use crate::agenda::{parse_message, AgendaPoint, Emoji};

use futures::join;
use slack::{Event, Message};
use slack_api::{reactions, users};
use std::{
    collections::{hash_map::Entry, HashMap},
    sync::{Arc, Mutex},
};
use tokio::{
    runtime::Runtime,
    sync::mpsc,
    task::{spawn, spawn_blocking},
};
use tokio_compat_02::FutureExt;

const TOKEN: Option<&str> = None;
const CHANNEL: Option<&str> = None;

struct Handler {
    sender: mpsc::UnboundedSender<AgendaPoint>,
    slack_sender: slack::Sender,
    slack_channel: Option<String>,
    print_channels: bool,
    slack_token: String,
    display_names: Arc<Mutex<HashMap<String, String>>>,
}

impl Handler {
    fn new(
        sender: mpsc::UnboundedSender<AgendaPoint>,
        slack_sender: slack::Sender,
        slack_channel: Option<String>,
        slack_token: String,
    ) -> Self {
        Self {
            sender,
            slack_sender,
            slack_channel: slack_channel.clone(),
            print_channels: slack_channel.is_none(),
            slack_token,
            display_names: Arc::new(Mutex::new(HashMap::new())),
        }
    }

}

async fn get_or_insert_display_name(
    display_names: Arc<Mutex<HashMap<String, String>>>,
    user_id: String,
    slack_token: &str,
) -> String {
    match display_names.lock().unwrap().entry(user_id.clone()) {
        Entry::Occupied(o) => o.get().to_string(),
        Entry::Vacant(v) => {
            let client = slack_api::requests::default_client().unwrap();
            if let Some(user) = users::list(
                &client,
                slack_token,
                &users::ListRequest {presence: None}
            ).compat()
             .await
             .unwrap()
             .members
             .unwrap()
             .iter()
             .find(|user| user.id.is_some() && user.id.as_deref().unwrap() == user_id)
            {
                v.insert(user.real_name.as_ref().unwrap().clone()).to_string()
            } else {
                user_id
            }
        }
    }
}

impl slack::EventHandler for Handler {
    fn on_event(&mut self, cli: &slack::RtmClient, event: slack::Event) {
        match event {
            Event::Hello => {
                if self.print_channels {
                    println!("Slack channels found: {:#?}",
                             cli
                             .start_response()
                             .channels
                             .as_ref()
                             .map(|channels| {
                                 channels
                                     .iter()
                                     .map(|channel| format!(
                                         "{}: {}",
                                         channel.name.as_deref().unwrap_or("??"),
                                         channel.id.as_deref().unwrap_or("??"),
                                     ))
                                     .collect::<Vec<_>>()
                             }));
                }
            }
            Event::Message(msg) => {
                if let Some(channel) = &self.slack_channel.clone() {
                    match *msg {
                        Message::Standard(msg) => {
                            if msg.channel.is_some() && *channel == msg.channel.unwrap() { //TODO
                                let user = match msg.user {
                                    Some(s) => Runtime::new().unwrap().block_on(
                                        get_or_insert_display_name(
                                            Arc::clone(&self.display_names),
                                            s,
                                            &self.slack_token,
                                        ).compat()),
                                    None => "??".to_string()
                                };
                                match parse_message(
                                    &msg.text.unwrap_or("".to_string()),
                                    &user,
                                    |s: String| {
                                        self.slack_sender
                                            .send_message(channel.as_str(), &s)
                                            .unwrap();
                                    },
                                    &self.sender,
                                ) {
                                    Some(Emoji::Ok) => {
                                        let client = slack_api::requests::default_client().unwrap();
                                        Runtime::new().unwrap().block_on(
                                            reactions::add(
                                                &client,
                                                &self.slack_token,
                                                &reactions::AddRequest{
                                                    name: "+1",
                                                    file: None,
                                                    file_comment: None,
                                                    channel: Some(channel.as_str()),
                                                    timestamp: Some(msg.ts.unwrap()),
                                                }).compat()
                                        ).unwrap();
                                    }
                                    _ => {}
                                }
                            }
                        }
                        _ => {} // message type
                    }
                }
            }
            _ => {} // event type
        }
    }

    fn on_close(&mut self, _cli: &slack::RtmClient) {}

    fn on_connect(&mut self, _cli: &slack::RtmClient) {}
}

pub async fn handle(
    sender: mpsc::UnboundedSender<AgendaPoint>,
    receiver: mpsc::UnboundedReceiver<AgendaPoint>,
) {
    println!("Setting up Slack");

    let token = std::env::var("SLACK_API_TOKEN").unwrap_or_else(|_| TOKEN.expect("Missing slack token").to_string());
    let channel = match std::env::var("SLACK_CHANNEL") {
        Ok(channel) => Some(channel),
        Err(_) => match CHANNEL {
            Some(channel) => Some(channel.to_string()),
            None => None
        }
    };
    let slack_token = token.to_string();
    let client = spawn_blocking(move || {
        slack::RtmClient::login(&token).unwrap()
    }).await.unwrap();

    let mut handler = Handler::new(sender, client.sender().clone(), channel.clone(), slack_token);
    let slack_sender = client.sender().clone();

    let (_, _) = join!(
        spawn_blocking(move || {
            match client.run(&mut handler) {
                Ok(_) => {}
                Err(e) => {
                    println!("Error: {}", e)
                }
            }
        }),
        spawn(receive_from_discord(receiver, slack_sender, channel))
    );
}

async fn receive_from_discord(
    mut receiver: mpsc::UnboundedReceiver<AgendaPoint>,
    sender: slack::Sender,
    channel: Option<String>,
) {
    if let Some(channel) = channel {
        while let Some(point) = receiver.recv().await {
            //TODO Sending messages is very slow sometimes. Have seen delays
            // from 5 up to 20(!) seconds.
            sender.send_typing(&channel).unwrap();
            sender.send_message(&channel, &point.to_add_message()).unwrap();
            println!("Slack message sent");
        }
    }
}