"""海报输出格式注册表。

逻辑尺寸用于 HTML 排版，输出尺寸用于最终 PNG，背景素材尺寸用于图片模型。
三者不得通过同一个宽高字符串互相推断。
"""
from copy import deepcopy


class PosterFormatError(ValueError):
    """海报格式不受支持。"""


CUSTOM_LONG_HEIGHT_MIN = 1920
CUSTOM_LONG_HEIGHT_MAX = 30000


_FORMATS = (
    {
        "id": "single_2_3",
        "label": "竖版单图 2:3",
        "outputMode": "single",
        "layout": {"width": 512, "height": 768},
        "output": {"width": 1024, "height": 1536},
        "exportSize": "1024x1536",
        "backgroundAssetSize": "1024x1536",
    },
    {
        "id": "single_9_16",
        "label": "竖屏单图 9:16",
        "outputMode": "single",
        "layout": {"width": 540, "height": 960},
        "output": {"width": 1080, "height": 1920},
        "exportSize": "1080x1920",
        "backgroundAssetSize": "1024x1536",
    },
    {
        "id": "long_1242_auto",
        "label": "完整方案长图",
        "outputMode": "long",
        "layout": {"width": 414, "height": None},
        "output": {"width": 1242, "height": None},
        "exportSize": "1242xauto",
        "backgroundAssetSize": "1024x1536",
    },
)

_FORMAT_BY_ID = {item["id"]: item for item in _FORMATS}
_DEFAULT_BY_MODE = {
    "single": "single_2_3",
    "long": "long_1242_auto",
}
_LEGACY_FORMATS = {
    ("single", "1024x1792"): "single_2_3",
    ("single", "1024x1536"): "single_2_3",
    ("single", "1080x1920"): "single_9_16",
    ("long", "1080x2160"): "long_1242_auto",
    ("long", "1080x3240"): "long_1242_auto",
    ("long", "1080x4320"): "long_1242_auto",
    ("long", "1242xauto"): "long_1242_auto",
}


def list_poster_formats() -> list[dict]:
    """返回可供前端选择的安全格式副本。"""
    return deepcopy(list(_FORMATS))


def resolve_custom_long_height(value, output_mode: str) -> int | None:
    """解析长图自定义输出高度；None 表示内容驱动的自动高度。"""
    if value is None or value == "" or value == "auto":
        return None
    if output_mode != "long":
        raise PosterFormatError("自定义高度仅长图模式可用")
    if isinstance(value, bool):
        raise PosterFormatError("长图高度必须是整数")
    try:
        height = int(value)
    except (TypeError, ValueError) as exc:
        raise PosterFormatError("长图高度必须是整数") from exc
    if isinstance(value, float) and not value.is_integer():
        raise PosterFormatError("长图高度必须是整数")
    if not CUSTOM_LONG_HEIGHT_MIN <= height <= CUSTOM_LONG_HEIGHT_MAX:
        raise PosterFormatError(
            f"长图高度必须在 {CUSTOM_LONG_HEIGHT_MIN} 到 {CUSTOM_LONG_HEIGHT_MAX}px 之间"
        )
    return height


def resolve_poster_format(
    format_id: str | None = None,
    legacy_size: str | None = None,
    output_mode: str = "single",
) -> dict:
    """解析并校验海报格式，未知值必须明确失败。"""
    mode = str(output_mode or "single")
    if mode not in _DEFAULT_BY_MODE:
        raise PosterFormatError(f"不支持的输出模式: {output_mode}")

    if format_id:
        spec = _FORMAT_BY_ID.get(str(format_id))
        if not spec:
            raise PosterFormatError(f"不支持的海报格式: {format_id}")
    elif legacy_size:
        resolved_id = _LEGACY_FORMATS.get((mode, str(legacy_size)))
        if not resolved_id:
            raise PosterFormatError(f"不支持的海报尺寸: {legacy_size}")
        spec = _FORMAT_BY_ID[resolved_id]
    else:
        spec = _FORMAT_BY_ID[_DEFAULT_BY_MODE[mode]]

    if spec["outputMode"] != mode:
        mode_label = "长图" if mode == "long" else "单图"
        raise PosterFormatError(f"格式 {spec['id']} 不支持{mode_label}模式")
    return deepcopy(spec)