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use core::u16;

use hal::{self, Direction};
use stm32f103xx::{TIM2, TIM3, TIM4};

use afio::MAPR;
use gpio::gpioa::{PA0, PA1, PA6, PA7};
use gpio::gpiob::{PB6, PB7};
use gpio::{Floating, Input};
use rcc::APB1;

pub trait Pins<TIM> {
    const REMAP: u8;
}

impl Pins<TIM2> for (PA0<Input<Floating>>, PA1<Input<Floating>>) {
    const REMAP: u8 = 0b00;
}

impl Pins<TIM3> for (PA6<Input<Floating>>, PA7<Input<Floating>>) {
    const REMAP: u8 = 0b00;
}

impl Pins<TIM4> for (PB6<Input<Floating>>, PB7<Input<Floating>>) {
    const REMAP: u8 = 0b00;
}

pub struct Qei<TIM, PINS> {
    tim: TIM,
    pins: PINS,
}

impl<PINS> Qei<TIM2, PINS> {
    pub fn tim2(tim: TIM2, pins: PINS, mapr: &mut MAPR, apb: &mut APB1) -> Self
    where
        PINS: Pins<TIM2>,
    {
        mapr.mapr()
            .modify(|_, w| unsafe { w.tim2_remap().bits(PINS::REMAP) });

        Qei::_tim2(tim, pins, apb)
    }
}

impl<PINS> Qei<TIM3, PINS> {
    pub fn tim3(tim: TIM3, pins: PINS, mapr: &mut MAPR, apb: &mut APB1) -> Self
        where
        PINS: Pins<TIM3>,
    {
        mapr.mapr()
            .modify(|_, w| unsafe { w.tim3_remap().bits(PINS::REMAP) });

        Qei::_tim3(tim, pins, apb)
    }
}

impl<PINS> Qei<TIM4, PINS> {
    pub fn tim4(tim: TIM4, pins: PINS, mapr: &mut MAPR, apb: &mut APB1) -> Self
        where
        PINS: Pins<TIM4>,
    {
        mapr.mapr()
            .modify(|_, w| w.tim4_remap().bit(PINS::REMAP == 1));

        Qei::_tim4(tim, pins, apb)
    }
}

macro_rules! hal {
    ($($TIMX:ident: ($timX:ident, $timXen:ident, $timXrst:ident),)+) => {
        $(
            impl<PINS> Qei<$TIMX, PINS> {
                fn $timX(tim: $TIMX, pins: PINS, apb: &mut APB1) -> Self {
                    // enable and reset peripheral to a clean slate state
                    apb.enr().modify(|_, w| w.$timXen().set_bit());
                    apb.rstr().modify(|_, w| w.$timXrst().set_bit());
                    apb.rstr().modify(|_, w| w.$timXrst().clear_bit());

                    // Configure TxC1 and TxC2 as captures
                    tim.ccmr1_output
                        .write(|w| unsafe { w.bits({ (0b01 << 0) | (0b01 << 8) }) });

                    // enable and configure to capture on rising edge
                    tim.ccer.write(|w| {
                        w.cc1e()
                            .set_bit()
                            .cc1p()
                            .clear_bit()
                            .cc2e()
                            .set_bit()
                            .cc2p()
                            .clear_bit()
                    });

                    // configure as quadrature encoder
                    tim.smcr.write(|w| w.sms().encoder_ti1ti2());

                    tim.arr.write(|w| w.arr().bits(u16::MAX));
                    tim.cr1.write(|w| w.cen().enabled());

                    Qei { tim, pins }
                }

                pub fn release(self) -> ($TIMX, PINS) {
                    (self.tim, self.pins)
                }
            }

            impl<PINS> hal::Qei for Qei<$TIMX, PINS> {
                type Count = u16;

                fn count(&self) -> u16 {
                    self.tim.cnt.read().cnt().bits()
                }

                fn direction(&self) -> Direction {
                    if self.tim.cr1.read().dir().bit_is_clear() {
                        hal::Direction::Upcounting
                    } else {
                        hal::Direction::Downcounting
                    }
                }
            }

        )+
    }
}

hal! {
    TIM2: (_tim2, tim2en, tim2rst),
    TIM3: (_tim3, tim3en, tim3rst),
    TIM4: (_tim4, tim4en, tim4rst),
}