use crate::pac::rcc::vals::{Hpre, Msirange, Pllsrc, Ppre, Sw};
use crate::pac::{FLASH, RCC};
use crate::rcc::{set_freqs, Clocks};
use crate::time::Hertz;
use crate::time::U32Ext;

/// HSI16 speed
pub const HSI16_FREQ: u32 = 16_000_000;

/// System clock mux source
#[derive(Clone, Copy)]
pub enum ClockSrc {
    MSI(MSIRange),
    PLL(PLLSource, PLLClkDiv, PLLSrcDiv, PLLMul, Option<PLL48Div>),
    HSE(Hertz),
    HSI16,
}

/// MSI Clock Range
///
/// These ranges control the frequency of the MSI. Internally, these ranges map
/// to the `MSIRANGE` bits in the `RCC_ICSCR` register.
#[derive(Clone, Copy)]
pub enum MSIRange {
    /// Around 100 kHz
    Range0,
    /// Around 200 kHz
    Range1,
    /// Around 400 kHz
    Range2,
    /// Around 800 kHz
    Range3,
    /// Around 1 MHz
    Range4,
    /// Around 2 MHz
    Range5,
    /// Around 4 MHz (reset value)
    Range6,
    /// Around 8 MHz
    Range7,
    /// Around 16 MHz
    Range8,
    /// Around 24 MHz
    Range9,
    /// Around 32 MHz
    Range10,
    /// Around 48 MHz
    Range11,
}

impl Default for MSIRange {
    fn default() -> MSIRange {
        MSIRange::Range6
    }
}

pub type PLL48Div = PLLClkDiv;

/// PLL divider
#[derive(Clone, Copy)]
pub enum PLLDiv {
    Div2,
    Div3,
    Div4,
}

/// AHB prescaler
#[derive(Clone, Copy, PartialEq)]
pub enum AHBPrescaler {
    NotDivided,
    Div2,
    Div4,
    Div8,
    Div16,
    Div64,
    Div128,
    Div256,
    Div512,
}

/// APB prescaler
#[derive(Clone, Copy)]
pub enum APBPrescaler {
    NotDivided,
    Div2,
    Div4,
    Div8,
    Div16,
}

/// PLL clock input source
#[derive(Clone, Copy)]
pub enum PLLSource {
    HSI16,
    HSE(Hertz),
}

seq_macro::seq!(N in 8..=86 {
    #[derive(Clone, Copy)]
    pub enum PLLMul {
        #(
            Mul#N,
        )*
    }

    impl From<PLLMul> for u8 {
        fn from(val: PLLMul) -> u8 {
            match val {
                #(
                    PLLMul::Mul#N => N,
                )*
            }
        }
    }

    impl PLLMul {
        pub fn to_mul(self) -> u32 {
            match self {
                #(
                    PLLMul::Mul#N => N,
                )*
            }
        }
    }
});

#[derive(Clone, Copy)]
pub enum PLLClkDiv {
    Div2,
    Div4,
    Div6,
    Div8,
}

impl PLLClkDiv {
    pub fn to_div(self) -> u32 {
        let val: u8 = self.into();
        (val as u32 + 1) * 2
    }
}

impl From<PLLClkDiv> for u8 {
    fn from(val: PLLClkDiv) -> u8 {
        match val {
            PLLClkDiv::Div2 => 0b00,
            PLLClkDiv::Div4 => 0b01,
            PLLClkDiv::Div6 => 0b10,
            PLLClkDiv::Div8 => 0b11,
        }
    }
}

#[derive(Clone, Copy)]
pub enum PLLSrcDiv {
    Div1,
    Div2,
    Div3,
    Div4,
    Div5,
    Div6,
    Div7,
    Div8,
}

impl PLLSrcDiv {
    pub fn to_div(self) -> u32 {
        let val: u8 = self.into();
        val as u32 + 1
    }
}

impl From<PLLSrcDiv> for u8 {
    fn from(val: PLLSrcDiv) -> u8 {
        match val {
            PLLSrcDiv::Div1 => 0b000,
            PLLSrcDiv::Div2 => 0b001,
            PLLSrcDiv::Div3 => 0b010,
            PLLSrcDiv::Div4 => 0b011,
            PLLSrcDiv::Div5 => 0b100,
            PLLSrcDiv::Div6 => 0b101,
            PLLSrcDiv::Div7 => 0b110,
            PLLSrcDiv::Div8 => 0b111,
        }
    }
}

