"""Gandalf – Global Advanced Network Detection And Link Facilitator.

Flask web application serving the monitoring dashboard and suppression
management UI. Authentication via Authelia forward-auth headers.
All monitoring and alerting is handled by the separate monitor.py daemon.
"""
import hashlib
import html
import ipaddress
import json
import logging
import os
import re
import tempfile
import threading
import time
import uuid
from datetime import datetime, timezone
from functools import wraps

from flask import Flask, jsonify, make_response, render_template, request, send_file

import db
import diagnose
from monitor import PulseClient

logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s %(levelname)s %(name)s %(message)s',
)
logger = logging.getLogger('gandalf.web')

app = Flask(__name__)

_AVATAR_COLORS = ['lt-avatar--orange', 'lt-avatar--green', 'lt-avatar--purple', '']


@app.template_filter('avatar_color')
def avatar_color_filter(name: str) -> str:
    return _AVATAR_COLORS[int(hashlib.md5(name.encode()).hexdigest(), 16) % len(_AVATAR_COLORS)]  # nosec B324

_cfg = None
_cfg_lock = threading.Lock()


@app.context_processor
def inject_config():
    """Inject safe config values into all templates."""
    cfg = _config()
    return {
        'config': {
            'ticket_api': {
                'web_url': cfg.get('ticket_api', {}).get('web_url', 'http://t.lotusguild.org/ticket/'),
            }
        }
    }


# In-memory diagnostic job store { job_id: { status, result, created_at } }
_diag_jobs: dict = {}
_diag_lock = threading.Lock()
# Per-user rate-limit: { username: [epoch_float, ...] } — cleaned inside _diag_lock
_diag_rate: dict = {}


def _purge_old_jobs_loop():
    """Background thread: remove stale diag jobs and run daily event purge."""
    while True:
        time.sleep(120)
        cutoff = time.time() - 600
        stuck_cutoff = time.time() - 300  # 5 min: job still 'running' → thread must have crashed
        with _diag_lock:
            stale = [jid for jid, j in _diag_jobs.items() if j.get('created_at', 0) < cutoff]
            for jid in stale:
                del _diag_jobs[jid]
            for jid, j in list(_diag_jobs.items()):
                if j['status'] == 'running' and j.get('created_at', 0) < stuck_cutoff:
                    j['status'] = 'done'
                    j['result'] = {'status': 'error', 'error': 'Diagnostic abandoned — no activity for 5 minutes.'}
                    logger.error(f'Diagnostic job {jid} stuck (no activity for 5 min); marked done/error')


_purge_thread = threading.Thread(target=_purge_old_jobs_loop, daemon=True)
_purge_thread.start()


def _config() -> dict:
    global _cfg
    if _cfg is None:
        with _cfg_lock:
            if _cfg is None:
                with open('config.json') as f:
                    _cfg = json.load(f)
    return _cfg


@app.after_request
def add_security_headers(response):
    response.headers.setdefault('X-Content-Type-Options', 'nosniff')
    response.headers.setdefault('X-Frame-Options', 'DENY')
    response.headers.setdefault('Referrer-Policy', 'strict-origin-when-cross-origin')
    return response


def _daemon_ok(last_check: str) -> bool:
    """Return True if monitor last checked within 20 minutes."""
    if not last_check or last_check == 'Never':
        return False
    try:
        ts = datetime.strptime(last_check, '%Y-%m-%d %H:%M:%S UTC').replace(tzinfo=timezone.utc)
        return (datetime.now(timezone.utc) - ts).total_seconds() < 1200
    except Exception:
        return False


