"""绿幕抠像配置领域模型 — 纯逻辑，无FFmpeg依赖.

抽离自 chroma_key_engine.py，包含：
- ChromaKeyConfig 数据类（解析/钳制/效果判断）
- 预设配置（绿幕/蓝幕/红幕等）
- 颜色归一化
- colorkey / chromakey 滤镜构建
- 便捷函数（apply_chroma_key_if_needed）
"""

from __future__ import annotations

import logging
import re
from dataclasses import dataclass
from typing import Any

logger = logging.getLogger(__name__)


# ── 预设配置 ──────────────────────────────────────────────────────────────────

# 常见绿幕/蓝幕预设
CHROMA_KEY_PRESETS: dict[str, dict[str, Any]] = {
    "green_screen": {
        "key_color": "#00FF00",
        "similarity": 0.3,
        "blend": 0.1,
        "spill_suppress": 0.5,
    },
    "blue_screen": {
        "key_color": "#0000FF",
        "similarity": 0.3,
        "blend": 0.1,
        "spill_suppress": 0.5,
    },
    "red_screen": {
        "key_color": "#FF0000",
        "similarity": 0.3,
        "blend": 0.1,
        "spill_suppress": 0.0,
    },
    "precise_green": {
        "key_color": "#00FF00",
        "similarity": 0.2,
        "blend": 0.05,
        "spill_suppress": 0.3,
    },
    "soft_green": {
        "key_color": "#00FF00",
        "similarity": 0.45,
        "blend": 0.2,
        "spill_suppress": 0.5,
    },
}

VALID_PRESETS = set(CHROMA_KEY_PRESETS.keys())

# 参数范围
MIN_SIMILARITY = 0.01
MAX_SIMILARITY = 1.0
MIN_BLEND = 0.0
MAX_BLEND = 1.0
MIN_SPILL_SUPPRESS = 0.0
MAX_SPILL_SUPPRESS = 1.0

# 默认值
DEFAULT_KEY_COLOR = "#00FF00"
DEFAULT_SIMILARITY = 0.3
DEFAULT_BLEND = 0.1
DEFAULT_SPILL_SUPPRESS = 0.0


# ── 配置模型 ──────────────────────────────────────────────────────────────────


@dataclass
class ChromaKeyConfig:
    """绿幕抠像配置.

    Attributes:
        enabled: 是否启用抠像
        key_color: 要抠除的颜色，支持 hex 格式（如 "#00FF00"）或颜色名
        similarity: 颜色相似度阈值 0.01~1.0，值越大抠除范围越大
        blend: 边缘平滑/混合度 0.0~1.0，值越大边缘越柔和
        spill_suppress: 溢色抑制 0.0~1.0，减少边缘的绿幕反光
    """

    enabled: bool = False
    key_color: str = DEFAULT_KEY_COLOR
    similarity: float = DEFAULT_SIMILARITY
    blend: float = DEFAULT_BLEND
    spill_suppress: float = DEFAULT_SPILL_SUPPRESS

    @classmethod
    def from_dict(cls, data: dict[str, Any] | None) -> ChromaKeyConfig:
        """从字典解析配置，参数越界自动钳制."""
        if not data or not data.get("enabled", False):
            return cls(enabled=False)

        key_color = str(data.get("key_color", DEFAULT_KEY_COLOR)).strip()

        def _safe_float(val: Any, default: float) -> float:
            try:
                return float(val)
            except (TypeError, ValueError):
                return default

        similarity = _safe_float(data.get("similarity", DEFAULT_SIMILARITY), DEFAULT_SIMILARITY)
        blend = _safe_float(data.get("blend", DEFAULT_BLEND), DEFAULT_BLEND)
        spill_suppress = _safe_float(data.get("spill_suppress", DEFAULT_SPILL_SUPPRESS), DEFAULT_SPILL_SUPPRESS)

        # 钳制到合法范围
        similarity = max(MIN_SIMILARITY, min(MAX_SIMILARITY, similarity))
        blend = max(MIN_BLEND, min(MAX_BLEND, blend))
        spill_suppress = max(MIN_SPILL_SUPPRESS, min(MAX_SPILL_SUPPRESS, spill_suppress))

        return cls(
            enabled=True,
            key_color=key_color,
            similarity=similarity,
            blend=blend,
            spill_suppress=spill_suppress,
        )

