._tx_buf.clear()
        return data

    def close(self):
        self.is_open = False


def _decode_sent(mock_serial) -> list[tuple[int, bytes]]:
    """Decode all COBS-framed messages sent to mock serial."""
    raw = mock_serial.get_sent()
    messages = []
    while raw:
        zero_idx = raw.find(b"\x00")
        if zero_idx == -1:
            break
        frame = raw[:zero_idx]
        raw = raw[zero_idx + 1:]
        if frame:
            decoded = cobs_decode(frame)
            messages.append(parse_frame(decoded))
    return messages


class TestDualInterfaceSession:
    def _make_session(self):
        """Create a DualInterfaceSession with mocks."""
        mock_serial = MockSerial()
        sim = MockSimSession()
        mcu = McuBridge(port=mock_serial)
        tag = Ntag5LinkTag()
        tag.sram_enable = True
        tag.arbiter_mode = 2  # PASSTHROUGH
        session = DualInterfaceSession(sim, mcu, tag)
        return session, sim, mcu, mock_serial, tag

    def test_start_wires_callbacks(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        session.start()
        time.sleep(0.05)

        assert sim._started
        assert mcu.on_i2c_write is not None
        assert mcu.on_i2c_read_req is not None
        assert tag.ed_pin_callback is not None
        assert sim.on_field_strength is not None

        session.stop()

    def test_start_pushes_initial_sram(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        tag._sram[0:4] = b"\xDE\xAD\xBE\xEF"
        session.start()
        time.sleep(0.05)
        session.stop()

        msgs = _decode_sent(mock_serial)
        # Should have WRITE_SRAM with full 256-byte SRAM
        sram_msgs = [m for m in msgs if m[0] == MsgType.WRITE_SRAM]
        assert len(sram_msgs) == 1
        assert sram_msgs[0][1][0] == 0x00  # offset 0
        assert sram_msgs[0][1][1:5] == b"\xDE\xAD\xBE\xEF"

    def test_i2c_write_updates_tag_sram(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        tag.config_pt_transfer_dir = False  # I2C→NFC
        session.start()
        time.sleep(0.05)

        # Simulate MCU pushing an I2C write event
        mock_serial.inject(build_frame(MsgType.I2C_WRITE,
                                        bytes([0x20, 0x00, 0xCA, 0xFE])))
        time.sleep(0.15)
        session.stop()

        # Tag SRAM should have the data
        assert tag._sram[0:2] == b"\xCA\xFE"

    def test_i2c_read_req_responds(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        # Preload SRAM
        tag._sram[0:4] = b"\x01\x02\x03\x04"
        session.start()
        time.sleep(0.05)

        # Clear initial WRITE_SRAM from get_sent
        mock_serial.get_sent()

        # Simulate MCU requesting I2C read
        mock_serial.inject(build_frame(MsgType.I2C_READ_REQ,
                                        bytes([0x20, 0x00, 0x04])))
        time.sleep(0.15)
        session.stop()

        msgs = _decode_sent(mock_serial)
        resp_msgs = [m for m in msgs if m[0] == MsgType.I2C_READ_RESPONSE]
        assert len(resp_msgs) == 1
        assert resp_msgs[0][1] == b"\x01\x02\x03\x04"

    def test_ed_pin_relayed_to_mcu(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        session.start()
        time.sleep(0.05)
        mock_serial.get_sent()  # clear initial WRITE_SRAM

        # Trigger ED on tag
        tag.assert_ed()
        time.sleep(0.05)
        session.stop()

        msgs = _decode_sent(mock_serial)
        ed_msgs = [m for m in msgs if m[0] == MsgType.SET_ED]
        assert len(ed_msgs) == 1
        assert ed_msgs[0][1] == bytes([0x01])

    def test_field_strength_above_threshold_activates_eh(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        session.eh_threshold = 500
        session.start()
        time.sleep(0.05)
        mock_serial.get_sent()  # clear initial

        # Simulate field strength above threshold
        sim.on_field_strength(600)
        time.sleep(0.05)
        session.stop()

        msgs = _decode_sent(mock_serial)
        eh_msgs = [m for m in msgs if m[0] == MsgType.SET_EH]
        assert len(eh_msgs) == 1
        assert eh_msgs[0][1] == bytes([0x01])
        assert tag.nfc_field_ok

    def test_field_strength_below_threshold_deactivates_eh(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        session.eh_threshold = 500
        session._eh_active = True  # pretend already active
        session.start()
        time.sleep(0.05)
        mock_serial.get_sent()

        sim.on_field_strength(300)
        time.sleep(0.05)
        session.stop()

        msgs = _decode_sent(mock_serial)
        eh_msgs = [m for m in msgs if m[0] == MsgType.SET_EH]
        assert len(eh_msgs) == 1
        assert eh_msgs[0][1] == bytes([0x00])

    def test_stop_unhooks_callbacks(self):
        session, sim, mcu, mock_serial, tag = self._make_session()
        session.start()
        time.sleep(0.05)
        session.stop()

        assert mcu.on_i2c_write is None
        assert mcu.on_i2c_read_req is None
        assert tag.ed_pin_callback is None
        assert sim.on_field_strength is None