use super::gpu::*;

/// Solve for a given N and return the resulting wall
pub struct NormalSolver {
    pub n: u32,
    /// calculated height [might not be correct!]
    pub h: u32,
    /// width
    pub w: u32,
    pub chunk: u32,
    pub mask: u64,
    /// Use to store already used blocks as a bitmask
    permutations: Vec<Vec<u32>>,
    masks: Vec<u64>,
    gpu_sender: std::sync::mpsc::Sender<super::gpu::Message>,
    gpu_handle: Option<std::thread::JoinHandle<()>>,
}

impl NormalSolver {
    pub fn new(n: u32) -> Self {
        let h = n / 2 + 1;
        let w = h * (n - 1);
        let mut heap: Vec<_> = (1..=n).collect();
        let heap = permutohedron::Heap::new(&mut heap);
        let n_f = permutohedron::factorial(n as usize);
        let chunk = n_f as u32 / n;
        let mut permutations = Vec::with_capacity(n_f);
        let mut masks: Vec<u64> = vec![0; n_f];
        println!("Generating permutations");
        for (j, data) in heap.enumerate() {
            permutations.push(data.clone());
            let mut sum = 0;
            for stone in permutations[j].iter().take(n as usize - 1) {
                //.take(n as usize - 1) {
                sum += stone;
                masks[j] |= 1 << sum;
            }
        }

        let (sender, receiver) = std::sync::mpsc::channel();
        let (gpu_sender, gpu_handle) =
            super::gpu::OclManager::launch_sevice(&permutations, &masks, n, 0, sender);
        Self {
            n,
            h,
            w,
            chunk,
            mask: (1 << w) - 2,
            permutations,
            masks,
            gpu_sender,
            gpu_handle: Some(gpu_handle),
        }
    }

    pub fn solve(&mut self) {
        //for (n, i) in self.permutations.iter().enumerate() {
        //let tmp: Vec<u32> = i.clone();
        //println!("perm {}: {:?}", n, tmp);
        //println!("perm {}: {:b}", n, self.masks[n]);
        //}
        println!("calculate results");
        self.permute(
            permutohedron::factorial(self.n as usize),
            0,
            0,
            ((0..(self.h - 1))
                .map(|x| x * self.chunk)
                .collect::<Vec<u32>>())
            .as_ref(),
        );
        self.gpu_sender.send(super::gpu::Message::CpuDone).unwrap();
        self.gpu_handle.take().unwrap().join().unwrap();
    }

    fn permute(&self, up: usize, index: usize, curr_mask: u64, numbers: &[u32]) {
        if curr_mask.count_ones() < index as u32 * (self.n - 1) {
            return;
        }
        let mut new_num = Vec::from(numbers);
        let start = numbers[index as usize] / self.chunk;
        if index as usize == numbers.len() - 1 {
            //#[cfg(feature = "gpu")]
            //{
            let mut info = sys_info::mem_info().unwrap();
            while info.avail < info.total / 8 {
                std::thread::sleep_ms(50);
                info = sys_info::mem_info().unwrap();
                println!("mem wait {:?}", info);
            }
            let i = self.n - 2 - numbers[index] / self.chunk;
            self.gpu_sender
                .send(Message::CheckRequest(CheckRequest::new(
                    new_num, curr_mask, i,
                )))
                .unwrap();
            return;
            //}
        }
        for i in start..self.n - (self.h - 1 - index as u32) {
            for n in 1..(numbers.len() - index) {
                new_num[n + index] = (n as u32 + i) * self.chunk;
            }
            /*if index == 0 {
                (0..self.chunk).into_par_iter().for_each(|j| {
                    let mut new_num = new_num.clone();
                    let tmp = i * self.chunk + j;
                    new_num[index] = tmp;
                    self.permute(
                        up,
                        index + 1,
                        curr_mask | self.masks[tmp as usize],
                        &new_num,
                    );
                });
            } else {*/
            for j in 0..self.chunk {
                new_num[index] = i * self.chunk + j;
                if index == 0 {
                    println!("progress: {}%", j as f64 / self.chunk as f64);
                }
                self.permute(
                    up,
                    index + 1,
                    curr_mask | self.masks[new_num[index] as usize],
                    &new_num,
                );
            }
            //}
        }
    }
}