use mcp23017;
use ad9959;

use serde::{Serialize, Deserialize};
mod attenuators;
mod rf_power;

use super::hal;

use attenuators::AttenuatorInterface;
use rf_power::PowerMeasurementInterface;

use embedded_hal::{
    blocking::spi::Transfer,
    adc::OneShot
};

const EXT_CLK_SEL_PIN: u8 = 8 + 7;
#[allow(dead_code)]
const OSC_EN_N_PIN: u8 = 8 + 6;
const ATT_RST_N_PIN: u8 = 8 + 5;
const ATT_LE3_PIN: u8 = 8 + 3;
const ATT_LE2_PIN: u8 = 8 + 2;
const ATT_LE1_PIN: u8 = 8 + 1;
const ATT_LE0_PIN: u8 = 8 + 0;

#[derive(Debug, Copy, Clone)]
pub enum Error {
    Spi,
    I2c,
    Dds,
    Qspi,
    Bounds,
    InvalidAddress,
    InvalidChannel,
    Adc,
}

#[derive(Debug, Copy, Clone)]
pub enum Channel {
    In0,
    In1,
    Out0,
    Out1,
}

#[derive(Serialize, Deserialize, Copy, Clone, Debug)]
pub struct DdsChannelState {
    pub phase_offset: f32,
    pub frequency: f64,
    pub amplitude: f32,
    pub enabled: bool,
}

#[derive(Serialize, Deserialize, Copy, Clone, Debug)]
pub struct ChannelState {
    pub parameters: DdsChannelState,
    pub attenuation: f32,
}

#[derive(Serialize, Deserialize, Copy, Clone, Debug)]
pub struct InputChannelState {
    pub attenuation: f32,
    pub power: f32,
    pub mixer: DdsChannelState,
}

#[derive(Serialize, Deserialize, Copy, Clone, Debug)]
pub struct OutputChannelState {
    pub attenuation: f32,
    pub channel: DdsChannelState,
}

#[derive(Serialize, Deserialize, Copy, Clone, Debug)]
pub struct DdsClockConfig {
    pub multiplier: u8,
    pub reference_clock: f32,
    pub external_clock: bool,
}

impl Into<ad9959::Channel> for Channel {
    fn into(self) -> ad9959::Channel {
        match self {
            Channel::In0 => ad9959::Channel::Two,
            Channel::In1 => ad9959::Channel::Four,
            Channel::Out0 => ad9959::Channel::One,
            Channel::Out1 => ad9959::Channel::Three,
        }
    }
}

pub struct QspiInterface {
    pub qspi: hal::qspi::Qspi,
    mode: ad9959::Mode,
}

impl QspiInterface {
    pub fn new(mut qspi: hal::qspi::Qspi) -> Result<Self, Error> {
        qspi.configure_mode(hal::qspi::QspiMode::FourBit).map_err(|_| Error::Qspi)?;
        Ok(Self { qspi: qspi, mode: ad9959::Mode::SingleBitTwoWire })
    }
}

impl ad9959::Interface for QspiInterface {
    type Error = Error;

    fn configure_mode(&mut self, mode: ad9959::Mode) -> Result<(), Error> {
        self.mode = mode;

        Ok(())
    }

    fn write(&mut self, addr: u8, data: &[u8]) -> Result<(), Error> {
        if (addr & 0x80) != 0 {
            return Err(Error::InvalidAddress);
        }

        // The QSPI interface implementation always operates in 4-bit mode because the AD9959 uses
        // IO3 as SYNC_IO in some output modes. In order for writes to be successful, SYNC_IO must
        // be driven low. However, the QSPI peripheral forces IO3 high when operating in 1 or 2 bit
        // modes. As a result, any writes while in single- or dual-bit modes has to instead write
        // the data encoded into 4-bit QSPI data so that IO3 can be driven low.
        match self.mode {
            ad9959::Mode::SingleBitTwoWire => {
                // Encode the data into a 4-bit QSPI pattern.

