use crate::{frame::Frame, pixel::Pixel};
use std::ops::{Index, IndexMut};

pub struct View<T> {
    pub frame: T,
    pub offset: (usize, usize),
    pub size: (usize, usize),
}

impl<T> View<T> {
    pub fn new(frame: T, offset: (usize, usize), size: (usize, usize)) -> Self {
        Self {
            frame,
            offset,
            size,
        }
    }
    pub fn area(&self) -> usize {
        self.size.0 * self.size.1
    }
}

impl<T> View<&mut T> {
    pub fn split_mut_unsafe(&mut self) -> [Self; 2] {
        let vert = self.size.0 > self.size.1;
        [
            Self {
                frame: unsafe { std::mem::transmute::<&mut T, &mut T>(&mut self.frame) },
                offset: self.offset,
                size: if vert {
                    (self.size.0 / 2, self.size.1)
                } else {
                    (self.size.0, self.size.1 / 2)
                },
            },
            Self {
                frame: unsafe { std::mem::transmute::<&mut T, &mut T>(&mut self.frame) },
                offset: if vert {
                    (self.offset.0 + self.size.0 / 2, self.offset.1)
                } else {
                    (self.offset.0, self.offset.1 + self.size.1 / 2)
                },
                size: if vert {
                    (self.size.0 - self.size.0 / 2, self.size.1)
                } else {
                    (self.size.0, self.size.1 - self.size.1 / 2)
                },
            },
        ]
    }
}
impl<T: Copy> View<T> {
    pub fn split(&self) -> [Self; 2] {
        let vert = self.size.0 > self.size.1;
        [
            Self {
                frame: self.frame,
                offset: self.offset,
                size: if vert {
                    (self.size.0 / 2, self.size.1)
                } else {
                    (self.size.0, self.size.1 / 2)
                },
            },
            Self {
                frame: self.frame,
                offset: if vert {
                    (self.offset.0 + self.size.0 / 2, self.offset.1)
                } else {
                    (self.offset.0, self.offset.1 + self.size.1 / 2)
                },
                size: if vert {
                    (self.size.0 - self.size.0 / 2, self.size.1)
                } else {
                    (self.size.0, self.size.1 - self.size.1 / 2)
                },
            },
        ]
    }
}
impl<T: Index<(usize, usize), Output = Pixel>> View<&T> {
    pub fn diff(va: &Self, vb: &Self) -> f64 {
        assert_eq!(va.size, vb.size);
        let mut acc = 0.0;
        for x in 0..va.size.0 {
            for y in 0..va.size.1 {
                let a = va[(x, y)];
                let b = vb[(x, y)];
                acc += Pixel::distance(a, b);
            }
        }
        acc
    }
    pub fn pixels(&self) -> Vec<Pixel> {
        let mut v = vec![];
        for x in 0..self.size.0 {
            for y in 0..self.size.1 {
                v.push(self[(x, y)]);
            }
        }
        v
    }
}
impl View<&mut Frame> {
    pub fn copy_from(&mut self, other: &View<&Frame>) {
        for x in 0..self.size.0 {
            for y in 0..self.size.1 {
                self[(x, y)] = other[(x, y)];
            }
        }
    }
    pub fn set_pixels(&mut self, pixels: &Vec<Pixel>) {
        for x in 0..self.size.0 {
            for y in 0..self.size.1 {
                self[(x, y)] = pixels[x * self.size.1 + y]
            }
        }
    }
}

impl<T: Index<(usize, usize), Output = Pixel>> Index<(usize, usize)> for View<&T> {
    type Output = Pixel;
    #[inline]
    fn index(&self, (x, y): (usize, usize)) -> &Self::Output {
        &self.frame[(x + self.offset.0, y + self.offset.1)]
    }
}
impl<T: Index<(usize, usize), Output = Pixel>> Index<(usize, usize)> for View<&mut T> {
    type Output = Pixel;
    #[inline]
    fn index(&self, (x, y): (usize, usize)) -> &Self::Output {
        &self.frame[(x + self.offset.0, y + self.offset.1)]
    }
}
impl<T: IndexMut<(usize, usize), Output = Pixel>> IndexMut<(usize, usize)> for View<&mut T> {
    #[inline]
    fn index_mut(&mut self, (x, y): (usize, usize)) -> &mut Self::Output {
        &mut self.frame[(x + self.offset.0, y + self.offset.1)]
    }
}