// src/bin/main.rs

#![no_std]
#![no_main]

use defmt::*;
use embassy_executor::Spawner;
use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
use embassy_time::{Duration, Timer};
use dma_gpio::dma_timer::init_tim6_for_uart;
use dma_gpio::dma_timer::init_tim7_for_uart;
use embassy_stm32::gpio::Input;
use embassy_stm32::gpio::Pull;
use dma_gpio::gpio_dma_uart_rx::GpioDmaRx;
use {defmt_rtt as _, panic_probe as _};

use embassy_stm32::{
    gpio::{Level, Output, Speed},
    peripherals::GPDMA1_CH0,
    peripherals::GPDMA1_CH1,
};
use embassy_stm32::Peri;

use dma_gpio::gpio_dma_uart_tx::{
    write_uart_frames_to_pipe, GpioDmaBsrrTx, Parity, StopBits, UartConfig,
};

static PIPE_TX: Pipe<CriticalSectionRawMutex, 256> = Pipe::new();
static PIPE_RX: Pipe<CriticalSectionRawMutex, 256> = Pipe::new();

// Baud rate: one TIM6 update equals one UART bit-time
const BAUD: u32 = 115_200;
const TX_PIN_BIT: u8 = 2; // PA2
const TX_OVERSAMPLE: u16 = 1;
const RX_OVERSAMPLE: u16 = 16;

const UART_CFG: UartConfig = UartConfig {
    data_bits: 8,
    parity: Parity::None,
    stop_bits: StopBits::One,
};
static mut RX_DMA_BUF: [u32; 512] = [0; 512];

fn dump_tim6_regs() {
    // PAC path for STM32U5: module `tim6`, type `Tim6` with ptr()
    use embassy_stm32::pac::timer::TimBasic;
    let tim = unsafe { TimBasic::from_ptr(0x4000_1000usize as _) };
    let sr = tim.sr().read();
    let dier = tim.dier().read();
    let cr1 = tim.cr1().read();
    let arr = tim.arr().read().arr();
    let psc = tim.psc().read();
    info!(
        "TIM6: CR1.CEN={} DIER.UDE={} SR.UIF={} PSC={} ARR={}",
        cr1.cen(),
        dier.ude(),
        sr.uif(),
        psc,
        arr
    );
}

fn dump_dma_ch0_regs() {
    // PAC path for GPDMA1: module `gpdma1`, type `Gpdma1`
    use embassy_stm32::pac::gpdma::Gpdma;
    let dma = unsafe { Gpdma::from_ptr(0x4002_0000usize as _) };
    let ch = dma.ch(0);
    let cr = ch.cr().read();
    let tr1 = ch.tr1().read();
    let tr2 = ch.tr2().read();
    let br1 = ch.br1().read();
    info!(
        "GPDMA1_CH0: EN={} PRIO={} SDW={} DDW={} SINC={} DINC={} REQSEL={} SWREQ={} DREQ={} BNDT={}",
        cr.en(),
        cr.prio(),
        tr1.sdw(),
        tr1.ddw(),
        tr1.sinc(),
        tr1.dinc(),
        tr2.reqsel(),
        tr2.swreq(),
        tr2.dreq(),
        br1.bndt()
    );
}

#[embassy_executor::main]
async fn main(spawner: Spawner) {
    let p = embassy_stm32::init(Default::default());
    info!("Hehe");

    // PA3 as Rx "wire"
    let pa3_rx = Input::new(p.PA3, Pull::Up);

    // PA2 is the TX "wire"
    let _pa2 = Output::new(p.PA2, Level::High, Speed::VeryHigh);
    // drop(_pa2);
    init_tim6_for_uart(p.TIM6, BAUD, TX_OVERSAMPLE); // TX
    init_tim7_for_uart(p.TIM7, BAUD, RX_OVERSAMPLE); // RX
    dump_tim6_regs();

    // Start DMA consumer task
    spawner.spawn(dma_tx_task(p.GPDMA1_CH0)).unwrap();
    spawner.spawn(rx_dma_task(p.GPDMA1_CH1)).unwrap();

    // Example: transmit a string as UART frames via the Pipe
    loop {
        write_uart_frames_to_pipe(
            &PIPE_TX,
            TX_PIN_BIT,
            b"Hello marshmallow\r\n",
            &UART_CFG,
        ).await;
        Timer::after(Duration::from_secs(2)).await;
    }
}

#[embassy_executor::task]
async fn rx_dma_task(ch: Peri<'static, GPDMA1_CH1>) {
    let buf_ptr = core::ptr::addr_of_mut!(RX_DMA_BUF);
    let buf = unsafe { &mut *buf_ptr };
    let mut rx = GpioDmaRx::new(ch, 3 /*PA3 bit*/, buf, &PIPE_RX);
    rx.run().await;
}

#[embassy_executor::task]
async fn dma_tx_task(ch: Peri<'static, GPDMA1_CH0>) {
    let mut tx = GpioDmaBsrrTx::new(ch);

    info!("DMA task started, waiting for frames...");
    loop {
        // Read one 32-bit BSRR word (4 bytes) from the Pipe
        let mut b = [0u8; 4];
        let n = PIPE_TX.read(&mut b).await;
        if n != 4 {
            continue;
        }
        let w = u32::from_le_bytes(b);

        info!("DMA write 0x{:08X} -> GPIOA.BSRR", w);
        match embassy_time::with_timeout(
            Duration::from_millis(20),
            tx.write_word(w),
        )
        .await
        {
            Ok(()) => {}
            Err(_) => {
                warn!("DMA timeout: no TIM6 request");
                dump_tim6_regs();
                dump_dma_ch0_regs();
            }
        }
    }
}