//! CDC-ACM serial port example using cortex-m-rtfm.
//! Target board: Blue Pill
#![no_main]
#![no_std]
#![allow(non_snake_case)]

extern crate panic_semihosting;

use cortex_m::asm::delay;
use embedded_hal::digital::v2::OutputPin;
use rtfm::app;
use stm32f1xx_hal::prelude::*;
use stm32f1xx_hal::usb::{Peripheral, UsbBus, UsbBusType};
use usb_device::bus;
use usb_device::prelude::*;
use usbd_serial::{SerialPort, USB_CLASS_CDC};

#[app(device = stm32f1xx_hal::stm32, peripherals = true)]
const APP: () = {
    struct Resources {
        usb_dev: UsbDevice<'static, UsbBusType>,
        serial: SerialPort<'static, UsbBusType>,
    }

    #[init]
    fn init(cx: init::Context) -> init::LateResources {
        static mut USB_BUS: Option<bus::UsbBusAllocator<UsbBusType>> = None;

        let mut flash = cx.device.FLASH.constrain();
        let mut rcc = cx.device.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 gpioa = cx.device.GPIOA.split(&mut rcc.apb2);

        // BluePill board has a pull-up resistor on the D+ line.
        // Pull the D+ pin down to send a RESET condition to the USB bus.
        // This forced reset is needed only for development, without it host
        // will not reset your device when you upload new firmware.
        let mut usb_dp = gpioa.pa12.into_push_pull_output(&mut gpioa.crh);
        usb_dp.set_low().unwrap();
        delay(clocks.sysclk().0 / 100);

        let usb_dm = gpioa.pa11;
        let usb_dp = usb_dp.into_floating_input(&mut gpioa.crh);

        let usb = Peripheral {
            usb: cx.device.USB,
            pin_dm: usb_dm,
            pin_dp: usb_dp,
        };

        *USB_BUS = Some(UsbBus::new(usb));

        let serial = SerialPort::new(USB_BUS.as_ref().unwrap());

        let usb_dev = UsbDeviceBuilder::new(USB_BUS.as_ref().unwrap(), UsbVidPid(0x16c0, 0x27dd))
            .manufacturer("Fake company")
            .product("Serial port")
            .serial_number("TEST")
            .device_class(USB_CLASS_CDC)
            .build();

        init::LateResources {
            usb_dev,
            serial,
        }
    }

    #[task(binds = USB_HP_CAN_TX, resources = [usb_dev, serial])]
    fn usb_tx(mut cx: usb_tx::Context) {
        usb_poll(&mut cx.resources.usb_dev, &mut cx.resources.serial);
    }

    #[task(binds = USB_LP_CAN_RX0, resources = [usb_dev, serial])]
    fn usb_rx0(mut cx: usb_rx0::Context) {
        usb_poll(&mut cx.resources.usb_dev, &mut cx.resources.serial);
    }
};

fn usb_poll<B: bus::UsbBus>(
    usb_dev: &mut UsbDevice<'static, B>,
    serial: &mut SerialPort<'static, B>,
) {
    if !usb_dev.poll(&mut [serial]) {
        return;
    }

    let mut buf = [0u8; 8];

    match serial.read(&mut buf) {
        Ok(count) if count > 0 => {
            // Echo back in upper case
            for c in buf[0..count].iter_mut() {
                if 0x61 <= *c && *c <= 0x7a {
                    *c &= !0x20;
                }
            }

            serial.write(&buf[0..count]).ok();
        }
        _ => {}
    }
}