use core::marker::PhantomData;
use core::ops::Deref;
use core::ptr;

use crate::dma::traits::PeriAddress;
use crate::gpio::{Const, NoPin, PinA, PushPull, SetAlternate};

/// Clock polarity
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Polarity {
    /// Clock signal low when idle
    IdleLow,
    /// Clock signal high when idle
    IdleHigh,
}

/// Clock phase
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Phase {
    /// Data in "captured" on the first clock transition
    CaptureOnFirstTransition,
    /// Data in "captured" on the second clock transition
    CaptureOnSecondTransition,
}

/// SPI mode
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct Mode {
    /// Clock polarity
    pub polarity: Polarity,
    /// Clock phase
    pub phase: Phase,
}

mod hal_02;

use crate::pac::{spi1, RCC, SPI1, SPI2};
use crate::rcc;

#[cfg(feature = "spi3")]
use crate::pac::SPI3;

#[cfg(feature = "spi4")]
use crate::pac::SPI4;

#[cfg(feature = "spi5")]
use crate::pac::SPI5;

#[cfg(feature = "spi6")]
use crate::pac::SPI6;

use crate::rcc::Clocks;
use crate::time::Hertz;

/// SPI error
#[non_exhaustive]
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
pub enum Error {
    /// Overrun occurred
    Overrun,
    /// Mode fault occurred
    ModeFault,
    /// CRC error
    Crc,
}

pub struct Sck;
impl crate::Sealed for Sck {}
pub struct Miso;
impl crate::Sealed for Miso {}
pub struct Mosi;
impl crate::Sealed for Mosi {}
pub struct Nss;
impl crate::Sealed for Nss {}

pub trait Pins<SPI> {
    fn set_alt_mode(&mut self);
    fn restore_mode(&mut self);
}

impl<SPI, SCK, MISO, MOSI, const SCKA: u8, const MISOA: u8, const MOSIA: u8> Pins<SPI>
    for (SCK, MISO, MOSI)
where
    SCK: PinA<Sck, SPI, A = Const<SCKA>> + SetAlternate<PushPull, SCKA>,
    MISO: PinA<Miso, SPI, A = Const<MISOA>> + SetAlternate<PushPull, MISOA>,
    MOSI: PinA<Mosi, SPI, A = Const<MOSIA>> + SetAlternate<PushPull, MOSIA>,
{
    fn set_alt_mode(&mut self) {
        self.0.set_alt_mode();
        self.1.set_alt_mode();
        self.2.set_alt_mode();
    }
    fn restore_mode(&mut self) {
        self.0.restore_mode();
        self.1.restore_mode();
        self.2.restore_mode();
    }
}

/// A filler type for when the SCK pin is unnecessary
pub type NoSck = NoPin;
/// A filler type for when the Miso pin is unnecessary
pub type NoMiso = NoPin;
/// A filler type for when the Mosi pin is unnecessary
pub type NoMosi = NoPin;

/// Interrupt events
pub enum Event {
    /// New data has been received
    Rxne,
    /// Data can be sent
    Txe,
    /// An error occurred
    Error,
}

/// Normal mode - RX and TX pins are independent
pub struct TransferModeNormal;
/// BIDI mode - use TX pin as RX then spi receive data
pub struct TransferModeBidi;

#[derive(Debug)]
pub struct Spi<SPI, PINS, TRANSFER_MODE> {
    spi: SPI,
    pins: PINS,
    _transfer_mode: PhantomData<TRANSFER_MODE>,
}

// Implemented by all SPI instances
pub trait Instance:
    crate::Sealed + Deref<Target = spi1::RegisterBlock> + rcc::Enable + rcc::Reset + rcc::BusClock
{
    #[doc(hidden)]
    fn ptr() -> *const spi1::RegisterBlock;
}

// Implemented by all SPI instances
macro_rules! spi {
    ($SPI:ident: ($spi:ident)) => {
        impl Instance for $SPI {
            fn ptr() -> *const spi1::RegisterBlock {
                <$SPI>::ptr() as *const _
            }
        }
    };
}

spi! { SPI1: (spi1) }
spi! { SPI2: (spi2) }

#[cfg(feature = "spi3")]
spi! { SPI3: (spi3) }

#[cfg(feature = "spi4")]
spi! { SPI4: (spi4) }

#[cfg(feature = "spi5")]
spi! { SPI5: (spi5) }

#[cfg(feature = "spi6")]
spi! { SPI6: (spi6) }

impl<SPI, PINS> Spi<SPI, PINS, TransferModeNormal>
where
    SPI: Instance,
    PINS: Pins<SPI>,
{
    pub fn new(
        spi: SPI,
        mut pins: PINS,
        mode: impl Into<Mode>,
        freq: impl Into<Hertz>,
        clocks: &Clocks,
    ) -> Self {
        unsafe {
            // NOTE(unsafe) this reference will only be used for atomic writes with no side effects.
            let rcc = &(*RCC::ptr());
            SPI::enable(rcc);
            SPI::reset(rcc);
        }

        pins.set_alt_mode();

