using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using SyncEngine.Sync;

namespace SyncEngine.Tests
{
    [TestClass]
    public class SyncInstanceLockTests
    {
        [TestMethod]
        public void TryAcquire_FirstCall_ReturnsLock()
        {
            var mutexName = UniqueMutexName();

            using (var instanceLock = SyncInstanceLock.TryAcquire(mutexName))
            {
                Assert.IsNotNull(instanceLock);
            }
        }

        [TestMethod]
        public void TryAcquire_SecondCallWhileHeld_ReturnsNull()
        {
            var mutexName = UniqueMutexName();

            using (var first = SyncInstanceLock.TryAcquire(mutexName))
            {
                Assert.IsNotNull(first);

                using (var second = SyncInstanceLock.TryAcquire(mutexName))
                {
                    Assert.IsNull(second);
                }
            }
        }

        [TestMethod]
        public void TryAcquire_AfterDispose_SucceedsAgain()
        {
            var mutexName = UniqueMutexName();

            using (var first = SyncInstanceLock.TryAcquire(mutexName))
            {
                Assert.IsNotNull(first);
            }

            using (var second = SyncInstanceLock.TryAcquire(mutexName))
            {
                Assert.IsNotNull(second);
            }
        }

        private static string UniqueMutexName()
        {
            return @"Global\SyncCoordinator.SyncEngine.Test." + Guid.NewGuid().ToString("N");
        }
    }
}