#![no_std]
#![no_main]

//extern crate panic_semihosting;

use luchie::{
    cirque::Cirque,
    event_filter::{AbsToRel, TrackBall},
    log, logger, logln,
};

use cortex_m::{
    asm::{bkpt, wfi},
    interrupt,
};
use cortex_m_rt::entry;
use embedded_hal::spi;
use stm32f1xx_hal::{
    pac,
    prelude::*,
    serial::{Config, Serial, StopBits, WordLength},
    spi::Spi,
    usb::{self, UsbBus},
};
use usb_device::prelude::*;
use usbd_human_interface_device::{
    device::mouse::{WheelMouseInterface, WheelMouseReport},
    prelude::*,
};
use usbd_serial::{SerialPort, USB_CLASS_CDC};

// Relies on cortex-m
struct SysTimer {
    syst: pac::SYST,
    last: u32,
    err: u32,
    reload: u32,
    ticks_per_microsec: u32,
}

impl SysTimer {
    pub fn new(mut syst: pac::SYST, ticks_per_microsec: u32) -> Self {
        syst.set_clock_source(cortex_m::peripheral::syst::SystClkSource::Core);
        let reload = 0xffffff;
        syst.set_reload(reload);
        syst.clear_current();
        syst.enable_counter();

        Self { syst, last: 0, err: 0, reload, ticks_per_microsec }
    }

    pub fn update(&mut self) -> u32 {
        let mut time = self.reload - cortex_m::peripheral::SYST::get_current();
        if self.syst.has_wrapped() {
            time += self.reload + 1;
        }
        let elapsed = time.wrapping_sub(self.last) + self.err;
        self.err = elapsed % self.ticks_per_microsec;
        let elapsed = elapsed / self.ticks_per_microsec;
        self.last = time & self.reload; // FIXME: might not be 2^x - 1

        elapsed
    }
}

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

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

    let clocks = rcc
        .cfgr
        .use_hse(8.MHz())
        .sysclk(72.MHz()) // TODO: gd32 can get up to 120MHz
        .pclk1(24.MHz())
        .freeze(&mut flash.acr);

    assert!(clocks.usbclk_valid());

    let mut afio = dp.AFIO.constrain();
    let mut gpioa = dp.GPIOA.split();

    let tx_pin = gpioa.pa9.into_alternate_push_pull(&mut gpioa.crh);
    let rx_pin = gpioa.pa10;
    let serial = Serial::usart1(
        dp.USART1,
        (tx_pin, rx_pin),
        &mut afio.mapr,
        Config::default()
            .baudrate(115200.bps())
            .wordlength(WordLength::Bits8)
            .parity_none()
            .stopbits(StopBits::STOP1),
        clocks,
    );
    let (tx, _) = serial.split();

    logger::init(tx);

    logln!("🐁 luchie starting…");

    logln!("⏲️ init timer");
    let mut sys_timer = SysTimer::new(cp.SYST, clocks.sysclk().to_MHz());

    logln!("🎹 init buttons");
    // fusion mouse button labels
    let mut gpiob = dp.GPIOB.split();
    let left_button = gpiob.pb9.into_pull_up_input(&mut gpiob.crh);
    let middle_button = gpiob.pb8.into_pull_up_input(&mut gpiob.crh);
    let forward_button = gpiob.pb7.into_pull_up_input(&mut gpiob.crl);
    let back_button = gpiob.pb6.into_pull_up_input(&mut gpiob.crl);
    let dpi_button = gpiob.pb5.into_pull_up_input(&mut gpiob.crl);

    // cirque spi connections to spi1:
    //
    // pb0 - dr
    // pa4 - ss1
    // pa5 - clk1
    // pa6 - miso1
    // pa7 - mosi1

    logln!("👆 init trackpad");
    // TODO: hook an interrupt up to the dr pin to trigger a poll.
    //let dr_pin = gpiob.pb1.into_pull_down_input(&mut gpiob.crl);
    let sck_pin = gpioa.pa5.into_alternate_push_pull(&mut gpioa.crl);
    let miso_pin = gpioa.pa6;
    let mosi_pin = gpioa.pa7.into_alternate_push_pull(&mut gpioa.crl);
    let cs_pin = gpioa.pa4.into_push_pull_output(&mut gpioa.crl);
    let mut spi = Spi::spi1(
        dp.SPI1,
        (sck_pin, miso_pin, mosi_pin),
        &mut afio.mapr,
        spi::MODE_1,
        1_000_000.Hz(), // pinnacle supports up to 13mhz
        clocks,
    );
    let mut cirque = match Cirque::new(cs_pin, &mut spi, clocks.sysclk().raw()) {
        Ok(c) => c,
        Err(e) => {
            logln!("err: {:?}", e);
            panic!();
        }
    };

