"""Database operations for Gandalf network monitor."""
import json
import logging
import threading
from contextlib import contextmanager
from datetime import datetime, timedelta
from typing import Optional

import pymysql
import pymysql.cursors

logger = logging.getLogger(__name__)

_config_cache = None
_local = threading.local()


def _config() -> dict:
    global _config_cache
    if _config_cache is None:
        with open('config.json') as f:
            _config_cache = json.load(f)['database']
    return _config_cache


@contextmanager
def get_conn():
    """Yield a per-thread cached database connection, reconnecting as needed."""
    cfg = _config()
    conn = getattr(_local, 'conn', None)
    if conn is None:
        conn = pymysql.connect(
            host=cfg['host'],
            port=cfg.get('port', 3306),
            user=cfg['user'],
            password=cfg['password'],
            database=cfg['name'],
            autocommit=True,
            cursorclass=pymysql.cursors.DictCursor,
            connect_timeout=10,
            charset='utf8mb4',
        )
        _local.conn = conn
    else:
        conn.ping(reconnect=True)
    yield conn


# ---------------------------------------------------------------------------
# Monitor state (key/value store)
# ---------------------------------------------------------------------------

def set_state(key: str, value) -> None:
    if not isinstance(value, str):
        value = json.dumps(value, default=str)
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """INSERT INTO monitor_state (key_name, value)
                   VALUES (%s, %s)
                   ON DUPLICATE KEY UPDATE value=VALUES(value), updated_at=NOW()""",
                (key, value),
            )


def get_state(key: str, default=None):
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute('SELECT value FROM monitor_state WHERE key_name=%s', (key,))
            row = cur.fetchone()
            return row['value'] if row else default


# ---------------------------------------------------------------------------
# Interface baseline tracking
# ---------------------------------------------------------------------------

def get_baseline() -> dict:
    raw = get_state('interface_baseline')
    if raw:
        try:
            return json.loads(raw)
        except Exception:
            logger.error('Failed to parse interface_baseline JSON; resetting baseline')
    return {}


def set_baseline(baseline: dict) -> None:
    set_state('interface_baseline', json.dumps(baseline))


# ---------------------------------------------------------------------------
# Network events
# ---------------------------------------------------------------------------

def upsert_event(
    event_type: str,
    severity: str,
    source_type: str,
    target_name: str,
    target_detail: str,
    description: str,
) -> tuple:
    """Insert or update a network event. Returns (id, is_new, consecutive_failures)."""
    detail = target_detail or ''
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """SELECT id, consecutive_failures FROM network_events
                   WHERE event_type=%s AND target_name=%s AND target_detail=%s
                   AND resolved_at IS NULL LIMIT 1""",
                (event_type, target_name, detail),
            )
            existing = cur.fetchone()

            if existing:
                new_count = existing['consecutive_failures'] + 1
                cur.execute(
                    """UPDATE network_events
                       SET last_seen=NOW(), consecutive_failures=%s, description=%s
                       WHERE id=%s""",
                    (new_count, description, existing['id']),
                )
                return existing['id'], False, new_count
            else:
                cur.execute(
                    """INSERT INTO network_events
                       (event_type, severity, source_type, target_name, target_detail, description)
                       VALUES (%s, %s, %s, %s, %s, %s)""",
                    (event_type, severity, source_type, target_name, detail, description),
                )
                return cur.lastrowid, True, 1


def resolve_event(event_type: str, target_name: str, target_detail: str = '') -> None:
    detail = target_detail or ''
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """UPDATE network_events SET resolved_at=NOW()
                   WHERE event_type=%s AND target_name=%s AND target_detail=%s
                   AND resolved_at IS NULL""",
                (event_type, target_name, detail),
            )


def set_ticket_id(event_id: int, ticket_id: str) -> None:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                'UPDATE network_events SET ticket_id=%s WHERE id=%s',
                (ticket_id, event_id),
            )


def get_active_events() -> list:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """SELECT * FROM network_events
                   WHERE resolved_at IS NULL
                   ORDER BY
                     FIELD(severity,'critical','warning','info'),
                     first_seen DESC"""
            )
            rows = cur.fetchall()
            for r in rows:
                for k in ('first_seen', 'last_seen'):
                    if r.get(k) and hasattr(r[k], 'isoformat'):
                        r[k] = r[k].isoformat()
            return rows


def get_recent_resolved(hours: int = 24, limit: int = 50) -> list:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """SELECT * FROM network_events
                   WHERE resolved_at IS NOT NULL
                   AND resolved_at > DATE_SUB(NOW(), INTERVAL %s HOUR)
                   ORDER BY resolved_at DESC LIMIT %s""",
                (hours, limit),
            )
            rows = cur.fetchall()
            for r in rows:
                for k in ('first_seen', 'last_seen', 'resolved_at'):
                    if r.get(k) and hasattr(r[k], 'isoformat'):
                        r[k] = r[k].isoformat()
            return rows


def get_status_summary() -> dict:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """SELECT severity, COUNT(*) as cnt FROM network_events
                   WHERE resolved_at IS NULL GROUP BY severity"""
            )
            counts = {r['severity']: r['cnt'] for r in cur.fetchall()}
            return {
                'critical': counts.get('critical', 0),
                'warning': counts.get('warning', 0),
                'info': counts.get('info', 0),
            }