impl From<PLLSource> for Pllsrc {
    fn from(val: PLLSource) -> Pllsrc {
        match val {
            PLLSource::HSI16 => Pllsrc::HSI16,
            PLLSource::HSE(_) => Pllsrc::HSE,
        }
    }
}

impl From<APBPrescaler> for Ppre {
    fn from(val: APBPrescaler) -> Ppre {
        match val {
            APBPrescaler::NotDivided => Ppre::DIV1,
            APBPrescaler::Div2 => Ppre::DIV2,
            APBPrescaler::Div4 => Ppre::DIV4,
            APBPrescaler::Div8 => Ppre::DIV8,
            APBPrescaler::Div16 => Ppre::DIV16,
        }
    }
}

impl From<AHBPrescaler> for Hpre {
    fn from(val: AHBPrescaler) -> Hpre {
        match val {
            AHBPrescaler::NotDivided => Hpre::DIV1,
            AHBPrescaler::Div2 => Hpre::DIV2,
            AHBPrescaler::Div4 => Hpre::DIV4,
            AHBPrescaler::Div8 => Hpre::DIV8,
            AHBPrescaler::Div16 => Hpre::DIV16,
            AHBPrescaler::Div64 => Hpre::DIV64,
            AHBPrescaler::Div128 => Hpre::DIV128,
            AHBPrescaler::Div256 => Hpre::DIV256,
            AHBPrescaler::Div512 => Hpre::DIV512,
        }
    }
}

impl From<MSIRange> for Msirange {
    fn from(val: MSIRange) -> Msirange {
        match val {
            MSIRange::Range0 => Msirange::RANGE100K,
            MSIRange::Range1 => Msirange::RANGE200K,
            MSIRange::Range2 => Msirange::RANGE400K,
            MSIRange::Range3 => Msirange::RANGE800K,
            MSIRange::Range4 => Msirange::RANGE1M,
            MSIRange::Range5 => Msirange::RANGE2M,
            MSIRange::Range6 => Msirange::RANGE4M,
            MSIRange::Range7 => Msirange::RANGE8M,
            MSIRange::Range8 => Msirange::RANGE16M,
            MSIRange::Range9 => Msirange::RANGE24M,
            MSIRange::Range10 => Msirange::RANGE32M,
            MSIRange::Range11 => Msirange::RANGE48M,
        }
    }
}

impl From<MSIRange> for u32 {
    fn from(val: MSIRange) -> u32 {
        match val {
            MSIRange::Range0 => 100_000,
            MSIRange::Range1 => 200_000,
            MSIRange::Range2 => 400_000,
            MSIRange::Range3 => 800_000,
            MSIRange::Range4 => 1_000_000,
            MSIRange::Range5 => 2_000_000,
            MSIRange::Range6 => 4_000_000,
            MSIRange::Range7 => 8_000_000,
            MSIRange::Range8 => 16_000_000,
            MSIRange::Range9 => 24_000_000,
            MSIRange::Range10 => 32_000_000,
            MSIRange::Range11 => 48_000_000,
        }
    }
}

/// Clocks configutation
pub struct Config {
    pub mux: ClockSrc,
    pub ahb_pre: AHBPrescaler,
    pub apb1_pre: APBPrescaler,
    pub apb2_pre: APBPrescaler,
}

impl Default for Config {
    #[inline]
    fn default() -> Config {
        Config {
            mux: ClockSrc::MSI(MSIRange::Range6),
            ahb_pre: AHBPrescaler::NotDivided,
            apb1_pre: APBPrescaler::NotDivided,
            apb2_pre: APBPrescaler::NotDivided,
        }
    }
}

pub(crate) unsafe fn init(config: Config) {
    let (sys_clk, sw) = match config.mux {
        ClockSrc::MSI(range) => {
            // Enable MSI
            RCC.cr().write(|w| {
                let bits: Msirange = range.into();
                w.set_msirange(bits);
                w.set_msipllen(false);
                w.set_msirgsel(true);
                w.set_msion(true);
            });
            while !RCC.cr().read().msirdy() {}

