"""像素级扰动滤镜单元测试（Issue #1765）。

覆盖：
- generate_pixel_perturbation：生成像素级扰动参数
- 滤镜组合：2-3 种滤镜随机组合
- 参数范围：肉眼不可见但帧级可检测
- FFmpeg 滤镜语法生成
"""

from __future__ import annotations

import random

import pytest

from packages.domain.variant_plan_selector import generate_pixel_perturbation


class TestGeneratePixelPerturbation:
    """generate_pixel_perturbation 测试。"""

    def test_returns_dict(self):
        """返回 dict。"""
        result = generate_pixel_perturbation()
        assert isinstance(result, dict)

    def test_has_filters_key(self):
        """包含 filters 键。"""
        result = generate_pixel_perturbation()
        assert "filters" in result

    def test_filters_count_2_or_3(self):
        """选 2-3 种滤镜。"""
        for _ in range(50):
            result = generate_pixel_perturbation()
            assert len(result["filters"]) in [2, 3]

    def test_filters_from_valid_options(self):
        """滤镜来自有效选项。"""
        valid_options = {"noise", "unsharp", "curves", "color_balance"}
        for _ in range(50):
            result = generate_pixel_perturbation()
            for f in result["filters"]:
                assert f in valid_options

    def test_noise_parameters(self):
        """noise 滤镜有正确参数范围。"""
        for _ in range(20):
            result = generate_pixel_perturbation()
            if "noise" in result["filters"]:
                strength = result.get("noise_strength", 0)
                assert 0.01 <= strength <= 0.02

    def test_unsharp_parameters(self):
        """unsharp 滤镜有正确参数范围。"""
        for _ in range(20):
            result = generate_pixel_perturbation()
            if "unsharp" in result["filters"]:
                amount = result.get("unsharp_amount", 0)
                assert -0.5 <= amount <= 0.5

    def test_curves_parameters(self):
        """curves 滤镜有正确参数范围。"""
        for _ in range(20):
            result = generate_pixel_perturbation()
            if "curves" in result["filters"]:
                contrast = result.get("curves_contrast", 1.0)
                assert 0.95 <= contrast <= 1.05

    def test_color_balance_parameters(self):
        """color_balance 滤镜有正确参数范围。"""
        valid_colors = [-5, -3, 0, 3, 5]
        for _ in range(20):
            result = generate_pixel_perturbation()
            if "color_balance" in result["filters"]:
                assert result.get("color_r") in valid_colors
                assert result.get("color_g") in valid_colors
                assert result.get("color_b") in valid_colors

    def test_same_seed_same_result(self):
        """相同 seed 返回相同结果。"""
        rng1 = random.Random(42)
        rng2 = random.Random(42)
        result1 = generate_pixel_perturbation(rng1)
        result2 = generate_pixel_perturbation(rng2)
        assert result1 == result2

    def test_different_seeds_may_differ(self):
        """不同 seed 可能返回不同结果。"""
        results = set()
        for seed in range(20):
            rng = random.Random(seed)
            result = generate_pixel_perturbation(rng)
            results.add(tuple(result["filters"]))
        # 20 个 seed 至少看到 3 种不同组合
        assert len(results) >= 3


class TestPixelPerturbationAcceptance:
    """Issue #1765 验收测试。"""

    def test_batch_3_variants_have_different_filters(self):
        """批量 3 个变体有不同的滤镜组合。"""
        results = []
        for seed in [100, 200, 300]:
            rng = random.Random(seed)
            result = generate_pixel_perturbation(rng)
            results.append(tuple(result["filters"]))

        # 至少 2 种不同组合
        unique = len(set(results))
        assert unique >= 2, f"Expected >= 2 unique filter combos, got {unique}: {results}"


class TestIntSeedSupport:
    """int seed 入参支持（与 get_rhythm_template(seed) 接口一致）。"""

    def test_int_seed_returns_dict(self):
        """int seed 正常返回 dict。"""
        result = generate_pixel_perturbation(42)
        assert isinstance(result, dict)
        assert "filters" in result

    def test_int_seed_reproducible(self):
        """相同 int seed 结果一致。"""
        assert generate_pixel_perturbation(42) == generate_pixel_perturbation(42)

    def test_int_seed_differs_across_seeds(self):
        """不同 int seed 大概率不同（遍历确认至少 2 种组合）。"""
        results = {tuple(generate_pixel_perturbation(s)["filters"]) for s in range(30)}
        assert len(results) >= 2

    def test_int_seed_matches_random_obj(self):
        """int seed 与等价 random.Random(seed) 结果一致。"""
        assert generate_pixel_perturbation(7) == generate_pixel_perturbation(random.Random(7))

    def test_none_seed_works(self):
        """None 入参（默认随机）正常返回。"""
        result = generate_pixel_perturbation(None)
        assert isinstance(result, dict)
        assert len(result["filters"]) in [2, 3]