use crate::{LayerSelect, Sequencer};
use embedded_hal::digital::v2::{InputPin, OutputPin};
use stm32f1xx_hal::gpio::{
    gpioa::{PA1, PA2, PA3, PA4},
    gpiob::{PB0, PB1, PB5, PB6, PB7, PB8, PB9},
    Input, Output, PullDown, PushPull,
};

struct NoneOutput;

impl OutputPin for NoneOutput {
    type Error = ();

    fn set_low(&mut self) -> Result<(), ()> {
        Ok(())
    }
    fn set_high(&mut self) -> Result<(), ()> {
        Ok(())
    }
}

/// An I/O abstraction for yesman
///
/// The main I/O of the yesman module is buttons as inputs that need
/// to be polled, and LEDs as outputs.  All LED states are written at
/// the same time.  An "active step" can be fed into the `Io`
/// abstraction from the `Sequencer` module.
pub struct Io {
    // LED output states
    pub led1: PA1<Output<PushPull>>,
    pub led2: PA2<Output<PushPull>>,
    pub led3: PA3<Output<PushPull>>,
    pub led4: PA4<Output<PushPull>>,

    // Button input states
    pub btn1: PB0<Input<PullDown>>,
    pub btn1_last: bool,

    pub btn2: PB1<Input<PullDown>>,
    pub btn2_last: bool,

    pub btn3: PB5<Input<PullDown>>,
    pub btn3_last: bool,

    pub btn4: PB6<Input<PullDown>>,
    pub btn4_last: bool,

    // Eurorack signal I/O
    pub clk: PB7<Input<PullDown>>,
    pub clk_last: bool,
    pub clk_led: PB9<Output<PushPull>>,

    pub gate: PB8<Output<PushPull>>,
}

impl Io {
    /// Check the state of each pin and update the sequencer accordingly
    pub fn update_sequence(&mut self, seq: &mut Sequencer) {
        // Update sequencer states based on button inputs
        // btn_rising_edge(&mut self.btn1_last, &mut self.btn1, || seq.toggle(0));
        // btn_rising_edge(&mut self.btn2_last, &mut self.btn2, || seq.toggle(1));
        // btn_rising_edge(&mut self.btn3_last, &mut self.btn3, || seq.toggle(2));
        // btn_rising_edge(&mut self.btn4_last, &mut self.btn4, || seq.toggle(3));

        // // Update LED states based on sequencer
        // let l = seq.layer(LayerSelect::A);
        // set_output(&mut self.led1, l[0]);
        // set_output(&mut self.led2, l[1]);
        // set_output(&mut self.led3, l[2]);
        // set_output(&mut self.led4, l[3]);
    }

    pub fn update_cv(&mut self, seq: &mut Sequencer) {
        // Always output the current steps - if no clock is coming in this will change nothing in our output
        // set_output(&mut self.gate, !seq.get().0);

        // // On a rising clock edge, step the sequencer
        // rising_edge(
        //     &mut self.clk_last,
        //     &mut self.clk,
        //     &mut self.clk_led,
        //     |led| {
        //         set_output(led, false);
        //     },
        // );

        // If the clock pin is high
        if let Ok(true) = self.clk.is_high() {
            // And this is the first time we run this code
            if !self.clk_last {
                // Just set the LED to on for now
                self.clk_led.set_high().ok();
                self.clk_last = true;
            }

            // If the clock pin goes low
        } else if let Ok(false) = self.clk.is_high() {
            // We set the `last` bool to false and reset the LED
            self.clk_last = false;
            self.clk_led.set_low().ok();
        }
    }
}

/// If the button is pressed _and_ it was previously not pressed,
/// run the given closure and update the button state to avoid
/// running it again
#[inline]
fn btn_rising_edge<I: InputPin, F: FnMut()>(last: &mut bool, i: &mut I, mut f: F) {
    rising_edge(last, i, &mut NoneOutput, |_: &mut NoneOutput| f());
}

/// If the button is pressed _and_ it was previously not pressed,
/// run the given closure and update the button state to avoid
/// running it again
#[inline]
fn rising_edge<I: InputPin, F: FnMut(&mut O), O: OutputPin>(
    last: &mut bool,
    i: &mut I,
    o: &mut O,
    mut f: F,
) {
    if let Ok(true) = i.is_high() {
        if !*last {
            f(o);
            *last = true;
        }
    } else if let Ok(false) = i.is_high() {
        *last = false;
    }
}

fn set_output<O: OutputPin>(o: &mut O, s: bool) {
    if s {
        o.set_high().ok();
    } else {
        o.set_low().ok();
    }
}