xiaoxia-saas/packages/domain/subtitle_style.py

"""字幕样式领域模型 — 纯逻辑，无外部依赖.

抽离自 subtitle_render_engine.py 的数据类和工具函数，
方便单测覆盖，同时保持向后兼容。
"""

from __future__ import annotations

from dataclasses import dataclass
from typing import Any

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

# 9宫格位置映射（ASS alignment 编号）
POSITION_ALIGNMENT: dict[str, int] = {
    "top_left": 7,
    "top_center": 8,
    "top_right": 9,
    "middle_left": 4,
    "center": 5,
    "middle_right": 6,
    "bottom_left": 1,
    "bottom_center": 2,
    "bottom_right": 3,
}

# 位置简称兼容
POSITION_ALIASES: dict[str, str] = {
    "top": "top_center",
    "bottom": "bottom_center",
    "middle": "center",
    "left": "middle_left",
    "right": "middle_right",
}

DEFAULT_FONT = "思源黑体"
DEFAULT_FONT_SIZE = 24
DEFAULT_COLOR = "#FFFFFF"
DEFAULT_STROKE_COLOR = "#000000"
DEFAULT_STROKE_WIDTH = 1.5
DEFAULT_POSITION = "bottom_center"
DEFAULT_MAX_CHARS_PER_LINE = 20

ALLOWED_SUBTITLE_EXTENSIONS = {".srt", ".ass", ".vtt", ".sub"}


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


def hex_to_ass_color(hex_color: str) -> str:
    """HEX → ASS 颜色 &HAABBGGRR（默认不透明）."""
    hex_color = hex_color.lstrip("#")
    if len(hex_color) != 6:
        return "&H00FFFFFF"
    r, g, b = hex_color[0:2], hex_color[2:4], hex_color[4:6]
    return f"&H00{b.upper()}{g.upper()}{r.upper()}"


def hex_to_ass_bgr(hex_color: str) -> str:
    """HEX → ASS BGR 部分（不含 alpha）."""
    hex_color = hex_color.lstrip("#")
    if len(hex_color) != 6:
        return "FFFFFF"
    r, g, b = hex_color[0:2], hex_color[2:4], hex_color[4:6]
    return f"{b.upper()}{g.upper()}{r.upper()}"


def opacity_to_ass_alpha(opacity: float) -> str:
    """不透明度 → ASS alpha（00=不透明，FF=完全透明）."""
    alpha = 255 - int(max(0.0, min(1.0, opacity)) * 255)
    return f"{alpha:02X}"


def escape_ass_text(text: str) -> str:
    """转义 ASS 文本特殊字符."""
    text = text.replace("\r\n", "\\N").replace("\n", "\\N").replace("\r", "\\N")
    text = text.replace("{", "(").replace("}", ")")
    return text


def format_ass_time(seconds: float) -> str:
    """秒 → ASS 时间格式 H:MM:SS.cc."""
    if seconds < 0:
        seconds = 0.0
    hours = int(seconds // 3600)
    minutes = int((seconds % 3600) // 60)
    secs = seconds % 60
    return f"{hours}:{minutes:02d}:{secs:05.2f}"


def wrap_text(text: str, max_chars: int) -> list[str]:
    """按字数换行，优先标点断开."""
    if max_chars <= 0:
        return [text]
    if not text or len(text) <= max_chars:
        return [text]

    lines: list[str] = []
    remaining = text
    punctuations = "，。！？、；：,.;:!?"

    while len(remaining) > max_chars:
        break_point = max_chars
        # 在 max_chars 到 max_chars//2 之间寻找标点断点
        for i in range(max_chars, max_chars // 2, -1):
            if i < len(remaining) and remaining[i] in punctuations:
                break_point = i + 1
                break

        lines.append(remaining[:break_point])
        remaining = remaining[break_point:]

    if remaining:
        lines.append(remaining)

    return lines


# ── 字幕样式配置 ────────────────────────────────────────────────────────────


@dataclass
class SubtitleStyle:
    """字幕样式配置."""

    font_name: str = DEFAULT_FONT
    font_size: int = DEFAULT_FONT_SIZE
    font_color: str = DEFAULT_COLOR
    bold: bool = False
    italic: bool = False

    # 描边
    stroke_enabled: bool = True
    stroke_color: str = DEFAULT_STROKE_COLOR
    stroke_width: float = DEFAULT_STROKE_WIDTH

    # 阴影
    shadow_enabled: bool = False
    shadow_color: str = "#000000"
    shadow_offset_x: int = 2
    shadow_offset_y: int = 2
    shadow_blur: float = 0.0