    @classmethod
    def from_preset(cls, preset_name: str) -> ChromaKeyConfig | None:
        """从预设名称创建配置."""
        preset = CHROMA_KEY_PRESETS.get(preset_name)
        if not preset:
            return None
        return cls(
            enabled=True,
            key_color=preset["key_color"],
            similarity=preset["similarity"],
            blend=preset["blend"],
            spill_suppress=preset["spill_suppress"],
        )

    def has_effect(self) -> bool:
        """判断是否有实际抠像效果."""
        return self.enabled and self.similarity > 0

    def validate(self) -> tuple[bool, str]:
        """校验配置是否有效."""
        if not self.enabled:
            return True, ""

        if not self.key_color:
            return False, "key_color 不能为空"

        if not (MIN_SIMILARITY <= self.similarity <= MAX_SIMILARITY):
            return False, f"similarity 必须在 {MIN_SIMILARITY}~{MAX_SIMILARITY} 之间"

        if not (MIN_BLEND <= self.blend <= MAX_BLEND):
            return False, f"blend 必须在 {MIN_BLEND}~{MAX_BLEND} 之间"

        if not (MIN_SPILL_SUPPRESS <= self.spill_suppress <= MAX_SPILL_SUPPRESS):
            return False, f"spill_suppress 必须在 {MIN_SPILL_SUPPRESS}~{MAX_SPILL_SUPPRESS} 之间"

        return True, ""


# ── 颜色归一化 ────────────────────────────────────────────────────────────────


def normalize_color(color_str: str) -> str:
    """将颜色字符串转为 FFmpeg colorkey 接受的格式.

    支持:
      - "#RRGGBB" / "#RRGGBBAA" → 0xRRGGBB
      - "0xRRGGBB" → 直接使用
      - 颜色名（green/blue/red/black/white 等）→ 直接透传
    """
    color = color_str.strip()

    # hex 格式
    hex_match = re.match(r"^#?([0-9a-fA-F]{6})([0-9a-fA-F]{2})?$", color)
    if hex_match:
        return f"0x{hex_match.group(1).upper()}"

    # 已经是 0x 格式
    if color.lower().startswith("0x"):
        return color.upper()

    # 颜色名直接透传（FFmpeg 支持常见颜色名）
    return color


# ── 滤镜构建 ────────────────────────────────────────────────────────────────


def build_colorkey_filter(
    config: ChromaKeyConfig,
    input_label: str,
    output_label: str,
) -> str:
    """构建 colorkey 滤镜字符串.

    Args:
        config: 抠像配置
        input_label: 输入标签，如 "[0:v]" 或 "[v0]"
        output_label: 输出标签，如 "[ck0]"

    Returns:
        FFmpeg 滤镜字符串
    """
    if not config.has_effect():
        return f"{input_label}copy{output_label}"

    color = normalize_color(config.key_color)
    similarity = config.similarity
    blend = config.blend

    # 基础 colorkey 滤镜
    parts = [f"colorkey=color={color}:similarity={similarity}:blend={blend}"]

    # 溢色抑制（通过 colorchannelmixer 降低绿色通道增益）
    if config.spill_suppress > 0:
        spill = config.spill_suppress
        g_gain = max(0.3, 1.0 - spill * 0.7)
        r_gain = 1.0 + spill * 0.15
        b_gain = 1.0 + spill * 0.15
        parts.append(f"colorchannelmixer=rr={r_gain}:gg={g_gain}:bb={b_gain}:aa=1")

    return f"{input_label}{','.join(parts)}{output_label}"


def build_chromakey_filter(
    config: ChromaKeyConfig,
    input_label: str,
    output_label: str,
) -> str:
    """使用 chromakey 滤镜（更高级的版本，支持更多参数）.

    注意：并非所有 FFmpeg 版本都支持 chromakey 滤镜，
    优先使用 colorkey（兼容性更好）。
    """
    if not config.has_effect():
        return f"{input_label}copy{output_label}"

    color = normalize_color(config.key_color)
    similarity = config.similarity
    blend = config.blend

    return f"{input_label}chromakey=color={color}:similarity={similarity}:blend={blend}{output_label}"


# ── 工具函数 ────────────────────────────────────────────────────────────────


def apply_chroma_key_if_needed(
    clip_config: dict[str, Any] | None,
    input_label: str,
    output_label: str,
) -> str | None:
    """便捷函数：根据 clip 配置判断是否需要应用绿幕抠像.

    Args:
        clip_config: clip 的 config 字典
        input_label: 输入标签
        output_label: 输出标签

    Returns:
        滤镜字符串，不需要抠像时返回 None
    """
    if not clip_config:
        return None

    chroma_key_data = clip_config.get("chroma_key")
    if not chroma_key_data:
        return None

    try:
        config = ChromaKeyConfig.from_dict(chroma_key_data)
        if not config.has_effect():
            return None

        return build_colorkey_filter(config, input_label, output_label)
    except Exception as e:
        logger.warning("[chroma-key] 应用抠像失败，跳过: %s", e)
        return None


def get_preset_names() -> list[str]:
    """获取所有预设名称列表."""
    return sorted(list(CHROMA_KEY_PRESETS.keys()))