use std::str::FromStr;
use nalgebra::{allocator::Allocator, DefaultAllocator, Dim, OVector};
use rand::{Rng, RngCore};
use thiserror::Error;

#[derive(Debug, Clone, PartialEq)]
pub struct Bounds {
    min: f64,
    max: f64,
}

impl Bounds {
    pub fn new(min: f64, max: f64) -> Self {
        Bounds {
            min,
            max
        }
    }

    pub fn min(&self) -> f64 {
        self.min
    }

    pub fn max(&self) -> f64 {
        self.max
    }
}

#[derive(Debug, Clone, PartialEq)]
pub struct BinaryString {
    pub vec: Vec<i8>
}

#[derive(Error, Debug, Clone, PartialEq)]
pub enum BinaryStringConversionError {
    #[error("The dimension of the bounds does not divide the length of the binary string.")]
    DimensionMismatch,
}

impl BinaryString {
    pub fn new(vec: Vec<i8>) -> BinaryString {
        BinaryString {
            vec
        }
    }

    pub fn vec(&self) -> &Vec<i8> {
        &self.vec
    }

    pub fn perturb(self: &Self, rng: &mut dyn RngCore, p: f64) -> Self
    {
        BinaryString::new(
            self.into_iter()
                .map(|c| if rng.random::<f64>() <= p { 1 - *c } else { *c })
                .collect::<Vec<i8>>()
        )
    }

    fn to_real_internal<'a, T: DoubleEndedIterator<Item = &'a i8>>(vec: T, len: usize, min: f64, max: f64) -> f64
    {
        let diff = max - min;
        let len = len as i32;
        let max_represent_num = 2f64.powi(len) - 1.0;
        let represented_num = vec
            .rev()
            .enumerate()
            .map(|(bit, c)| diff * (*c as f64) * 2f64.powi(bit as i32))
            .sum::<f64>();

        min + (represented_num / max_represent_num)
    }

    pub fn to_real_single(self: &Self, min: f64, max: f64) -> f64 {
        BinaryString::to_real_internal(self.vec.iter(), self.vec.len(), min, max)
    }

    pub fn to_real<TDim>(self: &Self, min: &OVector<f64, TDim>, max: &OVector<f64, TDim>) -> Result<OVector<f64, TDim>, BinaryStringConversionError>
    where
        TDim: Dim,
        DefaultAllocator: Allocator<TDim>,
    {
        let chunk_size = self.vec.len() / min.len();
        if self.vec.len() % min.len() != 0 {
            return Err(BinaryStringConversionError::DimensionMismatch);
        }

        let iter = self.vec.chunks(chunk_size)
                .zip(min.iter().zip(max))
            .map(|(chunk, (&min, &max))| BinaryString::to_real_internal(chunk.iter(), chunk_size, min, max));
        Ok(OVector::<f64, TDim>::from_iterator_generic(min.shape_generic().0, min.shape_generic().1, iter))
    }
}

impl FromStr for BinaryString {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let binary_vec: Vec<i8> = s
            .chars()
            // skip spaces
            .filter(|c| *c != ' ')
            // Map ones and zeros
            .map(|c| match c {
                '0' => Ok(0),
                '1' => Ok(1),
                _ => Err(format!("Invalid binary character: {}", c)),
            })
            .collect::<Result<Vec<i8>, Self::Err>>()?;

        Ok(BinaryString::new(binary_vec))
    }
}

impl<'a> IntoIterator for &'a BinaryString {
    type Item = &'a i8;
    type IntoIter = std::slice::Iter<'a, i8>;

    fn into_iter(self) -> Self::IntoIter {
        self.vec.iter()
    }
}

#[cfg(test)]
pub mod tests {
    use crate::{binary_string::{BinaryString, BinaryStringConversionError}, test_infra::{load_test_file, DataArrOfReals}};
    use nalgebra::SVector;

