import os

from flask import Blueprint, request, redirect, flash
from auth import require_level
from config_utils import load_core, save_core, verify_core_hash, queued_msg
import sanitize
import validation as validate

bp = Blueprint('action_apply_interface', __name__)

_VIEW = '/view/view_general'


_EXCLUDE_PREFIXES = ('lo', 'wg', 'docker', 'br-', 'veth',
                     'tun', 'tap', 'ppp', 'virbr',
                     'podman', 'vnet', 'macvtap', 'fc-')

def _get_system_interfaces():
    try:
        return {
            n for n in os.listdir('/sys/class/net')
            if not n.startswith(_EXCLUDE_PREFIXES)
            and os.path.exists(f'/sys/class/net/{n}/device')
        }
    except Exception:
        return set()


@bp.route('/action/apply_interface', methods=['POST'])
@require_level('administrator')
def apply_interface():
    wan = sanitize.interface_name(request.form.get('wan_interface', ''))
    lan = sanitize.interface_name(request.form.get('lan_interface', ''))

    if not wan or not lan:
        flash('Both WAN and LAN interfaces are required.', 'error')
        return redirect(_VIEW)

    if wan == lan:
        flash('WAN and LAN interfaces must be different.', 'error')
        return redirect(_VIEW)

    if not verify_core_hash(request.form.get('config_hash', '')):
        flash('Configuration was modified by another session. Please refresh and try again.', 'error')
        return redirect(_VIEW)

    available = _get_system_interfaces()
    for iface in (wan, lan):
        if available and iface not in available:
            flash(f"Interface '{iface}' does not exist on this system.", 'error')
            return redirect(_VIEW)

    core = load_core()
    gen  = core.setdefault('general', {})
    gen['wan_interface'] = wan
    gen['lan_interface'] = lan
    errors = validate.validate_config(core)
    if errors:
        for msg in errors:
            flash(msg, 'error')
        return redirect(_VIEW)
    save_core(core)

    flash(queued_msg('core apply'), 'success')
    return redirect(_VIEW)