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 * Copyright (c) 2005-2025 The OPC Foundation, Inc. All rights reserved.
 *
 * OPC Foundation MIT License 1.00
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * The complete license agreement can be found here:
 * http://opcfoundation.org/License/MIT/1.00/
 * ======================================================================*/

using System;
using System.Collections.Generic;
using Opc.Ua.Configuration;

namespace Opc.Ua.Server.Hosting
{
    /// <summary>
    /// Options for an OPC UA server hosted by the .NET Generic Host via
    /// <see cref="Microsoft.Extensions.DependencyInjection.OpcUaServerBuilderExtensions.AddServer(IOpcUaBuilder,Action{OpcUaServerOptions})"/>.
    /// </summary>
    /// <remarks>
    /// Only the most common knobs are exposed directly. Use
    /// <see cref="ConfigureBuilder"/> for full control of the underlying
    /// <see cref="IApplicationConfigurationBuilder"/> chain (security policies,
    /// transport quotas, custom security stores, etc.).
    /// </remarks>
    public sealed class OpcUaServerOptions
    {
        /// <summary>
        /// Application name. Used as the default for the certificate subject
        /// common-name and the PKI root path when those are not set explicitly.
        /// </summary>
        public string ApplicationName { get; set; } = "OpcUaServer";

        /// <summary>
        /// Application URI (e.g. <c>urn:localhost:Org:Product</c>).
        /// </summary>
        public string ApplicationUri { get; set; } = string.Empty;

        /// <summary>
        /// Product URI (e.g. <c>uri:org:product</c>).
        /// </summary>
        public string ProductUri { get; set; } = string.Empty;

        /// <summary>
        /// Optional explicit certificate subject. When not set, defaults to
        /// <c>CN={ApplicationName}, O=OPC Foundation, DC=localhost</c>.
        /// </summary>
        public string SubjectName { get; set; } = string.Empty;

        /// <summary>
        /// Listen URLs. Mutated in place by <c>options.EndpointUrls.Add(...)</c>.
        /// </summary>
        public IList<string> EndpointUrls { get; } = [];

        /// <summary>
        /// Filesystem root used for the certificate stores. When empty, defaults
        /// to <c>%TEMP%/OPC Foundation/{ApplicationName}/pki</c>.
        /// </summary>
        public string PkiRoot { get; set; } = string.Empty;

        /// <summary>
        /// Whether unknown peer certificates are auto-accepted. Convenient for
        /// quickstart samples; do not enable in production.
        /// </summary>
        public bool AutoAcceptUntrustedCertificates { get; set; }

        /// <summary>
        /// Toggle the OPC UA server diagnostics node manager.
        /// </summary>
        public bool DiagnosticsEnabled { get; set; } = true;

        /// <summary>
        /// Maximum byte-string length advertised on the transport. Defaults to
        /// 4 MiB.
        /// </summary>
        public uint MaxByteStringLength { get; set; } = 4 * 1024 * 1024;

        /// <summary>
        /// Maximum array length advertised on the transport. Defaults to 1 Mi
        /// elements.
        /// </summary>
        public uint MaxArrayLength { get; set; } = 1024 * 1024;

        /// <summary>
        /// When true (default), <c>AddSignAndEncryptPolicies()</c> is applied to
        /// the configuration builder.
        /// </summary>
        public bool IncludeSignAndEncryptPolicies { get; set; } = true;

        /// <summary>
        /// When true, <c>AddUnsecurePolicyNone()</c> is applied to the
        /// configuration builder. Off by default.
        /// </summary>
        public bool IncludeUnsecurePolicyNone { get; set; }

        /// <summary>
        /// When <c>true</c>, ECC sign-and-encrypt security policies are added
        /// to the configuration builder via
        /// <c>AddEccSignAndEncryptPolicies()</c>. Off by default.
        /// </summary>
        public bool IncludeEccPolicies { get; set; }

        /// <summary>
        /// User-token policies to advertise on every endpoint. Each entry
        /// is appended via
        /// <c>IApplicationConfigurationBuilderServerSelected.AddUserTokenPolicy</c>.
        /// When this list is empty the hosted service falls back to
        /// <see cref="UserTokenType.Anonymous"/>.
        /// </summary>
        public IList<OpcUaUserTokenPolicy> UserTokenPolicies { get; }
            = [];

        /// <summary>
        /// Server-side identity authenticators and trusted JWT issuers.
        /// </summary>
        public OpcUaServerIdentityOptions Identity { get; set; } = new();

        /// <summary>
        /// Maximum message size advertised on the transport, in bytes.
        /// When <c>null</c>, the stack default is kept. When set, the value
        /// is forwarded to
        /// <c>IApplicationConfigurationBuilderTransportQuotas.SetMaxMessageSize</c>.
        /// </summary>
        public int? MaxMessageSize { get; set; }

        /// <summary>
        /// Operation timeout advertised on the transport, in milliseconds.
        /// When <c>null</c>, the stack default is kept. When set, the value
        /// is forwarded to
        /// <c>IApplicationConfigurationBuilderTransportQuotas.SetOperationTimeout</c>.
        /// </summary>
        public int? OperationTimeoutMs { get; set; }

        /// <summary>
        /// Reject SHA-1-signed certificates during certificate validation
        /// (server-wide hardening). Defaults to <c>true</c>; flip to
        /// <c>false</c> only for legacy interop scenarios. Forwarded to
        /// <c>SetRejectSHA1SignedCertificates</c>.
        /// </summary>
        public bool RejectSHA1Certificates { get; set; } = true;

        /// <summary>
        /// Minimum accepted certificate RSA key size during validation.
        /// Defaults to 2048; set to <c>0</c> to keep the stack default.
        /// Forwarded to <c>SetMinimumCertificateKeySize</c>.
        /// </summary>
        public ushort MinCertificateKeySize { get; set; } = 2048;

        /// <summary>
        /// Optional URL of an LDS/GDS registration endpoint. When set, the
        /// hosted service builds a minimal
        /// <see cref="EndpointDescription"/> and forwards it to
        /// <c>SetRegistrationEndpoint</c> so the server registers itself
        /// with the configured discovery server on startup.
        /// </summary>
        public string? RegistrationEndpointUrl { get; set; }

        /// <summary>
        /// Server-side reverse-connect configuration. When non-null the
        /// hosted service builds the equivalent
        /// <see cref="ReverseConnectServerConfiguration"/> and forwards it
        /// to <c>SetReverseConnect</c>.
        /// </summary>
        public ServerReverseConnectOptions? ReverseConnect { get; set; }

        /// <summary>
        /// Operation limits advertised by the server (max nodes per read,
        /// write, browse, etc.). When non-null the hosted service projects
        /// the value into <see cref="OperationLimits"/> and forwards it to
        /// <c>SetOperationLimits</c>.
        /// </summary>
        public OperationLimitsOptions? OperationLimits { get; set; }

        /// <summary>
        /// Optional escape hatch invoked after the standard configuration steps
        /// (transport quotas, server policies, security configuration) but
        /// before <c>CreateAsync</c>. Use it to add bespoke security policies,
        /// override quotas, or add custom security stores.
        /// </summary>
        public Action<IApplicationConfigurationBuilderServerSelected>? ConfigureBuilder { get; set; }
    }
}