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//! # Use ws2812 leds via UART
//!
//! - For usage with `smart-leds`
//! - Implements the `SmartLedsWrite` trait
//!
//! The UART Tx pin has to be inverted (either in software or
//! in hardware). The UART itself should be pretty fast.
//! Recommended speed is 3_750_000 baud, 8-N-1.

#![no_std]

use core::marker::PhantomData;
use embedded_hal as hal;
use hal::serial::Write;
use nb::block;
use smart_leds_trait::{SmartLedsWrite, RGB8, RGBW};

pub mod device {
    pub struct Ws2812;
    pub struct Sk6812w;

    pub trait Ws2812Like {
        type Color: super::EncodeColor;
    }

    impl Ws2812Like for Ws2812 {
        type Color = super::RGB8;
    }

    impl Ws2812Like for Sk6812w {
        type Color = super::RGBW<u8>;
    }
}

pub trait EncodeColor {
    type Bytes: IntoIterator<Item = u8>;
    fn encode(self) -> Self::Bytes;
}

impl EncodeColor for RGB8 {
    type Bytes = [u8; 3];
    fn encode(self) -> Self::Bytes {
        [self.g, self.r, self.b]
    }
}

impl EncodeColor for RGBW<u8> {
    type Bytes = [u8; 4];
    fn encode(self) -> Self::Bytes {
        [self.g, self.r, self.b, self.a.0]
    }
}

pub struct Ws2812<UART, DEV = device::Ws2812> {
    uart: UART,
    _device: PhantomData<DEV>,
}

impl<UART, DEV> Ws2812<UART, DEV>
where
    UART: Write<u8>,
{
    pub fn new(uart: UART) -> Self {
        Self {
            uart,
            _device: PhantomData,
        }
    }

    fn send_byte(&mut self, mut byte: u8) -> Result<(), <UART as Write<u8>>::Error> {
        for _ in 0..4 {
            let bits = 0b_0001_0000
                | if (byte & 0b_10_00_0000) != 0 {
                    0b_0000_0011
                } else {
                    0
                }
                | if (byte & 0b_01_00_0000) != 0 {
                    0b_0110_0000
                } else {
                    0
                };
            block!(self.uart.write(!bits))?;
            byte <<= 2;
        }
        Ok(())
    }
}

impl<UART, DEV> SmartLedsWrite for Ws2812<UART, DEV>
where
    UART: Write<u8>,
    DEV: device::Ws2812Like,
{
    type Error = <UART as Write<u8>>::Error;
    type Color = DEV::Color;

    fn write<T, I>(&mut self, iterator: T) -> Result<(), Self::Error>
    where
        T: Iterator<Item = I>,
        I: Into<Self::Color>,
    {
        for item in iterator {
            let color = item.into();
            for byte in color.encode() {
                self.send_byte(byte)?;
            }
        }
        Ok(())
    }
}