# PATH: bot/integrations/http.py
import ssl
import json as _json
from typing import Any, Dict, Optional, Tuple, List
from urllib.parse import urlparse, urlunparse

import httpx


_DEFAULT_TIMEOUT = httpx.Timeout(20.0, connect=10.0)

_client: Optional[httpx.AsyncClient] = None
_client_insecure: Optional[httpx.AsyncClient] = None


def get_client() -> httpx.AsyncClient:
    global _client
    if _client is None:
        _client = httpx.AsyncClient(
            timeout=_DEFAULT_TIMEOUT,
            follow_redirects=True,
            http2=True,
        )
    return _client


def get_client_insecure() -> httpx.AsyncClient:
    """
    Insecure client used only for IP fallback (TLS verify off),
    because we connect to https://<IP> with Host header.
    """
    global _client_insecure
    if _client_insecure is None:
        _client_insecure = httpx.AsyncClient(
            timeout=_DEFAULT_TIMEOUT,
            follow_redirects=True,
            http2=True,
            verify=False,
        )
    return _client_insecure


def _is_dns_error(e: Exception) -> bool:
    s = str(e).lower()
    return ("no address associated with hostname" in s) or ("gaierror" in s) or ("name or service not known" in s)


async def doh_resolve_a(host: str) -> List[str]:
    """
    Resolve A records via DNS-over-HTTPS.
    Uses dns.google (since google.com resolves fine in your env).
    """
    c = get_client()
    try:
        r = await c.get("https://dns.google/resolve", params={"name": host, "type": "A"})
        if r.status_code != 200:
            return []
        j = r.json()
        ans = j.get("Answer") or []
        ips = []
        for a in ans:
            if a.get("type") == 1 and a.get("data"):
                ips.append(str(a["data"]))
        # unique keep order
        out = []
        for ip in ips:
            if ip not in out:
                out.append(ip)
        return out
    except Exception:
        return []


def _split_url(url: str) -> Tuple[str, str, str]:
    """
    Returns (scheme, host, rest(path+query+fragment))
    """
    u = urlparse(url)
    scheme = u.scheme or "https"
    host = u.netloc
    rest = urlunparse(("", "", u.path or "/", u.params, u.query, u.fragment))
    return scheme, host, rest


async def fetch_status(url: str) -> str:
    """
    Returns status code as string, or ERR:...
    Uses same DNS fallback logic.
    """
    try:
        r = await request_text("GET", url)
        return str(r[0])
    except Exception as e:
        return f"ERR:{type(e).__name__}:{e}"


async def request_text(method: str, url: str, headers: Optional[Dict[str, str]] = None) -> Tuple[int, str]:
    """
    Low-level text request with DNS fallback.
    Returns (status_code, text)
    """
    headers = dict(headers or {})
    c = get_client()
    try:
        r = await c.request(method, url, headers=headers)
        return r.status_code, r.text
    except Exception as e:
        # DNS fail -> DoH fallback
        if not _is_dns_error(e):
            raise

        scheme, host, rest = _split_url(url)
        if not host:
            raise

        ips = await doh_resolve_a(host)
        if not ips:
            raise

        ic = get_client_insecure()
        last_err = e
        for ip in ips:
            try:
                # connect to IP but keep routing via Host header
                h2 = dict(headers)
                h2["Host"] = host
                r = await ic.request(method, f"{scheme}://{ip}{rest}", headers=h2)
                return r.status_code, r.text
            except Exception as e2:
                last_err = e2
                continue
        raise last_err


async def post_json(url: str, headers: Optional[Dict[str, str]] = None, payload: Optional[Dict[str, Any]] = None) -> Dict[str, Any]:
    """
    POST JSON helper with DNS fallback.
    Returns dict: {ok, status, data?, err?}
    """
    headers = dict(headers or {})
    headers.setdefault("Content-Type", "application/json")

    c = get_client()
    payload = payload or {}

    try:
        r = await c.post(url, headers=headers, json=payload)
        try:
            data = r.json()
        except Exception:
            data = {"raw": r.text}
        return {"ok": r.status_code < 400, "status": r.status_code, "data": data}
    except Exception as e:
        if not _is_dns_error(e):
            return {"ok": False, "status": 0, "err": str(e)}

        # DNS fail -> DoH -> IP fallback (verify off + Host header)
        scheme, host, rest = _split_url(url)
        if not host:
            return {"ok": False, "status": 0, "err": str(e)}

        ips = await doh_resolve_a(host)
        if not ips:
            return {"ok": False, "status": 0, "err": str(e)}

        ic = get_client_insecure()
        last_err: Exception = e
        for ip in ips:
            try:
                h2 = dict(headers)
                h2["Host"] = host
                r = await ic.post(f"{scheme}://{ip}{rest}", headers=h2, json=payload)
                try:
                    data = r.json()
                except Exception:
                    data = {"raw": r.text}
                return {"ok": r.status_code < 400, "status": r.status_code, "data": data}
            except Exception as e2:
                last_err = e2
                continue

        return {"ok": False, "status": 0, "err": str(last_err)}