#![no_std]
#![no_main]

extern crate panic_semihosting;

use core::cell::RefCell;
use core::ops::DerefMut;

use cortex_m::asm::wfi;
use cortex_m::interrupt::{free as interrupt_free, Mutex};
use cortex_m::peripheral::NVIC;
use cortex_m_rt::entry;
use embedded_hal::digital::v2::OutputPin;
use stm32f1xx_hal::stm32::{self, interrupt, Interrupt};
use stm32f1xx_hal::usb::{Peripheral, UsbBusType};
use stm32f1xx_hal::{delay::Delay, prelude::*};
use usb_device::bus::UsbBusAllocator;
use usb_device::prelude::*;
use usbd_serial::{SerialPort, USB_CLASS_CDC};

#[cfg(not(feature = "atomic"))]
use bbqueue::{consts::*, BBBuffer, ConstBBBuffer, Producer};

static RX_QUEUE: BBBuffer<U128> = BBBuffer(ConstBBBuffer::new());
static RX_PROD: Mutex<RefCell<Option<Producer<U128>>>> = Mutex::new(RefCell::new(None));

static mut USB_BUS: Option<UsbBusAllocator<UsbBusType>> = None;
static USB_DEVICE: Mutex<RefCell<Option<UsbDevice<'static, UsbBusType>>>> =
    Mutex::new(RefCell::new(None));
static SERIAL: Mutex<RefCell<Option<SerialPort<'static, UsbBusType>>>> =
    Mutex::new(RefCell::new(None));

#[entry]
fn main() -> ! {
    let cp = cortex_m::Peripherals::take().unwrap();
    let dp = stm32::Peripherals::take().unwrap();

    let mut flash = dp.FLASH.constrain();
    let mut rcc = dp.RCC.constrain();

    let clocks = rcc
        .cfgr
        .use_hse(8.mhz())
        .sysclk(48.mhz())
        .pclk1(24.mhz())
        .freeze(&mut flash.acr);

    assert!(clocks.usbclk_valid());

    let mut delay = Delay::new(cp.SYST, clocks);

    // Configure the on-board LED (PC13, green)
    let mut gpioc = dp.GPIOC.split(&mut rcc.apb2);
    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
    led.set_high().ok(); // Turn off

    let mut gpioa = dp.GPIOA.split(&mut rcc.apb2);

    let mut usb_dp = gpioa.pa12.into_push_pull_output(&mut gpioa.crh);
    usb_dp.set_low().unwrap();
    delay.delay_ms(10u16);

    let usb_bus;
    unsafe {
        let usb_peripherial = Peripheral {
            usb: dp.USB,
            pin_dm: gpioa.pa11,
            pin_dp: usb_dp.into_floating_input(&mut gpioa.crh),
        };
        USB_BUS = Some(UsbBusType::new(usb_peripherial));
        usb_bus = USB_BUS.as_ref().unwrap();
    }

    let (rx_prod, mut rx_cons) = RX_QUEUE.try_split().unwrap();

    interrupt_free(|cs| {
        SERIAL.borrow(cs).replace(Some(SerialPort::new(usb_bus)));
        USB_DEVICE.borrow(cs).replace(Some(
            UsbDeviceBuilder::new(usb_bus, UsbVidPid(0x16c0, 0x27dd))
                .manufacturer("Ar3itrary Embedded")
                .product("usart-demo")
                .serial_number("2342")
                .device_class(USB_CLASS_CDC)
                .build(),
        ));

        RX_PROD.borrow(cs).replace(Some(rx_prod));
    });

    unsafe {
        NVIC::unmask(Interrupt::USB_HP_CAN_TX);
        NVIC::unmask(Interrupt::USB_LP_CAN_RX0);
    }

    loop {
        wfi();

        if let Ok(rgr) = rx_cons.read() {
            for c in rgr.iter() {
                let resp = match *c {
                    97u8 => {
                        led.set_high().unwrap();
                        "LED turned off\n\r"
                    }
                    98u8 => {
                        led.set_low().unwrap();
                        "LED turned on\n\r"
                    }
                    _ => "",
                };
                interrupt_free(|cs| {
                    if let Some(serial) = SERIAL.borrow(cs).borrow_mut().deref_mut() {
                        serial.write(resp.as_bytes()).unwrap();
                    }
                });
            }

            let len = rgr.len();
            rgr.release(len);
        }
    }
}

#[interrupt]
fn USB_HP_CAN_TX() {
    usb_interrupt();
}

#[interrupt]
fn USB_LP_CAN_RX0() {
    usb_interrupt();
}

fn usb_interrupt() {
    interrupt_free(|cs| {
        if let Some(usb_dev) = USB_DEVICE.borrow(cs).borrow_mut().deref_mut() {
            if let Some(serial) = SERIAL.borrow(cs).borrow_mut().deref_mut() {
                if !usb_dev.poll(&mut [serial]) {
                    return;
                }

                if let Some(rx_prod) = RX_PROD.borrow(cs).borrow_mut().deref_mut() {
                    if let Ok(mut wgr) = rx_prod.grant_exact(64) {
                        match serial.read(&mut wgr) {
                            Ok(count) if count > 0 => {
                                wgr.commit(count);
                            }
                            _ => wgr.commit(0),
                        }
                    }
                }
            }
        }
    });
}