use numpy::{Element, PyArray1};
use pyo3::exceptions::PyTypeError;
use pyo3::prelude::pyclass;
use pyo3::types::PyDict;
use pyo3::{FromPyObject, PyAny, PyObject, PyResult};
use std::convert::TryInto;
use std::ffi::CString;
use std::os::raw::c_char;

pub enum Vectorized<'lt, T: Copy + Clone> {
    Slice(&'lt [T]),
    Scalar(T),
}

impl<'lt, T: Copy + Clone> Vectorized<'lt, T> {
    #[allow(clippy::missing_safety_doc)]
    #[inline]
    pub unsafe fn get_unchecked(&self, index: usize) -> T {
        match self {
            Self::Scalar(res) => *res,
            Self::Slice(values) => *values.get_unchecked(index),
        }
    }
}

impl<'lt, T: Copy + Clone + Element + FromPyObject<'lt> + 'lt> Vectorized<'lt, T> {
    #[inline]
    pub fn from_python(from: &'lt PyAny, name: &str, iterations: &mut usize) -> PyResult<Self> {
        let res = if let Ok(val) = from.extract() {
            Vectorized::Scalar(val)
        } else if let Ok(values) = from.extract::<&PyArray1<T>>() {
            // Save because we only keep the slice as a temporary variable
            // The slice can not be mutated from rust and python doesn't run until the immutable view is dropped
            // As such this does not cause UB here
            match unsafe{values.as_slice()}.unwrap() {
                [val] => Vectorized::Scalar(*val),
                values if values.len() == *iterations => Vectorized::Slice(values),
                values if *iterations == 1 => {
                    *iterations = values.len();
                    Vectorized::Slice(values)
                },
                values => return Err(pyo3::exceptions::PyTypeError::new_err(
                    format!(
                        "Arguments must have the same length or be scalars but '{}' has length {} while previous arguments had length {}",
                        name,
                        values.len(),
                        *iterations
                    )
                )),
            }
        } else {
            return Err(pyo3::exceptions::PyTypeError::new_err(format!(
                "eval: Expected scalar {} value or 1d numpy {}-array for argument{}",
                std::any::type_name::<T>(),
                std::any::type_name::<T>(),
                name,
            )));
        };
        Ok(res)
    }

    #[inline]
    pub fn from_dict(
        dict: Option<&'lt PyDict>,
        name: &str,
        loc: &str,
        iterations: &mut usize,
    ) -> PyResult<Self> {
        if let Some(dict) = dict {
            if let Some(val) = dict.get_item(name) {
                return Vectorized::from_python(val, name, iterations);
            }
        }
        Err(pyo3::exceptions::PyTypeError::new_err(format!(
            "eval: Required argument '{}' is missing from {}",
            name, loc
        )))
    }
}

impl<'lt> Vectorized<'lt, f64> {
    #[inline]
    pub fn from_dict_opt(
        dict: Option<&'lt PyDict>,
        name: &str,
        iterations: &mut usize,
    ) -> PyResult<Self> {
        if let Some(dict) = dict {
            if let Some(val) = dict.get_item(name) {
                return Vectorized::from_python(val, name, iterations);
            }
        }
        Ok(Self::Scalar(0.0))
    }
}

#[pyclass]
pub struct NonNumericParameter {
    #[pyo3(get)]
    pub name: &'static str,
    #[pyo3(get)]
    pub description: &'static str,
    #[pyo3(get)]
    pub unit: &'static str,
    #[pyo3(get)]
    pub group: &'static str,

    #[pyo3(get)]
    pub default: PyObject,
}

#[pyclass]
pub struct RealParameter {
    #[pyo3(get)]
    pub name: &'static str,
    #[pyo3(get)]
    pub description: &'static str,
    #[pyo3(get)]
    pub unit: &'static str,
    #[pyo3(get)]
    pub group: &'static str,

