godot-host-test/addons/AetherBind/ServiceSource.cs

using System;
using System.Linq;
using Godot;
using Microsoft.Extensions.Logging;
using OwofGames.AetherBind;
using OwofGames.GodotLume;

namespace GodotHostTest.AetherBind;

[Icon("res://addons/AetherBind/ServiceSource.svg")]
public partial class ServiceSource : Node
{
    private static readonly string RootScopeQualifiedName = typeof(RootScope).AssemblyQualifiedName!;
    [Export] protected Node?[] InjectedNodes = [];
    [Export] private string _serviceScope = RootScopeQualifiedName;

    internal void ResolveInjectedNodes(IProvider provider, Delegate? onScopeCreated)
    {
        var logger = provider.Get<ILogger<ServiceSource>>();

        // if this service source must also act as a scope, create the scope and use its service provider
        if (_serviceScope != RootScopeQualifiedName)
        {
            // create the scoped provider
            var serviceScope = ScopeTypesAndNames.GetType(_serviceScope);
            provider = provider.GetScopedProvider(serviceScope);
            // invoke onScopeCreated, if present
            // TODO: replace with a source code generation by turning this method private with Action<IProvider> argument, and every invocation site calls the necessary provider.Get<...> to build the argument list
            if (onScopeCreated != null)
            {
                var parameters = onScopeCreated.Method
                    .GetParameters()
                    .Select(parameterInfo => provider.Get(parameterInfo.ParameterType))
                    .ToArray();
                onScopeCreated.DynamicInvoke(parameters);
            }

            OnScopeCreated(provider);
        }
        else if (onScopeCreated != null)
        {
            logger.LogWarning("onScopeCreated passed during instantiation, but no scoped provider was created.");
        }

        // resolve the injected nodes against the chosen service provider
        foreach (var node in InjectedNodes)
        {
            if (node == null) continue;
            logger.LogTrace("Injecting {Node}.", node.Name);

            if (node is IInjectable injectable)
            {
                injectable.Inject(provider);
            }

            // var nodeType = node.GetType();
            // foreach (var field in nodeType
            //              .GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic))
            // {
            //     if (field.GetCustomAttribute<InjectAttribute>() == null) continue;
            //     var fieldType = field.FieldType;
            //     var service = provider.Get(fieldType);
            //     field.SetValue(node, service);
            // }
            //
            // foreach (var method in nodeType.GetMethods(BindingFlags.Instance | BindingFlags.Public |
            //                                            BindingFlags.NonPublic))
            // {
            //     if (method.GetCustomAttribute<InjectAttribute>() == null) continue;
            //     var parameters = method.GetParameters();
            //     var values = new object?[parameters.Length];
            //     var i = 0;
            //     foreach (var parameter in parameters)
            //     {
            //         var parameterType = parameter.ParameterType;
            //         var service = provider.Get(parameterType);
            //         values[i++] = service;
            //     }
            //
            //     method.Invoke(node, values);
            // }
        }
    }

    // TODO: also add source generator to mark methods in derived classes with [OnScopeCreated] and perform parameter injection
    protected virtual void OnScopeCreated(IProvider serviceProvider)
    {
    }
}