    #[test]
    fn test_binary_string_to_real_single() {
        assert_eq!(
            BinaryString::new(vec![1])
                .to_real_single(0.0, 32.0),
            32.0
        );
        assert_eq!(
            BinaryString::new(vec![1, 1])
                .to_real_single(0.0, 32.0),
            32.0
        );
        assert_eq!(
            BinaryString::new(vec![0, 1])
                .to_real_single(0.0, 32.0),
            32.0 / 3.0
        );
        assert_eq!(
            BinaryString::new(vec![0, 0])
                .to_real_single(-16.0, 16.0),
            -16.0
        );
        assert_eq!(
            BinaryString::new(vec![0, 0, 0, 0, 1])
                .to_real_single(0.0, 31.0),
            1.0
        );
        assert_eq!(
            BinaryString::new(vec![1, 1, 1, 1, 1])
                .to_real_single(0.0, 31.0),
            31.0
        );
        assert_eq!(
            BinaryString::new(vec![0, 0, 0, 1, 0])
                .to_real_single(0.0, 31.0),
            2.0
        );

        assert_eq!(
            BinaryString::new(vec![1; 512])
                .to_real_single(0.0, 31.0),
            31.0
        );
    }

    fn test_binary_string_to_real<const LEN: usize>(file_name: &str, min: SVector<f64, LEN>, max: SVector<f64, LEN>) {
        let data = load_test_file::<i8, DataArrOfReals>(file_name);

        for test in data {
            let res = BinaryString::new(test.inp)
                .to_real(&min, &max);
            if !test.out.valid {
                assert_eq!(
                    res,
                    Err(BinaryStringConversionError::DimensionMismatch)
                );
            }
            else {
                assert_eq!(
                    res.unwrap().iter().map(|&x| x).collect::<Vec<_>>(),
                    test.out.vec
                );
            }
        }
    }

    #[test]
    fn test_binary_string_to_real_1d_1() {
        test_binary_string_to_real(
            "tests/Bin2Real_1D_1.txt",
            SVector::<f64, 1>::new(0.0),
            SVector::<f64, 1>::new(1.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_1d_2() {
        test_binary_string_to_real(
            "tests/Bin2Real_1D_2.txt",
            SVector::<f64, 1>::new(0.0),
            SVector::<f64, 1>::new(4095.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_1d_3() {
        test_binary_string_to_real(
            "tests/Bin2Real_1D_3.txt",
            SVector::<f64, 1>::new(-5.0),
            SVector::<f64, 1>::new(5.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_2d_1() {
        test_binary_string_to_real(
            "tests/Bin2Real_2D_1.txt",
            SVector::<f64, 2>::new(0.0, 0.0),
            SVector::<f64, 2>::new(1.0, 1.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_2d_2() {
        test_binary_string_to_real(
            "tests/Bin2Real_2D_2.txt",
            SVector::<f64, 2>::new(0.0, -32.0),
            SVector::<f64, 2>::new(63.0, 31.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_2d_3() {
        test_binary_string_to_real(
            "tests/Bin2Real_2D_3.txt",
            SVector::<f64, 2>::new(-5.0, 0.0),
            SVector::<f64, 2>::new(5.0, 10.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_3d_1() {
        test_binary_string_to_real(
            "tests/Bin2Real_3D_1.txt",
            SVector::<f64, 3>::new(0.0, 0.0, 0.0),
            SVector::<f64, 3>::new(1.0, 1.0, 1.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_3d_2() {
        test_binary_string_to_real(
            "tests/Bin2Real_3D_2.txt",
            SVector::<f64, 3>::new(0.0, -8.0, -8.0),
            SVector::<f64, 3>::new(15.0, 7.0, 8.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_4d_1() {
        test_binary_string_to_real(
            "tests/Bin2Real_4D_1.txt",
            SVector::<f64, 4>::new(0.0, 0.0, 0.0, 0.0),
            SVector::<f64, 4>::new(1.0, 1.0, 1.0, 1.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_4d_2() {
        test_binary_string_to_real(
            "tests/Bin2Real_4D_2.txt",
            SVector::<f64, 4>::new(0.0, -4.0, -4.0, -8.0),
            SVector::<f64, 4>::new(7.0, 3.0, 4.0, 0.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_6d_1() {
        test_binary_string_to_real(
            "tests/Bin2Real_6D_1.txt",
            SVector::<f64, 6>::zeros(),
            SVector::<f64, 6>::from_element(1.0),
        );
    }

    #[test]
    fn test_binary_string_to_real_6d_2() {
        test_binary_string_to_real(
            "tests/Bin2Real_6D_2.txt",
            SVector::<f64, 6>::from_iterator((0..=5).map(|x| x as f64)),
            SVector::<f64, 6>::from_iterator((0..=5).map(|x| (2 * (x + 1)) as f64)),
        );
    }
}