#![macro_use]

//! Provide access to the STM32 digital-to-analog converter (DAC).
use core::marker::PhantomData;

use embassy_hal_common::{into_ref, PeripheralRef};

use crate::dma::{Transfer, TransferOptions};
use crate::pac::dac;
use crate::rcc::RccPeripheral;
use crate::{peripherals, Peripheral};

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Curstom Errors
pub enum Error {
    UnconfiguredChannel,
    InvalidValue,
}

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// DAC Channels
pub enum Channel {
    Ch1,
    Ch2,
}

impl Channel {
    const fn index(&self) -> usize {
        match self {
            Channel::Ch1 => 0,
            Channel::Ch2 => 1,
        }
    }
}

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Trigger sources for CH1
pub enum Ch1Trigger {
    Tim6,
    Tim3,
    Tim7,
    Tim15,
    Tim2,
    Exti9,
    Software,
}

impl Ch1Trigger {
    fn tsel(&self) -> dac::vals::Tsel1 {
        match self {
            Ch1Trigger::Tim6 => dac::vals::Tsel1::TIM6_TRGO,
            Ch1Trigger::Tim3 => dac::vals::Tsel1::TIM3_TRGO,
            Ch1Trigger::Tim7 => dac::vals::Tsel1::TIM7_TRGO,
            Ch1Trigger::Tim15 => dac::vals::Tsel1::TIM15_TRGO,
            Ch1Trigger::Tim2 => dac::vals::Tsel1::TIM2_TRGO,
            Ch1Trigger::Exti9 => dac::vals::Tsel1::EXTI9,
            Ch1Trigger::Software => dac::vals::Tsel1::SOFTWARE,
        }
    }
}

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Trigger sources for CH2
pub enum Ch2Trigger {
    Tim6,
    Tim8,
    Tim7,
    Tim5,
    Tim2,
    Tim4,
    Exti9,
    Software,
}

impl Ch2Trigger {
    fn tsel(&self) -> dac::vals::Tsel2 {
        match self {
            Ch2Trigger::Tim6 => dac::vals::Tsel2::TIM6_TRGO,
            Ch2Trigger::Tim8 => dac::vals::Tsel2::TIM8_TRGO,
            Ch2Trigger::Tim7 => dac::vals::Tsel2::TIM7_TRGO,
            Ch2Trigger::Tim5 => dac::vals::Tsel2::TIM5_TRGO,
            Ch2Trigger::Tim2 => dac::vals::Tsel2::TIM2_TRGO,
            Ch2Trigger::Tim4 => dac::vals::Tsel2::TIM4_TRGO,
            Ch2Trigger::Exti9 => dac::vals::Tsel2::EXTI9,
            Ch2Trigger::Software => dac::vals::Tsel2::SOFTWARE,
        }
    }
}

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Single 8 or 12 bit value that can be output by the DAC
pub enum Value {
    // 8 bit value
    Bit8(u8),
    // 12 bit value stored in a u16, left-aligned
    Bit12Left(u16),
    // 12 bit value stored in a u16, right-aligned
    Bit12Right(u16),
}

#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Array variant of [`Value`]
pub enum ValueArray<'a> {
    // 8 bit values
    Bit8(&'a [u8]),
    // 12 bit value stored in a u16, left-aligned
    Bit12Left(&'a [u16]),
    // 12 bit values stored in a u16, right-aligned
    Bit12Right(&'a [u16]),
}
/// Provide common functions for DAC channels
pub trait DacChannel<T: Instance, Tx> {
    const CHANNEL: Channel;

    /// Enable trigger of the given channel
    fn set_trigger_enable(&mut self, on: bool) -> Result<(), Error> {
        T::regs().cr().modify(|reg| {
            reg.set_ten(Self::CHANNEL.index(), on);
        });
        Ok(())
    }

    /// Set mode register of the given channel
    fn set_channel_mode(&mut self, val: u8) -> Result<(), Error> {
        T::regs().mcr().modify(|reg| {
            reg.set_mode(Self::CHANNEL.index(), val);
        });
        Ok(())
    }

    /// Set enable register of the given channel
    fn set_channel_enable(&mut self, on: bool) -> Result<(), Error> {
        T::regs().cr().modify(|reg| {
            reg.set_en(Self::CHANNEL.index(), on);
        });
        Ok(())
    }

    /// Enable the DAC channel `ch`
    fn enable_channel(&mut self) -> Result<(), Error> {
        self.set_channel_enable(true)
    }

