"""Redis-backed counters, recent links and request lifecycle hooks."""
import redis
import socket
import time
import json
from datetime import datetime
from functools import wraps
from urllib.parse import quote
from flask import request, Response, g
import config

def build_redis():
    if config.REDIS_URL:
        return redis.Redis.from_url(config.REDIS_URL)
    return redis.Redis(
        host=config.REDIS_HOST, port=config.REDIS_PORT, db=config.REDIS_DB
    )

redis_client = build_redis()


def get_client_ip():
    xff = request.headers.get("X-Forwarded-For", "").split(",")
    if xff and xff[0].strip():
        return xff[0].strip()
    return request.remote_addr

def track_request_data():
    g.start_time = time.perf_counter()
    redis_client.incr(
        f"stats:user_agents:{quote(request.headers.get('User-Agent', 'Unknown'), safe='')}"
    )
    redis_client.incr(f"stats:client_ips:{get_client_ip()}")
    redis_client.incr(f"stats:methods:{request.method}")

def finalize_response(response):
    elapsed = time.perf_counter() - getattr(g, "start_time", time.perf_counter())
    redis_client.incrbyfloat("stats:processing_time_total", elapsed)
    redis_client.incr("stats:processing_time_count")
    try:
        current_min = float(redis_client.get("stats:processing_time_min") or elapsed)
        if elapsed < current_min:
            redis_client.set("stats:processing_time_min", elapsed)
    except Exception:
        redis_client.set("stats:processing_time_min", elapsed)
    try:
        current_max = float(redis_client.get("stats:processing_time_max") or elapsed)
        if elapsed > current_max:
            redis_client.set("stats:processing_time_max", elapsed)
    except Exception:
        redis_client.set("stats:processing_time_max", elapsed)

    path = request.path or "/"

    if response.status_code >= 400:
        response.headers["Cache-Control"] = "no-store"
        return response

    if path.startswith("/static/"):
        response.headers.pop("Content-Disposition", None)
        # Only versioned assets are immutable. Unversioned files must not stay stale after upgrades.
        if request.args.get("v"):
            response.headers["Cache-Control"] = "public, max-age=31536000, immutable"
        else:
            response.headers["Cache-Control"] = "public, max-age=3600"
        return response

    if path in {"/", "/stats", "/stats.json"}:
        # Only validated /convert outputs are public cache objects.
        response.headers["Cache-Control"] = "private, no-store"
        return response

    return response

def datetimeformat_filter(value, format="%Y-%m-%d %H:%M"):
    try:
        dt = datetime.fromisoformat(value)
        return dt.strftime(format)
    except (ValueError, AttributeError):
        return value

def basic_auth_required(realm: str, user: str, password: str):
    def decorator(f):
        @wraps(f)
        def wrapper(*args, **kwargs):
            if not config.STATS_BASIC_AUTH_ENABLED:
                return f(*args, **kwargs)

            auth = request.authorization

            if (
                auth
                and auth.type == "basic"
                and auth.username == user
                and auth.password == password
            ):
                return f(*args, **kwargs)

            resp = Response(status=401)
            resp.headers["WWW-Authenticate"] = f'Basic realm="{realm}"'
            return resp

        return wrapper

    return decorator

def track_url_request(url):
    redis_client.incr(f"stats:url_requests:{quote(url, safe='')}")

def add_recent_link(url, target_ip):
    ts = datetime.now().isoformat()
    new_item = f"{ts}|{url}|{target_ip}"
    key = "recent_links"

    current = redis_client.lrange(key, 0, -1)
    filtered = []
    for raw in current:
        try:
            s = raw.decode()
            parts = s.split("|")
            if len(parts) >= 3 and parts[1] == url and parts[2] == target_ip:
                continue
        except Exception:
            pass
        filtered.append(raw)

    with redis_client.pipeline() as pipe:
        pipe.delete(key)
        pipe.lpush(key, new_item)
        if filtered:
            pipe.rpush(key, *filtered[:99])
        pipe.ltrim(key, 0, 99)
        pipe.execute()

    redis_client.incr("stats:recent_links_added")

def get_recent_links():
    links = redis_client.lrange("recent_links", 0, 99)
    out = []
    for link in links:
        parts = link.decode().split("|")
        if len(parts) >= 3:
            out.append((parts[0], parts[1], parts[2]))
        elif len(parts) == 2:
            out.append((parts[0], parts[1], "127.0.0.1"))
    return out

def get_hostname(ip):
    key = f"reverse_dns:{ip}"
    cached = redis_client.get(key)
    if cached:
        return cached.decode()
    try:
        hostname = socket.gethostbyaddr(ip)[0]
    except Exception:
        hostname = ip
    redis_client.setex(key, 3600, hostname)
    return hostname

def add_recent_convert():
    ip = get_client_ip()
    hostname = get_hostname(ip)
    ua = request.headers.get("User-Agent", "Unknown")
    time_str = datetime.now().astimezone().isoformat()
    url = request.full_path
    data = {
        "url": url,
        "ip": ip,
        "hostname": hostname,
        "time": time_str,
        "user_agent": ua,
    }
    redis_client.lpush("recent_converts", json.dumps(data))
    redis_client.ltrim("recent_converts", 0, 99)