use crate::znx_base::ZnxInfos;
use crate::{
    Backend, DataView, DataViewMut, Module, VecZnx, VecZnxToMut, VecZnxToRef, ZnxSliceSize, ZnxView, ZnxViewMut, alloc_aligned,
};
use rand::seq::SliceRandom;
use rand_core::RngCore;
use rand_distr::{Distribution, weighted::WeightedIndex};
use sampling::source::Source;

pub struct ScalarZnx<D> {
    data: D,
    n: usize,
    cols: usize,
}

impl<D> ZnxInfos for ScalarZnx<D> {
    fn cols(&self) -> usize {
        self.cols
    }

    fn rows(&self) -> usize {
        1
    }

    fn n(&self) -> usize {
        self.n
    }

    fn size(&self) -> usize {
        1
    }
}

impl<D> ZnxSliceSize for ScalarZnx<D> {
    fn sl(&self) -> usize {
        self.n()
    }
}

impl<D> DataView for ScalarZnx<D> {
    type D = D;
    fn data(&self) -> &Self::D {
        &self.data
    }
}

impl<D> DataViewMut for ScalarZnx<D> {
    fn data_mut(&mut self) -> &mut Self::D {
        &mut self.data
    }
}

impl<D: AsRef<[u8]>> ZnxView for ScalarZnx<D> {
    type Scalar = i64;
}

impl<D: AsMut<[u8]> + AsRef<[u8]>> ScalarZnx<D> {
    pub fn fill_ternary_prob(&mut self, col: usize, prob: f64, source: &mut Source) {
        let choices: [i64; 3] = [-1, 0, 1];
        let weights: [f64; 3] = [prob / 2.0, 1.0 - prob, prob / 2.0];
        let dist: WeightedIndex<f64> = WeightedIndex::new(&weights).unwrap();
        self.at_mut(col, 0)
            .iter_mut()
            .for_each(|x: &mut i64| *x = choices[dist.sample(source)]);
    }

    pub fn fill_ternary_hw(&mut self, col: usize, hw: usize, source: &mut Source) {
        assert!(hw <= self.n());
        self.at_mut(col, 0)[..hw]
            .iter_mut()
            .for_each(|x: &mut i64| *x = (((source.next_u32() & 1) as i64) << 1) - 1);
        self.at_mut(col, 0).shuffle(source);
    }
}

impl<D: From<Vec<u8>>> ScalarZnx<D> {
    pub(crate) fn bytes_of<S: Sized>(n: usize, cols: usize) -> usize {
        n * cols * size_of::<S>()
    }

    pub(crate) fn new<S: Sized>(n: usize, cols: usize) -> Self {
        let data = alloc_aligned::<u8>(Self::bytes_of::<S>(n, cols));
        Self {
            data: data.into(),
            n,
            cols,
        }
    }

    pub(crate) fn new_from_bytes<S: Sized>(n: usize, cols: usize, bytes: impl Into<Vec<u8>>) -> Self {
        let data: Vec<u8> = bytes.into();
        assert!(data.len() == Self::bytes_of::<S>(n, cols));
        Self {
            data: data.into(),
            n,
            cols,
        }
    }
}

pub type ScalarZnxOwned = ScalarZnx<Vec<u8>>;

pub(crate) fn bytes_of_scalar_znx<B: Backend>(module: &Module<B>, cols: usize) -> usize {
    ScalarZnxOwned::bytes_of::<i64>(module.n(), cols)
}

pub trait ScalarZnxAlloc {
    fn bytes_of_scalar_znx(&self, cols: usize) -> usize;
    fn new_scalar_znx(&self, cols: usize) -> ScalarZnxOwned;
    fn new_scalar_znx_from_bytes(&self, cols: usize, bytes: Vec<u8>) -> ScalarZnxOwned;
}

impl<B: Backend> ScalarZnxAlloc for Module<B> {
    fn bytes_of_scalar_znx(&self, cols: usize) -> usize {
        ScalarZnxOwned::bytes_of::<i64>(self.n(), cols)
    }
    fn new_scalar_znx(&self, cols: usize) -> ScalarZnxOwned {
        ScalarZnxOwned::new::<i64>(self.n(), cols)
    }
    fn new_scalar_znx_from_bytes(&self, cols: usize, bytes: Vec<u8>) -> ScalarZnxOwned {
        ScalarZnxOwned::new_from_bytes::<i64>(self.n(), cols, bytes)
    }
}

impl<D> ScalarZnx<D> {
    pub(crate) fn from_data(data: D, n: usize, cols: usize) -> Self {
        Self { data, n, cols }
    }
}

pub trait ScalarZnxToRef {
    fn to_ref(&self) -> ScalarZnx<&[u8]>;
}

pub trait ScalarZnxToMut {
    fn to_mut(&mut self) -> ScalarZnx<&mut [u8]>;
}

impl ScalarZnxToMut for ScalarZnx<Vec<u8>> {
    fn to_mut(&mut self) -> ScalarZnx<&mut [u8]> {
        ScalarZnx {
            data: self.data.as_mut_slice(),
            n: self.n,
            cols: self.cols,
        }
    }
}

impl VecZnxToMut for ScalarZnx<Vec<u8>> {
    fn to_mut(&mut self) -> VecZnx<&mut [u8]> {
        VecZnx {
            data: self.data.as_mut_slice(),
            n: self.n,
            cols: self.cols,
            size: 1,
        }
    }
}

impl ScalarZnxToRef for ScalarZnx<Vec<u8>> {
    fn to_ref(&self) -> ScalarZnx<&[u8]> {
        ScalarZnx {
            data: self.data.as_slice(),
            n: self.n,
            cols: self.cols,
        }
    }
}

impl VecZnxToRef for ScalarZnx<Vec<u8>> {
    fn to_ref(&self) -> VecZnx<&[u8]> {
        VecZnx {
            data: self.data.as_slice(),
            n: self.n,
            cols: self.cols,
            size: 1,
        }
    }
}

impl ScalarZnxToMut for ScalarZnx<&mut [u8]> {
    fn to_mut(&mut self) -> ScalarZnx<&mut [u8]> {
        ScalarZnx {
            data: self.data,
            n: self.n,
            cols: self.cols,
        }
    }
}

impl VecZnxToMut for ScalarZnx<&mut [u8]> {
    fn to_mut(&mut self) -> VecZnx<&mut [u8]> {
        VecZnx {
            data: self.data,
            n: self.n,
            cols: self.cols,
            size: 1,
        }
    }
}

impl ScalarZnxToRef for ScalarZnx<&mut [u8]> {
    fn to_ref(&self) -> ScalarZnx<&[u8]> {
        ScalarZnx {
            data: self.data,
            n: self.n,
            cols: self.cols,
        }
    }
}

impl VecZnxToRef for ScalarZnx<&mut [u8]> {
    fn to_ref(&self) -> VecZnx<&[u8]> {
        VecZnx {
            data: self.data,
            n: self.n,
            cols: self.cols,
            size: 1,
        }
    }
}

impl ScalarZnxToRef for ScalarZnx<&[u8]> {
    fn to_ref(&self) -> ScalarZnx<&[u8]> {
        ScalarZnx {
            data: self.data,
            n: self.n,
            cols: self.cols,
        }
    }
}

impl VecZnxToRef for ScalarZnx<&[u8]> {
    fn to_ref(&self) -> VecZnx<&[u8]> {
        VecZnx {
            data: self.data,
            n: self.n,
            cols: self.cols,
            size: 1,
        }
    }
}