                // In 4-bit mode, we can send 2 bits of address and data per byte transfer. As
                // such, we need at least 4x more bytes than the length of data. To avoid dynamic
                // allocation, we assume the maximum transaction length for single-bit-two-wire is
                // 2 bytes.
                let mut encoded_data: [u8; 12] = [0; 12];

                if (data.len() * 4) > (encoded_data.len() - 4) {
                    return Err(Error::Bounds);
                }

                // Encode the address into the first 4 bytes.
                for address_bit in 0..8 {
                    let offset: u8 = {
                        if address_bit % 2 != 0 {
                            4
                        } else {
                            0
                        }
                    };

                    // Encode MSB first. Least significant bits are placed at the most significant
                    // byte.
                    let byte_position = 3 - (address_bit >> 1) as usize;

                    if addr & (1 << address_bit) != 0 {
                        encoded_data[byte_position] |= 1 << offset;
                    }
                }

                // Encode the data into the remaining bytes.
                for byte_index in 0..data.len() {
                    let byte = data[byte_index];
                    for bit in 0..8 {
                        let offset: u8 = {
                            if bit % 2 != 0 {
                                4
                            } else {
                                0
                            }
                        };

                        // Encode MSB first. Least significant bits are placed at the most
                        // significant byte.
                        let byte_position = 3 - (bit >> 1) as usize;

                        if byte & (1 << bit) != 0 {
                            encoded_data[(byte_index + 1) * 4 + byte_position] |= 1 << offset;
                        }
                    }
                }

                let (encoded_address, encoded_payload) = {
                    let end_index = (1 + data.len()) * 4;
                    (encoded_data[0], &encoded_data[1..end_index])
                };

                self.qspi.write(encoded_address, &encoded_payload).map_err(|_| Error::Qspi)
            },
            ad9959::Mode::FourBitSerial => {
                self.qspi.write(addr, &data).map_err(|_| Error::Qspi)
            },
            _ => {
                Err(Error::Qspi)
            }
        }
    }

    fn read(&mut self, addr: u8, mut dest: &mut [u8]) -> Result<(), Error> {
        if (addr & 0x80) != 0 {
            return Err(Error::InvalidAddress);
        }

        // This implementation only supports operation (read) in four-bit-serial mode.
        if self.mode != ad9959::Mode::FourBitSerial {
            return Err(Error::Qspi);
        }

        self.qspi.read(0x80_u8 | addr, &mut dest).map_err(|_| Error::Qspi)
    }
}

pub struct PounderDevices<DELAY> {
    pub ad9959: ad9959::Ad9959<QspiInterface,
                               DELAY,
                               hal::gpio::gpiog::PG7<hal::gpio::Output<hal::gpio::PushPull>>>,
    mcp23017: mcp23017::MCP23017<hal::i2c::I2c<hal::stm32::I2C1>>,
    attenuator_spi: hal::spi::Spi<hal::stm32::SPI1>,
    adc1: hal::adc::Adc<hal::stm32::ADC1, hal::adc::Enabled>,
    adc2: hal::adc::Adc<hal::stm32::ADC2, hal::adc::Enabled>,
    adc1_in_p: hal::gpio::gpiof::PF11<hal::gpio::Analog>,
    adc2_in_p: hal::gpio::gpiof::PF14<hal::gpio::Analog>,
}

