use core::mem::MaybeUninit;
use core::fmt::Write;
use stm32f1xx_hal::{
    pac,
    pac::{interrupt, Interrupt},
    gpio,
    timer::CountDownTimer,
};
use stm32f1xx_hal::usb::{Peripheral, UsbBus, UsbBusType};
use usb_device::{bus::UsbBusAllocator, prelude::*};
use usbd_serial::{SerialPort, USB_CLASS_CDC};
use arrayvec::{ArrayVec, ArrayString};

/* Transmit 17.5 columns per second
 * With 14 lines per column, this gives 245 lines per second
 */
pub const TIMER_FREQ_HZ : u32 = 245;

const FELDHELL_PATTERN_LEN : usize = 16;
const MESSAGE_LEN : usize = 64;

static mut FELDHELL_TIMER: MaybeUninit<CountDownTimer<pac::TIM4>> = MaybeUninit::uninit();

static mut SHARED_USB: MaybeUninit<USBSharedData> = MaybeUninit::uninit();

static mut USB_BUS: Option<UsbBusAllocator<UsbBusType>> = None;
static mut USB_SERIAL: Option<usbd_serial::SerialPort<UsbBusType>> = None;
static mut USB_DEVICE: Option<UsbDevice<UsbBusType>> = None;


/* Commands
 * ========
 * Commands end with \n
 *
 * Switch to transmit:
 * tx
 *
 * Switch to receive:
 * rx
 *
 * Set frequency:
 * f10121000
 *
 * Append to transmit message
 * mThe message to transmit
 *
 * Clear transmit message
 * clear
 *
 * Set FELDHELL wide font
 * fontw
 *
 * Set FELDHELL narrow font
 * fontn
*/


#[derive(Clone, Copy)]
enum Font {
    Narrow,
    Wide,
}

// Shared between application and interrupt context
struct USBSharedData {
    incoming_buf: ArrayVec::<[u8; MESSAGE_LEN]>,
    feldhell_pattern: ArrayVec::<[u16; FELDHELL_PATTERN_LEN]>, // FELDHELL columns to transmit
}

pub fn enable_interrupts() {
    unsafe {
        pac::NVIC::unmask(Interrupt::USB_HP_CAN_TX);
        pac::NVIC::unmask(Interrupt::USB_LP_CAN_RX0);
        pac::NVIC::unmask(Interrupt::TIM4);
    }
}

pub struct USBData {
    font : Font,
    pub frequency : u32,
    pub transmit : bool,

    current_str : ArrayVec::<[u8; 96]>,
    send_ix : usize,
}

impl USBData {
    pub fn new(
        timer4: CountDownTimer<pac::TIM4>,
        usb: pac::USB,
        pin_dm: gpio::gpioa::PA11<gpio::Input<gpio::Floating>>,
        pin_dp: gpio::gpioa::PA12<gpio::Input<gpio::Floating>>) -> USBData {

        let peripheral = Peripheral {
            usb,
            pin_dm,
            pin_dp,
        };

        {
            let timer = unsafe { &mut *FELDHELL_TIMER.as_mut_ptr() };
            *timer = timer4;
        }

        unsafe {
            USB_BUS = Some(UsbBus::new(peripheral));
            USB_SERIAL = Some(SerialPort::new(USB_BUS.as_ref().unwrap()));
            let usb_device = UsbDeviceBuilder::new(USB_BUS.as_ref().unwrap(), UsbVidPid(0x1d50, 0x5120)) // Openmoko Neo1973 serial
                .manufacturer("HB9EGM")
                .product("Beep Machine")
                .serial_number("1")
                .device_class(USB_CLASS_CDC)
                .build();
            USB_DEVICE = Some(usb_device);

            let shared_usb = &mut *SHARED_USB.as_mut_ptr();
            *shared_usb = USBSharedData {
                incoming_buf : ArrayVec::new(),
                feldhell_pattern : ArrayVec::new(),
            }
        }

        USBData {
            font : Font::Narrow,
            frequency : 10121000,
            transmit : false,
            current_str : ArrayVec::new(),
            send_ix : 0,
        }
    }

    fn send_once(&mut self, message : &[u8]) {
        cortex_m::interrupt::free(|_cs| {
            let serial = unsafe { USB_SERIAL.as_mut().unwrap() };
            serial.write(message).ok();
        });
    }

    pub fn send_receive(&mut self) {
        self.send_once(b"Switch RX\n");
    }

    pub fn send_transmit(&mut self) {
        self.send_once(b"Switch TX\n");
    }

    pub fn handle(&mut self) {
        let in_message = cortex_m::interrupt::free(|_cs| {
            let shared_usb = unsafe { &mut *SHARED_USB.as_mut_ptr() };

            let mut message = ArrayString::<[u8; MESSAGE_LEN]>::new();

            let mut split_at = None;
            for (i, c) in shared_usb.incoming_buf.iter().enumerate() {
                if *c == b'\n' {
                    split_at = Some(i);
                    break;
                }
            }

            match split_at {
                Some(i) if i+1 == shared_usb.incoming_buf.len() => {
                    write!(&mut message, "{}", core::str::from_utf8(&shared_usb.incoming_buf).unwrap()).ok();
                    shared_usb.incoming_buf.clear();
                }
                Some(i) => {
                    let (front, back) = shared_usb.incoming_buf.split_at(i+1);

                    write!(&mut message, "{}", core::str::from_utf8(front).unwrap()).ok();

                    let mut keep = ArrayVec::<[u8; MESSAGE_LEN]>::new();
                    keep.try_extend_from_slice(back).ok();

