56 lines
2.4 KiB
C#
56 lines
2.4 KiB
C#
using System.Collections.Immutable;
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using System.Linq.Expressions;
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using System.Reflection;
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using GameServer.Handlers.Attributes;
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using Microsoft.Extensions.DependencyInjection;
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using Microsoft.Extensions.Logging;
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using Protocol;
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namespace GameServer.Handlers.Factory;
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internal class MessageHandlerFactory
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{
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private readonly ImmutableDictionary<MessageId, MessageHandler> s_messageHandlers;
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public MessageHandlerFactory(ILogger<MessageHandlerFactory> logger)
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{
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IEnumerable<Type> handlerTypes = Assembly.GetExecutingAssembly().GetTypes()
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.Where(t => t.IsAssignableTo(typeof(MessageHandlerBase)) && !t.IsAbstract);
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s_messageHandlers = GenerateHandlerMethods(handlerTypes);
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logger.LogInformation("Registered {count} message handlers", s_messageHandlers.Count);
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}
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public MessageHandler? GetHandler(MessageId messageId)
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{
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s_messageHandlers.TryGetValue(messageId, out MessageHandler? handler);
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return handler;
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}
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private static ImmutableDictionary<MessageId, MessageHandler> GenerateHandlerMethods(IEnumerable<Type> handlerTypes)
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{
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var builder = ImmutableDictionary.CreateBuilder<MessageId, MessageHandler>();
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MethodInfo getServiceMethod = typeof(ServiceProviderServiceExtensions).GetMethod("GetRequiredService", [typeof(IServiceProvider)])!;
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foreach (Type type in handlerTypes)
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{
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IEnumerable<MethodInfo> methods = type.GetMethods()
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.Where(method => method.GetCustomAttribute<MessageHandlerAttribute>() != null);
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foreach (MethodInfo method in methods)
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{
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MessageHandlerAttribute attribute = method.GetCustomAttribute<MessageHandlerAttribute>()!;
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ParameterExpression serviceProviderParam = Expression.Parameter(typeof(IServiceProvider));
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ParameterExpression dataParam = Expression.Parameter(typeof(ReadOnlyMemory<byte>));
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MethodCallExpression getServiceCall = Expression.Call(getServiceMethod.MakeGenericMethod(type), serviceProviderParam);
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MethodCallExpression handlerCall = Expression.Call(getServiceCall, method, dataParam);
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Expression<MessageHandler> lambda = Expression.Lambda<MessageHandler>(handlerCall, serviceProviderParam, dataParam);
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builder.Add(attribute.MessageId, lambda.Compile());
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}
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}
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return builder.ToImmutable();
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}
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}
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