"""Подключение к PostgreSQL и ORM-сессии.

Основная БД — `clinic_tests`.
Опциональная вторая БД — `hr_bot_test` (когда HR_AUTH=1).
"""
from __future__ import annotations

import os
import threading
from typing import Optional

from sqlalchemy import create_engine
from sqlalchemy.engine import Engine
from sqlalchemy.orm import Session, scoped_session, sessionmaker
from sqlalchemy.pool import QueuePool

_engine_lock = threading.Lock()
_session_lock = threading.Lock()
_hr_engine_lock = threading.Lock()

_engine: Optional[Engine] = None
_session_factory: Optional[scoped_session] = None
_hr_engine: Optional[Engine] = None


# ─── URL helpers ─────────────────────────────────────────────────────────────

def get_database_url() -> str:
    if db_url := os.environ.get('DATABASE_URL'):
        return db_url.strip()
    host = os.environ.get('DB_HOST', 'localhost')
    port = os.environ.get('DB_PORT', '5432')
    name = os.environ.get('DB_NAME', 'clinic_tests')
    user = os.environ.get('DB_USER', 'hr_bot_user')
    password = os.environ.get('DB_PASSWORD', 'hrbot123')
    return f'postgresql+psycopg2://{user}:{password}@{host}:{port}/{name}'


def _hr_auth_enabled() -> bool:
    return (os.environ.get('HR_AUTH') or '').strip().lower() in ('1', 'true', 'yes', 'on')


def get_hr_database_url() -> Optional[str]:
    if not _hr_auth_enabled():
        return None
    url = (os.environ.get('HR_DATABASE_URL') or '').strip()
    return url or None


# ─── Main engine ─────────────────────────────────────────────────────────────

def get_engine() -> Engine:
    global _engine
    if _engine is not None:
        return _engine
    with _engine_lock:
        if _engine is None:
            _engine = create_engine(
                get_database_url(),
                poolclass=QueuePool,
                pool_size=5,
                max_overflow=10,
                pool_pre_ping=True,
            )
    return _engine


# ─── Scoped session ──────────────────────────────────────────────────────────

def get_session() -> Session:
    """Возвращает ORM-сессию для текущего потока (scoped_session)."""
    global _session_factory
    if _session_factory is None:
        with _session_lock:
            if _session_factory is None:
                # Инициализируем engine до захвата session_lock, чтобы не было вложенных блокировок
                engine = get_engine()
                _session_factory = scoped_session(
                    sessionmaker(bind=engine, autoflush=True, autocommit=False)
                )
    return _session_factory  # type: ignore[return-value]


def remove_session() -> None:
    """Освобождает сессию для текущего потока. Вызывается в teardown_appcontext."""
    if _session_factory is not None:
        _session_factory.remove()


# ─── HR engine (raw SQL only) ────────────────────────────────────────────────

def get_hr_engine() -> Optional[Engine]:
    if not _hr_auth_enabled():
        return None
    global _hr_engine
    if _hr_engine is not None:
        return _hr_engine
    url = get_hr_database_url()
    if not url:
        return None
    with _hr_engine_lock:
        if _hr_engine is None:
            _hr_engine = create_engine(
                url,
                poolclass=QueuePool,
                pool_size=3,
                max_overflow=5,
                pool_pre_ping=True,
            )
    return _hr_engine


# ─── Smoke check ─────────────────────────────────────────────────────────────

def ping() -> dict:
    out: dict = {'main': 'unknown'}
    try:
        with get_engine().connect() as conn:
            conn.exec_driver_sql('SELECT 1')
        out['main'] = 'ok'
    except Exception as e:
        out['main'] = f'error: {type(e).__name__}: {e}'

    if _hr_auth_enabled():
        out['hr'] = 'unknown'
        try:
            eng = get_hr_engine()
            if eng is None:
                out['hr'] = 'disabled (HR_DATABASE_URL not set)'
            else:
                with eng.connect() as conn:
                    conn.exec_driver_sql('SELECT 1')
                out['hr'] = 'ok'
        except Exception as e:
            out['hr'] = f'error: {type(e).__name__}: {e}'

    return out