"""Tests for AdalightClient frame construction (the LED hot path)."""

import numpy as np
import pytest

from ledgrab.core.devices.adalight_client import (
    AdalightClient,
    _build_adalight_header,
)


def _make_client(led_count: int = 10) -> AdalightClient:
    """Build a client without opening the serial port."""
    return AdalightClient(url="COM99", led_count=led_count)


def test_adalight_header_format():
    # Adalight protocol: 'A' 'd' 'a' <count_hi> <count_lo> <checksum>
    # where count = led_count - 1, checksum = hi ^ lo ^ 0x55
    header = _build_adalight_header(10)
    count = 9
    hi = (count >> 8) & 0xFF
    lo = count & 0xFF
    expected_checksum = hi ^ lo ^ 0x55
    assert header == bytes([ord("A"), ord("d"), ord("a"), hi, lo, expected_checksum])


def test_build_frame_uint8_fast_path():
    client = _make_client(led_count=3)
    pixels = np.array(
        [[10, 20, 30], [40, 50, 60], [70, 80, 90]],
        dtype=np.uint8,
    )

    frame = client._build_frame(pixels, brightness=255)

    # Header (6 bytes) + RGB (9 bytes)
    assert len(frame) == 6 + 9
    assert bytes(frame[:6]) == client._header
    assert bytes(frame[6:]) == bytes([10, 20, 30, 40, 50, 60, 70, 80, 90])


def test_build_frame_reuses_buffer_across_calls():
    client = _make_client(led_count=3)
    pixels = np.array([[1, 2, 3]] * 3, dtype=np.uint8)

    frame1 = client._build_frame(pixels, brightness=255)
    buf_id_1 = id(client._frame_buf)
    frame2 = client._build_frame(pixels, brightness=255)
    buf_id_2 = id(client._frame_buf)

    # Same bytearray reused — frame returned IS the internal buffer
    assert buf_id_1 == buf_id_2
    assert frame1 is frame2
    # Header preserved at front, payload identical
    assert bytes(frame2[:6]) == client._header


def test_build_frame_handles_non_contiguous_input():
    """Slicing a wider array yields a non-contiguous view; payload must
    still serialise to the same bytes as a contiguous copy."""
    client = _make_client(led_count=4)
    wide = np.arange(48, dtype=np.uint8).reshape(4, 4, 3)
    pixels = wide[:, 1, :]  # (4, 3) view, possibly non-contiguous

    frame = client._build_frame(pixels, brightness=255)

    expected = np.ascontiguousarray(pixels).tobytes()
    assert bytes(frame[6:]) == expected


def test_build_frame_clamps_wider_int_dtypes():
    """Wider integer inputs (e.g. uint16 from legacy code) clamp to [0, 255]
    before narrowing, matching historical behaviour."""
    client = _make_client(led_count=2)
    pixels = np.array([[100, 200, 300], [400, 50, 25]], dtype=np.uint16)

    frame = client._build_frame(pixels, brightness=255)

    # Values >255 clamp to 255, values <=255 pass through.
    assert bytes(frame[6:]) == bytes([100, 200, 255, 255, 50, 25])


def test_build_frame_accepts_list_of_tuples():
    """Legacy callers pass list[tuple]; should produce same output."""
    client = _make_client(led_count=2)
    pixels = [(10, 20, 30), (40, 50, 60)]

    frame = client._build_frame(pixels, brightness=255)

    assert bytes(frame[6:]) == bytes([10, 20, 30, 40, 50, 60])


def test_build_frame_resizes_buffer_on_led_count_change():
    """If led count changes between calls, the buffer is reallocated."""
    client = _make_client(led_count=5)
    small = np.zeros((3, 3), dtype=np.uint8)
    big = np.zeros((100, 3), dtype=np.uint8)

    client._build_frame(small, brightness=255)
    small_len = len(client._frame_buf)

    client._build_frame(big, brightness=255)
    big_len = len(client._frame_buf)

    # 6-byte header + 3-byte/LED RGB
    assert small_len == 6 + 3 * 3
    assert big_len == 6 + 100 * 3


def test_build_frame_no_uint16_round_trip():
    """The hot path must NOT promote uint8 → uint16 → uint8.

    Asserts the scratch buffer (used only for non-uint8 input) is never
    allocated when the input is already uint8.
    """
    client = _make_client(led_count=3)
    pixels = np.array([[1, 2, 3]] * 3, dtype=np.uint8)

    assert client._u8_scratch is None
    client._build_frame(pixels, brightness=255)
    # Scratch never touched on the fast path.
    assert client._u8_scratch is None


@pytest.mark.parametrize("led_count", [1, 50, 300, 1000])
def test_build_frame_total_length(led_count):
    client = _make_client(led_count=led_count)
    pixels = np.zeros((led_count, 3), dtype=np.uint8)

    frame = client._build_frame(pixels, brightness=255)

    assert len(frame) == 6 + led_count * 3