use std::{
    sync::{Arc, Mutex, MutexGuard},
    time::Duration,
};

use embedded_hal::digital::v2::{OutputPin, PinState};
use embedded_svc::event_bus::{EventBus, Postbox};
use esp_idf_hal::gpio::{Gpio7, Output};
use esp_idf_svc::eventloop::{
    Background, EspBackgroundEventLoop, EspEventFetchData, EspEventLoop, EspEventPostData,
    EspSubscription, EspTypedEventDeserializer, EspTypedEventSerializer, EspTypedEventSource, User,
};
use esp_idf_sys::c_types;
use log::warn;
use serde_json::json;

use crate::{
    time::Time,
    voltage_detection::{VoltageDetectionWorker, VOLTAGE_EVENTLOOP},
};

pub static mut CHARGE_STATE_EVENT_LOOP: Option<
    EspEventLoop<esp_idf_svc::eventloop::User<Background>>,
> = None;

#[derive(Debug, Clone, Copy, PartialEq)]
pub enum ChargeStatus {
    Charging,
    Charged,
}

#[derive(Debug, Clone, Copy)]
pub struct ChargeControllerState {
    pub status: ChargeStatus,
    pub pin_state: PinState,
    pub charge_deadline_at: Duration,
}

impl ChargeControllerState {
    pub fn new() -> Self {
        Self {
            status: ChargeStatus::Charging,
            pin_state: PinState::Low,
            charge_deadline_at: Duration::ZERO,
        }
    }

    pub fn to_json(&self) -> String {
        let status = match self.status {
            ChargeStatus::Charging => "Charging",
            ChargeStatus::Charged => "Charged",
        };
        let pin_state = match self.pin_state {
            PinState::Low => "Low",
            PinState::High => "High",
        };
        let now = Time::new().get_time();
        let charging_count_down = if now > self.charge_deadline_at {
            -1i64
        } else {
            (self.charge_deadline_at - now).as_secs() as i64
        };
        json!({ "status": status, "pin_state": pin_state, "charging_count_down": charging_count_down}).to_string()
    }
}

impl EspTypedEventSource for ChargeControllerState {
    fn source() -> *const c_types::c_char {
        b"Charge\0".as_ptr() as *const _
    }
}

impl EspTypedEventSerializer<ChargeControllerState> for ChargeControllerState {
    fn serialize<R>(
        event: &ChargeControllerState,
        f: impl for<'a> FnOnce(&'a EspEventPostData) -> R,
    ) -> R {
        f(&unsafe { EspEventPostData::new(Self::source(), Self::event_id(), event) })
    }
}

impl EspTypedEventDeserializer<ChargeControllerState> for ChargeControllerState {
    fn deserialize<R>(
        data: &EspEventFetchData,
        f: &mut impl for<'a> FnMut(&'a ChargeControllerState) -> R,
    ) -> R {
        f(unsafe { data.as_payload() })
    }
}

type ChargeCtlPin = Gpio7<Output>;

pub struct ChargeController {
    pub state: ChargeControllerState,
    voltage_subscription: Option<EspSubscription<User<Background>>>,
    pin: Arc<Mutex<ChargeCtlPin>>,
}

impl ChargeController {
    pub fn new() -> anyhow::Result<Self> {
        let pin = unsafe { Gpio7::<Output>::new() }
            .into_output()
            .map_err(|err| anyhow::anyhow!("Make Gpio6 Into output Failed. {}", err))?;

        match EspBackgroundEventLoop::new(&Default::default()) {
            Ok(eventloop) => unsafe { CHARGE_STATE_EVENT_LOOP = Some(eventloop) },
            Err(err) => anyhow::bail!("Init Event Loop failed. {:?}", err),
        }

        anyhow::Ok(Self {
            state: ChargeControllerState::new(),
            voltage_subscription: None,
            pin: Arc::new(Mutex::new(pin)),
        })
    }

    pub fn watch(&mut self) -> anyhow::Result<()> {
        let mut state = self.state.to_owned();
        let pin = self.pin.to_owned();

        if let Some(event_loop) = unsafe { VOLTAGE_EVENTLOOP.as_mut() } {
            let voltage_subscription = event_loop
                .subscribe(move |obj: &VoltageDetectionWorker| {
                    match state.status {
                        ChargeStatus::Charging => {
                            if obj.battery_voltage < 12600 {
                                state.status = ChargeStatus::Charging;
                            } else {
                                let now = Time::new().get_time();
                                if state.charge_deadline_at == Duration::ZERO {
                                    state.charge_deadline_at = now + Duration::from_secs(600);
                                } else if now > state.charge_deadline_at {
                                    state.status = ChargeStatus::Charged;
                                } else {
                                    state.status = ChargeStatus::Charging;
                                }
                            }
                        }
                        ChargeStatus::Charged => {
                            if obj.battery_voltage < 10500 {
                                state.status = ChargeStatus::Charging;
                            } else {
                                state.status = ChargeStatus::Charged;
                            }
                        }
                    }

                    match pin.lock() {
                        Ok(pin) => {
                            if let Err(err) = Self::output_ctl(&mut state, pin) {
                                warn!("Put Control Pin State Failed. {}", err);
                            }
                        }
                        Err(_) => todo!(),
                    }

                    if let Some(event_loop) = unsafe { CHARGE_STATE_EVENT_LOOP.as_mut() } {
                        if let Err(err) = event_loop.post(&state, None) {
                            warn!("Post DC Out Status Failed. {}", err);
                        }
                    } else {
                        warn!("CHARGE_STATE_EVENT_LOOP is None");
                    }
                })
                .map_err(|err| anyhow::anyhow!("Subscribe Voltage Failed. {}", err))?;
            self.voltage_subscription = Some(voltage_subscription);
        } else {
            anyhow::bail!("Voltage Event Loop is None");
        }
        anyhow::Ok(())
    }
    fn output_ctl(
        state: &mut ChargeControllerState,
        mut pin: MutexGuard<ChargeCtlPin>,
    ) -> anyhow::Result<()> {
        if ChargeStatus::Charging == state.status {
            pin.set_high()
                .map_err(|err| anyhow::anyhow!("Set DC Output Control Pin High Failed. {}", err))?;
            state.pin_state = PinState::High;
        } else if ChargeStatus::Charged == state.status {
            pin.set_low()
                .map_err(|err| anyhow::anyhow!("Set DC Output Control Pin Low Failed. {}", err))?;
            state.pin_state = PinState::Low;
        }
        return anyhow::Ok(());
    }
}