// Copyright (c) 2017-present PyO3 Project and Contributors
//
// based on Daniel Grunwald's https://github.com/dgrunwald/rust-cpython

use super::num_common::{err_if_invalid_value, IS_LITTLE_ENDIAN};
use crate::err::{PyErr, PyResult};
use crate::exceptions;
use crate::ffi;
use crate::instance::PyNativeType;
use crate::object::PyObject;
use crate::types::PyAny;
use crate::AsPyPointer;
use crate::Python;
use crate::{FromPyObject, IntoPyObject, ToPyObject};
use num_traits::cast::cast;
use std::i64;
use std::os::raw::{c_long, c_uchar};

/// Represents a Python `int` object.
///
/// You can usually avoid directly working with this type
/// by using [`ToPyObject`](trait.ToPyObject.html)
/// and [extract](struct.PyObject.html#method.extract)
/// with the primitive Rust integer types.
#[repr(transparent)]
pub struct PyLong(PyObject);

pyobject_native_type!(PyLong, ffi::PyLong_Type, ffi::PyLong_Check);

macro_rules! int_fits_c_long (
    ($rust_type:ty) => (
        impl ToPyObject for $rust_type {
            #![cfg_attr(feature="cargo-clippy", allow(clippy::cast_lossless))]
            fn to_object(&self, py: Python) -> PyObject {
                unsafe {
                    PyObject::from_owned_ptr_or_panic(py, ffi::PyLong_FromLong(*self as c_long))
                }
            }
        }
        impl IntoPyObject for $rust_type {
            #![cfg_attr(feature="cargo-clippy", allow(clippy::cast_lossless))]
            fn into_object(self, py: Python) -> PyObject {
                unsafe {
                    PyObject::from_owned_ptr_or_panic(py, ffi::PyLong_FromLong(self as c_long))
                }
            }
        }

        impl<'source> FromPyObject<'source> for $rust_type {
            fn extract(obj: &'source PyAny) -> PyResult<Self> {
                let ptr = obj.as_ptr();
                let val = unsafe {
                    let num = ffi::PyNumber_Index(ptr);
                    if num.is_null() {
                        Err(PyErr::fetch(obj.py()))
                    } else {
                        let val = err_if_invalid_value(obj.py(), -1, ffi::PyLong_AsLong(num));
                        ffi::Py_DECREF(num);
                        val
                    }
                }?;
                match cast::<c_long, $rust_type>(val) {
                    Some(v) => Ok(v),
                    None => Err(exceptions::OverflowError.into())
                }
            }
        }
    )
);

macro_rules! int_convert_u64_or_i64 (
    ($rust_type:ty, $pylong_from_ll_or_ull:expr, $pylong_as_ll_or_ull:expr) => (
        impl ToPyObject for $rust_type {
            #[inline]
            fn to_object(&self, py: Python) -> PyObject {
                unsafe {
                    PyObject::from_owned_ptr_or_panic(py, $pylong_from_ll_or_ull(*self))
                }
            }
        }
        impl IntoPyObject for $rust_type {
            #[inline]
            fn into_object(self, py: Python) -> PyObject {
                unsafe {
                    PyObject::from_owned_ptr_or_panic(py, $pylong_from_ll_or_ull(self))
                }
            }
        }
        impl<'source> FromPyObject<'source> for $rust_type {
            fn extract(ob: &'source PyAny) -> PyResult<$rust_type>
            {
                let ptr = ob.as_ptr();
                unsafe {
                    let num = ffi::PyNumber_Index(ptr);
                    if num.is_null() {
                        Err(PyErr::fetch(ob.py()))
                    } else {
                        let result = err_if_invalid_value(ob.py(), !0, $pylong_as_ll_or_ull(num));
                        ffi::Py_DECREF(num);
                        result
                    }
                }
            }
        }
    )
);

int_fits_c_long!(i8);
int_fits_c_long!(u8);
int_fits_c_long!(i16);
int_fits_c_long!(u16);
int_fits_c_long!(i32);

// If c_long is 64-bits, we can use more types with int_fits_c_long!:
#[cfg(all(target_pointer_width = "64", not(target_os = "windows")))]
int_fits_c_long!(u32);
#[cfg(any(target_pointer_width = "32", target_os = "windows"))]
int_fits_larger_int!(u32, u64);

#[cfg(all(target_pointer_width = "64", not(target_os = "windows")))]
int_fits_c_long!(i64);

// manual implementation for i64 on systems with 32-bit long
#[cfg(any(target_pointer_width = "32", target_os = "windows"))]
int_convert_u64_or_i64!(i64, ffi::PyLong_FromLongLong, ffi::PyLong_AsLongLong);

#[cfg(all(target_pointer_width = "64", not(target_os = "windows")))]
int_fits_c_long!(isize);
#[cfg(any(target_pointer_width = "32", target_os = "windows"))]
int_fits_larger_int!(isize, i64);

int_fits_larger_int!(usize, u64);

// u64 has a manual implementation as it never fits into signed long
int_convert_u64_or_i64!(
    u64,
    ffi::PyLong_FromUnsignedLongLong,
    ffi::PyLong_AsUnsignedLongLong
);

#[cfg(not(Py_LIMITED_API))]
int_convert_bignum!(i128, 16, IS_LITTLE_ENDIAN, 1);
#[cfg(not(Py_LIMITED_API))]
int_convert_bignum!(u128, 16, IS_LITTLE_ENDIAN, 0);

#[cfg(test)]
mod test {
    macro_rules! test_common (
        ($test_mod_name:ident, $t:ty) => (
            mod $test_mod_name {
                use crate::exceptions;
                use crate::ToPyObject;
                use crate::Python;

                #[test]
                fn from_py_string_type_error() {
                    let gil = Python::acquire_gil();
                    let py = gil.python();

                    let obj = ("123").to_object(py);
                    let err = obj.extract::<$t>(py).unwrap_err();
                    assert!(err.is_instance::<exceptions::TypeError>(py));
                }

                #[test]
                fn from_py_float_type_error() {
                    let gil = Python::acquire_gil();
                    let py = gil.python();

                    let obj = (12.3).to_object(py);
                    let err = obj.extract::<$t>(py).unwrap_err();
                    assert!(err.is_instance::<exceptions::TypeError>(py));
                }

                #[test]
                fn to_py_object_and_back() {
                    let gil = Python::acquire_gil();
                    let py = gil.python();

                    let val = 123 as $t;
                    let obj = val.to_object(py);
                    assert_eq!(obj.extract::<$t>(py).unwrap(), val as $t);
                }
            }
        )
    );

    test_common!(i8, i8);
    test_common!(u8, u8);
    test_common!(i16, i16);
    test_common!(u16, u16);
    test_common!(i32, i32);
    test_common!(u32, u32);
    test_common!(i64, i64);
    test_common!(u64, u64);
    test_common!(isize, isize);
    test_common!(usize, usize);
    #[cfg(not(Py_LIMITED_API))]
    test_common!(i128, i128);
    #[cfg(not(Py_LIMITED_API))]
    test_common!(u128, u128);
}