# ---------------------------------------------------------------------------
# Auth helpers
# ---------------------------------------------------------------------------

def _get_user() -> dict:
    return {
        'username': request.headers.get('Remote-User', ''),
        'name': request.headers.get('Remote-Name', ''),
        'email': request.headers.get('Remote-Email', ''),
        'groups': [
            g.strip()
            for g in request.headers.get('Remote-Groups', '').split(',')
            if g.strip()
        ],
    }


def require_auth(f):
    @wraps(f)
    def wrapper(*args, **kwargs):
        user = _get_user()
        if not user['username']:
            return (
                '<h1>401 – Not authenticated</h1>'
                '<p>Please access Gandalf through '
                '<a href="https://auth.lotusguild.org">auth.lotusguild.org</a>.</p>',
                401,
            )
        allowed = _config().get('auth', {}).get('allowed_groups', ['admin'])
        if not any(g in allowed for g in user['groups']):
            safe_user   = html.escape(user['username'])
            safe_groups = html.escape(', '.join(allowed))
            return (
                f'<h1>403 – Access denied</h1>'
                f'<p>Your account ({safe_user}) is not in an allowed group '
                f'({safe_groups}).</p>',
                403,
            )
        return f(*args, **kwargs)
    return wrapper


def require_admin(f):
    """Decorator: require require_auth AND membership in the 'admin' group."""
    @wraps(f)
    def wrapper(*args, **kwargs):
        user = _get_user()
        if 'admin' not in user.get('groups', []):
            return jsonify({'error': 'Admin access required'}), 403
        return f(*args, **kwargs)
    return wrapper


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

_PAGE_LIMIT = 200  # max events returned per request


def _annotate_suppressions(events: list, suppressions: list) -> None:
    """Annotate each event dict in-place with an is_suppressed bool."""
    for ev in events:
        sup_type = (
            'unifi_device' if ev.get('event_type') == 'unifi_device_offline'
            else 'interface' if ev.get('event_type') == 'interface_down'
            else 'host'
        )
        ev['is_suppressed'] = db.check_suppressed(
            suppressions, sup_type,
            ev.get('target_name', ''), ev.get('target_detail', '') or '',
        )


# ---------------------------------------------------------------------------
# Page routes
# ---------------------------------------------------------------------------


@app.route('/')
@require_auth
def index():
    user = _get_user()
    events = db.get_active_events(limit=_PAGE_LIMIT)
    total_active = db.count_active_events()
    summary = db.get_status_summary()
    snapshot_raw = db.get_state('network_snapshot')
    last_check = db.get_state('last_check', 'Never')
    try:
        snapshot = json.loads(snapshot_raw) if snapshot_raw else {}
    except Exception as e:
        logger.error(f'Failed to parse network_snapshot JSON: {e}')
        snapshot = {}
    suppressions = db.get_active_suppressions()
    _annotate_suppressions(events, suppressions)
    recent_resolved = db.get_recent_resolved(hours=24, limit=10)
    return render_template(
        'index.html',
        user=user,
        events=events,
        total_active=total_active,
        summary=summary,
        snapshot=snapshot,
        last_check=last_check,
        suppressions=suppressions,
        recent_resolved=recent_resolved,
        daemon_ok=_daemon_ok(last_check),
    )


@app.route('/links')
@require_auth
def links_page():
    user = _get_user()
    return render_template('links.html', user=user)


@app.route('/inspector')
@require_auth
def inspector():
    user = _get_user()
    return render_template('inspector.html', user=user)


@app.route('/suppressions')
@require_auth
@require_admin
def suppressions_page():
    user = _get_user()
    active = db.get_active_suppressions()
    history = db.get_suppression_history(limit=50)
    snapshot_raw = db.get_state('network_snapshot')
    try:
        snapshot = json.loads(snapshot_raw) if snapshot_raw else {}
    except Exception as e:
        logger.error(f'Failed to parse network_snapshot JSON: {e}')
        snapshot = {}
    return render_template(
        'suppressions.html',
        user=user,
        active=active,
        history=history,
        snapshot=snapshot,
    )


# ---------------------------------------------------------------------------
# API routes
# ---------------------------------------------------------------------------