                    shared_usb.incoming_buf.clear();
                    shared_usb.incoming_buf.try_extend_from_slice(&keep).ok();
                }
                _ => { }
            };

            if message.len() > 0 {
                Some(message)
            }
            else {
                None
            }
        });

        let mut outgoing = ArrayVec::<[u8; MESSAGE_LEN]>::new();
        if let Some(m) = in_message {
            if m.as_str() == "tx\n" {
                outgoing.try_extend_from_slice(b"TX ok\n").ok();
                self.transmit = true;
            }
            else if m.as_str() == "rx\n" {
                outgoing.try_extend_from_slice(b"RX ok\n").ok();
                self.current_str.clear();
                self.transmit = false;
            }
            else if m.chars().nth(0).unwrap() == 'm' {
                self.current_str.clear();
                for c in m.bytes().skip(1) {
                    self.current_str.push(c);
                }
                outgoing.try_extend_from_slice(b"m ok\n").ok();
            }
            else if m.as_str() == "fontw\n" {
                self.font = Font::Wide;
                outgoing.try_extend_from_slice(b"fontw ok\n").ok();
            }
            else if m.as_str() == "fontn\n" {
                self.font = Font::Narrow;
                outgoing.try_extend_from_slice(b"fontn ok\n").ok();
            }
            else if m.chars().nth(0).unwrap() == 'f' {
                let mut as_str = ArrayString::<[u8; MESSAGE_LEN]>::new();

                for c in m.chars().skip(1) {
                    as_str.push(c);
                }

                match u32::from_str_radix(as_str.as_str().trim(), 10) {
                    Ok(val) => {
                        self.frequency = val;
                        outgoing.try_extend_from_slice(b"f ok\n").ok();
                    }
                    _ => {
                        outgoing.try_extend_from_slice(b"F").ok();
                        outgoing.try_extend_from_slice(as_str.as_bytes()).ok();
                        outgoing.try_extend_from_slice(b" err\n").ok();
                    }
                }
            }
            else {
                outgoing.try_extend_from_slice(b"no\n").ok();
            }
        }

        let feldhell_pattern_length = cortex_m::interrupt::free(|_cs| {
            let serial = unsafe { USB_SERIAL.as_mut().unwrap() };
            serial.write(&outgoing).ok();

            let shared_usb = unsafe { &mut *SHARED_USB.as_mut_ptr() };
            shared_usb.feldhell_pattern.len()
        });

        if self.current_str.len() > 0 && feldhell_pattern_length < FELDHELL_PATTERN_LEN-8 {
            match self.current_str.get(self.send_ix) {
                Some(letter) => {
                    let fat = match self.font {
                        Font::Wide => true,
                        Font::Narrow => false,
                    };

                    match crate::feldhell_font::get_letter_by_columns(*letter, fat) {
                        Some(columns) => {
                            cortex_m::interrupt::free(|_cs| {
                                let shared_usb = unsafe { &mut *SHARED_USB.as_mut_ptr() };
                                shared_usb.feldhell_pattern.try_extend_from_slice(&columns).ok();
                            });

                        }
                        None => {}
                    }
                }
                None => {}
            }

            self.send_ix += 1;
            if self.send_ix >= self.current_str.len() {
                cortex_m::interrupt::free(|_cs| {
                    let serial = unsafe { USB_SERIAL.as_mut().unwrap() };
                    let mut outgoing = ArrayString::<[u8; 16]>::new();
                    write!(&mut outgoing, "FH sent {}\n", self.send_ix).ok();
                    serial.write(outgoing.as_bytes()).ok();
                });

                self.send_ix = 0;
                self.current_str.clear();
            }
        }
    }

    pub fn is_transmit(&self) -> bool { self.transmit }
}

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

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

fn usb_interrupt() {
    let usb_dev = unsafe { USB_DEVICE.as_mut().unwrap() };
    let serial = unsafe { USB_SERIAL.as_mut().unwrap() };

    if !usb_dev.poll(&mut [serial]) {
        return;
    }

    let mut buf = [0u8; MESSAGE_LEN];

    let shared_usb = unsafe { &mut *SHARED_USB.as_mut_ptr() };

    match serial.read(&mut buf) {
        Ok(count) if count > 0 => {
            if count > MESSAGE_LEN {
                panic!("illegal count");
            }
            shared_usb.incoming_buf.try_extend_from_slice(&buf[0..count]).ok();
        }
        _ => {}
    }
}

#[allow(non_snake_case)]
#[interrupt]
fn TIM4() {
    let timer = unsafe { &mut *FELDHELL_TIMER.as_mut_ptr() };
    timer.clear_update_interrupt_flag();

    let shared_usb = unsafe { &mut *SHARED_USB.as_mut_ptr() };
    while shared_usb.feldhell_pattern.len() > 0 && shared_usb.feldhell_pattern.as_slice()[0] == 0 {
        shared_usb.feldhell_pattern.pop_at(0);
    }

    if shared_usb.feldhell_pattern.len() > 0 {
        let remove_first_element = {
            let pat = shared_usb.feldhell_pattern.as_mut_slice().first_mut().unwrap();

            let shared = unsafe { &mut *crate::SHARED.as_mut_ptr() };

            use embedded_hal::digital::v2::OutputPin;

            if shared.state.allow_feldhell_keying() && (*pat & 0b1) == 0b1 {
                shared.cw_key_out_n.set_low().unwrap();
            }
            else {
                shared.cw_key_out_n.set_high().unwrap();
            }

            *pat >>= 1;
            assert_ne!(*pat, 0);
            *pat == 0b1
        };

        if remove_first_element {
            shared_usb.feldhell_pattern.pop_at(0);
        }
    }
}