        Self::_new(spi, pins)
            .pre_init(mode.into(), freq.into(), SPI::clock(clocks))
            .init()
    }

    pub fn to_bidi_transfer_mode(self) -> Spi<SPI, PINS, TransferModeBidi> {
        let mut dev_w_new_t_mode = self.into_mode::<TransferModeBidi>();
        dev_w_new_t_mode.enable(false);
        dev_w_new_t_mode.init()
    }
}

impl<SPI, PINS> Spi<SPI, PINS, TransferModeBidi>
where
    SPI: Instance,
    PINS: Pins<SPI>,
{
    pub fn new_bidi(
        spi: SPI,
        mut pins: PINS,
        mode: impl Into<Mode>,
        freq: impl Into<Hertz>,
        clocks: &Clocks,
    ) -> Self {
        unsafe {
            // NOTE(unsafe) this reference will only be used for atomic writes with no side effects.
            let rcc = &(*RCC::ptr());
            SPI::enable(rcc);
            SPI::reset(rcc);
        }

        pins.set_alt_mode();

        Self::_new(spi, pins)
            .pre_init(mode.into(), freq.into(), SPI::clock(clocks))
            .init()
    }

    pub fn to_normal_transfer_mode(self) -> Spi<SPI, PINS, TransferModeNormal> {
        let mut dev_w_new_t_mode = self.into_mode::<TransferModeNormal>();
        dev_w_new_t_mode.enable(false);
        dev_w_new_t_mode.init()
    }
}

impl<SPI, PINS, TRANSFER_MODE> Spi<SPI, PINS, TRANSFER_MODE>
where
    SPI: Instance,
    PINS: Pins<SPI>,
{
    pub fn release(mut self) -> (SPI, PINS) {
        self.pins.restore_mode();

        (self.spi, self.pins)
    }
}

impl<SPI, PINS> Spi<SPI, PINS, TransferModeNormal>
where
    SPI: Instance,
{
    pub fn init(self) -> Self {
        self.spi.cr1.modify(|_, w| {
            // bidimode: 2-line unidirectional
            w.bidimode()
                .clear_bit()
                .bidioe()
                .clear_bit()
                // spe: enable the SPI bus
                .spe()
                .set_bit()
        });

        self
    }
}

impl<SPI, PINS> Spi<SPI, PINS, TransferModeBidi>
where
    SPI: Instance,
{
    pub fn init(self) -> Self {
        self.spi.cr1.modify(|_, w| {
            // bidimode: 1-line unidirectional
            w.bidimode()
                .set_bit()
                .bidioe()
                .set_bit()
                // spe: enable the SPI bus
                .spe()
                .set_bit()
        });

        self
    }
}

impl<SPI, PINS, TRANSFER_MODE> Spi<SPI, PINS, TRANSFER_MODE>
where
    SPI: Instance,
{
    fn _new(spi: SPI, pins: PINS) -> Self {
        Self {
            spi,
            pins,
            _transfer_mode: PhantomData,
        }
    }

    /// Convert the spi to another transfer mode.
    fn into_mode<TRANSFER_MODE2>(self) -> Spi<SPI, PINS, TRANSFER_MODE2> {
        Spi::_new(self.spi, self.pins)
    }

    /// Enable/disable spi
    pub fn enable(&mut self, enable: bool) {
        self.spi.cr1.modify(|_, w| {
            // spe: enable the SPI bus
            w.spe().bit(enable)
        });
    }

    /// Pre initializing the SPI bus.
    fn pre_init(self, mode: Mode, freq: Hertz, clock: Hertz) -> Self {
        // disable SS output
        self.spi.cr2.write(|w| w.ssoe().clear_bit());

        let br = match clock.0 / freq.0 {
            0 => unreachable!(),
            1..=2 => 0b000,
            3..=5 => 0b001,
            6..=11 => 0b010,
            12..=23 => 0b011,
            24..=47 => 0b100,
            48..=95 => 0b101,
            96..=191 => 0b110,
            _ => 0b111,
        };

        self.spi.cr1.write(|w| {
            w.cpha()
                .bit(mode.phase == Phase::CaptureOnSecondTransition)
                .cpol()
                .bit(mode.polarity == Polarity::IdleHigh)
                // mstr: master configuration
                .mstr()
                .set_bit()
                .br()
                .bits(br)
                // lsbfirst: MSB first
                .lsbfirst()
                .clear_bit()
                // ssm: enable software slave management (NSS pin free for other uses)
                .ssm()
                .set_bit()
                // ssi: set nss high = master mode
                .ssi()
                .set_bit()
                .rxonly()
                .clear_bit()
                // dff: 8 bit frames
                .dff()
                .clear_bit()
        });

        self
    }

    /// Enable interrupts for the given `event`:
    ///  - Received data ready to be read (RXNE)
    ///  - Transmit data register empty (TXE)
    ///  - Transfer error
    pub fn listen(&mut self, event: Event) {
        match event {
            Event::Rxne => self.spi.cr2.modify(|_, w| w.rxneie().set_bit()),
            Event::Txe => self.spi.cr2.modify(|_, w| w.txeie().set_bit()),
            Event::Error => self.spi.cr2.modify(|_, w| w.errie().set_bit()),
        }
    }