# ---------------------------------------------------------------------------
# Suppression rules
# ---------------------------------------------------------------------------

def get_active_suppressions() -> list:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """SELECT * FROM suppression_rules
                   WHERE active=TRUE AND (expires_at IS NULL OR expires_at > NOW())
                   ORDER BY created_at DESC"""
            )
            rows = cur.fetchall()
            for r in rows:
                for k in ('created_at', 'expires_at'):
                    if r.get(k) and hasattr(r[k], 'isoformat'):
                        r[k] = r[k].isoformat()
            return rows


def get_suppression_history(limit: int = 50) -> list:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                'SELECT * FROM suppression_rules ORDER BY created_at DESC LIMIT %s',
                (limit,),
            )
            rows = cur.fetchall()
            for r in rows:
                for k in ('created_at', 'expires_at'):
                    if r.get(k) and hasattr(r[k], 'isoformat'):
                        r[k] = r[k].isoformat()
            return rows


def create_suppression(
    target_type: str,
    target_name: str,
    target_detail: str,
    reason: str,
    suppressed_by: str,
    expires_minutes: Optional[int] = None,
) -> int:
    expires_at = None
    if expires_minutes:
        expires_at = datetime.utcnow() + timedelta(minutes=int(expires_minutes))
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """INSERT INTO suppression_rules
                   (target_type, target_name, target_detail, reason, suppressed_by, expires_at, active)
                   VALUES (%s, %s, %s, %s, %s, %s, TRUE)""",
                (target_type, target_name or '', target_detail or '', reason, suppressed_by, expires_at),
            )
            return cur.lastrowid


def deactivate_suppression(sup_id: int) -> None:
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                'UPDATE suppression_rules SET active=FALSE WHERE id=%s', (sup_id,)
            )


def cleanup_expired_suppressions() -> int:
    """Mark expired time-limited suppressions as inactive. Returns count deactivated."""
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """UPDATE suppression_rules
                   SET active=FALSE
                   WHERE active=TRUE AND expires_at IS NOT NULL AND expires_at <= NOW()"""
            )
            n = cur.rowcount
    if n:
        logger.info(f'Deactivated {n} expired suppression(s)')
    return n


def purge_old_resolved_events(days: int = 90) -> int:
    """Delete resolved events older than `days` days. Returns count deleted."""
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                """DELETE FROM network_events
                   WHERE resolved_at IS NOT NULL
                   AND resolved_at < DATE_SUB(NOW(), INTERVAL %s DAY)""",
                (days,),
            )
            n = cur.rowcount
    if n:
        logger.info(f'Purged {n} old resolved event(s) (>{days}d)')
    return n


def check_suppressed(suppressions: list, target_type: str, target_name: str, target_detail: str = '') -> bool:
    """Check suppression against a pre-loaded list (avoids per-call DB queries)."""
    for s in suppressions:
        if s['target_type'] == 'all':
            return True
        if s['target_type'] == target_type and s['target_name'] == target_name:
            if not (s.get('target_detail') or ''):
                return True
            if target_detail and s.get('target_detail') == target_detail:
                return True
    return False


def is_suppressed(target_type: str, target_name: str, target_detail: str = '') -> bool:
    with get_conn() as conn:
        with conn.cursor() as cur:
            # Global suppression (all)
            cur.execute(
                """SELECT id FROM suppression_rules
                   WHERE active=TRUE AND (expires_at IS NULL OR expires_at > NOW())
                   AND target_type='all' LIMIT 1"""
            )
            if cur.fetchone():
                return True

            if not target_name:
                return False

            # Host-level suppression (covers all interfaces on that host)
            cur.execute(
                """SELECT id FROM suppression_rules
                   WHERE active=TRUE AND (expires_at IS NULL OR expires_at > NOW())
                   AND target_type=%s AND target_name=%s
                   AND (target_detail IS NULL OR target_detail='') LIMIT 1""",
                (target_type, target_name),
            )
            if cur.fetchone():
                return True

            # Interface/device-specific suppression
            if target_detail:
                cur.execute(
                    """SELECT id FROM suppression_rules
                       WHERE active=TRUE AND (expires_at IS NULL OR expires_at > NOW())
                       AND target_type=%s AND target_name=%s AND target_detail=%s LIMIT 1""",
                    (target_type, target_name, target_detail),
                )
                if cur.fetchone():
                    return True

            return False