#[allow(dead_code)]
#[derive(Clone, Copy)]
pub enum LseCfg {
    Oscillator(LseDrive),
    Bypass,
}

impl Default for LseCfg {
    fn default() -> Self {
        Self::Oscillator(Default::default())
    }
}

#[allow(dead_code)]
#[derive(Default, Clone, Copy)]
pub enum LseDrive {
    Low = 0,
    MediumLow = 0x01,
    #[default]
    MediumHigh = 0x02,
    High = 0x03,
}

// All families but these have the LSEDRV register
#[cfg(not(any(rcc_f1, rcc_f1cl, rcc_f100, rcc_f2, rcc_f4, rcc_f400, rcc_f410, rcc_l1)))]
impl From<LseDrive> for crate::pac::rcc::vals::Lsedrv {
    fn from(value: LseDrive) -> Self {
        use crate::pac::rcc::vals::Lsedrv;

        match value {
            LseDrive::Low => Lsedrv::LOW,
            LseDrive::MediumLow => Lsedrv::MEDIUMLOW,
            LseDrive::MediumHigh => Lsedrv::MEDIUMHIGH,
            LseDrive::High => Lsedrv::HIGH,
        }
    }
}

pub use crate::pac::rcc::vals::Rtcsel as RtcClockSource;

#[cfg(not(any(rtc_v2l0, rtc_v2l1, stm32c0)))]
#[allow(dead_code)]
type Bdcr = crate::pac::rcc::regs::Bdcr;

#[cfg(any(rtc_v2l0, rtc_v2l1))]
#[allow(dead_code)]
type Bdcr = crate::pac::rcc::regs::Csr;

#[allow(dead_code)]
pub struct BackupDomain {}

impl BackupDomain {
    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb, rtc_v3,
        rtc_v3u5
    ))]
    #[allow(dead_code, unused_variables)]
    fn modify<R>(f: impl FnOnce(&mut Bdcr) -> R) -> R {
        #[cfg(any(rtc_v2f2, rtc_v2f3, rtc_v2l1, rtc_v2l0))]
        let cr = crate::pac::PWR.cr();
        #[cfg(any(rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
        let cr = crate::pac::PWR.cr1();

        // TODO: Missing from PAC for l0 and f0?
        #[cfg(not(any(rtc_v2f0, rtc_v3u5)))]
        {
            cr.modify(|w| w.set_dbp(true));
            while !cr.read().dbp() {}
        }

        #[cfg(any(rtc_v2l0, rtc_v2l1))]
        let cr = crate::pac::RCC.csr();

        #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
        let cr = crate::pac::RCC.bdcr();

        cr.modify(|w| f(w))
    }

    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb, rtc_v3,
        rtc_v3u5
    ))]
    #[allow(dead_code)]
    fn read() -> Bdcr {
        #[cfg(any(rtc_v2l0, rtc_v2l1))]
        let r = crate::pac::RCC.csr().read();

        #[cfg(not(any(rtc_v2l0, rtc_v2l1)))]
        let r = crate::pac::RCC.bdcr().read();

        r
    }

    #[cfg(any(
        rtc_v2f0, rtc_v2f2, rtc_v2f3, rtc_v2f4, rtc_v2f7, rtc_v2h7, rtc_v2l0, rtc_v2l1, rtc_v2l4, rtc_v2wb, rtc_v3,
        rtc_v3u5
    ))]
    #[allow(dead_code, unused_variables)]
    pub fn configure_ls(clock_source: RtcClockSource, lsi: bool, lse: Option<LseCfg>) {
        use atomic_polyfill::{compiler_fence, Ordering};

        match clock_source {
            RtcClockSource::LSI => assert!(lsi),
            RtcClockSource::LSE => assert!(lse.is_some()),
            _ => {}
        };
        let (lse_en, lse_byp, lse_drv) = match lse {
            Some(LseCfg::Oscillator(lse_drv)) => (true, false, Some(lse_drv)),
            Some(LseCfg::Bypass) => (true, true, None),
            None => (false, false, None),
        };

        if lsi {
            #[cfg(rtc_v3u5)]
            let csr = crate::pac::RCC.bdcr();

            #[cfg(not(rtc_v3u5))]
            let csr = crate::pac::RCC.csr();

            // Disable backup domain write protection
            Self::modify(|_| {});

            #[cfg(not(any(rcc_wb, rcc_wba)))]
            csr.modify(|w| w.set_lsion(true));

            #[cfg(any(rcc_wb, rcc_wba))]
            csr.modify(|w| w.set_lsi1on(true));

            #[cfg(not(any(rcc_wb, rcc_wba)))]
            while !csr.read().lsirdy() {}

            #[cfg(any(rcc_wb, rcc_wba))]
            while !csr.read().lsi1rdy() {}
        }

        // backup domain configuration (LSEON, RTCEN, RTCSEL) is kept across resets.
        // once set, changing it requires a backup domain reset.
        // first check if the configuration matches what we want.

        // check if it's already enabled and in the source we want.
        let reg = Self::read();
        let mut ok = true;
        ok &= reg.rtcsel() == clock_source;
        #[cfg(not(rcc_wba))]
        {
            ok &= reg.rtcen() == (clock_source != RtcClockSource::NOCLOCK);
        }
        ok &= reg.lseon() == lse_en;
        ok &= reg.lsebyp() == lse_byp;
        #[cfg(not(any(rcc_f1, rcc_f1cl, rcc_f100, rcc_f2, rcc_f4, rcc_f400, rcc_f410, rcc_l1)))]
        if let Some(lse_drv) = lse_drv {
            ok &= reg.lsedrv() == lse_drv.into();
        }

        // if configuration is OK, we're done.
        if ok {
            // RTC code assumes backup domain is unlocked
            Self::modify(|w| {});

            trace!("BDCR ok: {:08x}", Self::read().0);
            return;
        }

        // If not OK, reset backup domain and configure it.
        #[cfg(not(any(rcc_l0, rcc_l1)))]
        {
            Self::modify(|w| w.set_bdrst(true));
            Self::modify(|w| w.set_bdrst(false));
        }

        if lse_en {
            Self::modify(|w| {
                #[cfg(not(any(rcc_f1, rcc_f1cl, rcc_f100, rcc_f2, rcc_f4, rcc_f400, rcc_f410, rcc_l1)))]
                if let Some(lse_drv) = lse_drv {
                    w.set_lsedrv(lse_drv.into());
                }
                w.set_lsebyp(lse_byp);
                w.set_lseon(true);
            });

            while !Self::read().lserdy() {}
        }

        if clock_source != RtcClockSource::NOCLOCK {
            Self::modify(|w| {
                #[cfg(any(rtc_v2h7, rtc_v2l4, rtc_v2wb, rtc_v3, rtc_v3u5))]
                assert!(!w.lsecsson(), "RTC is not compatible with LSE CSS, yet.");

                #[cfg(not(rcc_wba))]
                w.set_rtcen(true);
                w.set_rtcsel(clock_source);
            });
        }

        trace!("BDCR configured: {:08x}", Self::read().0);

        compiler_fence(Ordering::SeqCst);
    }
}