use cortex_m::singleton;
use stm32f1xx_hal::{dma, pac, prelude::*, rcc, serial};

type _TxDma = dma::TxDma<serial::Tx<pac::USART1>, dma::dma1::C4>;

pub struct DMXIdle {
    tx: Option<_TxDma>,
    txbuffer: Option<&'static mut [u8; 512]>,
}

pub enum DMX {
    Idle(DMXIdle),
    Busy(Option<dma::Transfer<dma::R, &'static mut [u8; 512], _TxDma>>),
}

impl DMX {
    pub fn new<PINS>(
        mut serial: serial::Serial<pac::USART1, PINS>,
        channel: dma::dma1::C4,
        clocks: &rcc::Clocks,
    ) -> Self
    where
        PINS: serial::Pins<pac::USART1>,
    {
        let _ = serial.reconfigure(250_000.bps(), &clocks);

        Self::Idle(DMXIdle {
            tx: Some(serial.tx.with_dma(channel)),
            txbuffer: None,
        })
    }

    pub fn send(&mut self, data: &[u8; 512]) {
        if let Self::Idle(idle) = self {
            let txbuffer = idle
                .txbuffer
                .take()
                .unwrap_or_else(|| singleton!(: [u8; 512] = [0; 512]).unwrap());
            let tx = idle.tx.take().unwrap();

            txbuffer.copy_from_slice(data);
            *self = Self::Busy(Some(tx.write(txbuffer)));
        }
    }

    pub fn wait(&mut self) {
        if let Self::Busy(xfer) = self {
            let xfer = xfer.take().unwrap();
            let (txbuffer, tx) = xfer.wait();

            *self = Self::Idle(DMXIdle {
                tx: Some(tx),
                txbuffer: Some(txbuffer),
            });
        }
    }
}