"""多轨道音频配置领域模型 — 纯逻辑，无外部依赖.

抽离自 multi_track_mixer.py 的数据类、常量和纯逻辑函数，
方便单测覆盖，同时保持向后兼容。
"""

from __future__ import annotations

import logging
from dataclasses import dataclass, field
from pathlib import Path

logger = logging.getLogger(__name__)


# ── 常量 ──────────────────────────────────────────────────────────────────────

TRACK_TYPE_MAIN = "main"  # 原音（视频原声）
TRACK_TYPE_BGM = "bgm"  # 背景音乐
TRACK_TYPE_VOICEOVER = "voiceover"  # 配音（TTS/人声）
TRACK_TYPE_SFX = "sfx"  # 音效
TRACK_TYPE_AMBIENT = "ambient"  # 环境音

MAX_AUDIO_TRACKS = 8  # 最大混音轨道数（安全上限，防止资源耗尽）

# 各轨道默认音量（相对主音频）
DEFAULT_VOLUMES = {
    TRACK_TYPE_MAIN: 1.0,
    TRACK_TYPE_BGM: 0.3,
    TRACK_TYPE_VOICEOVER: 1.0,
    TRACK_TYPE_SFX: 0.7,
    TRACK_TYPE_AMBIENT: 0.2,
}

ALLOWED_AUDIO_EXTENSIONS = {".mp3", ".wav", ".aac", ".ogg", ".flac", ".m4a", ".wma"}

_VALID_TRACK_TYPES = {
    TRACK_TYPE_MAIN,
    TRACK_TYPE_BGM,
    TRACK_TYPE_VOICEOVER,
    TRACK_TYPE_SFX,
    TRACK_TYPE_AMBIENT,
}


# ── 数据模型 ──────────────────────────────────────────────────────────────────


@dataclass
class AudioTrack:
    """单条音频轨道配置."""

    track_id: str = ""  # 轨道唯一标识
    track_type: str = TRACK_TYPE_SFX  # 轨道类型
    audio_path: str = ""  # 音频文件路径
    volume: float = 1.0  # 音量 0.0 ~ 2.0
    fade_in: float = 0.0  # 淡入时长（秒）
    fade_out: float = 0.0  # 淡出时长（秒）
    start_time: float = 0.0  # 开始时间（相对于视频起点，秒）
    duration: float = 0.0  # 持续时长（0表示到文件末尾）
    enabled: bool = True  # 是否启用

    @classmethod
    def from_dict(cls, track: dict) -> "AudioTrack":
        """从字典创建 AudioTrack，带安全类型转换."""
        track_type = str(track.get("track_type", TRACK_TYPE_SFX))
        default_vol = DEFAULT_VOLUMES.get(track_type, 1.0)

        try:
            volume = float(track.get("volume", default_vol))
        except (TypeError, ValueError):
            volume = default_vol
        volume = max(0.0, min(2.0, volume))

        try:
            fade_in = max(0.0, float(track.get("fade_in", 0.0)))
        except (TypeError, ValueError):
            fade_in = 0.0

        try:
            fade_out = max(0.0, float(track.get("fade_out", 0.0)))
        except (TypeError, ValueError):
            fade_out = 0.0

        try:
            start_time = max(0.0, float(track.get("start_time", 0.0)))
        except (TypeError, ValueError):
            start_time = 0.0

        try:
            duration = max(0.0, float(track.get("duration", 0.0)))
        except (TypeError, ValueError):
            duration = 0.0

        return cls(
            track_id=str(track.get("track_id", "")),
            track_type=track_type,
            audio_path=str(track.get("audio_path", "")),
            volume=volume,
            fade_in=fade_in,
            fade_out=fade_out,
            start_time=start_time,
            duration=duration,
            enabled=bool(track.get("enabled", True)),
        )

    def validate(self) -> tuple[bool, str]:
        """校验配置合法性，返回 (是否合法, 错误信息)."""
        if not self.audio_path:
            return False, "audio_path不能为空"

        if self.volume < 0.0 or self.volume > 2.0:
            return False, f"volume必须在0-2之间: {self.volume}"

        if self.fade_in < 0:
            return False, f"fade_in不能为负数: {self.fade_in}"

        if self.fade_out < 0:
            return False, f"fade_out不能为负数: {self.fade_out}"

        if self.start_time < 0:
            return False, f"start_time不能为负数: {self.start_time}"

        if self.duration < 0:
            return False, f"duration不能为负数: {self.duration}"

        return True, ""

    @property
    def is_effective(self) -> bool:
        """是否为有效轨道（启用+有路径）."""
        return self.enabled and bool(self.audio_path)


@dataclass
class MultiTrackMixConfig:
    """多轨道混音配置."""

    tracks: list[AudioTrack] = field(default_factory=list)
    master_volume: float = 1.0  # 主输出音量
    normalize: bool = True  # 是否自动归一化补偿
    max_output_volume: float = 1.5  # 最大输出音量（防止爆音）

    @classmethod
    def from_config_dict(cls, config: dict | None) -> "MultiTrackMixConfig":
        """从 plan.config.audio_tracks 字典创建配置."""
        if not config or not isinstance(config, dict):
            return cls()

        tracks_raw = config.get("tracks", [])
        tracks: list[AudioTrack] = []

        if isinstance(tracks_raw, list):
            for t in tracks_raw:
                if isinstance(t, dict) and t.get("audio_path"):
                    try:
                        track = AudioTrack.from_dict(t)
                        if track.enabled and track.audio_path:
                            tracks.append(track)
                    except Exception:
                        logger.warning("[multi-track] skip invalid track config: %s", t)
                        continue

        try:
            master_volume = float(config.get("master_volume", 1.0))
            master_volume = max(0.0, min(2.0, master_volume))
        except (TypeError, ValueError):
            master_volume = 1.0

        try:
            max_output_volume = float(config.get("max_output_volume", 1.5))
        except (TypeError, ValueError):
            max_output_volume = 1.5

        return cls(
            tracks=tracks,
            master_volume=master_volume,
            normalize=bool(config.get("normalize", True)),
            max_output_volume=max_output_volume,
        )

    @property
    def has_effect(self) -> bool:
        """是否有有效轨道需要混音."""
        return len([t for t in self.tracks if t.is_effective]) > 0

    @property
    def effective_track_count(self) -> int:
        """有效轨道数量."""
        return len([t for t in self.tracks if t.is_effective])

    @property
    def main_tracks(self) -> list[AudioTrack]:
        """主音轨列表."""
        return [t for t in self.tracks if t.track_type == TRACK_TYPE_MAIN and t.is_effective]

    @property
    def bgm_tracks(self) -> list[AudioTrack]:
        """BGM轨道列表."""
        return [t for t in self.tracks if t.track_type == TRACK_TYPE_BGM and t.is_effective]


# ── 纯逻辑工具函数 ───────────────────────────────────────────────────────────


def is_valid_audio_extension(filename: str) -> bool:
    """检查文件扩展名是否为支持的音频格式."""
    ext = Path(filename).suffix.lower()
    return ext in ALLOWED_AUDIO_EXTENSIONS


def clamp_volume(volume: float, min_vol: float = 0.0, max_vol: float = 2.0) -> float:
    """限制音量在合法范围内."""
    return max(min_vol, min(max_vol, volume))