import os

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

bp = Blueprint('action_apply_iface_config', __name__)

_VIEW = '/view/view_general'

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

def _valid_interface(name):
    try:
        return name in {
            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 False


@bp.route('/action/apply_iface_config', methods=['POST'])
@require_level('administrator')
def apply_iface_config():
    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)

    iface        = sanitize.interface_name(request.form.get('iface', ''))
    mtu          = request.form.get('mtu', '').strip()
    mac          = sanitize.mac(request.form.get('mac', ''))
    original_mtu = request.form.get('original_mtu', '').strip()
    original_mac = sanitize.mac(request.form.get('original_mac', ''))

    if not iface:
        flash('No interface specified.', 'error')
        return redirect(_VIEW)

    if not _valid_interface(iface):
        flash(f"Interface '{iface}' does not exist on this system.", 'error')
        return redirect(_VIEW)

    mtu_int = None
    if mtu:
        mtu_int = validate.int_range(mtu, 68, 9000)
        if mtu_int is None:
            flash('MTU must be an integer between 68 and 9000.', 'error')
            return redirect(_VIEW)

    mac_raw = request.form.get('mac', '').strip()
    if mac_raw and not mac:
        flash('MAC address must be in the format aa:bb:cc:dd:ee:ff.', 'error')
        return redirect(_VIEW)

    if not mtu_int and not mac:
        flash('No changes specified.', 'error')
        return redirect(_VIEW)

    queued = False
    if mtu_int and str(mtu_int) != original_mtu:
        queue_command(f'mtu {iface} {mtu_int}')
        queued = True
    if mac and mac != original_mac:
        queue_command(f'mac {iface} {mac}')
        queued = True

    if not queued:
        flash('No changes detected.', 'info')
        return redirect(_VIEW)

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