"""造影画面在哪一半：两半各自选提示帧，恰好一半有才定（任务书 02 第一阶段第 2 条）。

合成 400×200 的分屏视频，分屏线在 x=200；绿框是 120×100 的实心框（外接框面积 12000，
大于 config/ceus.yaml 的 min_area 10000），画在顶部文字带之下。预期值按画框位置手算。
"""

import cv2
import numpy as np
import pytest

from cadx.ceus import (
    CeusCaseError,
    CeusConfig,
    ContrastSideError,
    ViewRect,
    locate_contrast_side,
    map_source_mask_to_target,
    split_views,
)
from cadx.ceus._geometry import Frame

_WIDTH, _HEIGHT, _SPLIT = 400, 200, 200
_GREEN = (0, 255, 0)


def _frames(green_boxes_x1: list[int]) -> list[Frame]:
    """10 帧分屏画面；每个 x1 画一个整帧坐标 [x1, x1+119] × [60, 159] 的绿框。"""
    frame = np.zeros((_HEIGHT, _WIDTH, 3), dtype=np.uint8)
    frame[:, :_SPLIT] = 120
    frame[:, _SPLIT + 1 :] = 90
    for x1 in green_boxes_x1:
        cv2.rectangle(frame, (x1, 60), (x1 + 119, 159), _GREEN, thickness=-1)
    return [frame.copy() for _ in range(10)]


def test_green_box_in_left_half(ceus_config: CeusConfig) -> None:
    frames = _frames([40])
    _, left, right = split_views(frames, ceus_config.views)
    assert (left, right) == (ViewRect(0, 0, 200, 200), ViewRect(200, 0, 400, 200))

    side = locate_contrast_side(
        frames, left, right, ceus_config.prompt_source, ceus_config.keyframes
    )

    assert side.side == "left"
    assert side.contrast_view == left
    assert side.target_view == right
    # 10 帧绿框不变：只有第一帧是提示帧。
    assert [p.frame_index for p in side.prompt_frames] == [0]
    x1, y1, _, _ = side.prompt_frames[0].bbox_xyxy
    assert abs(x1 - 40) <= 3 and abs(y1 - 60) <= 3


def test_green_box_in_right_half(ceus_config: CeusConfig) -> None:
    frames = _frames([250])
    _, left, right = split_views(frames, ceus_config.views)

    side = locate_contrast_side(
        frames, left, right, ceus_config.prompt_source, ceus_config.keyframes
    )

    assert side.side == "right"
    assert side.contrast_view == right
    assert side.target_view == left
    # 整帧 x=250 在右半局部是 250 − 200 = 50。
    prompt = side.prompt_frames[0]
    assert abs(prompt.bbox_xyxy[0] - 50) <= 3
    # 挪到左半（灰阶那一半），两半扇形对齐、配准平移为 (0, 0)：局部 x 仍是 50。
    mapped = map_source_mask_to_target(prompt.mask, (0, 0), side.target_view)
    xs = np.where(mapped)[1]
    assert abs(int(xs.min()) - 50) <= 3
    assert abs(int(xs.max()) - 169) <= 3


def test_frames_are_iterated_once(ceus_config: CeusConfig) -> None:
    """帧只遍历一遍：传逐帧交出的生成器，结果与传列表相同。"""
    frames = _frames([250])
    _, left, right = split_views(frames, ceus_config.views)
    from_list = locate_contrast_side(
        frames, left, right, ceus_config.prompt_source, ceus_config.keyframes
    )
    from_generator = locate_contrast_side(
        (frame for frame in frames), left, right, ceus_config.prompt_source, ceus_config.keyframes
    )
    assert from_generator.side == from_list.side == "right"
    assert [p.frame_index for p in from_generator.prompt_frames] == [0]
    assert np.array_equal(from_generator.prompt_frames[0].mask, from_list.prompt_frames[0].mask)


def test_green_box_in_both_halves_fails_case(ceus_config: CeusConfig) -> None:
    frames = _frames([40, 250])
    _, left, right = split_views(frames, ceus_config.views)

    with pytest.raises(ContrastSideError, match="两半都找到绿框") as raised:
        locate_contrast_side(frames, left, right, ceus_config.prompt_source, ceus_config.keyframes)

    assert isinstance(raised.value, CeusCaseError)
    assert raised.value.step == 2


def test_no_green_box_fails_case(ceus_config: CeusConfig) -> None:
    frames = _frames([])
    _, left, right = split_views(frames, ceus_config.views)

    with pytest.raises(ContrastSideError, match="两半都没有找到绿框") as raised:
        locate_contrast_side(frames, left, right, ceus_config.prompt_source, ceus_config.keyframes)

    assert raised.value.step == 2