@app.route('/api/status')
@require_auth
def api_status():
    active = db.get_active_events(limit=_PAGE_LIMIT)
    suppressions = db.get_active_suppressions()
    _annotate_suppressions(active, suppressions)
    last_check = db.get_state('last_check', 'Never')
    return jsonify({
        'summary': db.get_status_summary(),
        'last_check': last_check,
        'events': active,
        'total_active': db.count_active_events(),
        'daemon_ok': _daemon_ok(last_check),
    })


@app.route('/api/network')
@require_auth
def api_network():
    raw = db.get_state('network_snapshot')
    if raw:
        try:
            return jsonify(json.loads(raw))
        except Exception:
            logger.error('Failed to parse network_snapshot JSON')
    return jsonify({'hosts': {}, 'unifi': [], 'updated': None})


@app.route('/api/links')
@require_auth
def api_links():
    raw = db.get_state('link_stats')
    if raw:
        if len(raw) > 10_000_000:
            logger.error(f'link_stats exceeds 10 MB ({len(raw)} bytes); possible corruption')
            return jsonify({'error': 'Invalid cached data'}), 503
        try:
            return jsonify(json.loads(raw))
        except Exception as e:
            logger.error(f'Failed to parse link_stats JSON: {e}')
    return jsonify({'hosts': {}, 'unifi_switches': {}, 'updated': None})


@app.route('/api/events')
@require_auth
def api_events():
    try:
        limit = min(int(request.args.get('limit', _PAGE_LIMIT)), 1000)
        offset = max(int(request.args.get('offset', 0)), 0)
    except ValueError:
        return jsonify({'error': 'limit and offset must be integers'}), 400
    status_filter = request.args.get('status', 'active')
    if status_filter not in ('active', 'resolved', 'all'):
        return jsonify({'error': 'status must be active, resolved, or all'}), 400

    result: dict = {}
    if status_filter in ('active', 'all'):
        result['active'] = db.get_active_events(limit=limit, offset=offset)
        result['total_active'] = db.count_active_events()
    if status_filter in ('resolved', 'all'):
        result['resolved'] = db.get_recent_resolved(hours=24, limit=30)
    return jsonify(result)


@app.route('/api/suppressions', methods=['GET'])
@require_auth
def api_get_suppressions():
    return jsonify(db.get_active_suppressions())


@app.route('/api/suppressions', methods=['POST'])
@require_auth
@require_admin
def api_create_suppression():
    user = _get_user()
    data = request.get_json(silent=True) or {}

    target_type = data.get('target_type', 'host')
    target_name = (data.get('target_name') or '').strip()
    target_detail = (data.get('target_detail') or '').strip()
    reason = (data.get('reason') or '').strip()
    expires_minutes = data.get('expires_minutes')  # None = manual/permanent

    if target_type not in ('host', 'interface', 'unifi_device', 'all'):
        return jsonify({'error': 'Invalid target_type'}), 400
    if target_type != 'all' and not target_name:
        return jsonify({'error': 'target_name required'}), 400
    if not reason:
        return jsonify({'error': 'reason required'}), 400
    if len(reason) > 500:
        return jsonify({'error': 'reason must be 500 characters or fewer'}), 400
    if len(target_name) > 255:
        return jsonify({'error': 'target_name must be 255 characters or fewer'}), 400
    if len(target_detail) > 255:
        return jsonify({'error': 'target_detail must be 255 characters or fewer'}), 400

    if expires_minutes is not None:
        try:
            expires_minutes = int(expires_minutes)
            if expires_minutes <= 0 or expires_minutes > 43200:
                return jsonify({'error': 'expires_minutes must be between 1 and 43200 (30 days)'}), 400
        except (ValueError, TypeError):
            return jsonify({'error': 'expires_minutes must be a valid integer'}), 400

    sup_id = db.create_suppression(
        target_type=target_type,
        target_name=target_name,
        target_detail=target_detail,
        reason=reason,
        suppressed_by=user['username'],
        expires_minutes=expires_minutes,
    )
    logger.info(
        f'Suppression #{sup_id} created by {user["username"]}: '
        f'{target_type}/{target_name}/{target_detail} – {reason}'
    )
    return jsonify({'success': True, 'id': sup_id})


