"""
Shared fixtures for laser_control tests.
"""

import pytest
import struct
from unittest.mock import MagicMock, patch
from laser_control.protocol import Protocol, _build_crc, _flipfour, _int_to_hex4
from laser_control.controller import LaserController
from laser_control.conversions import (
    current_n_to_ma, temp_n_to_c, temp_ext_n_to_c,
    voltage_3v3_n_to_v, voltage_5v_n_to_v, voltage_7v_n_to_v,
)


def make_valid_response(
    current1_n: int = 10000,
    current2_n: int = 12000,
    temp1_n: int = 30000,
    temp2_n: int = 32000,
    temp_ext1_n: int = 2048,
    temp_ext2_n: int = 2048,
    mon_3v3_n: int = 2703,   # ~3.3V
    mon_5v1_n: int = 2731,   # ~5.0V
    mon_5v2_n: int = 2731,
    mon_7v0_n: int = 1042,   # ~7.0V
    message_id: int = 12345,
) -> bytes:
    """
    Build a syntactically valid 30-byte DATA response.

    Words (each 2 bytes, little-endian via flipfour):
      0  header
      1  I1
      2  I2
      3  TO6_LSB
      4  TO6_MSB
      5  Temp_1
      6  Temp_2
      7  Temp_Ext_1
      8  Temp_Ext_2
      9  MON_3V3
      10 MON_5V1
      11 MON_5V2
      12 MON_7V0
      13 Message_ID
      14 CRC
    """
    words_raw = [
        0xABCD,       # Word 0 header
        current1_n,   # Word 1
        current2_n,   # Word 2
        0,            # Word 3 TO6_LSB
        0,            # Word 4 TO6_MSB
        temp1_n,      # Word 5
        temp2_n,      # Word 6
        temp_ext1_n,  # Word 7
        temp_ext2_n,  # Word 8
        mon_3v3_n,    # Word 9
        mon_5v1_n,    # Word 10
        mon_5v2_n,    # Word 11
        mon_7v0_n,    # Word 12
        message_id,   # Word 13
        0,            # Word 14 CRC placeholder
    ]

    # Build hex string with flipfour applied
    hex_str = ""
    for w in words_raw:
        hex_str += _flipfour(_int_to_hex4(w))

    # Compute CRC over words 1..13 (indices 4..55 in hex, i.e. skip word 0)
    words_hex = [hex_str[i:i+4] for i in range(0, len(hex_str), 4)]
    crc_words = words_hex[1:14]  # words 1..13
    crc_val = int(crc_words[0], 16)
    for w in crc_words[1:]:
        crc_val ^= int(w, 16)

    # Replace CRC word
    hex_str = hex_str[:56] + _flipfour(_int_to_hex4(crc_val))
    return bytes.fromhex(hex_str)


@pytest.fixture
def valid_response_bytes():
    """Pre-built valid 30-byte device response."""
    return make_valid_response()


@pytest.fixture
def mock_serial():
    """Mock serial.Serial object."""
    with patch('serial.Serial') as mock_cls:
        mock_instance = MagicMock()
        mock_instance.is_open = True
        mock_cls.return_value = mock_instance
        yield mock_instance


@pytest.fixture
def connected_controller(mock_serial):
    """LaserController with mocked serial connection."""
    mock_serial.read.return_value = make_valid_response()

    ctrl = LaserController(port='/dev/ttyUSB0')
    with patch('serial.Serial', return_value=mock_serial):
        ctrl._protocol._serial = mock_serial
        mock_serial.is_open = True
    return ctrl