from __future__ import annotations

import json
import os
import re
import time
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Dict, Optional, Tuple

import jwt
import psycopg2
import psycopg2.pool
import requests
from dotenv import load_dotenv
from flask import Flask, Response, jsonify, request, send_from_directory
from flask_cors import CORS


load_dotenv()


def env(name: str, default: str = "") -> str:
    return str(os.getenv(name, default))


_IDENT_RE = re.compile(r"^[a-zA-Z_][a-zA-Z0-9_]*$")


def safe_ident(s: str) -> str:
    v = str(s or "").strip()
    if not _IDENT_RE.match(v):
        raise RuntimeError("Invalid TABLE identifier")
    return v


def parse_csv(s: str) -> list[str]:
    return [x.strip() for x in str(s or "").split(",") if x.strip()]


def parse_email_csv(s: str) -> list[str]:
    return [x.lower() for x in parse_csv(s)]


PORT = int(env("PORT", "8023") or "8023")

DB_HOST = env("DB_HOST", "").strip()
DB_PORT = int(env("DB_PORT", "5432") or "5432")
DB_NAME = env("DB_NAME", "").strip()
DB_USER = env("DB_USER", "").strip()
DB_PASSWORD = env("DB_PASSWORD", "").strip()
DB_SSLMODE = env("DB_SSLMODE", "prefer").strip() or "prefer"
DB_CONNECT_TIMEOUT = int(env("DB_CONNECT_TIMEOUT", "5") or "5")

TABLE = safe_ident(env("TABLE", "ncue_user") or "ncue_user")
CONFIG_TABLE = "ncue_app_config"
CONFIG_TOKEN = env("CONFIG_TOKEN", "").strip()

ADMIN_EMAILS = set(parse_email_csv(env("ADMIN_EMAILS", "dosangyoon@gmail.com,dsyoon@ncue.net")))

# Auth0 config via .env (preferred)
AUTH0_DOMAIN = env("AUTH0_DOMAIN", "").strip()
AUTH0_CLIENT_ID = env("AUTH0_CLIENT_ID", "").strip()
AUTH0_GOOGLE_CONNECTION = env("AUTH0_GOOGLE_CONNECTION", "").strip()

# Optional CORS (for static on different origin)
CORS_ORIGINS = env("CORS_ORIGINS", "*").strip() or "*"

_POOL: Optional[psycopg2.pool.SimpleConnectionPool] = None


def db_configured() -> bool:
    return bool(DB_HOST and DB_NAME and DB_USER and DB_PASSWORD)


def get_pool() -> psycopg2.pool.SimpleConnectionPool:
    """
    Lazy DB pool creation.
    - prevents app import failure (which causes Apache 503) when DB is temporarily unavailable
    - /api/config/auth can still work purely from .env without DB
    """
    global _POOL
    if _POOL is not None:
        return _POOL
    if not db_configured():
        raise RuntimeError("db_not_configured")
    _POOL = psycopg2.pool.SimpleConnectionPool(
        minconn=1,
        maxconn=10,
        host=DB_HOST,
        port=DB_PORT,
        dbname=DB_NAME,
        user=DB_USER,
        password=DB_PASSWORD,
        sslmode=DB_SSLMODE,
        connect_timeout=DB_CONNECT_TIMEOUT,
    )
    return _POOL


def db_exec(sql: str, params: Tuple[Any, ...] = ()) -> None:
    pool = get_pool()
    conn = pool.getconn()
    try:
        conn.autocommit = True
        with conn.cursor() as cur:
            cur.execute(sql, params)
    finally:
        pool.putconn(conn)


def db_one(sql: str, params: Tuple[Any, ...] = ()) -> Optional[tuple]:
    pool = get_pool()
    conn = pool.getconn()
    try:
        conn.autocommit = True
        with conn.cursor() as cur:
            cur.execute(sql, params)
            row = cur.fetchone()
            return row
    finally:
        pool.putconn(conn)


def ensure_user_table() -> None:
    db_exec(
        f"""
        create table if not exists public.{TABLE} (
          sub            text primary key,
          email          text,
          name           text,
          picture        text,
          provider       text,
          first_login_at timestamptz,
          last_login_at  timestamptz,
          last_logout_at timestamptz,
          can_manage     boolean not null default false,
          created_at     timestamptz not null default now(),
          updated_at     timestamptz not null default now()
        )
        """
    )
    db_exec(f"create index if not exists idx_{TABLE}_email on public.{TABLE} (email)")
    db_exec(f"alter table public.{TABLE} add column if not exists first_login_at timestamptz")
    db_exec(f"alter table public.{TABLE} add column if not exists last_logout_at timestamptz")


def ensure_config_table() -> None:
    db_exec(
        f"""
        create table if not exists public.{CONFIG_TABLE} (
          key        text primary key,
          value      jsonb not null,
          updated_at timestamptz not null default now()
        )
        """
    )


def is_admin_email(email: str) -> bool:
    e = str(email or "").strip().lower()
    return e in ADMIN_EMAILS


def bearer_token() -> str:
    h = request.headers.get("Authorization", "")
    m = re.match(r"^Bearer\s+(.+)$", h, flags=re.IGNORECASE)
    return m.group(1).strip() if m else ""