            // Enable as clock source for USB, RNG if running at 48 MHz
            if let MSIRange::Range11 = range {
                RCC.ccipr().modify(|w| {
                    w.set_clk48sel(0b11);
                });
            }
            (range.into(), Sw::MSI)
        }
        ClockSrc::HSI16 => {
            // Enable HSI16
            RCC.cr().write(|w| w.set_hsion(true));
            while !RCC.cr().read().hsirdy() {}

            (HSI16_FREQ, Sw::HSI16)
        }
        ClockSrc::HSE(freq) => {
            // Enable HSE
            RCC.cr().write(|w| w.set_hseon(true));
            while !RCC.cr().read().hserdy() {}

            (freq.0, Sw::HSE)
        }
        ClockSrc::PLL(src, div, prediv, mul, pll48div) => {
            let freq = match src {
                PLLSource::HSE(freq) => {
                    // Enable HSE
                    RCC.cr().write(|w| w.set_hseon(true));
                    while !RCC.cr().read().hserdy() {}
                    freq.0
                }
                PLLSource::HSI16 => {
                    // Enable HSI
                    RCC.cr().write(|w| w.set_hsion(true));
                    while !RCC.cr().read().hsirdy() {}
                    HSI16_FREQ
                }
            };

            // Disable PLL
            RCC.cr().modify(|w| w.set_pllon(false));
            while RCC.cr().read().pllrdy() {}

            let freq = (freq / prediv.to_div() * mul.to_mul()) / div.to_div();

            assert!(freq <= 80_000_000);

            RCC.pllcfgr().write(move |w| {
                w.set_plln(mul.into());
                w.set_pllm(prediv.into());
                w.set_pllr(div.into());
                if let Some(pll48div) = pll48div {
                    w.set_pllq(pll48div.into());
                    w.set_pllqen(true);
                }
                w.set_pllsrc(src.into());
            });

            // Enable as clock source for USB, RNG if PLL48 divisor is provided
            if pll48div.is_some() {
                RCC.ccipr().modify(|w| {
                    w.set_clk48sel(0b10);
                });
            }

            // Enable PLL
            RCC.cr().modify(|w| w.set_pllon(true));
            while !RCC.cr().read().pllrdy() {}
            RCC.pllcfgr().modify(|w| w.set_pllren(true));

            (freq, Sw::PLL)
        }
    };

    // Set flash wait states
    FLASH.acr().modify(|w| {
        w.set_latency(if sys_clk <= 16_000_000 {
            0b000
        } else if sys_clk <= 32_000_000 {
            0b001
        } else if sys_clk <= 48_000_000 {
            0b010
        } else if sys_clk <= 64_000_000 {
            0b011
        } else {
            0b100
        });
    });

    RCC.cfgr().modify(|w| {
        w.set_sw(sw);
        w.set_hpre(config.ahb_pre.into());
        w.set_ppre1(config.apb1_pre.into());
        w.set_ppre2(config.apb2_pre.into());
    });

    let ahb_freq: u32 = match config.ahb_pre {
        AHBPrescaler::NotDivided => sys_clk,
        pre => {
            let pre: Hpre = pre.into();
            let pre = 1 << (pre.0 as u32 - 7);
            sys_clk / pre
        }
    };

    let (apb1_freq, apb1_tim_freq) = match config.apb1_pre {
        APBPrescaler::NotDivided => (ahb_freq, ahb_freq),
        pre => {
            let pre: Ppre = pre.into();
            let pre: u8 = 1 << (pre.0 - 3);
            let freq = ahb_freq / pre as u32;
            (freq, freq * 2)
        }
    };

    let (apb2_freq, apb2_tim_freq) = match config.apb2_pre {
        APBPrescaler::NotDivided => (ahb_freq, ahb_freq),
        pre => {
            let pre: Ppre = pre.into();
            let pre: u8 = 1 << (pre.0 - 3);
            let freq = ahb_freq / (1 << (pre as u8 - 3));
            (freq, freq * 2)
        }
    };

    set_freqs(Clocks {
        sys: sys_clk.hz(),
        ahb1: ahb_freq.hz(),
        ahb2: ahb_freq.hz(),
        ahb3: ahb_freq.hz(),
        apb1: apb1_freq.hz(),
        apb2: apb2_freq.hz(),
        apb1_tim: apb1_tim_freq.hz(),
        apb2_tim: apb2_tim_freq.hz(),
    });
}