@app.route('/api/suppressions/<int:sup_id>', methods=['DELETE'])
@require_auth
@require_admin
def api_delete_suppression(sup_id: int):
    user = _get_user()
    db.deactivate_suppression(sup_id)
    logger.info(f'Suppression #{sup_id} removed by {user["username"]}')
    return jsonify({'success': True})


@app.route('/api/diagnose', methods=['POST'])
@require_auth
def api_diagnose_start():
    """Start a link diagnostic job. Returns {job_id}."""
    data = request.get_json(silent=True) or {}
    switch_name = (data.get('switch_name') or '').strip()
    try:
        port_idx = int(data.get('port_idx'))
    except (TypeError, ValueError):
        return jsonify({'error': 'port_idx must be an integer'}), 400

    if not switch_name:
        return jsonify({'error': 'switch_name and port_idx required'}), 400

    # Look up switch + port in cached link_stats
    raw = db.get_state('link_stats')
    if not raw:
        return jsonify({'error': 'No link_stats data available'}), 503
    try:
        link_data = json.loads(raw)
    except Exception as e:
        logger.error(f'Failed to parse link_stats JSON in /api/diagnose: {e}')
        return jsonify({'error': 'Internal data error'}), 500

    switches = link_data.get('unifi_switches', {})
    sw = switches.get(switch_name)
    if not sw:
        return jsonify({'error': f'Switch "{switch_name}" not found'}), 404

    # Find port by port_idx
    port_data = None
    for pname, pd in sw.get('ports', {}).items():
        if pd.get('port_idx') == port_idx:
            port_data = dict(pd)
            port_data['name'] = pname
            break
    if not port_data:
        return jsonify({'error': f'Port {port_idx} not found on switch "{switch_name}"'}), 404

    # LLDP neighbor required to know which host+iface to SSH into
    lldp = port_data.get('lldp')
    if not lldp or not lldp.get('system_name'):
        return jsonify({'error': 'No LLDP neighbor data for this port'}), 400

    server_name = lldp['system_name']
    if not re.fullmatch(r'[a-zA-Z0-9._-]+', server_name):
        logger.error(f'Refusing diagnostic: invalid server_name from LLDP: {server_name!r}')
        return jsonify({'error': 'LLDP neighbor name contains invalid characters'}), 400
    lldp_port_id = lldp.get('port_id', '')

    # Find matching host + interface in link_stats hosts
    hosts = link_data.get('hosts', {})
    server_ifaces = hosts.get(server_name)
    if not server_ifaces:
        return jsonify({'error': f'Host "{server_name}" not in link stats'}), 404

    # Match interface by LLDP port_id (exact then fuzzy)
    matched_iface = None
    if lldp_port_id and lldp_port_id in server_ifaces:
        matched_iface = lldp_port_id
    if not matched_iface and lldp_port_id:
        matched_iface = next(
            (k for k in server_ifaces if lldp_port_id in k or k in lldp_port_id),
            None
        )
    if not matched_iface:
        matched_iface = next(iter(server_ifaces), None)
    if not matched_iface:
        return jsonify({'error': 'Cannot determine server interface'}), 400

    # Resolve host IP from link_stats host data
    host_ip = (server_ifaces.get(matched_iface) or {}).get('host_ip')
    if not host_ip:
        # Fallback: use first valid IP from LLDP mgmt IPs
        for candidate in (lldp.get('mgmt_ips') or []):
            try:
                ipaddress.ip_address(candidate)
                host_ip = candidate
                break
            except ValueError:
                continue
    if not host_ip:
        return jsonify({'error': 'Cannot determine host IP for SSH'}), 400

