main.py

import logging

import aiohttp
from bs4 import BeautifulSoup, SoupStrainer
from fastapi import FastAPI, Request
from fastapi.responses import HTMLResponse, RedirectResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates

app = FastAPI(
    title="Fx dcinside",
    summary="Fix dcinside link preview on Discord.",
    docs_url=None,
    redoc_url=None,
)

app.mount("/static", StaticFiles(directory="static"), name="static")

templates = Jinja2Templates(directory="templates")

only_meta_tags = SoupStrainer("meta")


async def fetch_og_tags(url: str) -> dict[str, str]:
    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36"
    }
    buf = b""

    try:
        async with aiohttp.ClientSession() as session:
            async with session.get(url, headers=headers) as resp:
                resp.raise_for_status()
                async for chunk in resp.content.iter_chunked(1024 * 16):
                    buf += chunk
                    if b"</head>" in buf.lower():
                        break

                soup = BeautifulSoup(buf.decode(errors="ignore"), "html.parser", parse_only=only_meta_tags)

                return {
                    "title": soup.find("meta", property="og:title")["content"],
                    "description": soup.find("meta", property="og:description")["content"],
                    #"image": soup.find("meta", property="og:image")["content"],
                    "image": "...",
                }
    except Exception as e:
        logging.exception(e)

        return {
            "title": "We are with you all the way! IT is Life! 디시인사이드 입니다.",
            "description": "접속불가",
            "image": "/static/descrip_img.png",
        }


async def template_or_redirect(
    request: Request,
    id: str,
    no: int,
    base_url: str = "https://gall.dcinside.com",
    infix: str = "",
):
    url = f"{base_url}{infix}/{id}/{no}"
    ua = (request.headers.get("user-agent") or "").lower()

    if "discordbot" in ua:
        og = await fetch_og_tags(url)

        return templates.TemplateResponse(
            "index.html", {"request": request, "og": og, "path": request['path']}
        )
    else:
        return RedirectResponse(url)


@app.get("/", include_in_schema=False)
async def root():
    return RedirectResponse("https://github.com/KOZ39/fxdcinside.com")


@app.get("/board/view/", response_class=HTMLResponse)
async def gallery(id: str, no: int, request: Request):
    return await template_or_redirect(request, id, no)


@app.get("/m/{id}/{no}", response_class=HTMLResponse)
@app.get("/mgallery/board/view/", response_class=HTMLResponse)
async def minor_gallery(id: str, no: int, request: Request):
    return await template_or_redirect(request, id, no, infix="/m")


@app.get("/mini/{id}/{no}", response_class=HTMLResponse)
@app.get("/mini/board/view/", response_class=HTMLResponse)
async def mini_gallery(id: str, no: int, request: Request):
    return await template_or_redirect(request, id, no, infix="/mini")


@app.get("/person/{id}/{no}", response_class=HTMLResponse)
@app.get("/person/board/view/", response_class=HTMLResponse)
async def person_gallery(id: str, no: int, request: Request):
    return await template_or_redirect(request, id, no, infix="/person")


# HACK: 마이너 갤러리 단축 주소의 301 리다이렉션 판단 불가
# Ref: https://github.com/KOZ39/fxdcinside.com/issues/1
@app.get("/board/{id}/{no}", response_class=HTMLResponse) # Mobile
@app.get("/{id}/{no}", response_class=HTMLResponse) # Short
async def short_or_mobile(id: str, no: int, request: Request):
    return await template_or_redirect(request, id, no, base_url="https://m.dcinside.com", infix="/board")