#![deny(unsafe_code)]
#![no_std]
#![no_main]

use panic_halt as _;
use cortex_m_semihosting::hprintln; // logs messages to the host; requires a debugger

use nb::block;

use stm32f1xx_hal::{
    prelude::*,
    pac,
    i2c,
    timer::Timer,
};
use cortex_m_rt::entry;
use embedded_hal::digital::v2::OutputPin;

#[entry]
fn main() -> ! {

    // Get access to the core peripherals from the cortex-m crate
    let cp = cortex_m::Peripherals::take().unwrap();
    // Get access to the device specific peripherals from the peripheral access crate
    let dp = pac::Peripherals::take().unwrap();

    // Take ownership over the raw flash and rcc devices and convert them into the corresponding
    // HAL structs
    let mut flash = dp.FLASH.constrain();
    let mut rcc = dp.RCC.constrain();
    let mut afio = dp.AFIO.constrain(&mut rcc.apb2);

    // Freeze the configuration of all the clocks in the system and store the frozen frequencies in
    // `clocks`
    let clocks = rcc.cfgr.freeze(&mut flash.acr);

    // Acquire the GPIOC peripheral
    let mut gpioc = dp.GPIOC.split(&mut rcc.apb2);

    let mut gpiob = dp.GPIOB.split(&mut rcc.apb2);
    let scl = gpiob.pb6.into_alternate_open_drain(&mut gpiob.crl);
    let sda = gpiob.pb7.into_alternate_open_drain(&mut gpiob.crl);

    let mut i2c = i2c::BlockingI2c::i2c1(dp.I2C1, (scl, sda),
        &mut afio.mapr,
        i2c::Mode::Standard{frequency: 400_000},
        clocks,
        &mut rcc.apb1,
        5,
        1,
        5,
        5);

    hprintln!("I2C setup").unwrap();


    // Configure gpio C pin 13 as a push-pull output. The `crh` register is passed to the function
    // in order to configure the port. For pins 0-7, crl should be passed instead.
    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
    // Configure the syst timer to trigger an update every second
    let mut timer = Timer::syst(cp.SYST, 1.hz(), clocks);

    // Wait for the timer to trigger an update and change the state of the LED
    loop {
        block!(timer.wait()).unwrap();
        led.set_high().unwrap();

        let res = i2c.write(96, &[0x23, 0x82]);
        if res.is_ok() {
            hprintln!("write worked!").unwrap();
        } else {
            hprintln!("write failed!").unwrap();
        }

        block!(timer.wait()).unwrap();
        led.set_low().unwrap();
    }
}