use std::collections::HashMap;

use chrono::{Datelike, Local, NaiveTime, Weekday};
use common::{ClientMessage, ServerMessage};
use lighter_lib::{BulbColor, BulbId};
use lighter_manager::manager::{BulbCommand, BulbManager, BulbSelector};
use serde::{Deserialize, Serialize};
use std::time::Duration;
use tokio::select;
use tokio::sync::{broadcast, mpsc};
use tokio::task::{spawn, JoinHandle};
use tokio::time::sleep;

use crate::persistence::PersistenceFile;
use crate::{ClientRequest, State};

#[derive(Default, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct LightsState {
    wake_schedule: HashMap<BulbId, HashMap<Weekday, NaiveTime>>,
}

pub async fn lights_task(state: &State) {
    let config = &state.config;
    let server_message = &state.server_message;
    let mut client_message = state.client_message.subscribe();
    let mut lights_state: PersistenceFile<LightsState> = state
        .persistence
        .open("lights".into())
        .await
        .expect("Failed to open lights config");

    let (cmd, bulb_states) = BulbManager::launch(config.bulbs.clone(), config.mqtt.clone())
        .await
        .expect("Failed to launch bulb manager");

    let mut wake_tasks: HashMap<(BulbId, Weekday), JoinHandle<()>> = lights_state
        .get()
        .wake_schedule
        .iter()
        .flat_map(|(bulb, schedule)| schedule.iter().map(move |(day, time)| (bulb, day, time)))
        .map(|(bulb, day, time)| {
            let handle = spawn(wake_task(
                state.client_message.subscribe(),
                cmd.clone(),
                bulb.clone(),
                *day,
                *time,
            ));

            ((bulb.clone(), *day), handle)
        })
        .collect();

    loop {
        let notify = bulb_states.notify_on_change();
        sleep(tokio::time::Duration::from_millis(1000 / 10)).await; // limit to 10 updates/second
        select! {
            _ = notify => {
                let lights_state = lights_state.get();
                for (id, mode) in bulb_states.bulbs().await.clone().into_iter() {
                    let wake_schedule = lights_state.wake_schedule.get(&id).cloned().unwrap_or_default();
                    let msg = ServerMessage::BulbState { id, mode, wake_schedule };
                    if let Err(e) = server_message.send(msg) {
                        error!("broadcast channel error: {e}");
                        return;
                    }
                }
            }
            request = client_message.recv() => {
                let request = match request {
                    Ok(r) => r,
                    Err(_) => continue,
                };

                match request.message {
                    ClientMessage::SetBulbColor { id, color } =>  {
                        if let Err(e) = cmd.send(BulbCommand::SetColor(BulbSelector::Id(id), color)).await {
                            error!("bulb manager error: {e}");
                        }
                    }
                    ClientMessage::SetBulbPower { id, power } =>  {
                        if let Err(e) = cmd.send(BulbCommand::SetPower(BulbSelector::Id(id), power)).await {
                            error!("bulb manager error: {e}");
                        }
                    }
                    ClientMessage::GetBulbs => {
                        if let Err(e) = request.response.send(ServerMessage::BulbMap(config.bulb_map.clone())).await {
                            error!("GetBulbs response channel error: {e}");
                            return;
                        }
                        let lights_state = lights_state.get();
                        for (id, mode) in bulb_states.bulbs().await.clone().into_iter() {
                            let wake_schedule = lights_state.wake_schedule.get(&id).cloned().unwrap_or_default();
                            let msg = ServerMessage::BulbState { id, mode, wake_schedule };
                            if let Err(e) = request.response.send(msg).await {
                                error!("GetBulbs response channel error: {e}");
                                return;
                            }
                        }
                    }
                    ClientMessage::SetBulbWakeTime { id, day, time } => {
                        if let Err(e) = lights_state.update(|lights_state| {
                            let schedule = lights_state.wake_schedule.entry(id.clone()).or_default();
                            if let Some(time) = time {
                                schedule.insert(day, time);
                            }
                            else {
                                schedule.remove(&day);
                            }
                        }).await {
                            error!("Failed to save wake schedule: {e}");
                        };

                        if let Some(time) = time {
                        let handle = spawn(wake_task(
                            state.client_message.subscribe(),
                            cmd.clone(),
                            id.clone(),
                            day,
                            time,
                        ));

                        if let Some(old_handle) = wake_tasks.insert((id, day), handle) {
                            old_handle.abort();
                        }} else {
                            if let Some(old_handle) = wake_tasks.remove(&(id, day)) {
                                old_handle.abort();
                            }
                        }
                    }
                    _ => {}
                }
            }
        }
    }
}

async fn wake_task(
    mut client_messages: broadcast::Receiver<ClientRequest>,
    cmd: mpsc::Sender<BulbCommand>,
    id: BulbId,
    day: Weekday,
    time: NaiveTime,
) {
    let now = Local::now();
    let day_num = day.num_days_from_monday();
    let now_day = now.weekday();
    let now_day_num = now_day.num_days_from_monday();

    let mut alarm = now;
    if day_num >= now_day_num {
        // next alarm is this week
        alarm += chrono::Duration::days((day_num - now_day_num).into());
        alarm = alarm.date().and_time(time).unwrap();
    } else {
        // next alarm is next week
        alarm += chrono::Duration::weeks(1);
        alarm -= chrono::Duration::days((now_day_num - day_num).into());
        alarm = alarm.date().and_time(time).unwrap();
    }

    loop {
        info!("sleeping until {alarm}");
        sleep((alarm - Local::now()).to_std().unwrap()).await;
        alarm += chrono::Duration::weeks(1);

        // slowly turn up brightness of bulb
        for brightness in (1..=75).map(|i| (i as f32) * 0.01) {
            select! {
                // abort if the client pokes the bulb
                _ = wait_for_bulb_command(&id, &mut client_messages) => break,
                _ = sleep(Duration::from_secs(12)) => {}
            };

            if cmd
                .send(BulbCommand::SetColor(
                    BulbSelector::Id(id.clone()),
                    BulbColor::Kelvin {
                        t: 0.0,
                        b: brightness,
                    },
                ))
                .await
                .is_err()
            {
                return;
            };
        }
    }
}

/// Wait until we receive a client request that mutates the given bulb
async fn wait_for_bulb_command(
    bulb_id: &BulbId,
    client_messages: &mut broadcast::Receiver<ClientRequest>,
) {
    loop {
        match client_messages.recv().await {
            Err(_) => return,
            Ok(request) => match request.message {
                ClientMessage::SetBulbColor { id, .. }
                | ClientMessage::SetBulbPower { id, .. }
                | ClientMessage::SetBulbWakeTime { id, .. }
                    if &id == bulb_id =>
                {
                    break
                }
                _ => continue,
            },
        }
    }
}