using ZB.MOM.WW.CBDDC.Core.Network;
using ZB.MOM.WW.CBDDC.Core.Sync;

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

public class OfflineQueueTests
{
    /// <summary>
    /// Verifies that enqueuing beyond capacity drops the oldest operation.
    /// </summary>
    [Fact]
    public async Task Enqueue_WhenQueueIsFull_DropsOldestOperation()
    {
        var queue = new OfflineQueue(CreateConfigProvider(maxQueueSize: 2));
        await queue.Enqueue(CreateOperation("1"));
        await queue.Enqueue(CreateOperation("2"));
        await queue.Enqueue(CreateOperation("3"));

        var flushed = new List<string>();
        (int successful, int failed) = await queue.FlushAsync(op =>
        {
            flushed.Add(op.Key);
            return Task.CompletedTask;
        });

        successful.ShouldBe(2);
        failed.ShouldBe(0);
        flushed.ShouldBe(["2", "3"]);
    }

    /// <summary>
    /// Verifies that flush continues when an executor throws and returns the failure count.
    /// </summary>
    [Fact]
    public async Task FlushAsync_WhenExecutorThrows_ContinuesAndReturnsFailureCount()
    {
        var queue = new OfflineQueue(CreateConfigProvider(maxQueueSize: 10));
        await queue.Enqueue(CreateOperation("1"));
        await queue.Enqueue(CreateOperation("2"));

        (int successful, int failed) = await queue.FlushAsync(op =>
        {
            if (op.Key == "1") throw new InvalidOperationException("boom");
            return Task.CompletedTask;
        });

        successful.ShouldBe(1);
        failed.ShouldBe(1);
        queue.Count.ShouldBe(0);
    }

    /// <summary>
    /// Verifies that clear removes all queued operations.
    /// </summary>
    [Fact]
    public async Task Clear_RemovesAllQueuedOperations()
    {
        var queue = new OfflineQueue(CreateConfigProvider(maxQueueSize: 10));
        await queue.Enqueue(CreateOperation("1"));
        await queue.Enqueue(CreateOperation("2"));
        queue.Count.ShouldBe(2);

        await queue.Clear();

        queue.Count.ShouldBe(0);
        (int successful, int failed) = await queue.FlushAsync(_ => Task.CompletedTask);
        successful.ShouldBe(0);
        failed.ShouldBe(0);
    }

    private static PendingOperation CreateOperation(string key)
    {
        return new PendingOperation
        {
            Type = "upsert",
            Collection = "users",
            Key = key,
            Data = new { Value = key },
            QueuedAt = DateTime.UtcNow
        };
    }

    private static IPeerNodeConfigurationProvider CreateConfigProvider(int maxQueueSize)
    {
        var configProvider = Substitute.For<IPeerNodeConfigurationProvider>();
        configProvider.GetConfiguration().Returns(new PeerNodeConfiguration
        {
            MaxQueueSize = maxQueueSize
        });
        return configProvider;
    }
}