from dataclasses import dataclass
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from app.core.config import Settings

DEFAULT_LIBLIB_TEMPLATE_UUID = "5d7e67009b344550bc1aa6ccbfa1d7f4"
DEFAULT_MAX_IMAGES_PER_CHAPTER = 2
DEFAULT_CHARS_PER_EXTRA_IMAGE = 1500
DEFAULT_MAX_IMAGES_CAP = 8
DEFAULT_IMAGE_PROVIDER = "liblib"
DEFAULT_IMAGE_STYLE = "watercolor"
DEFAULT_IMAGE_SIZE = "1280x720"
DEFAULT_POLL_INTERVAL_SECONDS = 5
DEFAULT_MAX_ATTEMPTS = 60


@dataclass(frozen=True)
class MemoirImageSettings:
    enabled: bool = False
    max_per_chapter: int = DEFAULT_MAX_IMAGES_PER_CHAPTER
    chars_per_extra_image: int = DEFAULT_CHARS_PER_EXTRA_IMAGE
    max_images_cap: int = DEFAULT_MAX_IMAGES_CAP
    provider: str = DEFAULT_IMAGE_PROVIDER
    default_style: str = DEFAULT_IMAGE_STYLE
    default_size: str = DEFAULT_IMAGE_SIZE
    poll_interval_seconds: int = DEFAULT_POLL_INTERVAL_SECONDS
    max_attempts: int = DEFAULT_MAX_ATTEMPTS
    liblib_template_uuid: str = DEFAULT_LIBLIB_TEMPLATE_UUID

    @classmethod
    def from_settings(cls, settings: "Settings") -> "MemoirImageSettings":
        s = settings
        return cls(
            enabled=bool(s.memoir_image_enabled),
            max_per_chapter=s.memoir_image_max_per_chapter,
            chars_per_extra_image=s.memoir_image_chars_per_extra,
            max_images_cap=s.memoir_image_max_cap,
            provider=s.memoir_image_provider or DEFAULT_IMAGE_PROVIDER,
            default_style=s.memoir_image_style_default or DEFAULT_IMAGE_STYLE,
            default_size=s.memoir_image_size_default or DEFAULT_IMAGE_SIZE,
            poll_interval_seconds=s.memoir_image_poll_interval,
            max_attempts=s.memoir_image_max_attempts,
            liblib_template_uuid=s.liblib_template_uuid or DEFAULT_LIBLIB_TEMPLATE_UUID,
        )

    @classmethod
    def from_env(cls) -> "MemoirImageSettings":
        from app.core.config import settings as _s

        return cls.from_settings(_s)

    def effective_max_images(self, content_length: int) -> int:
        """根据正文字数动态计算单章允许的最大图片数。"""
        base_max = max(self.max_per_chapter, 0)
        effective_cap = max(self.max_images_cap, base_max)
        safe_length = max(content_length, 0)
        extra = safe_length // self.chars_per_extra_image if self.chars_per_extra_image > 0 else 0
        return min(base_max + extra, effective_cap)