use std::convert::TryFrom;
use std::fmt;

#[repr(packed)]
#[derive(Copy, Clone, Default, Eq, PartialEq)]
pub struct Register {
    page: u8,
    offset: u8,
    value: u8,
}

impl Register {
    fn new(address: Address, value: u8) -> Register {
        Register {
            page: address.address().0,
            offset: address.address().1,
            value,
        }
    }

    pub fn decode_raw<'a>(
        page: u8,
        base_offset: u8,
        values: &'a [u8],
    ) -> impl Iterator<Item = Register> + 'a {
        values
            .iter()
            .enumerate()
            .filter_map(move |(offset, value)| {
                Address::try_from((page, base_offset + offset as u8))
                    .map(|a| Register::new(a, *value))
                    .ok()
            })
    }

    pub fn page(self) -> u8 {
        self.page
    }

    pub fn same_address(self, other: Register) -> bool {
        self.page == other.page && self.offset == other.offset
    }

    // Default value: 320x240
    pub fn resolution(resolution: Resolution) -> Register {
        Register::new(Resolution, resolution as u8)
    }

    // default 200µs, max 600µs
    pub fn exposure_us(exposure: u32) -> [Register; 2] {
        let raw_exposure = exposure * 31200 / 1000;
        [
            Register::new(ExposureLSB, (raw_exposure & 0xff) as u8),
            Register::new(ExposureMSB, (raw_exposure >> 8) as u8),
        ]
    }

    // default: Manual
    pub fn exposure_mode(mode: ExposureMode) -> Register {
        Register::new(ExposureMode, mode as u8)
    }

    // TODO default 0x10 0x0
    pub fn digital_gain(gain: u16) -> [Register; 2] {
        // todo: check
        [
            Register::new(DigitalGainLSB, ((gain & 0x0f) << 4) as u8),
            Register::new(DigitalGainMSB, ((gain & 0xf0) >> 4) as u8),
        ]
    }

    // default value: 0x10 TODO
    pub fn ir_leds(leds: Leds) -> Register {
        Register::new(IRLeds, leds.0)
    }

    // default value: X1
    pub fn external_light_filter(filter: ExternalLightFilter) -> Register {
        Register::new(ExternalLightFilter, filter as u8)
    }

    // default value: 0xc8
    pub fn white_pixel_threshold(threshold: u8) -> Register {
        Register::new(WhitePixelThreshold, threshold)
    }

    // default: 0, 0xe, 1, 1
    pub fn leds_intensity(far: u8, near: u8) -> [Register; 2] {
        assert_eq!(0, (far | near) & 0xf0);
        [
            Register::new(IntensityLedsFar12, far),
            Register::new(IntensityLedsNear34, near),
        ]
    }

    // default: Normal
    pub fn flip(side: Flip) -> Register {
        Register::new(Flip, side as u8)
    }

    // default : enabled
    pub fn denoise(enabled: bool) -> Register {
        Register::new(Denoise, enabled as u8)
    }

    /// default: 0x23
    pub fn edge_smoothing_threshold(threshold: u8) -> Register {
        Register::new(EdgeSmoothingThreshold, threshold)
    }

    // Default: 0x44
    pub fn color_interpolation_threshold(threshold: u8) -> Register {
        Register::new(ColorInterpolationThreshold, threshold)
    }

    // Default value: 0x32
    pub fn buffer_update_time(time: u8) -> Register {
        Register::new(BufferUpdateTimeLSB, time)
    }

    pub fn finish() -> Register {
        Register::new(Finish, 1)
    }
}

impl fmt::Debug for Register {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let mut out = f.debug_struct("ir::Register");
        match Address::try_from((self.page, self.offset)) {
            Ok(a) => out.field("name", &a),
            Err(_) => out.field(
                "address",
                &format_args!("0x{:x?}:0x{:x?}", self.page, self.offset),
            ),
        };
        out.field("value", &format_args!("0x{:x?}", self.value));
        out.finish()
    }
}

