// Copyright 2013 The OMath Developers. For a full listing of the authors,
// refer to the Cargo.toml file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::mem;
use std::ptr;
use std::ops::*;

/// An array containing elements of type `Element`
pub trait Array1 where
    // FIXME: Ugly type signatures - blocked by rust-lang/rust#24092
    Self: Index<usize, Output = <Self as Array1>::Element>,
    Self: IndexMut<usize, Output = <Self as Array1>::Element>,
{
    type Element: Copy;

    /// Get the pointer to the first element of the array.
    fn ptr<'a>(&'a self) -> &'a Self::Element {
        &self[0]
    }

    /// Get a mutable pointer to the first element of the array.
    fn mut_ptr<'a>(&'a mut self) -> &'a mut Self::Element {
        &mut self[0]
    }

    /// Swap the elements at indices `i` and `j` in-place.
    #[inline]
    fn swap_elems(&mut self, i: usize, j: usize) {
        // Yeah, ok borrow checker – I know what I'm doing here
        unsafe { ptr::swap(&mut self[i], &mut self[j]) };
    }

    /// Replace an element in the array.
    #[inline]
    fn replace_elem(&mut self, i: usize, src: Self::Element) -> Self::Element {
        mem::replace(&mut self[i], src)
    }
}

/// A column-major array
pub trait Array2 where
    // FIXME: Ugly type signatures - blocked by rust-lang/rust#24092
    Self: Index<usize, Output = <Self as Array2>::Column>,
    Self: IndexMut<usize, Output = <Self as Array2>::Column>,
{
    type Element: Copy;
    type Column: Array1<Element = Self::Element>;
    type Row: Array1<Element = Self::Element>;

    /// Get the pointer to the first element of the array.
    fn ptr<'a>(&'a self) -> &'a Self::Element {
        &self[0][0]
    }

    /// Get a mutable pointer to the first element of the array.
    fn mut_ptr<'a>(&'a mut self) -> &'a mut Self::Element {
        &mut self[0][0]
    }

    /// Swap two columns of this array.
    #[inline]
    fn swap_cols(&mut self, a: usize, b: usize) {
        unsafe { ptr::swap(&mut self[a], &mut self[b]) };
    }

    /// Replace a column in the array.
    #[inline]
    fn replace_col(&mut self, c: usize, src: Self::Column) -> Self::Column {
        mem::replace(&mut self[c], src)
    }

    /// Get a row from this array by-value.
    fn row(&self, r: usize) -> Self::Row;

    /// Swap two rows of this array.
    fn swap_rows(&mut self, a: usize, b: usize);

    /// Swap the values at index `a` and `b`
    #[inline]
    fn swap_elems(&mut self, a: (usize, usize), b: (usize, usize)) {
        let (ac, ar) = a;
        let (bc, br) = b;
        unsafe { ptr::swap(&mut self[ac][ar], &mut self[bc][br]) };
    }
}