impl<DELAY> PounderDevices<DELAY>
where
    DELAY: embedded_hal::blocking::delay::DelayMs<u8>,
{
    pub fn new(mcp23017: mcp23017::MCP23017<hal::i2c::I2c<hal::stm32::I2C1>>,
               ad9959: ad9959::Ad9959<QspiInterface,
                                      DELAY,
                                      hal::gpio::gpiog::PG7<
                                        hal::gpio::Output<hal::gpio::PushPull>>>,
               attenuator_spi: hal::spi::Spi<hal::stm32::SPI1>,
               adc1: hal::adc::Adc<hal::stm32::ADC1, hal::adc::Enabled>,
               adc2: hal::adc::Adc<hal::stm32::ADC2, hal::adc::Enabled>,
               adc1_in_p: hal::gpio::gpiof::PF11<hal::gpio::Analog>,
               adc2_in_p: hal::gpio::gpiof::PF14<hal::gpio::Analog>,
               ) -> Result<Self, Error> {
        let mut devices = Self {
            mcp23017,
            ad9959,
            attenuator_spi,
            adc1,
            adc2,
            adc1_in_p,
            adc2_in_p,
        };

        // Configure power-on-default state for pounder. All LEDs are on, on-board oscillator
        // selected, attenuators out of reset.
        devices.mcp23017.write_gpio(mcp23017::Port::GPIOA, 0x3F).map_err(|_| Error::I2c)?;
        devices.mcp23017.write_gpio(mcp23017::Port::GPIOB, 1 << 5).map_err(|_| Error::I2c)?;
        devices.mcp23017.all_pin_mode(mcp23017::PinMode::OUTPUT).map_err(|_| Error::I2c)?;

        // Select the on-board clock with a 5x prescaler (500MHz).
        devices.select_onboard_clock(4u8)?;

        Ok(devices)
    }

    fn select_external_clock(&mut self, frequency: f32, prescaler: u8) -> Result<(), Error>{
        self.mcp23017.digital_write(EXT_CLK_SEL_PIN, true).map_err(|_| Error::I2c)?;
        self.ad9959.configure_system_clock(frequency, prescaler).map_err(|_| Error::Dds)?;

        Ok(())
    }

    fn select_onboard_clock(&mut self, prescaler: u8) -> Result<(), Error> {
        self.mcp23017.digital_write(EXT_CLK_SEL_PIN, false).map_err(|_| Error::I2c)?;
        self.ad9959.configure_system_clock(100_000_000f32, prescaler).map_err(|_| Error::Dds)?;

        Ok(())
    }

    pub fn configure_dds_clock(&mut self, config: DdsClockConfig) -> Result<(), Error> {
        if config.external_clock {
            self.select_external_clock(config.reference_clock, config.multiplier)
        } else {
            self.select_onboard_clock(config.multiplier)
        }
    }

    pub fn get_dds_clock_config(&mut self) -> Result<DdsClockConfig, Error> {
        let external_clock = self.mcp23017.digital_read(EXT_CLK_SEL_PIN).map_err(|_| Error::I2c)?;
        let multiplier = self.ad9959.get_reference_clock_multiplier().map_err(|_| Error::Dds)?;
        let reference_clock = self.ad9959.get_reference_clock_frequency();

        Ok(DdsClockConfig{multiplier, reference_clock, external_clock})
    }

    pub fn get_input_channel_state(&mut self, channel: Channel) -> Result<InputChannelState, Error> {
        match channel {
            Channel::In0 | Channel::In1 => {
                let channel_state = self.get_dds_channel_state(channel)?;

                let attenuation = self.get_attenuation(channel)?;
                let power = self.measure_power(channel)?;

                Ok(InputChannelState {
                    attenuation: attenuation,
                    power: power,
                    mixer: channel_state
                })
            }
            _ => Err(Error::InvalidChannel),
        }
    }

    fn get_dds_channel_state(&mut self, channel: Channel) -> Result<DdsChannelState, Error> {
        let frequency = self.ad9959.get_frequency(channel.into()).map_err(|_| Error::Dds)?;
        let phase_offset = self.ad9959.get_phase(channel.into()).map_err(|_| Error::Dds)?;
        let amplitude = self.ad9959.get_amplitude(channel.into()).map_err(|_| Error::Dds)?;
        let enabled = self.ad9959.is_enabled(channel.into()).map_err(|_| Error::Dds)?;

