/*
Technitium DNS Server
Copyright (C) 2021  Shreyas Zare (shreyas@technitium.com)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

using System;
using System.Net;
using System.Threading.Tasks;
using TechnitiumLibrary.Net.Dns;

namespace DnsServerCore.ApplicationCommon
{
    /// <summary>
    /// Lets a DNS App to handle incoming requests for the DNS server's authoritative zone allowing it to act as an authoritative zone by itself and respond to any requests.
    /// </summary>
    public interface IDnsAuthoritativeRequestHandler : IDisposable
    {
        /// <summary>
        /// Allows initializing the DNS application with a config. This function is also called when the config is updated to allow reloading.
        /// </summary>
        /// <param name="dnsServer">The DNS server interface object that allows access to DNS server properties.</param>
        /// <param name="config">The DNS application config stored in the <c>dnsApp.config</c> file.</param>
        Task InitializeAsync(IDnsServer dnsServer, string config);

        /// <summary>
        /// Allows a DNS App to respond to an incoming DNS request for the DNS server's authoritative zone. This method is called by the DNS Server's authoritative zone before querying its built in zone database. Response returned may be further processed to resolve CNAME or ANAME records, or referral response.
        /// </summary>
        /// <param name="request">The incoming DNS request to be processed.</param>
        /// <param name="remoteEP">The end point (IP address and port) of the client making the request.</param>
        /// <param name="protocol">The protocol using which the request was received.</param>
        /// <param name="isRecursionAllowed">Tells if the DNS server is configured to allow recursion for the client making this request.</param>
        /// <returns>The DNS response for the DNS request or <c>null</c> to let the DNS server core process the request as usual.</returns>
        Task<DnsDatagram> ProcessRequestAsync(DnsDatagram request, IPEndPoint remoteEP, DnsTransportProtocol protocol, bool isRecursionAllowed);

        /// <summary>
        /// The description about this app to be shown in the Apps section of the DNS web console.
        /// </summary>
        string Description { get; }
    }
}