from __future__ import annotations

import asyncio
import json
import logging
import time
from typing import Callable

import httpx

log = logging.getLogger(__name__)

# Secondary fallback endpoints for IP resolution
_IP_FALLBACKS = [
    "https://api.ipify.org?format=json",
    "https://httpbin.org/ip",
    "https://ifconfig.me/ip",
]


def _parse_ip(text: str) -> str | None:
    """Parse an IP string from JSON or plain-text response body."""
    body = text.strip()
    if not body:
        return None
    if body.startswith("{"):
        try:
            d = json.loads(body)
            ip = d.get("ip") or d.get("origin") or d.get("query")
            return str(ip).split(",")[0].strip() if ip else None
        except Exception:
            return None
    # Plain-text: must look like an IP (short, no HTML)
    if len(body) < 50 and "<" not in body:
        candidate = body.split()[0].strip()
        if candidate.count(".") >= 3 or ":" in candidate:
            return candidate
    return None


async def validate_proxies(
    proxy_urls: list[str],
    check_url: str,
    concurrency: int,
    timeout_seconds: float,
    on_progress: Callable[[int, int], None] | None = None,
) -> list[str]:
    if not proxy_urls:
        return []
    sem = asyncio.Semaphore(max(1, concurrency))
    ok: list[str] = []
    lock = asyncio.Lock()
    total = len(proxy_urls)
    done = 0
    c = max(1, concurrency)
    waves = (total + c - 1) // c
    cap = min(600.0, float(waves) * float(timeout_seconds) + 45.0)
    cap = max(90.0, cap)
    log.info(
        "validate_proxies: n=%d concurrency=%d per_timeout=%.1fs wall_cap~=%.0fs check=%s",
        total,
        c,
        timeout_seconds,
        cap,
        (check_url[:70] + "…") if len(check_url) > 70 else check_url,
    )

    t = httpx.Timeout(timeout_seconds, connect=min(8.0, timeout_seconds))
    lim = max(32, min(256, c * 8))
    limits = httpx.Limits(max_connections=lim, max_keepalive_connections=max(16, c * 4))

    last_prog_t = 0.0
    prog_step = max(1, total // 120)

    async def _run_all(client: httpx.AsyncClient) -> None:
        nonlocal done, last_prog_t

        async def one(u: str) -> None:
            nonlocal done, last_prog_t
            async with sem:
                try:
                    r = await client.get(check_url, proxy=u)
                    good = r.status_code == 200 and len(r.content) > 0
                except Exception:
                    good = False
            async with lock:
                done += 1
                if good:
                    ok.append(u)
                if on_progress:
                    now = time.monotonic()
                    if (
                        done == total
                        or done == 1
                        or done % prog_step == 0
                        or (now - last_prog_t) >= 0.1
                    ):
                        last_prog_t = now
                        on_progress(done, total)

        await asyncio.gather(*(one(u) for u in proxy_urls))

    try:
        async with httpx.AsyncClient(
            timeout=t,
            verify=False,
            follow_redirects=True,
            limits=limits,
        ) as client:
            await asyncio.wait_for(_run_all(client), timeout=cap)
    except asyncio.TimeoutError:
        log.warning(
            "validate_proxies wall-clock cap %.0fs exceeded (%d URLs) — returning partial results",
            cap,
            total,
        )
    log.info("validate_proxies: finished ok=%d / %d", len(ok), total)
    return ok


async def check_chain_exit_ip(
    listen_proxy: str,
    check_url: str,
    timeout_seconds: float,
) -> str | None:
    """Query the IP-check URL through the local chain proxy.
    Bounded total time — never stacks one slow request per fallback URL forever."""
    per = max(5.0, min(20.0, float(timeout_seconds)))
    budget = max(15.0, min(60.0, float(timeout_seconds) * 2 + 5.0))
    urls = [check_url] + [u for u in _IP_FALLBACKS if u != check_url][:2]
    log.debug(
        "check_chain_exit_ip: budget=%.1fs per_req=%.1fs fallback_count=%d",
        budget,
        per,
        len(urls),
    )

    async def _run() -> str | None:
        t = httpx.Timeout(per, connect=min(8.0, per))
        try:
            async with httpx.AsyncClient(
                proxy=listen_proxy,
                timeout=t,
                verify=False,
                follow_redirects=True,
            ) as c:
                for url in urls:
                    try:
                        r = await c.get(url)
                        if r.status_code == 200:
                            ip = _parse_ip(r.text)
                            if ip:
                                return ip
                    except Exception:
                        continue
        except Exception:
            pass
        return None

    try:
        return await asyncio.wait_for(_run(), timeout=budget)
    except asyncio.TimeoutError:
        log.debug("check_chain_exit_ip timed out after %.1fs", budget)
        return None


async def get_direct_ip(check_url: str, timeout_seconds: float = 15.0) -> str | None:
    """Get our own exit IP without the proxy chain (so we can compare)."""
    per = max(5.0, min(15.0, float(timeout_seconds)))
    budget = max(12.0, min(45.0, float(timeout_seconds) * 2))
    urls = [check_url] + [u for u in _IP_FALLBACKS if u != check_url][:2]

    async def _run() -> str | None:
        t = httpx.Timeout(per)
        try:
            async with httpx.AsyncClient(
                timeout=t,
                verify=False,
                follow_redirects=True,
            ) as c:
                for url in urls:
                    try:
                        r = await c.get(url)
                        if r.status_code == 200:
                            ip = _parse_ip(r.text)
                            if ip:
                                return ip
                    except Exception:
                        continue
        except Exception:
            pass
        return None

    try:
        return await asyncio.wait_for(_run(), timeout=budget)
    except asyncio.TimeoutError:
        log.debug("get_direct_ip timed out after %.1fs", budget)
        return None