using ZB.MOM.WW.CBDDC.Core.Exceptions;
using ZB.MOM.WW.CBDDC.Core.Network;
using ZB.MOM.WW.CBDDC.Core.Resilience;

namespace ZB.MOM.WW.CBDDC.Core.Tests;

public class RetryPolicyTests
{
    /// <summary>
    ///     Verifies transient failures are retried until a successful result is returned.
    /// </summary>
    [Fact]
    public async Task ExecuteAsync_WhenTransientFailureEventuallySucceeds_RetriesAndReturnsResult()
    {
        var policy = new RetryPolicy(CreateConfigProvider(retryAttempts: 3, retryDelayMs: 1));
        var attempts = 0;

        int result = await policy.ExecuteAsync(async () =>
        {
            attempts++;
            if (attempts < 3) throw new NetworkException("transient");
            await Task.CompletedTask;
            return 42;
        }, "test-op");

        result.ShouldBe(42);
        attempts.ShouldBe(3);
    }

    /// <summary>
    ///     Verifies transient failures throw retry exhausted when all retries are consumed.
    /// </summary>
    [Fact]
    public async Task ExecuteAsync_WhenTransientFailureExhausted_ThrowsRetryExhaustedException()
    {
        var policy = new RetryPolicy(CreateConfigProvider(retryAttempts: 2, retryDelayMs: 1));
        var attempts = 0;

        var ex = await Should.ThrowAsync<CBDDCException>(() => policy.ExecuteAsync<int>(() =>
        {
            attempts++;
            throw new NetworkException("still transient");
        }, "test-op"));

        ex.ErrorCode.ShouldBe("RETRY_EXHAUSTED");
        ex.InnerException.ShouldBeOfType<NetworkException>();
        attempts.ShouldBe(2);
    }

    /// <summary>
    ///     Verifies non-transient failures are not retried.
    /// </summary>
    [Fact]
    public async Task ExecuteAsync_WhenFailureIsNonTransient_DoesNotRetry()
    {
        var policy = new RetryPolicy(CreateConfigProvider(retryAttempts: 3, retryDelayMs: 1));
        var attempts = 0;

        await Should.ThrowAsync<InvalidOperationException>(() => policy.ExecuteAsync<int>(() =>
        {
            attempts++;
            throw new InvalidOperationException("non-transient");
        }, "test-op"));

        attempts.ShouldBe(1);
    }

    private static IPeerNodeConfigurationProvider CreateConfigProvider(int retryAttempts, int retryDelayMs)
    {
        var configProvider = Substitute.For<IPeerNodeConfigurationProvider>();
        configProvider.GetConfiguration().Returns(new PeerNodeConfiguration
        {
            RetryAttempts = retryAttempts,
            RetryDelayMs = retryDelayMs
        });
        return configProvider;
    }
}