#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum Address {
    Resolution,
    DigitalGainLSB,
    DigitalGainMSB,
    ExposureLSB,
    ExposureMSB,
    ExposureMode,
    ExternalLightFilter,
    WhitePixelThreshold,
    IntensityLedsFar12,
    IntensityLedsNear34,
    Flip,
    Denoise,
    EdgeSmoothingThreshold,
    ColorInterpolationThreshold,
    BufferUpdateTimeLSB,
    IRLeds,
    Finish,
}
use Address::*;

impl Address {
    /// page + offset
    fn address(self) -> (u8, u8) {
        match self {
            BufferUpdateTimeLSB => (0, 0x04),
            Finish => (0, 0x07),
            ExternalLightFilter => (0, 0x0e),
            IRLeds => (0, 0x10),
            IntensityLedsFar12 => (0, 0x11),
            IntensityLedsNear34 => (0, 0x12),
            Flip => (0, 0x2d),
            Resolution => (0, 0x2e),
            DigitalGainLSB => (1, 0x2e),
            DigitalGainMSB => (1, 0x2f),
            ExposureLSB => (1, 0x30),
            ExposureMSB => (1, 0x31),
            ExposureMode => (1, 0x32),
            WhitePixelThreshold => (1, 0x43),
            Denoise => (1, 0x67),
            EdgeSmoothingThreshold => (1, 0x68),
            ColorInterpolationThreshold => (1, 0x69),
        }
    }
}
const ALL_ADDRESSES: &[Address] = &[
    Resolution,
    DigitalGainLSB,
    DigitalGainMSB,
    ExposureLSB,
    ExposureMSB,
    ExposureMode,
    ExternalLightFilter,
    WhitePixelThreshold,
    IntensityLedsFar12,
    IntensityLedsNear34,
    Flip,
    Denoise,
    EdgeSmoothingThreshold,
    ColorInterpolationThreshold,
    BufferUpdateTimeLSB,
    IRLeds,
    Finish,
];

impl TryFrom<(u8, u8)> for Address {
    type Error = ();

    fn try_from(raw: (u8, u8)) -> Result<Address, ()> {
        for address in ALL_ADDRESSES {
            if address.address() == raw {
                return Ok(*address);
            }
        }
        Err(())
    }
}

#[repr(u8)]
#[derive(Copy, Clone, Debug, Eq, PartialEq, FromPrimitive, ToPrimitive)]
pub enum Resolution {
    /// Full pixel array
    R320x240 = 0b0000_0000,
    /// Sensor Binning [2 X 2]
    R160x120 = 0b0101_0000,
    /// Sensor Binning [4 x 2] and Skipping [1 x 2]
    R80x60 = 0b0110_0100,
    /// Sensor Binning [4 x 2] and Skipping [2 x 4]
    R40x30 = 0b0110_1001,
}

impl Resolution {
    pub fn max_fragment_id(self) -> u8 {
        match self {
            Resolution::R320x240 => 0xff,
            Resolution::R160x120 => 0x3f,
            Resolution::R80x60 => 0x0f,
            Resolution::R40x30 => 0x03,
        }
    }

    pub fn size(self) -> (u32, u32) {
        match self {
            Resolution::R320x240 => (320, 240),
            Resolution::R160x120 => (160, 120),
            Resolution::R80x60 => (80, 60),
            Resolution::R40x30 => (40, 30),
        }
    }
}

impl Default for Resolution {
    fn default() -> Self {
        Resolution::R160x120
    }
}

#[repr(u8)]
#[derive(Copy, Clone, Debug, Eq, PartialEq, FromPrimitive, ToPrimitive)]
pub enum ExposureMode {
    Manual = 0,
    Max = 1,
}

#[repr(u8)]
#[derive(Copy, Clone, Debug, Eq, PartialEq, FromPrimitive, ToPrimitive)]
pub enum ExternalLightFilter {
    Off = 0b00,
    X1 = 0b11,
}

#[repr(u8)]
#[derive(Copy, Clone, Debug, Eq, PartialEq, FromPrimitive, ToPrimitive)]
pub enum Flip {
    Normal = 0,
    Vertically = 1,
    Horizontally = 2,
    Both = 3,
}

bitfield::bitfield! {
    #[repr(transparent)]
    #[derive(Copy, Clone)]
    pub struct Leds(u8);
    impl Debug;
    pub flashlight, set_flashlight: 0;
    pub disable_far_narrow12, set_disable_far_narrow12: 4;
    pub disable_near_wide34, set_disable_near_wide34: 5;
    pub strobe, set_strobe: 7;
}