"""BGM 配置工具函数单元测试."""

import pytest

from packages.domain.bgm_utils import merge_bgm_config


class TestMergeBgmConfig:
    """merge_bgm_config 测试"""

    def test_user_bgm_empty_returns_template_copy(self):
        """用户配置为空时，返回模板配置的拷贝"""
        template = {"enabled": True, "volume": 0.5, "asset_id": "tpl_123"}
        result = merge_bgm_config(template, {})
        assert result == template
        assert result is not template

    def test_user_bgm_none_returns_template_copy(self):
        """用户配置为 None 时，返回模板配置的拷贝"""
        template = {"enabled": True, "volume": 0.5}
        result = merge_bgm_config(template, None)  # type: ignore
        assert result == template

    def test_template_bgm_empty_returns_user_copy(self):
        """模板配置为空时，返回用户配置的拷贝"""
        user = {"enabled": False, "volume": 0.8, "asset_id": "user_456"}
        result = merge_bgm_config({}, user)
        assert result == user
        assert result is not user

    def test_template_bgm_none_returns_user_copy(self):
        """模板配置为 None 时，返回用户配置的拷贝"""
        user = {"enabled": False, "volume": 0.8}
        result = merge_bgm_config(None, user)  # type: ignore
        assert result == user

    def test_user_fields_override_template(self):
        """用户显式指定的字段覆盖模板对应字段"""
        template = {
            "enabled": True,
            "volume": 0.5,
            "asset_id": "tpl_123",
            "fade_in": 1.0,
        }
        user = {
            "volume": 0.8,
            "asset_id": "user_456",
        }
        result = merge_bgm_config(template, user)
        assert result["volume"] == 0.8
        assert result["asset_id"] == "user_456"
        assert result["fade_in"] == 1.0  # 模板值保留

    def test_enabled_not_in_user_preserves_template_enabled(self):
        """enabled 特殊处理：用户没传 enabled 时保留模板的 enabled 值"""
        template = {"enabled": True, "volume": 0.5}
        user = {"volume": 0.8}  # 没传 enabled
        result = merge_bgm_config(template, user)
        assert result["enabled"] is True  # 保留模板的
        assert result["volume"] == 0.8  # 用户指定的覆盖

    def test_enabled_in_user_overrides_template(self):
        """用户传了 enabled 时覆盖模板的 enabled"""
        template = {"enabled": True, "volume": 0.5}
        user = {"enabled": False, "volume": 0.8}
        result = merge_bgm_config(template, user)
        assert result["enabled"] is False
        assert result["volume"] == 0.8

    def test_user_adds_new_fields(self):
        """用户配置中的新字段会被添加到结果中"""
        template = {"enabled": True, "volume": 0.5}
        user = {"sidechain_enabled": True, "sidechain_ratio": 0.6}
        result = merge_bgm_config(template, user)
        assert result["enabled"] is True
        assert result["volume"] == 0.5
        assert result["sidechain_enabled"] is True
        assert result["sidechain_ratio"] == 0.6

    def test_both_empty_returns_empty_dict(self):
        """两者都为空时返回空字典"""
        result = merge_bgm_config({}, {})
        assert result == {}

    def test_nested_dict_shallow_merge(self):
        """嵌套字典是浅合并（当前设计）"""
        template = {"enabled": True, "config": {"eq": True, "compression": False}}
        user = {"config": {"compression": True, "reverb": 0.5}}
        result = merge_bgm_config(template, user)
        # 浅合并：整个 config 被用户值覆盖
        assert result["config"] == {"compression": True, "reverb": 0.5}

    def test_does_not_mutate_template(self):
        """不修改原始模板配置"""
        template = {"enabled": True, "volume": 0.5}
        original = dict(template)
        merge_bgm_config(template, {"volume": 0.8})
        assert template == original

    def test_does_not_mutate_user(self):
        """不修改原始用户配置"""
        user = {"volume": 0.8}
        original = dict(user)
        merge_bgm_config({"enabled": True}, user)
        assert user == original