    /// Disable the DAC channel `ch`
    fn disable_channel(&mut self) -> Result<(), Error> {
        self.set_channel_enable(false)
    }

    /// Perform a software trigger on `ch`
    fn trigger(&mut self) -> Result<(), Error> {
        T::regs().swtrigr().write(|reg| {
            reg.set_swtrig(Self::CHANNEL.index(), true);
        });
        Ok(())
    }

    /// Set a value to be output by the DAC on trigger.
    ///
    /// The `value` is written to the corresponding "data holding register".
    fn set(&mut self, value: Value) -> Result<(), Error> {
        match value {
            Value::Bit8(v) => T::regs().dhr8r(Self::CHANNEL.index()).write(|reg| reg.set_dhr(v)),
            Value::Bit12Left(v) => T::regs().dhr12l(Self::CHANNEL.index()).write(|reg| reg.set_dhr(v)),
            Value::Bit12Right(v) => T::regs().dhr12r(Self::CHANNEL.index()).write(|reg| reg.set_dhr(v)),
        }
        Ok(())
    }

    /// Write `data` to the DAC channel via DMA.
    ///
    /// `circular` sets the DMA to circular mode.
    async fn write(&mut self, data: ValueArray<'_>, circular: bool) -> Result<(), Error>
    where
        Tx: Dma<T>;
}

/// Hold two DAC channels
///
/// Note: This consumes the DAC `Instance` only once, allowing to get both channels simultaneously.
///
/// # Example for obtaining both DAC channels
///
/// ```no_run
/// // DMA channels and pins may need to be changed for your controller
/// let (dac_ch1, dac_ch2) =
///     embassy_stm32::dac::Dac::new(p.DAC1, p.DMA1_CH3, p.DMA1_CH4, p.PA4, p.PA5).split();
/// ```
pub struct Dac<'d, T: Instance, TxCh1, TxCh2> {
    ch1: DacCh1<'d, T, TxCh1>,
    ch2: DacCh2<'d, T, TxCh2>,
}

/// DAC CH1
///
/// Note: This consumes the DAC `Instance`. Use [`Dac::new`] to get both channels simultaneously.
pub struct DacCh1<'d, T: Instance, Tx> {
    /// To consume T
    _peri: PeripheralRef<'d, T>,
    dma: PeripheralRef<'d, Tx>,
}

/// DAC CH2
///
/// Note: This consumes the DAC `Instance`. Use [`Dac::new`] to get both channels simultaneously.
pub struct DacCh2<'d, T: Instance, Tx> {
    /// Instead of PeripheralRef to consume T
    phantom: PhantomData<&'d mut T>,
    dma: PeripheralRef<'d, Tx>,
}

impl<'d, T: Instance, Tx> DacCh1<'d, T, Tx> {
    /// Obtain DAC CH1
    pub fn new(
        peri: impl Peripheral<P = T> + 'd,
        dma: impl Peripheral<P = Tx> + 'd,
        _pin: impl Peripheral<P = impl DacPin<T, 1>> + 'd,
    ) -> Self {
        into_ref!(peri, dma);
        T::enable();
        T::reset();

        let mut dac = Self { _peri: peri, dma };

        // Configure each activated channel. All results can be `unwrap`ed since they
        // will only error if the channel is not configured (i.e. ch1, ch2 are false)
        dac.set_channel_mode(0).unwrap();
        dac.enable_channel().unwrap();
        dac.set_trigger_enable(true).unwrap();

        dac
    }

    /// Select a new trigger for this channel
    pub fn select_trigger(&mut self, trigger: Ch1Trigger) -> Result<(), Error> {
        unwrap!(self.disable_channel());
        T::regs().cr().modify(|reg| {
            reg.set_tsel1(trigger.tsel());
        });
        Ok(())
    }
}

impl<'d, T: Instance, Tx> DacCh2<'d, T, Tx> {
    /// Obtain DAC CH2
    pub fn new(
        _peri: impl Peripheral<P = T> + 'd,
        dma: impl Peripheral<P = Tx> + 'd,
        _pin: impl Peripheral<P = impl DacPin<T, 2>> + 'd,
    ) -> Self {
        into_ref!(_peri, dma);
        T::enable();
        T::reset();

        let mut dac = Self {
            phantom: PhantomData,
            dma,
        };

