from pathlib import Path
import copy
import ipaddress

from flask import Blueprint, request, redirect, flash
from auth import require_level
from config_utils import load_config, record_group, diff_fields, verify_config_hash
import sanitize
import mod_validation as validate

_PAGE = Path(__file__).parent.name

bp = Blueprint(_PAGE, __name__)

def _row_index():
    try:
        return int(request.form.get('row_index', ''))
    except (ValueError, TypeError):
        return None


def _hash_ok():
    if not verify_config_hash(request.form.get('config_hash', '')):
        flash('Configuration was modified by another session. Please refresh and try again.', 'error')
        return False
    return True


def _parse_ip():
    raw = request.form.get('ip', '').strip()
    if not raw:
        return ''
    ip = validate.ip(raw)
    if not ip:
        flash(f'The configuration has not been saved because "{raw}" is not a valid IP address.', 'error')
        return None
    return ip


def _check_ip_in_vlan_subnet(ip, vlan):
    if not ip:
        return None
    subnet = vlan.get('subnet')
    prefix = vlan.get('subnet_mask')
    if not subnet or prefix is None:
        return None
    try:
        network = ipaddress.IPv4Network(f'{subnet}/{prefix}', strict=False)
        addr    = ipaddress.IPv4Address(ip)
        if addr == network.network_address:
            return f'{ip} is the network address and cannot be assigned.'
        if addr == network.broadcast_address:
            return f'{ip} is the broadcast address and cannot be assigned.'
        if addr not in network:
            return f'{ip} is not within the {vlan["name"]} subnet ({subnet}/{prefix}).'
    except ValueError:
        return f'{ip} is not a valid IP address.'
    return None


@bp.route('/action/dhcpreservations/addreservation_add', methods=['POST'])
@require_level('administrator')
def addreservation_add():
    vlan_name     = sanitize.name(request.form.get('vlan_name', ''))
    description   = sanitize.text(request.form.get('description', ''))
    hostname      = validate.domainname(request.form.get('hostname', ''))
    mac           = sanitize.mac(request.form.get('mac', ''))
    ip            = _parse_ip()
    radius_client = 'radius_client' in request.form

    if ip is None:
        return redirect(f'/{_PAGE}')
    if not vlan_name:
        flash('The configuration has not been saved because a VLAN is required.', 'error')
        return redirect(f'/{_PAGE}')
    if not mac:
        flash('The configuration has not been saved because a MAC address is required.', 'error')
        return redirect(f'/{_PAGE}')
    if not _hash_ok():
        return redirect(f'/{_PAGE}')

    cfg   = load_config()
    vlans = cfg.get('vlans', [])
    vlan  = next((v for v in vlans if v.get('name') == vlan_name), None)
    if vlan is None:
        flash(f'The configuration has not been saved because VLAN "{vlan_name}" was not found.', 'error')
        return redirect(f'/{_PAGE}')

    subnet_err = _check_ip_in_vlan_subnet(ip, vlan)
    if subnet_err:
        flash(f'The configuration has not been saved because {subnet_err}', 'error')
        return redirect(f'/{_PAGE}')

    conflict = validate.check_reservation_ip_conflicts(ip, vlan)
    if conflict:
        flash(f'The configuration has not been saved because {conflict}', 'error')
        return redirect(f'/{_PAGE}')

    entry = {
        'description':   description,
        'mac':           mac,
        'ip':            ip,
        'radius_client': radius_client,
        'enabled':       True,
        'vlan':          vlan_name,
    }
    if hostname:
        entry['hostname'] = hostname
    cfg.setdefault('dhcp_reservations', []).append(entry)
    errors = validate.validate_config(cfg)
    if errors:
        for msg in errors:
            flash(msg, 'error')
        return redirect(f'/{_PAGE}')

    changes = diff_fields(None, entry)
    flash(record_group(cfg, 'dhcp_reservations', 'mac', mac, changes, 'core apply'), 'success')
    return redirect(f'/{_PAGE}')


