use super::{CheckRequest, Message, RowResult};
use std::sync::mpsc::{channel, Receiver, Sender};
use std::thread::JoinHandle;

#[derive(Debug)]
struct RequestBuffer {
    mask_buff: Vec<u64>,
    row_buff: Vec<Vec<u32>>,
    pointer: usize,
}

impl RequestBuffer {
    pub fn new(size: usize) -> Self {
        RequestBuffer {
            mask_buff: vec![0; size],
            row_buff: vec![Vec::new(); size],
            pointer: 0,
        }
    }
    pub fn read(&mut self, request: CheckRequest) -> Option<(&[u64], &[Vec<u32>])> {
        self.mask_buff[self.pointer] = request.bitmask;
        self.row_buff[self.pointer] = request.rows;
        self.pointer += 1;
        if self.pointer == self.mask_buff.len() {
            self.pointer = 0;
            return Some((self.mask_buff.as_ref(), self.row_buff.as_ref()));
        }
        None
    }
}

pub struct OclManager {
    job_id: u64,
    host_sender: Sender<Message>,
    output_sender: Sender<Message>,
    receiver: Receiver<Message>,
    buffers: Vec<RequestBuffer>,
    output_handle: JoinHandle<()>,
    host_handle: Option<JoinHandle<()>>,
}

impl OclManager {
    pub fn launch_sevice(
        permutations: &[Vec<u32>],
        permutations_mask: &[u64],
        n: u32,
        // Workgroup size, set to 0 for max
        mut wg_size: usize,
        result_output: Sender<Message>,
    ) -> (Sender<Message>, JoinHandle<()>) {
        let (h, w) = crate::solvers::wall_stats(n);
        let src = include_str!("check.cl");

        let platform = ocl::Platform::default();
        let device = ocl::Device::first(platform).expect("failed to create opencl device");
        let max_wg_size = device.max_wg_size().expect("failed to query max_wg_size");
        if wg_size == 0 {
            wg_size = max_wg_size;
        } else if wg_size > max_wg_size {
            println!("invalid workgroup size");
        }

        let (output_sender, output_handle) =
            super::output::Output::launch_sevice(permutations, permutations_mask, result_output);
        let (host_sender, host_handle) = super::host::Host::launch_sevice(
            permutations_mask,
            n,
            h,
            w,
            wg_size,
            src,
            output_sender.clone(),
        )
        .unwrap();

        let (sender, receiver) = channel();

        println!("wg {}", wg_size);
        let mut buffers = Vec::with_capacity((n - h + 1) as usize);
        for _ in 0..=(n - h) {
            buffers.push(RequestBuffer::new(wg_size as usize));
        }

        let manager = Self {
            job_id: 0,
            host_sender,
            output_sender,
            receiver,
            buffers,
            output_handle,
            host_handle: Some(host_handle),
        };
        (
            sender,
            std::thread::Builder::new()
                .name("GPU Manager Deamon".into())
                .spawn(move || {
                    manager.run();
                })
                .unwrap(),
        )
    }

    fn run(mut self) {
        loop {
            match self.receiver.recv().expect("Channel to GPU Manager broke") {
                Message::CheckRequest(request) => {
                    let queue = request.queue;
                    if let Some(buffer) = self.buffers[queue as usize].read(request) {
                        self.host_sender
                            .send(Message::HostMessage((self.job_id, queue, buffer.0.into())))
                            .unwrap();
                        self.output_sender
                            .send(Message::OutputMessage((self.job_id, buffer.1.into())))
                            .unwrap();
                        self.job_id += 1;
                    }
                }
                Message::CpuDone => {
                    //TODO panic!("flush buffers");
                    self.host_sender.send(Message::CpuDone);
                    self.host_handle.take().unwrap().join();
                }
                Message::Terminate => {
                    self.output_sender.send(Message::Terminate);
                    self.output_handle.join();
                    return;
                }
                _ => println!("Invalid MessageType"),
            }
        }
    }
}