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


def _new_conn(cfg: dict):
    return 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',
    )


@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 = _new_conn(cfg)
        _local.conn = conn
    else:
        try:
            conn.ping(reconnect=True)
        except Exception:
            try:
                conn.close()
            except Exception:
                pass
            _local.conn = None
            conn = _new_conn(cfg)
            _local.conn = conn
    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(limit: int = 200, offset: int = 0) -> 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
                   LIMIT %s OFFSET %s""",
                (limit, offset),
            )
            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() + 'Z'
            return rows


def count_active_events() -> int:
    """Return count of all unresolved events (for pagination)."""
    with get_conn() as conn:
        with conn.cursor() as cur:
            cur.execute(
                "SELECT COUNT(*) AS n FROM network_events WHERE resolved_at IS NULL"
            )
            return cur.fetchone()['n']


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() + 'Z'
            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()}
            cur.execute(
                """SELECT COUNT(*) as cnt FROM network_events
                   WHERE resolved_at IS NOT NULL
                   AND resolved_at > DATE_SUB(NOW(), INTERVAL 24 HOUR)"""
            )
            resolved_24h = cur.fetchone()['cnt']
            return {
                'critical': counts.get('critical', 0),
                'warning': counts.get('warning', 0),
                'info': counts.get('info', 0),
                'resolved_24h': resolved_24h,
            }


# ---------------------------------------------------------------------------
# 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() + 'Z'
            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() + 'Z'
            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.now(timezone.utc) + 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='' 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