# -*- coding: utf-8 -*-
"""Shared helper for the L2 collectors: read the module config, resolve the
selected templates to template ids, and list the hosts that should be collected.
"""
import os
import json
import time

try:
    import l2db
except Exception:  # pragma: no cover - only used on an installed host
    l2db = None

DEFAULT_PATHS = [
    os.environ.get('L2_CONFIG') or '',
    '/opt/zabbix/zabbix-server/web-modules/WecomCenter/assets/l2topology/config.json',
    '/usr/share/zabbix/modules/WecomCenter/assets/l2topology/config.json',
    os.path.join(os.path.dirname(os.path.abspath(__file__)), 'config.json'),
]


_CACHE = None
_CACHE_AT = 0


def _from_db():
    """Read the module config from Zabbix's own DB (primary source)."""
    if l2db is None:
        return None
    try:
        raw = l2db.scalar('SELECT HEX(config) FROM l2_topology_config WHERE id=1')
        if raw:
            return json.loads(bytes.fromhex(raw).decode('utf-8'))
    except Exception:
        pass
    return None


def _from_mirror():
    """Fallback for a fresh install before the first DB save."""
    for p in DEFAULT_PATHS:
        if p and os.path.isfile(p):
            try:
                with open(p, encoding='utf-8') as f:
                    return json.load(f)
            except Exception:
                pass
    return None


def config():
    """Return the L2 configuration, DB first and JSON mirror as fallback."""
    global _CACHE, _CACHE_AT
    now = time.time()
    if _CACHE is not None and now - _CACHE_AT < 30:
        return _CACHE
    data = _from_db()
    if data is None:
        data = _from_mirror()
    if data is None:
        data = {}
    _CACHE = data
    _CACHE_AT = now
    return data


def template_ids(call):
    """Resolve configured template names -> [templateid]. Empty list => no filter."""
    cfg = config()
    names = [str(n).strip() for n in (cfg.get('templates') or []) if str(n).strip()]
    if not names:
        return []
    try:
        tpls = call('template.get', {'output': ['templateid', 'name']})['result']
    except Exception:
        return []
    want = {n.lower() for n in names}
    return [t['templateid'] for t in tpls if t.get('name', '').strip().lower() in want]


def hosts(call, output=None, interfaces='extend'):
    """host.get restricted to the configured templates (when resolvable)."""
    p = {'output': output or ['hostid', 'name'], 'selectInterfaces': interfaces}
    tids = template_ids(call)
    if tids:
        p['templateids'] = tids
    return call('host.get', p)['result']