use crate::device::sys_timer::sleep;
use fugit::MegahertzU32;
use stm32f4xx_hal::{
    hal::{spi::SpiBus, digital::OutputPin},
    spi,
};

pub const SPI_MODE: spi::Mode = spi::Mode {
    polarity: spi::Polarity::IdleLow,
    phase: spi::Phase::CaptureOnFirstTransition,
};
// MAX5719 Max Frequency: 50MHz | SPI2 Max Frequency: 21MHz
pub const SPI_CLOCK_MHZ: MegahertzU32 = MegahertzU32::from_raw(21);

pub const MAX_VALUE: u32 = 0xFFFFF;

pub struct Dac<SPI: SpiBus<u8>, S1: OutputPin, S2:OutputPin> {
    spi: SPI,
    cs_n: S1,
    load_n: S2,
}

impl<SPI: SpiBus<u8>, S1: OutputPin, S2: OutputPin> Dac<SPI, S1, S2> {
    pub fn new(spi: SPI, mut cs_n: S1, mut load_n: S2) -> Self {
        let _ = cs_n.set_high();
        let _ = load_n.set_high();

        Dac { spi, cs_n, load_n}
    }

    fn write(&mut self, buf: &mut [u8]) -> Result<(), SPI::Error> {
        let _ = self.cs_n.set_low();
        self.spi.write(buf)?;
        let _ = self.cs_n.set_high();
        sleep(1);
        // must be high for >= 20 ns
        let _ = self.load_n.set_low();
        // must be low for >= 20 ns
        sleep(1);
        let _ = self.load_n.set_high();
        Ok(())
    }

    pub fn set(&mut self, value: u32) -> Result<u32, SPI::Error> {
        let value = value.min(MAX_VALUE) << 4;
        let mut buf = [
            ((value >> 16) & 0xFF) as u8,
            ((value >> 8) & 0xFF) as u8,
            ((value >> 0) & 0xFF) as u8,
        ];
        self.write(&mut buf)?;
        Ok(value)
    }
}