#[cfg(test)]
mod e2e_tests {
    use dmc_lib::compile_compilation_unit;
    use dmc_lib::constants_table::ConstantsTable;
    use dmc_lib::diagnostic::{Diagnostic, Diagnostics};
    use dvm_lib::vm::constant::{Constant, StringConstant};
    use dvm_lib::vm::value::Value;
    use dvm_lib::vm::{DvmContext, call};
    use std::rc::Rc;

    const REGISTER_COUNT: usize = 16;

    fn report_diagnostics(diagnostics: &[Diagnostic]) -> ! {
        eprintln!(
            "{}",
            diagnostics
                .iter()
                .map(|d| format!("{:?}", d))
                .collect::<Vec<_>>()
                .join("\n")
        );
        panic!("There were diagnostics.");
    }

    fn prepare_context(input: &str) -> Result<DvmContext, Diagnostics> {
        let mut constants_table = ConstantsTable::new();

        let compile_compilation_unit_result = compile_compilation_unit(input, &mut constants_table);

        let mut dvm_context = DvmContext::new();

        for (name, function) in compile_compilation_unit_result?.functions {
            dvm_context.functions_mut().insert(name, function);
        }

        for (name, content) in &constants_table.string_constants() {
            dvm_context.constants_mut().insert(
                name.clone(),
                Constant::String(StringConstant::new(name.clone(), content.clone())),
            );
        }

        Ok(dvm_context)
    }

    fn get_result(
        dvm_context: &DvmContext,
        function_name: &str,
        arguments: &[Value],
    ) -> Option<Value> {
        call(&dvm_context, function_name, &arguments, REGISTER_COUNT)
    }

    fn assert_result(input: &str, function_name: &str, arguments: &[Value], expected_value: Value) {
        let context = match prepare_context(input) {
            Ok(context) => context,
            Err(diagnostics) => report_diagnostics(&diagnostics),
        };
        match get_result(&context, function_name, arguments) {
            None => panic!("Call returned no value"),
            Some(result_value) => {
                assert_eq!(result_value, expected_value);
            }
        }
    }

    #[test]
    fn add_1_2() {
        assert_result(
            "
            fn add(a: Int, b: Int) -> Int
                a + b
            end
            ",
            "add",
            &vec![Value::Int(1), Value::Int(2)],
            Value::Int(3),
        );
    }

    #[test]
    fn bunch_of_adding() {
        assert_result(
            "
            fn add(a: Int, b: Int) -> Int
                a + b
            end

            fn greetAndAdd(a: Int, b: Int) -> String
                \"Hello. \" + a + \" plus \" + b + \" is \" + add(a, b)
            end
            ",
            "greetAndAdd",
            &vec![Value::Int(1), Value::Int(2)],
            Value::String(Rc::from("Hello. 1 plus 2 is 3")),
        );
    }

    #[test]
    fn simple_subtract() {
        assert_result("fn sub() -> Int 3 - 2 end", "sub", &vec![], Value::Int(1))
    }

    #[test]
    fn add_two_doubles() {
        assert_result(
            "fn add(a: Double, b: Double) -> Double a + b end",
            "add",
            &vec![Value::Double(1.23), Value::Double(1.23)],
            Value::Double(1.23 + 1.23),
        );
    }

    #[test]
    fn add_two_double_variables() {
        assert_result(
            "
            fn add() -> Double
                let a = 1.0
                let b = 2.0
                a + b
            end
            ",
            "add",
            &vec![Value::Double(1.0), Value::Double(2.0)],
            Value::Double(3.0),
        );
    }

    #[test]
    fn subtract_two_doubles() {
        assert_result(
            "fn subtract(a: Double, b: Double) -> Double a - b end",
            "subtract",
            &vec![Value::Double(3.0), Value::Double(2.0)],
            Value::Double(1.0),
        );
    }

    #[test]
    fn subtract_two_double_variables() {
        assert_result(
            "
            fn subtract() -> Double
                let a = 3.0
                let b = 2.0
                a - b
            end
            ",
            "subtract",
            &vec![],
            Value::Double(1.0),
        )
    }

    #[test]
    fn simple_assign() {
        assert_result(
            "
            fn assign() -> Int
                let mut x = 21
                x = x + x
                x
            end
            ",
            "assign",
            &vec![],
            Value::Int(42),
        );
    }

    #[test]
    fn assign_field() -> Result<(), Vec<Diagnostic>> {
        let context = prepare_context(
            "
            class Foo
                mut bar = 21

                ctor(_bar: Int)
                    bar = _bar
                end
            end

            fn foo() -> Foo
                Foo(42)
            end
            ",
        )?;
        let result = get_result(&context, "foo", &vec![]);
        assert!(result.is_some());
        let value = result.unwrap();
        assert!(matches!(value, Value::Object(_)));
        let o = value.unwrap_object().borrow();
        assert_eq!(o.fields().len(), 1);
        assert_eq!(o.fields()[0].unwrap_int(), 42);
        Ok(())
    }

    #[test]
    fn generic_field_and_ctor_param() -> Result<(), Vec<Diagnostic>> {
        let context = prepare_context(
            "
            class Foo<T>
                mut t: T
                ctor(_t: T)
                    t = _t
                end
            end

            fn main() -> Foo<Int>
                Foo(42)
            end
            ",
        )?;
        let result = get_result(&context, "main", &vec![]);
        assert!(result.is_some());
        let value = result.unwrap();
        assert!(matches!(value, Value::Object(_)));
        let o = value.unwrap_object().borrow();
        assert_eq!(o.fields().len(), 1);
        assert_eq!(o.fields()[0].unwrap_int(), 42);
        Ok(())
    }
}