Telegrator/src/Telegrator.Hosting/Providers/HostHandlersProvider.cs

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using Telegrator.Core;
using Telegrator.Core.Descriptors;
using Telegrator.Core.Handlers;

namespace Telegrator.Providers;

/// <inheritdoc/>
public class HostHandlersProvider : HandlersProvider
{
    private readonly IServiceProvider Services;

    /// <inheritdoc/>
    public HostHandlersProvider(
        IHandlersCollection handlers,
        IOptions<TelegratorOptions> options,
        IServiceProvider serviceProvider) : base(handlers, options.Value)
    {
        Services = serviceProvider;
    }

    /// <inheritdoc/>
    public override UpdateHandlerBase GetHandlerInstance(HandlerDescriptor descriptor, CancellationToken cancellationToken = default)
    {
        cancellationToken.ThrowIfCancellationRequested();
        IServiceScope scope = Services.CreateScope();

        object handlerInstance = descriptor.ServiceKey == null
            ? scope.ServiceProvider.GetRequiredService(descriptor.HandlerType)
            : scope.ServiceProvider.GetRequiredKeyedService(descriptor.HandlerType, descriptor.ServiceKey);

        if (handlerInstance is not UpdateHandlerBase updateHandler)
            throw new InvalidOperationException("Failed to resolve " + descriptor.HandlerType + " as UpdateHandlerBase");

        descriptor.LazyInitialization?.Invoke(updateHandler);
        updateHandler.LifetimeToken.OnLifetimeEnded += _ => scope.Dispose();
        return updateHandler;
    }
}