        // Configure each activated channel. All results can be `unwrap`ed since they
        // will only error if the channel is not configured (i.e. ch1, ch2 are false)
        dac.set_channel_mode(0).unwrap();
        dac.enable_channel().unwrap();
        dac.set_trigger_enable(true).unwrap();

        dac
    }

    /// Select a new trigger for this channel
    pub fn select_trigger(&mut self, trigger: Ch2Trigger) -> Result<(), Error> {
        unwrap!(self.disable_channel());
        T::regs().cr().modify(|reg| {
            reg.set_tsel2(trigger.tsel());
        });
        Ok(())
    }
}

impl<'d, T: Instance, TxCh1, TxCh2> Dac<'d, T, TxCh1, TxCh2> {
    /// Create a new DAC instance with both channels.
    ///
    /// This is used to obtain two independent channels via `split()` for use e.g. with DMA.
    pub fn new(
        peri: impl Peripheral<P = T> + 'd,
        dma_ch1: impl Peripheral<P = TxCh1> + 'd,
        dma_ch2: impl Peripheral<P = TxCh2> + 'd,
        _pin_ch1: impl Peripheral<P = impl DacPin<T, 1>> + 'd,
        _pin_ch2: impl Peripheral<P = impl DacPin<T, 2>> + 'd,
    ) -> Self {
        into_ref!(peri, dma_ch1, dma_ch2);
        T::enable();
        T::reset();

        let mut dac_ch1 = DacCh1 {
            _peri: peri,
            dma: dma_ch1,
        };

        let mut dac_ch2 = DacCh2 {
            phantom: PhantomData,
            dma: dma_ch2,
        };

        // Configure each activated channel. All results can be `unwrap`ed since they
        // will only error if the channel is not configured (i.e. ch1, ch2 are false)
        dac_ch1.set_channel_mode(0).unwrap();
        dac_ch1.enable_channel().unwrap();
        dac_ch1.set_trigger_enable(true).unwrap();

        dac_ch2.set_channel_mode(0).unwrap();
        dac_ch2.enable_channel().unwrap();
        dac_ch2.set_trigger_enable(true).unwrap();

        Self {
            ch1: dac_ch1,
            ch2: dac_ch2,
        }
    }

    /// Split the DAC into CH1 and CH2 for independent use.
    pub fn split(self) -> (DacCh1<'d, T, TxCh1>, DacCh2<'d, T, TxCh2>) {
        (self.ch1, self.ch2)
    }

    /// Get mutable reference to CH1
    pub fn ch1_mut(&mut self) -> &mut DacCh1<'d, T, TxCh1> {
        &mut self.ch1
    }

    /// Get mutable reference to CH2
    pub fn ch2_mut(&mut self) -> &mut DacCh2<'d, T, TxCh2> {
        &mut self.ch2
    }

    /// Get reference to CH1
    pub fn ch1(&mut self) -> &DacCh1<'d, T, TxCh1> {
        &self.ch1
    }

    /// Get reference to CH2
    pub fn ch2(&mut self) -> &DacCh2<'d, T, TxCh2> {
        &self.ch2
    }
}

impl<'d, T: Instance, Tx> DacChannel<T, Tx> for DacCh1<'d, T, Tx> {
    const CHANNEL: Channel = Channel::Ch1;

    /// Write `data` to the DAC CH1 via DMA.
    ///
    /// To prevent delays/glitches when outputting a periodic waveform, the `circular` flag can be set.
    /// This will configure a circular DMA transfer that periodically outputs the `data`.
    /// Note that for performance reasons in circular mode the transfer complete interrupt is disabled.
    ///
    /// **Important:** Channel 1 has to be configured for the DAC instance!
    async fn write(&mut self, data: ValueArray<'_>, circular: bool) -> Result<(), Error>
    where
        Tx: Dma<T>,
    {
        write_inner(Self::CHANNEL, &self.dma, data, circular).await
    }
}

impl<'d, T: Instance, Tx> DacChannel<T, Tx> for DacCh2<'d, T, Tx> {
    const CHANNEL: Channel = Channel::Ch2;

    /// Write `data` to the DAC CH2 via DMA.
    ///
    /// To prevent delays/glitches when outputting a periodic waveform, the `circular` flag can be set.
    /// This will configure a circular DMA transfer that periodically outputs the `data`.
    /// Note that for performance reasons in circular mode the transfer complete interrupt is disabled.
    ///
    /// **Important:** Channel 2 has to be configured for the DAC instance!
    async fn write(&mut self, data: ValueArray<'_>, circular: bool) -> Result<(), Error>
    where
        Tx: Dma<T>,
    {
        write_inner(Self::CHANNEL, &self.dma, data, circular).await
    }
}

