use libmodbus_rs::{Modbus, ModbusClient, ModbusRTU};
use prometheus::core::{AtomicI64, GenericGauge};

use crate::{charge_controllers::gauges::*, errors::TristarError};

const DEVICE_ID: u8 = 0x01;
const RAM_DATA_SIZE: u16 = 0x005B;
const RAM_ARRAY_SIZE: usize = RAM_DATA_SIZE as usize + 1;

#[derive(Debug, Clone)]
pub struct Scaling {
    pub v_scale: f64,
    pub i_scale: f64,
}

impl Scaling {
    fn from(data: &[u16]) -> Self {
        Self::from_internal(data[0], data[1], data[2], data[3])
    }

    fn from_internal(v_pu_hi: u16, v_pu_lo: u16, i_pu_hi: u16, i_pu_lo: u16) -> Self {
        Self {
            v_scale: v_pu_hi as f64 + (v_pu_lo as f64 / f64::powf(2., 16.)),
            i_scale: i_pu_hi as f64 + (i_pu_lo as f64 / f64::powf(2., 16.)),
        }
    }

    fn get_voltage(&self, data: u16) -> f64 {
        data as f64 * self.v_scale * f64::powf(2., -15.)
    }

    fn get_current(&self, data: u16) -> f64 {
        data as f64 * self.i_scale * f64::powf(2., -15.)
    }

    fn get_power(&self, data: u16) -> f64 {
        data as f64 * self.v_scale * self.i_scale * f64::powf(2., -17.)
    }
}

pub struct Tristar {
    state: TristarState,
    port_name: String,
    modbus: Modbus,
    data_in: [u16; RAM_ARRAY_SIZE],
    charge_state_gauges: ChargeStateGauges,
}

#[derive(Default, Debug, Clone, Copy)]
pub struct TristarState {
    battery_voltage: f64,
    target_voltage: f64,
    input_current: f64,
    battery_temp: u16,
    charge_state: ChargeState,
    tristar_input_voltage: f64,
    tristar_charge_current: f64,
    tristar_power_out: f64,
    tristar_power_in: f64,
    tristar_max_array_power: f64,
    tristar_max_array_voltage: f64,
    tristar_open_circuit_voltage: f64,
}

impl TristarState {
    fn from_ram(scaling: Scaling, ram: &[u16]) -> Self {
        Self {
            battery_voltage: scaling.get_voltage(ram[TristarRamAddress::AdcVbFMed]),
            target_voltage: scaling.get_voltage(ram[TristarRamAddress::VbRef]),
            input_current: scaling.get_current(ram[TristarRamAddress::AdcIaFShadow]),
            battery_temp: ram[TristarRamAddress::Tbatt],
            charge_state: ChargeState::from(ram[TristarRamAddress::ChargeState]),
            tristar_input_voltage: scaling.get_voltage(ram[TristarRamAddress::AdcVaF]),
            tristar_charge_current: scaling.get_current(ram[TristarRamAddress::AdcIbFShadow]),
            tristar_power_out: scaling.get_power(ram[TristarRamAddress::PowerOutShadow]),
            tristar_power_in: scaling.get_power(ram[TristarRamAddress::PowerInShadow]),
            tristar_max_array_power: scaling.get_power(ram[TristarRamAddress::SweepPinMax]),
            tristar_max_array_voltage: scaling.get_voltage(ram[TristarRamAddress::SweepVmp]),
            tristar_open_circuit_voltage: scaling.get_voltage(ram[TristarRamAddress::SweepVoc]),
        }
    }
}

#[derive(Debug, Clone, Copy)]
enum ChargeState {
    Start,
    NightCheck,
    Disconnect,
    Night,
    Fault,
    Mppt,
    Absorption,
    Float,
    Equalize,
    Slave,
    Unknown,
}

impl Default for ChargeState {
    fn default() -> Self {
        Self::Unknown
    }
}

impl From<u16> for ChargeState {
    fn from(value: u16) -> Self {
        match value {
            0 => Self::Start,
            1 => Self::NightCheck,
            2 => Self::Disconnect,
            3 => Self::Night,
            4 => Self::Fault,
            5 => Self::Mppt,
            6 => Self::Absorption,
            7 => Self::Float,
            8 => Self::Equalize,
            9 => Self::Slave,
            _ => Self::Unknown,
        }
    }
}

struct ChargeStateGauges {
    start: GenericGauge<AtomicI64>,
    night_check: GenericGauge<AtomicI64>,
    disconnect: GenericGauge<AtomicI64>,
    night: GenericGauge<AtomicI64>,
    fault: GenericGauge<AtomicI64>,
    mppt: GenericGauge<AtomicI64>,
    absorption: GenericGauge<AtomicI64>,
    float: GenericGauge<AtomicI64>,
    equalize: GenericGauge<AtomicI64>,
    slave: GenericGauge<AtomicI64>,
    unknown: GenericGauge<AtomicI64>,
}