@dataclass(frozen=True)
class JwksCacheEntry:
    jwks_url: str
    fetched_at: float
    keys: dict


_JWKS_CACHE: Dict[str, JwksCacheEntry] = {}
_JWKS_TTL_SECONDS = 60 * 15


def _jwks_url(issuer: str) -> str:
    iss = issuer.rstrip("/") + "/"
    return iss + ".well-known/jwks.json"


def fetch_jwks(issuer: str) -> dict:
    url = _jwks_url(issuer)
    now = time.time()
    cached = _JWKS_CACHE.get(url)
    if cached and (now - cached.fetched_at) < _JWKS_TTL_SECONDS:
        return cached.keys

    r = requests.get(url, timeout=5)
    r.raise_for_status()
    keys = r.json()
    if not isinstance(keys, dict) or "keys" not in keys:
        raise RuntimeError("invalid_jwks")
    _JWKS_CACHE[url] = JwksCacheEntry(jwks_url=url, fetched_at=now, keys=keys)
    return keys


def verify_id_token(id_token: str, issuer: str, audience: str) -> dict:
    # 1) read header -> kid
    header = jwt.get_unverified_header(id_token)
    kid = header.get("kid")
    if not kid:
        raise RuntimeError("missing_kid")

    jwks = fetch_jwks(issuer)
    key = None
    for k in jwks.get("keys", []):
        if k.get("kid") == kid:
            key = k
            break
    if not key:
        raise RuntimeError("kid_not_found")

    public_key = jwt.algorithms.RSAAlgorithm.from_jwk(json.dumps(key))
    payload = jwt.decode(
        id_token,
        key=public_key,
        algorithms=["RS256"],
        audience=audience,
        issuer=issuer.rstrip("/") + "/",
        options={"require": ["exp", "iat", "iss", "aud", "sub"]},
    )
    if not isinstance(payload, dict):
        raise RuntimeError("invalid_payload")
    return payload


ROOT_DIR = Path(__file__).resolve().parent

app = Flask(__name__)

if CORS_ORIGINS:
    origins = CORS_ORIGINS if CORS_ORIGINS == "*" else [o.strip() for o in CORS_ORIGINS.split(",") if o.strip()]
    CORS(app, resources={r"/api/*": {"origins": origins}})


ALLOWED_STATIC = {
    "index.html",
    "styles.css",
    "script.js",
    "links.json",
    "favicon.ico",
}


@app.get("/")
def home() -> Response:
    return send_from_directory(ROOT_DIR, "index.html")


@app.get("/<path:filename>")
def static_files(filename: str) -> Response:
    # Prevent exposing .env etc. Serve only allowlisted files.
    if filename not in ALLOWED_STATIC:
        return jsonify({"ok": False, "error": "not_found"}), 404
    return send_from_directory(ROOT_DIR, filename)


@app.get("/healthz")
def healthz() -> Response:
    try:
        if not db_configured():
            return jsonify({"ok": False, "error": "db_not_configured"}), 500
        row = db_one("select 1 as ok")
        if not row:
            return jsonify({"ok": False}), 500
        return jsonify({"ok": True})
    except Exception:
        # Keep response minimal but actionable
        return jsonify({"ok": False, "error": "db_connect_failed"}), 500


@app.post("/api/auth/sync")
def api_auth_sync() -> Response:
    try:
        if not db_configured():
            return jsonify({"ok": False, "error": "db_not_configured"}), 500
        ensure_user_table()
        id_token = bearer_token()
        if not id_token:
            return jsonify({"ok": False, "error": "missing_token"}), 401

        issuer = str(request.headers.get("X-Auth0-Issuer", "")).strip()
        audience = str(request.headers.get("X-Auth0-ClientId", "")).strip()
        if not issuer or not audience:
            return jsonify({"ok": False, "error": "missing_auth0_headers"}), 400

        payload = verify_id_token(id_token, issuer=issuer, audience=audience)

        sub = str(payload.get("sub") or "").strip()
        email = (str(payload.get("email")).strip().lower() if payload.get("email") else None)
        name = (str(payload.get("name")).strip() if payload.get("name") else None)
        picture = (str(payload.get("picture")).strip() if payload.get("picture") else None)
        provider = sub.split("|", 1)[0] if "|" in sub else None
        admin = bool(email and is_admin_email(email))

        if not sub:
            return jsonify({"ok": False, "error": "missing_sub"}), 400

        sql = f"""
          insert into public.{TABLE}
            (sub, email, name, picture, provider, first_login_at, last_login_at, can_manage, updated_at)
          values
            (%s, %s, %s, %s, %s, now(), now(), %s, now())
          on conflict (sub) do update set
            email = excluded.email,
            name = excluded.name,
            picture = excluded.picture,
            provider = excluded.provider,
            first_login_at = coalesce(public.{TABLE}.first_login_at, excluded.first_login_at),
            last_login_at = now(),
            can_manage = (public.{TABLE}.can_manage or %s),
            updated_at = now()
          returning can_manage, first_login_at, last_login_at, last_logout_at
        """

        row = db_one(sql, (sub, email, name, picture, provider, admin, admin))
        can_manage = bool(row[0]) if row else False
        user = (
            {
                "can_manage": can_manage,
                "first_login_at": row[1],
                "last_login_at": row[2],
                "last_logout_at": row[3],
            }
            if row
            else None
        )
        return jsonify({"ok": True, "canManage": can_manage, "user": user})
    except Exception:
        return jsonify({"ok": False, "error": "verify_failed"}), 401


