using System;
using System.Threading.Tasks;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Host.Utilities;

namespace ZB.MOM.WW.OtOpcUa.Tests.Utilities
{
    /// <summary>
    ///     Tests for the bounded sync-over-async wrapper introduced by stability review 2026-04-13
    ///     Finding 3. The wrapper is a backstop applied at every LmxNodeManager sync-over-async site
    ///     (Read, Write, HistoryRead*, BuildAddressSpace probe sync).
    /// </summary>
    public class SyncOverAsyncTests
    {
        [Fact]
        public void WaitSync_CompletedTask_ReturnsResult()
        {
            var task = Task.FromResult(42);
            SyncOverAsync.WaitSync(task, TimeSpan.FromSeconds(1), "test").ShouldBe(42);
        }

        [Fact]
        public void WaitSync_CompletedNonGenericTask_Returns()
        {
            var task = Task.CompletedTask;
            Should.NotThrow(() => SyncOverAsync.WaitSync(task, TimeSpan.FromSeconds(1), "test"));
        }

        [Fact]
        public void WaitSync_NeverCompletingTask_ThrowsTimeoutException()
        {
            var tcs = new TaskCompletionSource<int>();
            var ex = Should.Throw<TimeoutException>(() =>
                SyncOverAsync.WaitSync(tcs.Task, TimeSpan.FromMilliseconds(100), "op"));
            ex.Message.ShouldContain("op");
        }

        [Fact]
        public void WaitSync_NeverCompletingNonGenericTask_ThrowsTimeoutException()
        {
            var tcs = new TaskCompletionSource<bool>();
            Should.Throw<TimeoutException>(() =>
                SyncOverAsync.WaitSync((Task)tcs.Task, TimeSpan.FromMilliseconds(100), "op"));
        }

        [Fact]
        public void WaitSync_FaultedNonGenericTask_UnwrapsInnerException()
        {
            var task = Task.FromException(new InvalidOperationException("boom"));
            Should.Throw<InvalidOperationException>(() =>
                SyncOverAsync.WaitSync(task, TimeSpan.FromSeconds(1), "op"));
        }

        [Fact]
        public void WaitSync_FaultedGenericTask_UnwrapsInnerException()
        {
            var task = Task.FromException<int>(new InvalidOperationException("boom"));
            Should.Throw<InvalidOperationException>(() =>
                SyncOverAsync.WaitSync(task, TimeSpan.FromSeconds(1), "op"));
        }

        [Fact]
        public void WaitSync_NullTask_ThrowsArgumentNullException()
        {
            Should.Throw<ArgumentNullException>(() =>
                SyncOverAsync.WaitSync((Task)null!, TimeSpan.FromSeconds(1), "op"));
            Should.Throw<ArgumentNullException>(() =>
                SyncOverAsync.WaitSync((Task<int>)null!, TimeSpan.FromSeconds(1), "op"));
        }
    }
}