/// Shared utility function to perform the actual DMA config and write.
async fn write_inner<T: Instance, Tx>(
    ch: Channel,
    dma: &PeripheralRef<'_, Tx>,
    data: ValueArray<'_>,
    circular: bool,
) -> Result<(), Error>
where
    Tx: Dma<T>,
{
    let channel = ch.index();
    debug!("Writing to channel {}", channel);

    // Enable DAC and DMA
    T::regs().cr().modify(|w| {
        w.set_en(channel, true);
        w.set_dmaen(channel, true);
    });

    let tx_request = dma.request();
    let dma_channel = dma;

    // Initiate the correct type of DMA transfer depending on what data is passed
    let tx_f = match data {
        ValueArray::Bit8(buf) => unsafe {
            Transfer::new_write(
                dma_channel,
                tx_request,
                buf,
                T::regs().dhr8r(channel).as_ptr() as *mut u8,
                TransferOptions {
                    circular,
                    half_transfer_ir: false,
                    complete_transfer_ir: !circular,
                },
            )
        },
        ValueArray::Bit12Left(buf) => unsafe {
            Transfer::new_write(
                dma_channel,
                tx_request,
                buf,
                T::regs().dhr12l(channel).as_ptr() as *mut u16,
                TransferOptions {
                    circular,
                    half_transfer_ir: false,
                    complete_transfer_ir: !circular,
                },
            )
        },
        ValueArray::Bit12Right(buf) => unsafe {
            Transfer::new_write(
                dma_channel,
                tx_request,
                buf,
                T::regs().dhr12r(channel).as_ptr() as *mut u16,
                TransferOptions {
                    circular,
                    half_transfer_ir: false,
                    complete_transfer_ir: !circular,
                },
            )
        },
    };

    tx_f.await;

    // finish dma
    // TODO: Do we need to check any status registers here?
    T::regs().cr().modify(|w| {
        // Disable the DAC peripheral
        w.set_en(channel, false);
        // Disable the DMA. TODO: Is this necessary?
        w.set_dmaen(channel, false);
    });

    Ok(())
}

pub(crate) mod sealed {
    pub trait Instance {
        fn regs() -> &'static crate::pac::dac::Dac;
    }
}

pub trait Instance: sealed::Instance + RccPeripheral + 'static {}
dma_trait!(Dma, Instance);

/// Marks a pin that can be used with the DAC
pub trait DacPin<T: Instance, const C: u8>: crate::gpio::Pin + 'static {}

foreach_peripheral!(
    (dac, $inst:ident) => {
        // H7 uses single bit for both DAC1 and DAC2, this is a hack until a proper fix is implemented
        #[cfg(rcc_h7)]
        impl crate::rcc::sealed::RccPeripheral for peripherals::$inst {
            fn frequency() -> crate::time::Hertz {
                critical_section::with(|_| unsafe {
                    crate::rcc::get_freqs().apb1
                })
            }

            fn reset() {
                critical_section::with(|_| unsafe {
                    crate::pac::RCC.apb1lrstr().modify(|w| w.set_dac12rst(true));
                    crate::pac::RCC.apb1lrstr().modify(|w| w.set_dac12rst(false));
                })
            }

            fn enable() {
                critical_section::with(|_| unsafe {
                    crate::pac::RCC.apb1lenr().modify(|w| w.set_dac12en(true));
                })
            }

            fn disable() {
                critical_section::with(|_| unsafe {
                    crate::pac::RCC.apb1lenr().modify(|w| w.set_dac12en(false));
                })
            }
        }

        #[cfg(rcc_h7)]
        impl crate::rcc::RccPeripheral for peripherals::$inst {}

        impl crate::dac::sealed::Instance for peripherals::$inst {
            fn regs() -> &'static crate::pac::dac::Dac {
                &crate::pac::$inst
            }
        }

        impl crate::dac::Instance for peripherals::$inst {}
    };
);

macro_rules! impl_dac_pin {
    ($inst:ident, $pin:ident, $ch:expr) => {
        impl crate::dac::DacPin<peripherals::$inst, $ch> for crate::peripherals::$pin {}
    };
}