using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UnitTestSharp;

namespace TestsForUnitTestSharp
{
    public class CpuTimeoutAttributeTests : TestFixture
    {
        [IgnoreFixture]
        public class SpinningFixture : TestFixture
        {
            private static void BurnCpu()
            {
                var elapsed = Stopwatch.StartNew();
                double accumulator = 0;
                while (elapsed.ElapsedMilliseconds < 100)
                {
                    accumulator += Math.Sqrt(accumulator + 1);
                }
            }

            [CpuTimeout(10000)]
            public void WithAllowance()
            {
                BurnCpu();
            }

            public void WithoutAllowance()
            {
                BurnCpu();
            }
        }

        [IgnoreTest]
        public bool RunSpinningTest(string methodName, out string output)
        {
            int? oldTimeout = TestRunner.TestCpuTimeoutInMilliseconds;
            bool oldIgnoreDebugger = TestRunner.IgnoreDebugger;

            TestRunner.TestCpuTimeoutInMilliseconds = 10;
            TestRunner.IgnoreDebugger = true;
            try
            {
                int failedChecks = 0;
                string captured = "";
                bool passed = TestRunner.RunTest(new SpinningFixture(),
                    typeof(SpinningFixture).GetMethod(methodName), null, 0,
                    (outputString) => captured += outputString, ref failedChecks);
                output = captured;
                return passed;
            }
            finally
            {
                TestRunner.TestCpuTimeoutInMilliseconds = oldTimeout;
                TestRunner.IgnoreDebugger = oldIgnoreDebugger;
            }
        }

        public void OverDefaultBudget_WithAttribute_Passes()
        {
            string output;
            Check(RunSpinningTest("WithAllowance", out output));
            CheckNotEqualRegex("error", output);
        }

        public void OverDefaultBudget_WithoutAttribute_FailsOnCpuTime()
        {
            string output;
            CheckFalse(RunSpinningTest("WithoutAllowance", out output));
            CheckEqualRegex("CPU time", output);
        }
    }
}