import json


def collect_tokens(cfg):
    vlans = cfg.get('vlans', [])
    vlan_names = [v.get('name', '') for v in vlans]
    res_ips_by_vlan, res_hosts_by_vlan = {}, {}
    for v in vlans:
        vn = v.get('name', '')
        if not vn:
            continue
        vlan_res = [r for r in cfg.get('dhcp_reservations', []) if r.get('vlan') == vn]
        res_ips_by_vlan[vn]   = [r['ip']      for r in vlan_res if r.get('ip') and r['ip'] != 'dynamic']
        res_hosts_by_vlan[vn] = [r['hostname'] for r in vlan_res if r.get('hostname')]
    filter_opts = '<option value="all">All VLANs</option>' + ''.join(
        f'<option value="{n}">{n}</option>' for n in vlan_names
    )
    return {
        'VLAN_FILTER_OPTIONS':               filter_opts,
        'VLAN_NAMES_AS_OPTIONS':             json.dumps([{'value': n, 'label': n} for n in vlan_names]),
        'VLAN_SUBNET_INFO_JSON':             json.dumps({
            v.get('name', ''): {'subnet': v.get('subnet', ''), 'prefix': v.get('subnet_mask', 0)}
            for v in vlans if v.get('name') and v.get('subnet')
        }),
        'RESERVATION_IPS_BY_VLAN_JSON':       json.dumps(res_ips_by_vlan),
        'RESERVATION_HOSTNAMES_BY_VLAN_JSON': json.dumps(res_hosts_by_vlan),
    }