    # Validate resolved values before passing to SSH command builder
    try:
        ipaddress.ip_address(host_ip)
    except ValueError:
        logger.error(f'Refusing diagnostic: invalid host_ip "{host_ip}" for {server_name}')
        return jsonify({'error': 'Resolved host IP is not a valid IP address'}), 400
    if not re.fullmatch(r'[a-zA-Z0-9._-]+', matched_iface):
        logger.error(f'Refusing diagnostic: invalid iface "{matched_iface}" for {server_name}')
        return jsonify({'error': 'Resolved interface name contains invalid characters'}), 400

    job_id = str(uuid.uuid4())
    requesting_user = _get_user()['username']
    now = time.time()
    with _diag_lock:
        # Rate limit: max 5 diagnostic jobs per user per minute; prune stale user entries
        stale_users = [u for u, ts in _diag_rate.items() if not ts or max(ts) < now - 3600]
        for u in stale_users:
            del _diag_rate[u]
        recent = [t for t in _diag_rate.get(requesting_user, []) if now - t < 60]
        if len(recent) >= 5:
            return jsonify({'error': 'Rate limit exceeded: max 5 diagnostics per minute'}), 429
        recent.append(now)
        _diag_rate[requesting_user] = recent
        _diag_jobs[job_id] = {
            'status': 'running', 'result': None,
            'created_at': now, 'user': requesting_user,
        }

    def _run():
        try:
            cfg = _config()
            pulse = PulseClient(cfg)
            runner = diagnose.DiagnosticsRunner(pulse)
            result = runner.run(host_ip, server_name, matched_iface, port_data)
        except Exception as e:
            logger.error(f'Diagnostic job {job_id} failed: {e}', exc_info=True)
            result = {'status': 'error', 'error': 'Diagnostic failed; check server logs.'}
        with _diag_lock:
            if job_id in _diag_jobs:
                _diag_jobs[job_id]['status'] = 'done'
                _diag_jobs[job_id]['result'] = result

    t = threading.Thread(target=_run, daemon=True)
    t.start()

    return jsonify({'job_id': job_id})


@app.route('/api/diagnose/<job_id>', methods=['GET'])
@require_auth
def api_diagnose_poll(job_id: str):
    """Poll a diagnostic job. Returns {status, result}."""
    current_user = _get_user()['username']
    with _diag_lock:
        job = _diag_jobs.get(job_id)
        if not job:
            return jsonify({'error': 'Job not found'}), 404
        if job.get('user') != current_user:
            return jsonify({'error': 'Forbidden'}), 403
        snapshot = {'status': job['status'], 'result': job.get('result')}
    return jsonify(snapshot)


@app.route('/api/avatar')
@require_auth
def api_avatar():
    """Serve the current user's LDAP avatar photo (JPEG), cached to disk."""
    username = request.headers.get('Remote-User', '').strip()
    if not username:
        return '', 404

    ldap_cfg = _config().get('ldap', {})
    if not ldap_cfg.get('host') or not ldap_cfg.get('bind_dn'):
        return '', 404

    # Build a safe cache filename from the username (alphanumeric + - _ .)
    safe_name = re.sub(r'[^a-zA-Z0-9._-]', '_', username)
    cache_dir = os.path.abspath(
        ldap_cfg.get('cache_dir', os.path.join(tempfile.gettempdir(), 'gandalf_avatars'))
    )
    os.makedirs(cache_dir, exist_ok=True)
    cache_file = os.path.abspath(os.path.join(cache_dir, f'user_{safe_name}.jpg'))
    sentinel   = os.path.abspath(os.path.join(cache_dir, f'user_{safe_name}.none'))
    # Guard against path escape (shouldn't happen with sanitised safe_name, but be explicit)
    if not cache_file.startswith(cache_dir + os.sep) or not sentinel.startswith(cache_dir + os.sep):
        logger.error(f'Avatar path escape detected for user {username!r}')
        return '', 404
    try:
        cache_ttl = int(ldap_cfg.get('cache_ttl', 3600))
    except (ValueError, TypeError):
        logger.warning('Invalid cache_ttl in ldap config; using default 3600')
        cache_ttl = 3600

    now = time.time()