impl ChargeStateGauges {
    fn new(label: &str) -> Self {
        let start = CHARGE_STATE.with_label_values(&[label, "start"]);
        let night_check = CHARGE_STATE.with_label_values(&[label, "night_check"]);
        let disconnect = CHARGE_STATE.with_label_values(&[label, "disconnect"]);
        let night = CHARGE_STATE.with_label_values(&[label, "night"]);
        let fault = CHARGE_STATE.with_label_values(&[label, "fault"]);
        let mppt = CHARGE_STATE.with_label_values(&[label, "mppt"]);
        let absorption = CHARGE_STATE.with_label_values(&[label, "absorption"]);
        let float = CHARGE_STATE.with_label_values(&[label, "float"]);
        let equalize = CHARGE_STATE.with_label_values(&[label, "equalize"]);
        let slave = CHARGE_STATE.with_label_values(&[label, "slave"]);
        let unknown = CHARGE_STATE.with_label_values(&[label, "unknown"]);
        Self {
            start,
            night_check,
            disconnect,
            night,
            fault,
            mppt,
            absorption,
            float,
            equalize,
            slave,
            unknown,
        }
    }

    fn zero_all(&mut self) {
        self.start.set(0);
        self.night_check.set(0);
        self.disconnect.set(0);
        self.night.set(0);
        self.fault.set(0);
        self.mppt.set(0);
        self.absorption.set(0);
        self.float.set(0);
        self.equalize.set(0);
        self.slave.set(0);
        self.unknown.set(0);
    }

    fn set(&mut self, state: ChargeState) {
        match state {
            ChargeState::Start => {
                self.zero_all();
                self.start.set(1);
            }
            ChargeState::NightCheck => {
                self.zero_all();
                self.night_check.set(1);
            }
            ChargeState::Disconnect => {
                self.zero_all();
                self.disconnect.set(1);
            }
            ChargeState::Night => {
                self.zero_all();
                self.night.set(1);
            }
            ChargeState::Fault => {
                self.zero_all();
                self.fault.set(1);
            }
            ChargeState::Mppt => {
                self.zero_all();
                self.mppt.set(1);
            }
            ChargeState::Absorption => {
                self.zero_all();
                self.absorption.set(1);
            }
            ChargeState::Float => {
                self.zero_all();
                self.float.set(1);
            }
            ChargeState::Equalize => {
                self.zero_all();
                self.equalize.set(1);
            }
            ChargeState::Slave => {
                self.zero_all();
                self.slave.set(1);
            }
            ChargeState::Unknown => {
                self.zero_all();
                self.unknown.set(1);
            }
        }
    }
}

impl Tristar {
    pub fn new(serial_port: String, baud_rate: i32) -> Result<Self, TristarError> {
        let parity = 'N';
        let data_bit = 8;
        let stop_bit = 2;
        let mut modbus = Modbus::new_rtu(&serial_port, baud_rate, parity, data_bit, stop_bit)?;
        modbus.set_slave(DEVICE_ID)?;
        modbus.connect()?;
        let charge_state_gauges = ChargeStateGauges::new(&serial_port);
        Ok(Self {
            state: Default::default(),
            port_name: serial_port,
            modbus,
            data_in: [0; RAM_ARRAY_SIZE],
            charge_state_gauges,
        })
    }

    pub fn refresh(&mut self) {
        if let Ok(new_state) = self
            .get_data()
            .map(|scaling| TristarState::from_ram(scaling, &self.data_in))
        {
            BATTERY_VOLTAGE
                .with_label_values(&[&self.port_name])
                .set(new_state.battery_voltage);
            TARGET_VOLTAGE
                .with_label_values(&[&self.port_name])
                .set(new_state.target_voltage);
            INPUT_CURRENT
                .with_label_values(&[&self.port_name])
                .set(new_state.input_current);
            BATTERY_TEMP
                .with_label_values(&[&self.port_name])
                .set(new_state.battery_temp.into());
            TRISTAR_INPUT_VOLTAGE
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_input_voltage);
            TRISTAR_CHARGE_CURRENT
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_charge_current);
            TRISTAR_POWER_OUT
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_power_out);
            TRISTAR_POWER_IN
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_power_in);
            TRISTAR_MAX_ARRAY_POWER
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_max_array_power);
            TRISTAR_MAX_ARRAY_VOLTAGE
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_max_array_voltage);
            TRISTAR_OPEN_CIRCUIT_VOLTAGE
                .with_label_values(&[&self.port_name])
                .set(new_state.tristar_open_circuit_voltage);

            self.charge_state_gauges.set(new_state.charge_state);
            self.state = new_state;
        }
    }

    fn get_data(&mut self) -> Result<Scaling, TristarError> {
        self.modbus
            .read_registers(0x0000, RAM_DATA_SIZE + 1, &mut self.data_in)?;
        let scaling = Scaling::from(&self.data_in);
        Ok(scaling)
    }
}

enum TristarRamAddress {
    AdcVbFMed = 25,
    AdcVaF = 28,
    Tbatt = 38,
    AdcIbFShadow = 29,
    AdcIaFShadow = 30,
    ChargeState = 51,
    VbRef = 52,
    PowerOutShadow = 59,
    PowerInShadow = 60,
    SweepPinMax = 61,
    SweepVmp = 62,
    SweepVoc = 63,
}

impl std::ops::Index<TristarRamAddress> for [u16] {
    type Output = u16;

    fn index(&self, index: TristarRamAddress) -> &Self::Output {
        &self[index as usize]
    }
}