use std::sync::{Arc, RwLock};

use metrics::{describe_gauge, gauge, Gauge};
use serde::{Deserialize, Serialize};
use teslatte::vehicles::ChargingState;

use crate::{
    api_interface::InterfaceRequest,
    charge_controllers::pl::PlState,
    config::access_config,
    types::{CarState, ChargeState},
};

pub struct TeslaChargeRateController {
    pub car_state: Arc<RwLock<CarState>>,
    pub pl_state: Option<Arc<RwLock<PlState>>>,
    pub tcrc_state: Arc<RwLock<TcrcState>>,
    control_enable_gauge: Gauge,
}

pub enum TcrcRequest {
    DisableAutomaticControl,
    EnableAutomaticControl,
}

#[derive(Clone, Copy, Serialize, Deserialize, Debug)]
pub struct TcrcState {
    pub control_enable: bool,
}

impl Default for TcrcState {
    fn default() -> Self {
        Self {
            control_enable: true,
        }
    }
}

impl TeslaChargeRateController {
    pub fn new(car_state: Arc<RwLock<CarState>>, pl_state: Option<Arc<RwLock<PlState>>>) -> Self {
        describe_gauge!("tcrc_control_enable", "Enable Tesla charge rate control");
        Self {
            car_state,
            pl_state,
            tcrc_state: Default::default(),
            control_enable_gauge: gauge!("tcrc_control_enable"),
        }
    }

    pub fn control_charge_rate(&mut self) -> Option<InterfaceRequest> {
        if let Some(pl_state) = self.pl_state.as_ref().and_then(|v| v.read().ok()) {
            if let Ok(car_state) = self.car_state.read() {
                if let Some(charge_state) = car_state.charge_state {
                    // check if we're charging at home
                    if charge_state.charging_state == ChargingState::Charging
                        && car_state.location_data.is_some_and(|v| v.home)
                    {
                        // automatic control or not, check if we're below shutoff voltage
                        if pl_state.battery_voltage < access_config().shutoff_voltage {
                            return Some(InterfaceRequest::StopCharge);
                        } else if self.tcrc_state.read().is_ok_and(|v| v.control_enable) {
                            return get_control(&pl_state, &charge_state);
                        }
                    } else if charge_state.charging_state == ChargingState::Disconnected {
                        // only disable automatic control until the next time we're unplugged
                        self.tcrc_state
                            .write()
                            .expect("failed to write to tcrc state")
                            .control_enable = true;
                        self.control_enable_gauge.set(1.);
                    }
                }
            }
        }
        None
    }

    pub fn process_request(&mut self, message: TcrcRequest) {
        match message {
            TcrcRequest::DisableAutomaticControl => {
                self.tcrc_state
                    .write()
                    .expect("failed to write to tcrc state")
                    .control_enable = false;
                self.control_enable_gauge.set(0.);
            }
            TcrcRequest::EnableAutomaticControl => {
                self.tcrc_state
                    .write()
                    .expect("failed to write to tcrc state")
                    .control_enable = true;
                self.control_enable_gauge.set(1.);
            }
        }
    }
}

fn get_control(pl_state: &PlState, charge_state: &ChargeState) -> Option<InterfaceRequest> {
    let config = access_config();
    if pl_state.duty_cycle > config.duty_cycle_too_high {
        let new_rate = charge_state.charge_amps - 1;
        return if new_rate >= config.min_rate {
            Some(InterfaceRequest::SetChargeRate(new_rate))
        } else {
            None
        };
    } else if pl_state.duty_cycle < config.duty_cycle_too_low {
        let new_rate = charge_state.charge_amps + 1;
        return if new_rate <= config.max_rate {
            Some(InterfaceRequest::SetChargeRate(new_rate))
        } else {
            None
        };
    }

    None
}