import os
from dataclasses import dataclass

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_env(cls) -> "MemoirImageSettings":
        return cls(
            enabled=os.getenv("MEMOIR_IMAGE_ENABLED", "").lower() in {"1", "true", "yes"},
            max_per_chapter=_get_int_env("MEMOIR_IMAGE_MAX_PER_CHAPTER", DEFAULT_MAX_IMAGES_PER_CHAPTER),
            chars_per_extra_image=_get_int_env("MEMOIR_IMAGE_CHARS_PER_EXTRA", DEFAULT_CHARS_PER_EXTRA_IMAGE),
            max_images_cap=_get_int_env("MEMOIR_IMAGE_MAX_CAP", DEFAULT_MAX_IMAGES_CAP),
            provider=os.getenv("MEMOIR_IMAGE_PROVIDER", DEFAULT_IMAGE_PROVIDER),
            default_style=os.getenv("MEMOIR_IMAGE_STYLE_DEFAULT", DEFAULT_IMAGE_STYLE),
            default_size=os.getenv("MEMOIR_IMAGE_SIZE_DEFAULT", DEFAULT_IMAGE_SIZE),
            poll_interval_seconds=_get_int_env("MEMOIR_IMAGE_POLL_INTERVAL", DEFAULT_POLL_INTERVAL_SECONDS),
            max_attempts=_get_int_env("MEMOIR_IMAGE_MAX_ATTEMPTS", DEFAULT_MAX_ATTEMPTS),
            liblib_template_uuid=os.getenv("LIBLIB_TEMPLATE_UUID") or DEFAULT_LIBLIB_TEMPLATE_UUID,
        )

    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)


def _get_int_env(name: str, default: int) -> int:
    value = os.getenv(name, str(default))
    try:
        return int(value)
    except (TypeError, ValueError):
        return default