"""本地文件存储：落 data/media/，由 FastAPI /media 静态托管。"""
from __future__ import annotations

import mimetypes
import uuid
from pathlib import Path

import httpx

from config import get_settings


def media_root() -> Path:
    root = Path(get_settings().data_dir) / "media"
    root.mkdir(parents=True, exist_ok=True)
    return root


def public_url(key: str) -> str:
    """media key → 可访问 URL。"""
    settings = get_settings()
    return f"{settings.app_base_url.rstrip('/')}/media/{key}"


def _ext_from_url_or_type(hint: str, content_type: str = "") -> str:
    if content_type:
        ctype = content_type.split(";")[0].strip().lower()
        mapping = {
            "image/jpeg": ".jpg", "image/png": ".png", "image/webp": ".webp",
            "image/gif": ".gif", "image/bmp": ".bmp", "video/mp4": ".mp4",
        }
        if ctype in mapping:
            return mapping[ctype]
    ext = mimetypes.guess_extension(hint.split("?")[0].lower()) or ".jpg"
    return ".jpg" if ext == ".jpe" else ext


def write_bytes(data: bytes, key_prefix: str = "", ext: str = ".jpg") -> str:
    """写文件，返回 media key（相对 media 根的路径）。"""
    key = f"{key_prefix + '/' if key_prefix else ''}{uuid.uuid4().hex}{ext}"
    path = media_root() / key
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_bytes(data)
    return key


async def download_bytes(url: str, referer: str | None = None, timeout: float = 60.0) -> tuple[bytes, str]:
    """下载远程字节。返回 (bytes, content_type)。"""
    headers = {"Referer": referer} if referer else {}
    headers.setdefault("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)")
    async with httpx.AsyncClient(timeout=timeout, follow_redirects=True, verify=False) as client:
        resp = await client.get(url, headers=headers)
        resp.raise_for_status()
        ctype = (resp.headers.get("content-type") or "application/octet-stream").split(";")[0].strip()
        return resp.content, ctype


async def save_from_url(url: str, key_prefix: str = "", referer: str | None = None) -> str:
    data, ctype = await download_bytes(url, referer)
    key = write_bytes(data, key_prefix, _ext_from_url_or_type(url, ctype))
    return public_url(key)


def local_path(stored_url_or_key: str) -> Path | None:
    """stored_url（http.../media/xxx）或 key → 本地文件路径。"""
    s = stored_url_or_key
    if "/media/" in s:
        s = s.split("/media/", 1)[1]
    p = media_root() / s
    return p if p.exists() else None