//
// Copyright 2019 Google LLC
//
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
// 
//   http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
//

using Google.Solutions.IapDesktop.Extensions.Management.Auditing.Logs;
using System.Diagnostics;

namespace Google.Solutions.IapDesktop.Extensions.Management.Auditing.Events.Access
{
    public class AuthorizeUserTunnelEvent : EventBase
    {
        public const string ServiceName = "iap.googleapis.com";
        public const string Method = "AuthorizeUser";

        public override EventCategory Category => EventCategory.Access;

        internal AuthorizeUserTunnelEvent(LogRecord logRecord) : base(logRecord)
        {
            Debug.Assert(IsAuthorizeUserEvent(logRecord));
        }

        public static bool IsAuthorizeUserEvent(LogRecord record)
        {
            return record.IsDataAccessEvent &&
                record.ProtoPayload?.MethodName == Method &&
                record.Resource?.Type == "gce_instance"; // Distinguish from IAP-Web events.
        }

        public bool IsError => this.Severity == "ERROR";

        public override string Message => this.IsError
            ? $"{this.TunnelDescription} [{this.Status?.Message}]"
            : this.TunnelDescription;

        private string TunnelDescription
            => $"Authorize tunnel from {this.SourceHost ?? "(unknown)"} to " +
                $"{this.DestinationHost ?? "(unknown host)"}:{this.DestinationPort ?? "(unknown port)"} " +
                $"using {base.UserAgentShort ?? "(unknown agent"}";

        //---------------------------------------------------------------------
        // Record-specific fields.
        //---------------------------------------------------------------------

        public string? DestinationHost =>
            base.LogRecord.ProtoPayload?.RequestMetadata?["destinationAttributes"]?.Value<string>("ip");
        public string? DestinationPort =>
            base.LogRecord.ProtoPayload?.RequestMetadata?["destinationAttributes"]?.Value<string>("port");

        public ulong InstanceId => string.IsNullOrEmpty(base.LogRecord.Resource?.Labels?["instance_id"])
            ? 0
            : ulong.Parse(base.LogRecord.Resource?.Labels?["instance_id"]);

        public string? ProjectId => base.LogRecord.Resource?.Labels?["project_id"];
        public string? Zone => base.LogRecord.Resource?.Labels?["zone"];

    }
}