    #[pyo3(get)]
    pub default: f64,

    #[pyo3(get)]
    pub min: f64,
    #[pyo3(get)]
    pub max: f64,

    #[pyo3(get)]
    pub min_inclusive: bool,
    #[pyo3(get)]
    pub max_inclusive: bool,
}

#[pyclass]
pub struct IntegerParameter {
    #[pyo3(get)]
    pub name: &'static str,
    #[pyo3(get)]
    pub description: &'static str,
    #[pyo3(get)]
    pub unit: &'static str,
    #[pyo3(get)]
    pub group: &'static str,

    #[pyo3(get)]
    pub default: i64,

    #[pyo3(get)]
    pub min: i64,
    #[pyo3(get)]
    pub max: i64,

    #[pyo3(get)]
    pub min_inclusive: bool,
    #[pyo3(get)]
    pub max_inclusive: bool,
}

#[repr(transparent)]
pub struct PyFfiString(*mut c_char);

impl<'source> FromPyObject<'source> for PyFfiString {
    fn extract(ob: &'source PyAny) -> PyResult<Self> {
        let string: &str = ob.extract()?;
        let cstr = CString::new(string).map_err(PyTypeError::new_err)?;
        Ok(Self(cstr.into_raw()))
    }
}

impl Drop for PyFfiString {
    fn drop(&mut self) {
        unsafe {
            CString::from_raw(self.0);
        }
    }
}

pub trait FFI {
    type FfiTy;
    fn into_ffi(self) -> Self::FfiTy;
}

impl FFI for PyFfiString {
    type FfiTy = *const c_char;

    #[inline(always)]
    fn into_ffi(self) -> Self::FfiTy {
        self.0
    }
}

// Identity for primitives

impl FFI for bool {
    type FfiTy = bool;

    #[inline(always)]
    fn into_ffi(self) -> Self::FfiTy {
        self
    }
}

impl FFI for f64 {
    type FfiTy = f64;

    #[inline(always)]
    fn into_ffi(self) -> Self::FfiTy {
        self
    }
}

impl FFI for i64 {
    type FfiTy = i64;

    #[inline(always)]
    fn into_ffi(self) -> Self::FfiTy {
        self
    }
}

#[repr(transparent)]
struct PyFfiPtr<A>(*mut A);

impl<A> Drop for PyFfiPtr<A> {
    fn drop(&mut self) {
        unsafe {
            Box::from_raw(self.0);
        }
    }
}

#[pyclass]
pub struct OpVar {
    #[pyo3(get)]
    pub name: &'static str,
    #[pyo3(get)]
    pub description: &'static str,
    #[pyo3(get)]
    pub unit: &'static str,
}

// Arrays can't be passed directly over C-ABI instead pointers have to be used
// For multidimensional arrays pointers to arrays are used

macro_rules! array_ffi_impl(
    ($($len:expr),*) => {
        $(
            impl<'a, T: FromPyObject<'a> > FromPyObject<'a> for PyFfiPtr<[T; $len]> {
                fn extract(ob: &'a PyAny) -> PyResult<Self> {
                    let data: Vec<T> = ob.extract()?;
                    let len = data.len();
                    let data: Box<[T; $len]> = data.into_boxed_slice().try_into().map_err(|_|PyTypeError::new_err(format!("Expected array of size {} but found {}",$len,len)))?;
                    Ok(Self(Box::into_raw(data)))
                }
            }

            impl<T: FFI> FFI for PyFfiPtr<[T; $len]> {
                type FfiTy = * const T::FfiTy;

                fn into_ffi(self) -> Self::FfiTy {
                    self.0 as *const T::FfiTy
                }
            }

            impl<T: FFI> FFI for [T; $len] {
                type FfiTy = Self;

                fn into_ffi(self) -> Self::FfiTy {
                    self
                }
            }
        )*
    }
);

array_ffi_impl!(
    32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9,
    8, 7, 6, 5, 4, 3, 2, 1, 0
);