@app.post("/api/auth/logout")
def api_auth_logout() -> Response:
    try:
        if not db_configured():
            return jsonify({"ok": False, "error": "db_not_configured"}), 500
        ensure_user_table()
        id_token = bearer_token()
        if not id_token:
            return jsonify({"ok": False, "error": "missing_token"}), 401

        issuer = str(request.headers.get("X-Auth0-Issuer", "")).strip()
        audience = str(request.headers.get("X-Auth0-ClientId", "")).strip()
        if not issuer or not audience:
            return jsonify({"ok": False, "error": "missing_auth0_headers"}), 400

        payload = verify_id_token(id_token, issuer=issuer, audience=audience)
        sub = str(payload.get("sub") or "").strip()
        if not sub:
            return jsonify({"ok": False, "error": "missing_sub"}), 400

        sql = f"""
          update public.{TABLE}
          set last_logout_at = now(),
              updated_at = now()
          where sub = %s
          returning last_logout_at
        """
        row = db_one(sql, (sub,))
        return jsonify({"ok": True, "last_logout_at": row[0] if row else None})
    except Exception:
        return jsonify({"ok": False, "error": "verify_failed"}), 401


@app.get("/api/config/auth")
def api_config_auth_get() -> Response:
    try:
        # Prefer .env config (no UI needed)
        if AUTH0_DOMAIN and AUTH0_CLIENT_ID and AUTH0_GOOGLE_CONNECTION:
            return jsonify(
                {
                    "ok": True,
                    "value": {
                        "auth0": {"domain": AUTH0_DOMAIN, "clientId": AUTH0_CLIENT_ID},
                        "connections": {"google": AUTH0_GOOGLE_CONNECTION},
                        "adminEmails": sorted(list(ADMIN_EMAILS)),
                    },
                    "updated_at": None,
                    "source": "env",
                }
            )

        if not db_configured():
            return jsonify({"ok": False, "error": "not_set"}), 404
        ensure_config_table()
        row = db_one(f"select value, updated_at from public.{CONFIG_TABLE} where key = %s", ("auth",))
        if not row:
            return jsonify({"ok": False, "error": "not_set"}), 404

        value = row[0] or {}
        if isinstance(value, str):
            value = json.loads(value)

        if isinstance(value, dict) and "adminEmails" not in value and isinstance(value.get("allowedEmails"), list):
            value["adminEmails"] = value.get("allowedEmails")

        return jsonify({"ok": True, "value": value, "updated_at": row[1], "source": "db"})
    except Exception:
        return jsonify({"ok": False, "error": "server_error"}), 500


@app.post("/api/config/auth")
def api_config_auth_post() -> Response:
    try:
        if not db_configured():
            return jsonify({"ok": False, "error": "db_not_configured"}), 500
        ensure_config_table()
        if not CONFIG_TOKEN:
            return jsonify({"ok": False, "error": "config_token_not_set"}), 403

        token = str(request.headers.get("X-Config-Token", "")).strip()
        if token != CONFIG_TOKEN:
            return jsonify({"ok": False, "error": "forbidden"}), 403

        body = request.get_json(silent=True) or {}
        auth0 = body.get("auth0") or {}
        connections = body.get("connections") or {}

        admin_emails = body.get("adminEmails")
        if not isinstance(admin_emails, list):
            # legacy
            admin_emails = body.get("allowedEmails")
        if not isinstance(admin_emails, list):
            admin_emails = []

        domain = str(auth0.get("domain") or "").strip()
        client_id = str(auth0.get("clientId") or "").strip()
        google_conn = str(connections.get("google") or "").strip()
        emails = [str(x).strip().lower() for x in admin_emails if str(x).strip()]

        if not domain or not client_id or not google_conn:
            return jsonify({"ok": False, "error": "missing_fields"}), 400

        value = {"auth0": {"domain": domain, "clientId": client_id}, "connections": {"google": google_conn}, "adminEmails": emails}

        sql = f"""
          insert into public.{CONFIG_TABLE} (key, value, updated_at)
          values (%s, %s::jsonb, now())
          on conflict (key) do update set value = excluded.value, updated_at = now()
        """
        db_exec(sql, ("auth", json.dumps(value)))
        return jsonify({"ok": True})
    except Exception:
        return jsonify({"ok": False, "error": "server_error"}), 500


if __name__ == "__main__":
    # Production should run behind a reverse proxy (nginx) or gunicorn.
    app.run(host="0.0.0.0", port=PORT, debug=False)