    # Serve cached image if fresh
    if os.path.exists(cache_file) and now - os.path.getmtime(cache_file) < cache_ttl:
        return send_file(cache_file, mimetype='image/jpeg',
                         max_age=cache_ttl, conditional=True)

    # Skip LDAP if we already know this user has no avatar
    try:
        if os.path.exists(sentinel) and now - os.path.getmtime(sentinel) < cache_ttl:
            return '', 404
    except OSError:
        pass

    # Query lldap
    bind_pw = ldap_cfg.get('bind_pw', '')
    if not bind_pw:
        logger.error('LDAP bind_pw not configured — avatar lookup disabled')
        return '', 404

    avatar_data = None
    conn = None
    try:
        import ldap3
        server = ldap3.Server(ldap_cfg['host'], port=int(ldap_cfg.get('port', 3890)))
        conn   = ldap3.Connection(server,
                                  user=ldap_cfg['bind_dn'],
                                  password=bind_pw,
                                  auto_bind=True, receive_timeout=5)
        safe_uid = ldap3.utils.conv.escape_filter_chars(username)
        conn.search(ldap_cfg.get('user_base', 'ou=people,dc=example,dc=com'),
                    f'(uid={safe_uid})', attributes=['avatar'])
        if conn.entries and conn.entries[0]['avatar'].value:
            avatar_data = conn.entries[0]['avatar'].value
    except ImportError:
        logger.error('ldap3 not installed — run: pip install ldap3')
        return '', 404
    except Exception as e:
        logger.error(f'LDAP avatar lookup failed for {username}: {e}')
        return '', 404
    finally:
        if conn is not None:
            try:
                conn.unbind()
            except Exception:
                pass

    if not avatar_data or len(avatar_data) < 100:
        with open(sentinel, 'w'):
            pass
        return '', 404

    # Validate JPEG magic bytes (FF D8 FF)
    if isinstance(avatar_data, str):
        avatar_data = avatar_data.encode('latin-1')
    if avatar_data[:3] != b'\xFF\xD8\xFF':
        logger.warning(f'Non-JPEG avatar data for {username}')
        with open(sentinel, 'w'):
            pass
        return '', 404

    with open(cache_file, 'wb') as f:
        f.write(avatar_data)
    if os.path.exists(sentinel):
        os.unlink(sentinel)

    resp = make_response(avatar_data)
    resp.headers['Content-Type']  = 'image/jpeg'
    resp.headers['Cache-Control'] = f'private, max-age={cache_ttl}'
    return resp


@app.route('/health')
def health():
    """Health check endpoint (no auth). Checks DB and monitor freshness."""
    checks = {}
    overall = 'ok'

    # DB connectivity
    try:
        db.get_state('last_check')
        checks['db'] = 'ok'
    except Exception as e:
        logger.error(f'Health check db error: {e}')
        checks['db'] = 'error'
        overall = 'degraded'

    # Monitor freshness: fail if last_check is older than 20 minutes
    try:
        last_check = db.get_state('last_check', '')
        if last_check:
            ts = datetime.strptime(last_check, '%Y-%m-%d %H:%M:%S UTC').replace(tzinfo=timezone.utc)
            age_s = (datetime.now(timezone.utc) - ts).total_seconds()
            if age_s > 1200:
                checks['monitor'] = 'stale'
                overall = 'degraded'
            else:
                checks['monitor'] = 'ok'
        else:
            checks['monitor'] = 'no data yet'
    except Exception as e:
        logger.error(f'Health check monitor error: {e}')
        checks['monitor'] = 'error'
        overall = 'degraded'

    status_code = 200 if overall == 'ok' else 503
    return jsonify({'status': overall, 'service': 'gandalf', 'checks': checks}), status_code


if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0', port=5000)  # nosec B201 B104 — dev runner only; production uses gunicorn