    /// Disable interrupts for the given `event`:
    ///  - Received data ready to be read (RXNE)
    ///  - Transmit data register empty (TXE)
    ///  - Transfer error
    pub fn unlisten(&mut self, event: Event) {
        match event {
            Event::Rxne => self.spi.cr2.modify(|_, w| w.rxneie().clear_bit()),
            Event::Txe => self.spi.cr2.modify(|_, w| w.txeie().clear_bit()),
            Event::Error => self.spi.cr2.modify(|_, w| w.errie().clear_bit()),
        }
    }

    /// Return `true` if the TXE flag is set, i.e. new data to transmit
    /// can be written to the SPI.
    pub fn is_txe(&self) -> bool {
        self.spi.sr.read().txe().bit_is_set()
    }

    /// Return `true` if the RXNE flag is set, i.e. new data has been received
    /// and can be read from the SPI.
    pub fn is_rxne(&self) -> bool {
        self.spi.sr.read().rxne().bit_is_set()
    }

    /// Return `true` if the MODF flag is set, i.e. the SPI has experienced a
    /// Master Mode Fault. (see chapter 28.3.10 of the STM32F4 Reference Manual)
    pub fn is_modf(&self) -> bool {
        self.spi.sr.read().modf().bit_is_set()
    }

    /// Return `true` if the OVR flag is set, i.e. new data has been received
    /// while the receive data register was already filled.
    pub fn is_ovr(&self) -> bool {
        self.spi.sr.read().ovr().bit_is_set()
    }

    pub fn use_dma(self) -> DmaBuilder<SPI> {
        DmaBuilder { spi: self.spi }
    }

    #[inline(always)]
    fn check_read(&mut self) -> nb::Result<u8, Error> {
        let sr = self.spi.sr.read();

        Err(if sr.ovr().bit_is_set() {
            Error::Overrun.into()
        } else if sr.modf().bit_is_set() {
            Error::ModeFault.into()
        } else if sr.crcerr().bit_is_set() {
            Error::Crc.into()
        } else if sr.rxne().bit_is_set() {
            return Ok(self.read_u8());
        } else {
            nb::Error::WouldBlock
        })
    }

    #[inline(always)]
    fn check_send(&mut self, byte: u8) -> nb::Result<(), Error> {
        let sr = self.spi.sr.read();

        Err(if sr.ovr().bit_is_set() {
            // Read from the DR to clear the OVR bit
            let _ = self.spi.dr.read();
            Error::Overrun.into()
        } else if sr.modf().bit_is_set() {
            // Write to CR1 to clear MODF
            self.spi.cr1.modify(|_r, w| w);
            Error::ModeFault.into()
        } else if sr.crcerr().bit_is_set() {
            // Clear the CRCERR bit
            self.spi.sr.modify(|_r, w| {
                w.crcerr().clear_bit();
                w
            });
            Error::Crc.into()
        } else if sr.txe().bit_is_set() {
            self.send_u8(byte);
            return Ok(());
        } else {
            nb::Error::WouldBlock
        })
    }

    #[inline(always)]
    fn read_u8(&mut self) -> u8 {
        // NOTE(read_volatile) read only 1 byte (the svd2rust API only allows reading a half-word)
        unsafe { ptr::read_volatile(&self.spi.dr as *const _ as *const u8) }
    }

    #[inline(always)]
    fn send_u8(&mut self, byte: u8) {
        // NOTE(write_volatile) see note above
        unsafe { ptr::write_volatile(&self.spi.dr as *const _ as *mut u8, byte) }
    }
}

pub struct DmaBuilder<SPI> {
    spi: SPI,
}

pub struct Tx<SPI> {
    spi: PhantomData<SPI>,
}

pub struct Rx<SPI> {
    spi: PhantomData<SPI>,
}

impl<SPI> DmaBuilder<SPI>
where
    SPI: Instance,
{
    pub fn tx(self) -> Tx<SPI> {
        self.new_tx()
    }

    pub fn rx(self) -> Rx<SPI> {
        self.new_rx()
    }

    pub fn txrx(self) -> (Tx<SPI>, Rx<SPI>) {
        (self.new_tx(), self.new_rx())
    }

    fn new_tx(&self) -> Tx<SPI> {
        self.spi.cr2.modify(|_, w| w.txdmaen().enabled());
        Tx { spi: PhantomData }
    }

    fn new_rx(self) -> Rx<SPI> {
        self.spi.cr2.modify(|_, w| w.rxdmaen().enabled());
        Rx { spi: PhantomData }
    }
}

unsafe impl<SPI> PeriAddress for Rx<SPI>
where
    SPI: Instance,
{
    #[inline(always)]
    fn address(&self) -> u32 {
        unsafe { &(*SPI::ptr()).dr as *const _ as u32 }
    }

    type MemSize = u8;
}

unsafe impl<SPI> PeriAddress for Tx<SPI>
where
    SPI: Instance,
{
    #[inline(always)]
    fn address(&self) -> u32 {
        unsafe { &(*SPI::ptr()).dr as *const _ as u32 }
    }

    type MemSize = u8;
}