using System;
using NUnit.Framework;
using Python.Runtime;

namespace Python.EmbeddingTest
{
    public class TestPythonException
    {
        [Test]
        public void TestMessage()
        {
            var list = new PyList();
            PyObject foo = null;

            var ex = Assert.Throws(() => foo = list[0]);

            Assert.That(ex.Message, Is.EqualTo("list index out of range"));
            Assert.IsNull(foo);
        }

        [Test]
        public void TestType()
        {
            var list = new PyList();
            PyObject foo = null;

            var ex = Assert.Throws(() => foo = list[0]);

            Assert.That(ex.Type.Name, Is.EqualTo("IndexError"));
            Assert.IsNull(foo);
        }

        [Test]
        public void TestNoError()
        {
            // There is no PyErr to fetch
            Assert.Throws(() => PythonException.FetchCurrentRaw());
            var currentError = PythonException.FetchCurrentOrNullRaw();
            Assert.IsNull(currentError);
        }

        [Test]
        public void TestNestedExceptions()
        {
            try
            {
                PythonEngine.Exec(@"
try:
  raise Exception('inner')
except Exception as ex:
  raise Exception('outer') from ex
");
            }
            catch (PythonException ex)
            {
                Assert.That(ex.InnerException, Is.InstanceOf());
                Assert.That(ex.InnerException.Message, Is.EqualTo("inner"));
            }
        }

        [Test]
        public void InnerIsEmptyWithNoCause()
        {
            var list = new PyList();
            PyObject foo = null;

            var ex = Assert.Throws(() => foo = list[0]);

            Assert.IsNull(ex.InnerException);
        }

        [Test]
        public void TestPythonExceptionFormat()
        {
            try
            {
                PythonEngine.Exec("raise ValueError('Error!')");
                Assert.Fail("Exception should have been raised");
            }
            catch (PythonException ex)
            {
                // Console.WriteLine($"Format: {ex.Format()}");
                // Console.WriteLine($"Stacktrace: {ex.StackTrace}");
                Assert.That(
                    ex.Format(),
                    Does.Contain("Traceback")
                    .And.Contains("(most recent call last):")
                    .And.Contains("ValueError: Error!")
                );

                // Check that the stacktrace is properly formatted
                Assert.That(
                    ex.StackTrace,
                    Does.Not.StartWith("[")
                    .And.Not.Contain("\\n")
                );
            }
        }

        [Test]
        public void TestPythonExceptionFormatNoTraceback()
        {
            try
            {
                var module = PyModule.Import("really____unknown___module");
                Assert.Fail("Unknown module should not be loaded");
            }
            catch (PythonException ex)
            {
                // ImportError/ModuleNotFoundError do not have a traceback when not running in a script
                Assert.That(ex.Format(), Is.EqualTo(ex.StackTrace));
            }
        }

        [Test]
        public void TestPythonExceptionFormatNormalized()
        {
            try
            {
                PythonEngine.Exec("a=b\n");
                Assert.Fail("Exception should have been raised");
            }
            catch (PythonException ex)
            {
                Assert.AreEqual("Traceback (most recent call last):\n  File \"\", line 1, in \nNameError: name 'b' is not defined\n", ex.Format());
            }
        }

        [Test]
        public void TestPythonException_PyErr_NormalizeException()
        {
            using (var scope = Py.CreateScope())
            {
                scope.Exec(@"
class TestException(NameError):
    def __init__(self, val):
        super().__init__(val)
        x = int(val)");
                Assert.IsTrue(scope.TryGet("TestException", out PyObject type));

                PyObject str = "dummy string".ToPython();
                var typePtr = new NewReference(type.Reference);
                var strPtr = new NewReference(str.Reference);
                var tbPtr = new NewReference(Runtime.Runtime.None.Reference);
                Runtime.Runtime.PyErr_NormalizeException(ref typePtr, ref strPtr, ref tbPtr);

                using var typeObj = typePtr.MoveToPyObject();
                using var strObj = strPtr.MoveToPyObject();
                using var tbObj = tbPtr.MoveToPyObject();
                // the type returned from PyErr_NormalizeException should not be the same type since a new
                // exception was raised by initializing the exception
                Assert.IsFalse(PythonReferenceComparer.Instance.Equals(type, typeObj));
                // the message should now be the string from the throw exception during normalization
                Assert.That(strObj.ToString(), Is.EqualTo("invalid literal for int() with base 10: 'dummy string'"));
            }
        }

        [Test]
        public void TestPythonException_Normalize_ThrowsWhenErrorSet()
        {
            Exceptions.SetError(Exceptions.TypeError, "Error!");
            var pythonException = PythonException.FetchCurrentRaw();
            Exceptions.SetError(Exceptions.TypeError, "Another error");
            Assert.Throws(() => pythonException.Normalize());
            Exceptions.Clear();
        }
    }
}