import json
import logging
import time
import os
import aiohttp
import random
from fastapi import FastAPI, Header, Request, Query, HTTPException
from fastapi.responses import JSONResponse, PlainTextResponse
from contextlib import asynccontextmanager

logging.basicConfig(level=logging.INFO)


class Manager:
    def __init__(self, api: FastAPI):
        self.app = api
        self.waiting = 0

    def __enter__(self) -> "Manager":
        self.waiting += 1
        if self.waiting >= 2048:
            logging.critical("TCP pool full! %d/2048. Requests are now being backlogged.")
        elif self.waiting > 1024:
            logging.warning("TCP pool half full! %d/2048.")
        return self

    def __exit__(self, *args):
        self.waiting -= 1


@asynccontextmanager
async def lifespan(_app: FastAPI):
    async with aiohttp.ClientSession(
        "https://ip.shronk.tech",
        connector=aiohttp.TCPConnector(limit=2048),
        raise_for_status=True
    ) as client:
        _app.state.session = client
        yield


app = FastAPI(lifespan=lifespan)
app.state.cache = {}
app.state.meta = Manager(app)


@app.middleware("http")
async def http_middleware(request: Request, call_next):
    if app.state.meta.waiting >= 2512:
        return JSONResponse({"error": os.urandom(512).decode("latin-1", "replace")}, status_code=503)
    with app.state.meta:
        return await call_next(request)


async def make_request(ip: str, headers: dict[str, str]) -> dict | HTTPException:
    if ip in app.state.cache:
        data, timestamp = app.state.cache[ip]
        if time.time() - timestamp < 3600:
            logging.info("cache hit for %s", ip)
            return data
        logging.info("cache expired for %s", ip)

    try:
        async with app.state.session.get(f"/lookup?ip={ip}") as response:
            data = await response.json()
    except json.JSONDecodeError as e:
        logging.error("Failed to parse data for %s: %s", ip, e, exc_info=True)
        return HTTPException(500, "Failed to parse upstream response.")
    except Exception as e:
        logging.error("Failed to get data for %s: %s", ip, e, exc_info=True)
        return HTTPException(500, "Failed to get upstream data.")
    return data


@app.get("/")
async def ip(
    request: Request,
    X_Forwarded_For: str = Header(None),
    User_Agent: str = Header("Mozilla/5.0"),
    lookup: str = Query(None),
):
    if lookup:
        ip = lookup
    elif X_Forwarded_For:
        ip = X_Forwarded_For
    else:
        ip = request.client.host

    logging.info("looking up IP info for %s", ip)
    data = await make_request(
        ip,
        {"User-Agent": User_Agent}
    )
    if isinstance(data, HTTPException):
        raise data
    data["ip"] = ip
    data.pop("legalese", None)
    data.pop("source", None)
    data.pop("brexitRequired", None)
    logging.info("%s -> %r", ip, data)
    app.state.cache[ip] = [data, time.time()]
    return JSONResponse(data)


@app.get("/lookup")
async def lookup(ip: str = Query(...), User_Agent: str = Header("Mozilla/5.0")):
    if ip in app.state.cache:
        data, timestamp = app.state.cache[ip]
        if time.time() - timestamp < 3600:
            logging.info("cache hit for %s", ip)
            return JSONResponse(data)
        logging.info("cache expired for %s", ip)

    logging.info("looking up IP info for %s", ip)
    data = await make_request(
        ip,
        {"User-Agent": User_Agent}
    )
    if isinstance(data, HTTPException):
        raise data
    data["ip"] = ip
    data.pop("legalese", None)
    data.pop("source", None)
    data.pop("brexitRequired", None)
    logging.info("%s -> %r", ip, data)
    app.state.cache[ip] = [data, time.time()]
    return JSONResponse(data)


@app.get("/imfeelinglucky")
async def im_feeling_lucky(req: Request):
    host = req.client.host
    if host.count(".") != 3:
        raise HTTPException(400, "IPv4 only endpoint.")

    data = await make_request(host, {"User-Agent": "Mozilla/5.0 Nex/19.04.2024"})
    if not isinstance(data, dict):
        raise data
    data = data.copy()

    parts = list(map(int, host.split(".")))
    n = random.randint(1, 1000)
    if n in range(50, 54):
        if n > 400:
            parts[n % 4] += 1
        else:
            parts[n % 4] -= 1
    data["ip"] = ".".join(map(str, parts))
    return JSONResponse(data)


@app.get("/raw")
def get_raw(req: Request):
    return PlainTextResponse(req.client.host)


@app.get("/health")
async def get_health():
    detail = {"issues": []}
    if app.state.meta.waiting >= 2048:
        detail["status"] = "critical"
        detail["issues"].append("(C) Connection pool full.")
    elif app.state.meta.waiting >= 1024:
        detail["status"] = "warning"
        detail["issues"].append("(W) TCP pool half full.")
    else:
        detail["status"] = "ok"

    try:
        t = time.perf_counter()
        async with app.state.session.get("/") as response:
            await response.text()
        detail["latency"] = time.perf_counter() - t
    except Exception as e:
        detail["issues"].append(f"(E) Failed to check upstream: {e}")
        detail["status"] = "critical"

    return JSONResponse(detail)