#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#endregion

using Google.Protobuf.Collections;
using System;
using System.Collections.Generic;

namespace Google.Protobuf.Reflection
{
    /// <summary>
    /// Describes a service type.
    /// </summary>
    public sealed class ServiceDescriptor : DescriptorBase
    {
        internal ServiceDescriptor(ServiceDescriptorProto proto, FileDescriptor file, int index)
            : base(file, file.ComputeFullName(null, proto.Name), index, file.Features.MergedWith(proto.Options?.Features))
        {
            Proto = proto;
            Methods = DescriptorUtil.ConvertAndMakeReadOnly(proto.Method,
                                                            (method, i) => new MethodDescriptor(method, file, this, i));

            file.DescriptorPool.AddSymbol(this);
        }

        /// <summary>
        /// The brief name of the descriptor's target.
        /// </summary>
        public override string Name => Proto.Name;

        internal override IReadOnlyList<DescriptorBase> GetNestedDescriptorListForField(int fieldNumber) =>
            fieldNumber switch
            {
                ServiceDescriptorProto.MethodFieldNumber => (IReadOnlyList<DescriptorBase>)Methods,
                _ => null,
            };

        internal ServiceDescriptorProto Proto { get; }

        /// <summary>
        /// Returns a clone of the underlying <see cref="ServiceDescriptorProto"/> describing this service.
        /// Note that a copy is taken every time this method is called, so clients using it frequently
        /// (and not modifying it) may want to cache the returned value.
        /// </summary>
        /// <returns>A protobuf representation of this service descriptor.</returns>
        public ServiceDescriptorProto ToProto() => Proto.Clone();

        /// <value>
        /// An unmodifiable list of methods in this service.
        /// </value>
        public IList<MethodDescriptor> Methods { get; }

        /// <summary>
        /// Finds a method by name.
        /// </summary>
        /// <param name="name">The unqualified name of the method (e.g. "Foo").</param>
        /// <returns>The method's descriptor, or null if not found.</returns>
        public MethodDescriptor FindMethodByName(string name) =>
            File.DescriptorPool.FindSymbol<MethodDescriptor>(FullName + "." + name);

        /// <summary>
        /// The (possibly empty) set of custom options for this service.
        /// </summary>
        [Obsolete("CustomOptions are obsolete. Use the GetOptions() method.")]
        public CustomOptions CustomOptions => new CustomOptions(Proto.Options?._extensions?.ValuesByNumber);

        /// <summary>
        /// The <c>ServiceOptions</c>, defined in <c>descriptor.proto</c>.
        /// If the options message is not present (i.e. there are no options), <c>null</c> is returned.
        /// Custom options can be retrieved as extensions of the returned message.
        /// NOTE: A defensive copy is created each time this property is retrieved.
        /// </summary>
        public ServiceOptions GetOptions()
        {
            var clone = Proto.Options?.Clone();
            if (clone is null)
            {
                return null;
            }
            // Clients should be using feature accessor methods, not accessing features on the
            // options proto.
            clone.Features = null;
            return clone;
        }

        /// <summary>
        /// Gets a single value service option for this descriptor
        /// </summary>
        [Obsolete("GetOption is obsolete. Use the GetOptions() method.")]
        public T GetOption<T>(Extension<ServiceOptions, T> extension)
        {
            var value = Proto.Options.GetExtension(extension);
            return value is IDeepCloneable<T> ? (value as IDeepCloneable<T>).Clone() : value;
        }

        /// <summary>
        /// Gets a repeated value service option for this descriptor
        /// </summary>
        [Obsolete("GetOption is obsolete. Use the GetOptions() method.")]
        public RepeatedField<T> GetOption<T>(RepeatedExtension<ServiceOptions, T> extension)
        {
            return Proto.Options.GetExtension(extension).Clone();
        }

        internal void CrossLink()
        {
            foreach (MethodDescriptor method in Methods)
            {
                method.CrossLink();
            }
        }
    }
}