#![no_std]

use stm32h7xx_hal::{
	hal::{
		digital::v2::{
			InputPin,
			OutputPin,
		},
		blocking::spi::Transfer,
		spi::FullDuplex,
	},
	pac,
	prelude::*,
	spi,
};

use core::cell;

use cortex_m;
use cortex_m::asm::nop;
use cortex_m_semihosting::hprintln;

use nb::block;

pub mod spi_slave;
use crate::spi_slave::{SPISlave, Parts};


/*
 *	Enum for structuring error
 */
#[derive(Debug)]
pub enum Error<E> {
	SPI(E),
	CSError,
	GetRefMutDataError,
}

/*
 *	Basic structure for CPLD signal multiplexing
 */
#[derive(Debug)]
pub struct CPLDData<SPI, CS0, CS1, CS2> {
	pub(crate) spi: SPI,
	pub(crate) chip_select: (CS0, CS1, CS2),
}

#[derive(Debug)]
pub struct CPLD<SPI, CS0, CS1, CS2> {
	pub(crate) data: cell::RefCell<CPLDData<SPI, CS0, CS1, CS2>>,
}

pub trait SelectChip {
	type Error;
	fn select_chip(&mut self, chip: u8) -> Result<(), Self::Error>;
}

impl<SPI, CS0, CS1, CS2, E> SelectChip for CPLDData<SPI, CS0, CS1, CS2>
where
	SPI: Transfer<u8, Error = E>,
	CS0: OutputPin,
	CS1: OutputPin,
	CS2: OutputPin,
{
	type Error = Error<E>;
	fn select_chip(&mut self, chip: u8) -> Result<(), Self::Error> {
		match chip & (1 << 0) {
			0 => self.chip_select.0.set_low(),
			_ => self.chip_select.0.set_high(),
		}.map_err(|_| Error::CSError)?;
		match chip & (1 << 1) {
			0 => self.chip_select.1.set_low(),
			_ => self.chip_select.1.set_high(),
		}.map_err(|_| Error::CSError)?;
		match chip & (1 << 2) {
			0 => self.chip_select.2.set_low(),
			_ => self.chip_select.2.set_high(),
		}.map_err(|_| Error::CSError)?;
		Ok(())
	}
}

pub trait DoOnGetRefMutData<SPI, CS0, CS1, CS2> {
	fn do_on_get_ref_mut_data<R, E>(
		&self,
		f: impl FnOnce(cell::RefMut<CPLDData<SPI, CS0, CS1, CS2>>) -> Result<R, Error<E>>,
	) -> Result<R, Error<E>>;
}

impl<SPI, CS0, CS1, CS2> DoOnGetRefMutData<SPI, CS0, CS1, CS2> for CPLD<SPI, CS0, CS1, CS2> {
	fn do_on_get_ref_mut_data<R, E>(
		&self,
		f: impl FnOnce(cell::RefMut<CPLDData<SPI, CS0, CS1, CS2>>) -> Result<R, Error<E>>,
	) -> Result<R, Error<E>> {
		let dev = self
			.data
			.try_borrow_mut()
			.map_err(|_| Error::GetRefMutDataError)?;
		f(dev)
	}
}

impl<SPI, CS0, CS1, CS2, E> Transfer<u8> for CPLD<SPI, CS0, CS1, CS2>
where
	SPI: Transfer<u8, Error = E>,
	CS0: OutputPin,
	CS1: OutputPin,
	CS2: OutputPin,
{
	type Error = Error<E>;

	fn transfer<'w>(&mut self, words: &'w mut [u8]) -> Result<&'w [u8], Self::Error> {
		self.do_on_get_ref_mut_data(move |mut dev| dev.spi.transfer(words).map_err(Error::SPI))
	}
}

impl<SPI, CS0, CS1, CS2, E> CPLD<SPI, CS0, CS1, CS2> where
	SPI: Transfer<u8, Error = E>,
	CS0: OutputPin,
	CS1: OutputPin,
	CS2: OutputPin,
{
	// Constructor for CPLD
	pub fn new(spi: SPI, chip_select: (CS0, CS1, CS2)) -> Self {

		// Init data
		let data = CPLDData {
			spi,
			chip_select,
		};

		// Init CPLD
		CPLD {
			data: cell::RefCell::new(data),
		}
	}

	// Destroy the wrapper, return the CPLD data
	pub fn destroy(self) -> (SPI, (CS0, CS1, CS2)) {
		let cpld = self.data.into_inner();
		(cpld.spi, cpld.chip_select)
	}

	// Split SPI into chips, wrapped by Parts struct
	pub fn split<'a>(&'a self) -> Parts<'a, CPLD<SPI, CS0, CS1, CS2>, SPI, CS0, CS1, CS2> {
		Parts::new(&self)
	}

	// Select Chip
	pub fn select_chip(&mut self, channel: u8) -> Result<(), Error<E>> {
		self.do_on_get_ref_mut_data(|mut dev| dev.select_chip(channel))
	}
}