    logln!("🖥️ init usb");
    // 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();
    cortex_m::asm::delay(clocks.sysclk().raw() / 100);

    let usb = usb::Peripheral {
        usb: dp.USB,
        pin_dm: gpioa.pa11,
        pin_dp: usb_dp.into_floating_input(&mut gpioa.crh),
    };
    let usb_bus = UsbBus::new(usb);

    let mut serial = SerialPort::new(&usb_bus);

    let mut mouse_report = WheelMouseReport::default();
    let mut mouse = UsbHidClassBuilder::new()
        .add_interface(WheelMouseInterface::default_config())
        .build(&usb_bus);

    let mut usb_dev = UsbDeviceBuilder::new(&usb_bus, UsbVidPid(0xdead, 0xbeef))
        .manufacturer("Fake company")
        .product("Serial port")
        .serial_number("TEST")
        .device_class(USB_CLASS_CDC)
        .build();

    while usb_dev.state() != UsbDeviceState::Configured {
        usb_dev.poll(&mut [&mut serial, &mut mouse]);
    }


    logln!("💡 init led");
    let mut led = gpiob.pb2.into_push_pull_output(&mut gpiob.crl);
    led.set_low();

    logln!("🎉 luchie started!");

    let mut abs_to_rel = AbsToRel::new();
    let mut trackball = TrackBall::new(1);
    let mut last_buttons = 0;
    loop {
        let elapsed = sys_timer.update();

        usb_dev.poll(&mut [&mut serial, &mut mouse]);
        if usb_dev.state() != UsbDeviceState::Configured {
            continue;
        }

        let mut buf = [0u8; 64];

        match serial.read(&mut buf) {
            Ok(count) if count > 0 => {
                led.set_high();

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

                let mut write_offset = 0;
                while write_offset < count {
                    match serial.write(&buf[write_offset..count]) {
                        Ok(len) if len > 0 => {
                            write_offset += len;
                        }
                        _ => {}
                    }
                }
                led.set_low();
            }
            _ => {}
        }

        if left_button.is_low() {
            logln!("lb");
            mouse_report.buttons |= 1;
        }
        if middle_button.is_low() {
            logln!("mb");
            mouse_report.buttons |= 2;
        }
        if forward_button.is_low() {
            logln!("fb");
            mouse_report.buttons |= 4;
        }
        if back_button.is_low() {
            logln!("bb");
            mouse_report.buttons |= 8;
        }
        if dpi_button.is_low() {
            logln!("db");
            mouse_report.buttons |= 16;
        }

        let rel_p = cirque
            .poll(&mut spi)
            .ok()
            .map(|td| {
                //logln!("td: {:?}", td);
                abs_to_rel.update(&td)
            })
            .flatten();
        if let Some(p) = rel_p {
            logln!("rel_p: {:?}", p);
        }
        let p = trackball.update(rel_p, elapsed);
        if p.0 != 0 || p.1 != 0 || mouse_report.buttons ^ last_buttons != 0 {
            mouse_report.x = p.0;
            mouse_report.y = p.1;
            logln!("p: {:?}", p);
            match mouse.interface().write_report(&mouse_report) {
                Err(UsbHidError::WouldBlock) => {}
                Err(e) => {
                    panic!("couldn't write mouse report: {:?}", e)
                }
                _ => {}
            }
        }
        last_buttons = mouse_report.buttons;
    }
}

#[panic_handler]
fn panic(info: &core::panic::PanicInfo) -> ! {
    interrupt::free(|_cs| {
        log!("!!! panic ");
        if let Some(loc) = info.location() {
            log!("in {}:{} ", loc.file(), loc.line());
        }
        if let Some(msg) = info.payload().downcast_ref::<&str>() {
            log!("⇒ {} ", msg);
        }
        logln!("!!!");
    });
    spin();
}

fn spin() -> ! {
    bkpt();
    loop {
        wfi();
    }
}