        Ok(DdsChannelState {phase_offset, frequency, amplitude, enabled})
    }

    pub fn get_output_channel_state(&mut self, channel: Channel) -> Result<OutputChannelState, Error> {
        match channel {
            Channel::Out0 | Channel::Out1 => {
                let channel_state = self.get_dds_channel_state(channel)?;
                let attenuation = self.get_attenuation(channel)?;

                Ok(OutputChannelState {
                    attenuation: attenuation,
                    channel: channel_state,
                })
            }
            _ => Err(Error::InvalidChannel),
        }
    }

    pub fn set_channel_state(&mut self, channel: Channel, state: ChannelState) -> Result<(), Error> {
        self.ad9959.set_frequency(channel.into(), state.parameters.frequency).map_err(|_| Error::Dds)?;
        self.ad9959.set_phase(channel.into(), state.parameters.phase_offset).map_err(|_| Error::Dds)?;
        self.ad9959.set_amplitude(channel.into(), state.parameters.amplitude).map_err(|_| Error::Dds)?;

        if state.parameters.enabled {
            self.ad9959.enable_channel(channel.into()).map_err(|_| Error::Dds)?;
        } else {
            self.ad9959.disable_channel(channel.into()).map_err(|_| Error::Dds)?;
        }

        self.set_attenuation(channel, state.attenuation)?;

        Ok(())
    }
}

impl<DELAY> AttenuatorInterface for PounderDevices<DELAY>
{
    fn reset_attenuators(&mut self) -> Result<(), Error> {
        self.mcp23017.digital_write(ATT_RST_N_PIN, false).map_err(|_| Error::I2c)?;
        // TODO: Measure the I2C transaction speed to the RST pin to ensure that the delay is
        // sufficient. Document the delay here.
        self.mcp23017.digital_write(ATT_RST_N_PIN, true).map_err(|_| Error::I2c)?;

        Ok(())
    }

    fn latch_attenuators(&mut self, channel: Channel) -> Result<(), Error> {
        let pin = match channel {
            Channel::In0 => ATT_LE0_PIN,
            Channel::In1 => ATT_LE2_PIN,
            Channel::Out0 => ATT_LE1_PIN,
            Channel::Out1 => ATT_LE3_PIN,
        };

        self.mcp23017.digital_write(pin, true).map_err(|_| Error::I2c)?;
        // TODO: Measure the I2C transaction speed to the RST pin to ensure that the delay is
        // sufficient. Document the delay here.
        self.mcp23017.digital_write(pin, false).map_err(|_| Error::I2c)?;

        Ok(())
    }

    fn read_all_attenuators(&mut self, channels: &mut [u8; 4]) -> Result<(), Error> {
        self.attenuator_spi.transfer(channels).map_err(|_| Error::Spi)?;

        Ok(())
    }

    fn write_all_attenuators(&mut self, channels: &[u8; 4]) -> Result<(), Error> {
        let mut result = [0_u8; 4];
        result.clone_from_slice(channels);
        self.attenuator_spi.transfer(&mut result).map_err(|_| Error::Spi)?;

        Ok(())
    }
}

impl<DELAY> PowerMeasurementInterface for PounderDevices<DELAY> {
    fn sample_converter(&mut self, channel: Channel) -> Result<f32, Error> {
        let adc_scale = match channel {
            Channel::In0 => {
                let adc_reading: u32 = self.adc1.read(&mut self.adc1_in_p).map_err(|_| Error::Adc)?;
                adc_reading as f32 / self.adc1.max_sample() as f32
            },
            Channel::In1 => {
                let adc_reading: u32 = self.adc2.read(&mut self.adc2_in_p).map_err(|_| Error::Adc)?;
                adc_reading as f32 / self.adc2.max_sample() as f32
            },
            _ => return Err(Error::InvalidChannel),
        };

        // Convert analog percentage to voltage.
        Ok(adc_scale * 3.3)
    }
}