ItayPodhajcer

[Binding]
[AttributeUsage(AttributeTargets.Parameter)]
public sealed class EthereumEventTriggerAttribute : Attribute 
{
	private const string DefaultUrl = "http://localhost:8545/";

	public EthereumEventTriggerAttribute(string abi, string contractAddress, string eventName, string url = DefaultUrl)
	{
		Url = url;  
		Abi = abi;

ItayPodhajcer

public async Task StartAsync(CancellationToken cancellationToken)
{
	_cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);

	var web3 = new Web3(_attribute.Url);
	var contract = web3.Eth.GetContract(_attribute.Abi, _attribute.ContractAddress);

	_event = contract.GetEvent(_attribute.EventName);
	_filter = await _event.CreateFilterAsync();

ItayPodhajcer

private async void ListenAsync(CancellationToken cancellationToken)
{
	await Task.Run(async () =>
	{
		while (!cancellationToken.IsCancellationRequested)
		{
			var eventsData = await _event.GetFilterChangeDefault(_filter);

			ProcessEvents(eventsData, cancellationToken);
			await Task.Delay(EventPollingDelay);

ItayPodhajcer

private void ProcessEvents(List<EventLog<List<ParameterOutput>>> eventsData, CancellationToken cancellationToken)
{
	eventsData
		.Select(eventData => ExtractEventData(eventData.Event, eventData.Log))
		.ToList()
		.ForEach(ethereumEventData => _executor.TryExecuteAsync(new TriggeredFunctionData { TriggerValue = ethereumEventData }, cancellationToken));
}

ItayPodhajcer

private EthereumEventData ExtractEventData(List<ParameterOutput> eventParams, FilterLog log)
{
    Dictionary<string, string> values = eventParams.ToDictionary(eventParam => eventParam.Parameter.Name, eventParam => eventParam.Result.ToString());

    return new EthereumEventData
    {
        Values = values,
        BlockNumber = log.BlockNumber
    };
}

ItayPodhajcer

internal class EthereumEventTriggerBinding : ITriggerBinding
{
	private readonly EthereumEventTriggerAttribute _attribute;

	public EthereumEventTriggerBinding(EthereumEventTriggerAttribute attribute)
	{
		_attribute = attribute;
	}

	public Type TriggerValueType => typeof(EthereumEventData);

ItayPodhajcer

public class EthereumEventTriggerBindingProvider : ITriggerBindingProvider
{
	public Task<ITriggerBinding> TryCreateAsync(TriggerBindingProviderContext context)
	{
		var result = Task.FromResult<ITriggerBinding>(default);
		var attribute = context.Parameter.GetCustomAttribute<EthereumEventTriggerAttribute>(false);

		if (attribute != null)
		{
			result = Task.FromResult<ITriggerBinding>(new EthereumEventTriggerBinding(attribute));

ItayPodhajcer

[Extension("EthereumEventTrigger")]
public class EtheremEventConfigProvider : IExtensionConfigProvider
{
	public void Initialize(ExtensionConfigContext context)
	{
		context
			.AddBindingRule<EthereumEventTriggerAttribute>()
			.BindToTrigger<EthereumEventData>(new EthereumEventTriggerBindingProvider());
	}
}

ItayPodhajcer

public class EthereumEventListener : IListener
{
	private const int EventPollingDelay = 1000;

	private readonly ITriggeredFunctionExecutor _executor;
	private readonly EthereumEventTriggerAttribute _attribute;
	private CancellationTokenSource _cts = null;
	private Event _event = null;
	private HexBigInteger _filter = null;

ItayPodhajcer

public static class EthereumEventTriggeredFunction
{
	private const string Abi = "";
	private const string ContractAddress = "";
	private const string EventName = "";

	[FunctionName(nameof(EthereumEventTriggeredFunction))]
	public static void Run([EthereumEventTrigger(abi: Abi, contractAddress: ContractAddress, eventName: EventName)]EthereumEventData eventData, ILogger logger)
	{
		string logMessage = $"Event data:\nBlock number: {eventData.BlockNumber}\n{string.Join('\n', eventData.Values.Select(value => $"{value.Key}: {value.Value}"))}";