"""媒体文件 → base64 data URI 转换工具。"""
import base64
import mimetypes
import os

import httpx
from sqlalchemy import select

from app.config import settings
from app.models.system_config import SystemConfig


async def get_llm_media_as_base64(db=None) -> bool:
    """读取 SystemConfig 中的 llm_media_as_base64 设置。无 DB 连接时回退到 env。"""
    if db is not None:
        try:
            result = await db.execute(
                select(SystemConfig).where(SystemConfig.key == "llm_media_as_base64").limit(1)
            )
            config = result.scalar_one_or_none()
            if config:
                return config.value.lower() in ("true", "1", "yes")
        except Exception:
            pass
    return settings.LLM_MEDIA_AS_BASE64


async def media_to_base64(url: str, fallback_mime: str = "image/png", max_mb: int = 20) -> str:
    """将任意媒体 URL/路径转为 base64 data URI。

    - data: URI → 原样返回
    - http(s):// → 下载后编码（受 max_mb 限制）
    - /uploads/xxx 或本地路径 → 读盘编码
    """
    if url.startswith("data:"):
        return url

    if url.startswith(("http://", "https://")):
        async with httpx.AsyncClient(timeout=60) as client:
            resp = await client.get(url)
        size_mb = len(resp.content) / (1024 * 1024)
        if size_mb > max_mb:
            raise ValueError(f"媒体文件过大 ({size_mb:.1f}MB > {max_mb}MB)")
        b64 = base64.b64encode(resp.content).decode()
        mime = resp.headers.get("content-type") or fallback_mime
        return f"data:{mime};base64,{b64}"

    # 本地路径
    if url.startswith("/generate/"):
        type_pre = '/generate/videos/' if url.startswith("/generate/videos/") else '/generate/images/'
        type_path = settings.STORAGE_LOCAL_PATH if url.startswith("/generate/videos/") else settings.STORAGE_IMAGE_LOCAL_PATH
        relative_path = url.replace(type_pre, "", 1).lstrip("/")
        file_path = os.path.join(type_path, relative_path)
    else:
        relative_path = url.replace("/uploads/", "", 1).lstrip("/")
        file_path = os.path.join(settings.UPLOAD_LOCAL_PATH, relative_path)
    mime = mimetypes.guess_type(file_path)[0] or fallback_mime
    with open(file_path, "rb") as f:
        b64 = base64.b64encode(f.read()).decode()
    return f"data:{mime};base64,{b64}"