    # 背景框
    background_enabled: bool = False
    background_color: str = "#000000"
    background_opacity: float = 0.5
    background_padding: int = 8
    background_radius: int = 4

    # 位置
    position: str = DEFAULT_POSITION
    margin_v: int = 60
    margin_l: int = 40
    margin_r: int = 40

    # 多行
    max_chars_per_line: int = DEFAULT_MAX_CHARS_PER_LINE
    line_spacing: int = 0

    # 动画
    fade_in: float = 0.0
    fade_out: float = 0.0
    animation_type: str = "none"

    @classmethod
    def from_dict(cls, config: dict[str, Any] | None) -> "SubtitleStyle":
        """从字典创建样式配置，带安全类型转换."""
        if not config or not isinstance(config, dict):
            return cls()

        def safe_str(key: str, default: str) -> str:
            val = config.get(key, default)
            return str(val) if val is not None else default

        def safe_int(key: str, default: int) -> int:
            try:
                return int(config.get(key, default))
            except (TypeError, ValueError):
                return default

        def safe_float(key: str, default: float) -> float:
            try:
                return float(config.get(key, default))
            except (TypeError, ValueError):
                return default

        def safe_bool(key: str, default: bool) -> bool:
            return bool(config.get(key, default))

        position = safe_str("position", DEFAULT_POSITION)
        position = POSITION_ALIASES.get(position, position)
        if position not in POSITION_ALIGNMENT:
            position = DEFAULT_POSITION

        return cls(
            font_name=safe_str("font", DEFAULT_FONT),
            font_size=safe_int("size", DEFAULT_FONT_SIZE),
            font_color=safe_str("color", DEFAULT_COLOR),
            bold=safe_bool("bold", False),
            italic=safe_bool("italic", False),
            stroke_enabled=safe_bool("stroke_enabled", True),
            stroke_color=safe_str("stroke_color", DEFAULT_STROKE_COLOR),
            stroke_width=safe_float("stroke_width", DEFAULT_STROKE_WIDTH),
            shadow_enabled=safe_bool("shadow_enabled", False),
            shadow_color=safe_str("shadow_color", "#000000"),
            shadow_offset_x=safe_int("shadow_offset_x", 2),
            shadow_offset_y=safe_int("shadow_offset_y", 2),
            shadow_blur=safe_float("shadow_blur", 0.0),
            background_enabled=safe_bool("background_enabled", False),
            background_color=safe_str("background_color", "#000000"),
            background_opacity=max(0.0, min(1.0, safe_float("background_opacity", 0.5))),
            background_padding=safe_int("background_padding", 8),
            background_radius=safe_int("background_radius", 4),
            position=position,
            margin_v=safe_int("margin_v", 60),
            margin_l=safe_int("margin_l", 40),
            margin_r=safe_int("margin_r", 40),
            max_chars_per_line=safe_int("max_chars_per_line", DEFAULT_MAX_CHARS_PER_LINE),
            line_spacing=safe_int("line_spacing", 0),
            fade_in=max(0.0, safe_float("fade_in", 0.0)),
            fade_out=max(0.0, safe_float("fade_out", 0.0)),
            animation_type=safe_str("animation_type", "none"),
        )

    @property
    def alignment(self) -> int:
        """获取 ASS alignment 编号."""
        return POSITION_ALIGNMENT.get(self.position, 2)

    @property
    def ass_font_color(self) -> str:
        """ASS 格式颜色 &HAABBGGRR."""
        return hex_to_ass_color(self.font_color)

    @property
    def ass_stroke_color(self) -> str:
        return hex_to_ass_color(self.stroke_color)

    @property
    def ass_shadow_color(self) -> str:
        return hex_to_ass_color(self.shadow_color)

    @property
    def ass_background_color(self) -> str:
        """背景框颜色（ASS BackColour），带透明度."""
        alpha_hex = opacity_to_ass_alpha(self.background_opacity)
        color_bgr = hex_to_ass_bgr(self.background_color)
        return f"&H{alpha_hex}{color_bgr}"


# ── 字幕片段 ──────────────────────────────────────────────────────────────────


@dataclass
class SubtitleSegment:
    """单个字幕片段."""

    start: float  # 开始时间（秒）
    end: float  # 结束时间（秒）
    text: str  # 字幕文本
    style_name: str = "Default"  # 使用的样式名

    @property
    def duration(self) -> float:
        """字幕时长."""
        return max(0.0, self.end - self.start)

    @property
    def is_valid(self) -> bool:
        """是否有效（有文本且时长>0）."""
        return bool(self.text) and self.end > self.start