@bp.route('/action/dhcpreservations/reservations_toggle', methods=['POST'])
@require_level('administrator')
def reservations_toggle():
    idx = _row_index()
    if idx is None:
        flash('Invalid request.', 'error')
        return redirect(f'/{_PAGE}')
    if not _hash_ok():
        return redirect(f'/{_PAGE}')

    cfg   = load_config()
    items = cfg.get('dhcp_reservations', [])
    if idx < 0 or idx >= len(items):
        flash('Entry not found.', 'error')
        return redirect(f'/{_PAGE}')

    res         = items[idx]
    old_enabled = res.get('enabled', True)
    before      = copy.deepcopy(res)
    res['enabled'] = not old_enabled
    errors = validate.validate_config(cfg)
    if errors:
        for msg in errors:
            flash(msg, 'error')
        return redirect(f'/{_PAGE}')

    changes = diff_fields(before, res)
    flash(record_group(cfg, 'dhcp_reservations', 'mac', res['mac'], changes, 'core apply'), 'success')
    return redirect(f'/{_PAGE}')


@bp.route('/action/dhcpreservations/reservations_edit', methods=['POST'])
@require_level('administrator')
def reservations_edit():
    idx = _row_index()
    if idx is None:
        flash('Invalid request.', 'error')
        return redirect(f'/{_PAGE}')

    description   = sanitize.text(request.form.get('description', ''))
    hostname      = validate.domainname(request.form.get('hostname', ''))
    mac           = sanitize.mac(request.form.get('mac', ''))
    ip            = _parse_ip()
    radius_client = 'radius_client' in request.form

    if ip is None:
        return redirect(f'/{_PAGE}')
    if not mac:
        flash('The configuration has not been saved because a MAC address is required.', 'error')
        return redirect(f'/{_PAGE}')
    if not _hash_ok():
        return redirect(f'/{_PAGE}')

    cfg   = load_config()
    items = cfg.get('dhcp_reservations', [])
    if idx < 0 or idx >= len(items):
        flash('Entry not found.', 'error')
        return redirect(f'/{_PAGE}')

    res       = items[idx]
    vlan_name = res.get('vlan', '')
    vlan      = next((v for v in cfg.get('vlans', []) if v.get('name') == vlan_name), None)
    if vlan:
        subnet_err = _check_ip_in_vlan_subnet(ip, vlan)
        if subnet_err:
            flash(f'The configuration has not been saved because {subnet_err}', 'error')
            return redirect(f'/{_PAGE}')
        conflict = validate.check_reservation_ip_conflicts(ip, vlan)
        if conflict:
            flash(f'The configuration has not been saved because {conflict}', 'error')
            return redirect(f'/{_PAGE}')

    before = copy.deepcopy(res)
    res.update({
        'description':   description,
        'mac':           mac,
        'ip':            ip,
        'radius_client': radius_client,
        'enabled':       'enabled' in request.form,
    })
    if hostname:
        res['hostname'] = hostname
    else:
        res.pop('hostname', None)
    errors = validate.validate_config(cfg)
    if errors:
        for msg in errors:
            flash(msg, 'error')
        return redirect(f'/{_PAGE}')

    changes = diff_fields(before, res)
    flash(record_group(cfg, 'dhcp_reservations', 'mac', mac, changes, 'core apply'), 'success')
    return redirect(f'/{_PAGE}')


@bp.route('/action/dhcpreservations/reservations_delete', methods=['POST'])
@require_level('administrator')
def reservations_delete():
    idx = _row_index()
    if idx is None:
        flash('Invalid request.', 'error')
        return redirect(f'/{_PAGE}')
    if not _hash_ok():
        return redirect(f'/{_PAGE}')

    cfg   = load_config()
    items = cfg.get('dhcp_reservations', [])
    if idx < 0 or idx >= len(items):
        flash('Entry not found.', 'error')
        return redirect(f'/{_PAGE}')

    removed = items.pop(idx)
    errors = validate.validate_config(cfg)
    if errors:
        for msg in errors:
            flash(msg, 'error')
        return redirect(f'/{_PAGE}')

    changes = diff_fields(removed, None)
    flash(record_group(cfg, 'dhcp_reservations', 'mac', removed['mac'], changes, 'core apply'), 'success')
    return redirect(f'/{_PAGE}')