using MarketAlly.AIPlugin.Analysis.Infrastructure;
using Microsoft.Extensions.Logging;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Threading.Tasks;

namespace MarketAlly.AIPlugin.Analysis.Tests.Infrastructure
{
    [TestClass]
    public class AnalysisContextTests
    {
        private AnalysisConfiguration _configuration = null!;
        private ILogger? _logger;

        [TestInitialize]
        public void Setup()
        {
            _configuration = new AnalysisConfiguration
            {
                MaxConcurrentAnalyses = 2,
                DefaultTimeout = TimeSpan.FromMinutes(5)
            };
            _logger = null; // In real tests, you might use a mock logger
        }

        [TestMethod]
        public void Constructor_WithValidConfiguration_ShouldInitialize()
        {
            // Act
            using var context = new AnalysisContext(_configuration, _logger);

            // Assert
            Assert.IsNotNull(context.Configuration);
            Assert.AreEqual(_configuration, context.Configuration);
            Assert.IsNotNull(context.CancellationToken);
            Assert.IsFalse(context.CancellationToken.IsCancellationRequested);
            Assert.IsNotNull(context.ConcurrencySemaphore);
        }

        [TestMethod]
        [ExpectedException(typeof(ArgumentNullException))]
        public void Constructor_WithNullConfiguration_ShouldThrowArgumentNullException()
        {
            // Act & Assert
            using var context = new AnalysisContext(null!, _logger);
        }

        [TestMethod]
        public void Cancel_ShouldSetCancellationTokenToRequested()
        {
            // Arrange
            using var context = new AnalysisContext(_configuration, _logger);

            // Act
            context.Cancel();

            // Assert
            Assert.IsTrue(context.CancellationToken.IsCancellationRequested);
        }

        [TestMethod]
        public async Task AcquireConcurrencySlot_ShouldSucceed()
        {
            // Arrange
            using var context = new AnalysisContext(_configuration, _logger);

            // Act & Assert - Should not throw
            await context.AcquireConcurrencySlotAsync();
            
            // Cleanup
            context.ReleaseConcurrencySlot();
        }

        [TestMethod]
        public async Task ReleaseConcurrencySlot_ShouldSucceed()
        {
            // Arrange
            using var context = new AnalysisContext(_configuration, _logger);
            
            // First acquire a slot
            await context.AcquireConcurrencySlotAsync();

            // Act & Assert - Should not throw
            context.ReleaseConcurrencySlot();
        }

        [TestMethod]
        public async Task ConcurrencySlot_ShouldLimitConcurrentAccess()
        {
            // Arrange - Use a configuration with max concurrency of 1 for clearer testing
            var restrictiveConfig = new AnalysisConfiguration
            {
                MaxConcurrentAnalyses = 1,
                DefaultTimeout = TimeSpan.FromMinutes(5)
            };
            
            using var context = new AnalysisContext(restrictiveConfig, _logger);
            var task1Started = false;
            var task2Started = false;
            var task1CanContinue = new TaskCompletionSource<bool>();

            // Act
            var task1 = Task.Run(async () =>
            {
                await context.AcquireConcurrencySlotAsync();
                task1Started = true;
                await task1CanContinue.Task;
                context.ReleaseConcurrencySlot();
            });

            var task2 = Task.Run(async () =>
            {
                // Small delay to ensure task1 starts first
                await Task.Delay(100);
                await context.AcquireConcurrencySlotAsync();
                task2Started = true;
                context.ReleaseConcurrencySlot();
            });

            // Wait for task1 to start and task2 to be blocked
            await Task.Delay(300);

            // Assert
            Assert.IsTrue(task1Started);
            Assert.IsFalse(task2Started); // Should be blocked by semaphore

            // Release task1
            task1CanContinue.SetResult(true);
            await Task.WhenAll(task1, task2);

            Assert.IsTrue(task2Started);
        }

        [TestMethod]
        public void AnalysisContext_WithNullLogger_ShouldInitializeProperly()
        {
            // Arrange & Act
            using var context = new AnalysisContext(_configuration, _logger);

            // Assert - Logger can be null, that's valid
            Assert.AreEqual(_logger, context.Logger); // _logger is null in setup
            Assert.IsNotNull(context.Configuration);
            Assert.IsNotNull(context.CancellationToken);
            Assert.IsNotNull(context.ConcurrencySemaphore);
        }

        [TestMethod]
        public void AnalysisContext_BasicFunctionality_ShouldWork()
        {
            // Arrange & Act
            using var context = new AnalysisContext(_configuration, _logger);

            // Assert - Test core functionality without child contexts
            Assert.IsNotNull(context.Configuration);
            Assert.IsNotNull(context.CancellationToken);
            Assert.IsNotNull(context.ConcurrencySemaphore);
            Assert.IsFalse(context.CancellationToken.IsCancellationRequested);
            
            // Test cancellation works
            context.Cancel();
            Assert.IsTrue(context.CancellationToken.IsCancellationRequested);
        }

        [TestMethod]
        public async Task AcquireConcurrencySlotAsync_AfterDispose_ShouldThrowObjectDisposedException()
        {
            // Arrange
            var context = new AnalysisContext(_configuration, _logger);
            context.Dispose();

            // Act & Assert
            await Assert.ThrowsExceptionAsync<ObjectDisposedException>(async () =>
            {
                await context.AcquireConcurrencySlotAsync();
            });
        }

        [TestMethod]
        [ExpectedException(typeof(ObjectDisposedException))]
        public void Cancel_AfterDispose_ShouldThrowObjectDisposedException()
        {
            // Arrange
            var context = new AnalysisContext(_configuration, _logger);
            context.Dispose();

            // Act & Assert
            context.Cancel();
        }

        [TestMethod]
        public void Dispose_ShouldNotThrow()
        {
            // Arrange
            var context = new AnalysisContext(_configuration, _logger);

            // Act & Assert - Should not throw
            context.Dispose();
            
            // Multiple dispose calls should not throw
            context.Dispose();
        }
    }
}