import httpx
from fastapi import FastAPI, Request, HTTPException
from starlette.responses import StreamingResponse, JSONResponse
from starlette.background import BackgroundTask
import os
import random
import logging
import time
import asyncio
from contextlib import asynccontextmanager

# --- Production-Ready Configuration ---
LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO").upper()
logging.basicConfig(
    level=LOG_LEVEL,
    format='%(asctime)s - %(levelname)s - %(message)s'
)

TARGET_URL = os.getenv("TARGET_URL", "https://gpt4free.pro")
MAX_RETRIES = int(os.getenv("MAX_RETRIES", "15"))
DEFAULT_RETRY_CODES = "429,500,502,503,504"
RETRY_CODES_STR = os.getenv("RETRY_CODES", DEFAULT_RETRY_CODES)

try:
    RETRY_STATUS_CODES = {int(code.strip()) for code in RETRY_CODES_STR.split(',')}
    logging.info(f"Will retry on the following status codes: {RETRY_STATUS_CODES}")
except ValueError:
    logging.error(f"Invalid RETRY_CODES format: '{RETRY_CODES_STR}'. Falling back to default: {DEFAULT_RETRY_CODES}")
    RETRY_STATUS_CODES = {int(code.strip()) for code in DEFAULT_RETRY_CODES.split(',')}

# --- Randomization Helpers ---
USER_AGENTS = [
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36",
    "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36",
    "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36",
    "Mozilla/5.0 (iPhone; CPU iPhone OS 15_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.0 Mobile/15E148 Safari/604.1",
]

def generate_random_ip():
    """Generates a random, valid-looking IPv4 address."""
    return ".".join(str(random.randint(1, 254)) for _ in range(4))

# --- HTTPX Client Lifecycle Management ---
@asynccontextmanager
async def lifespan(app: FastAPI):
    """Manages the lifecycle of the HTTPX client."""
    async with httpx.AsyncClient(base_url=TARGET_URL, timeout=None) as client:
        app.state.http_client = client
        yield

# Initialize the FastAPI app
app = FastAPI(docs_url=None, redoc_url=None, lifespan=lifespan)

# --- API Endpoints ---
@app.get("/")
async def health_check():
    """Provides a basic health check endpoint."""
    return JSONResponse({"status": "ok", "target": TARGET_URL})

@app.api_route("/{full_path:path}", methods=["GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS", "HEAD"])
async def reverse_proxy_handler(request: Request):
    """
    A catch-all reverse proxy that forwards requests to the target URL
    with enhanced retry logic, IP spoofing, and randomized headers.
    """
    start_time = time.monotonic()
    client: httpx.AsyncClient = request.app.state.http_client
    url = httpx.URL(path=request.url.path, query=request.url.query.encode("utf-8"))
    request_headers = dict(request.headers)
    request_headers.pop("host", None)

    # --- Enhanced Spoofing ---
    random_ip = generate_random_ip()
    specific_headers = {
        "user-agent": random.choice(USER_AGENTS),
        "x-forwarded-for": random_ip,
        "x-real-ip": random_ip,
        "x-client-ip": random_ip,
        "x-originating-ip": random_ip,
        "x-remote-ip": random_ip,
        "x-remote-addr": random_ip,
        "x-host": random_ip,
        "x-forwarded-host": random_ip,
        "cf-connecting-ip": random_ip,
        "true-client-ip": random_ip,
        "client-ip": random_ip,
        "via": f"1.1 {random_ip}",
        "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
        "accept-language": "en-US,en;q=0.5",
        "referer": "https://www.google.com/",
        "dnt": "1",
        "upgrade-insecure-requests": "1",
    }

    if "authorization" in request.headers:
        specific_headers["authorization"] = request.headers["authorization"]

    request_headers.update(specific_headers)
    body = await request.body()
    last_exception = None

    for attempt in range(MAX_RETRIES):
        try:
            rp_req = client.build_request(
                method=request.method,
                url=url,
                headers=request_headers,
                content=body
            )
            rp_resp = await client.send(rp_req, stream=True)

            if rp_resp.status_code not in RETRY_STATUS_CODES or attempt == MAX_RETRIES - 1:
                duration_ms = (time.monotonic() - start_time) * 1000
                log_func = logging.info if rp_resp.is_success else logging.warning
                log_func(
                    f"Request finished: {request.method} {request.url.path} "
                    f"status_code={rp_resp.status_code} latency={duration_ms:.2f}ms"
                )
                return StreamingResponse(
                    rp_resp.aiter_raw(),
                    status_code=rp_resp.status_code,
                    headers=rp_resp.headers,
                    background=BackgroundTask(rp_resp.aclose),
                )

            logging.warning(
                f"Attempt {attempt + 1}/{MAX_RETRIES} for {url.path} "
                f"failed with status {rp_resp.status_code}. Retrying..."
            )
            await rp_resp.aclose()
            await asyncio.sleep(random.uniform(0.5, 2.0))  # Random delay between retries

        except httpx.ConnectError as e:
            last_exception = e
            logging.warning(
                f"Attempt {attempt + 1}/{MAX_RETRIES} for {url.path} "
                f"failed with connection error: {e}"
            )
            await asyncio.sleep(random.uniform(1.0, 3.0))  # Longer delay on connection errors

    duration_ms = (time.monotonic() - start_time) * 1000
    logging.critical(
        f"Request failed, cannot connect to target: "
        f"{request.method} {request.url.path} status_code=502 latency={duration_ms:.2f}ms"
    )

    raise HTTPException(
        status_code=502,
        detail=f"Bad Gateway: Cannot connect to target service after {MAX_RETRIES} attempts. {last_exception}"
    )

# --- Run the app (for testing) ---
if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)