use std::collections::{HashMap, HashSet};

// Db Commons
use uuid::Uuid;

use failure::Error;

use crossbeam_channel::{Sender, Receiver};

use account;
use account::Account;
use game;
use instance;

use pg::{Db, PgPool};
use rpc::RpcMessage;
use warden::{GameEvent};
use mail::Mail;

pub type EventsTx = Sender<Event>;
type Id = usize;

// this is pretty heavyweight
// but it makes the ergonomics easy
// and prevents message mania
// good candidate to trim if the mm is slow
#[derive(Debug, Clone)]
pub struct PvpRequest {
    pub id: Id,
    pub tx: Sender<RpcMessage>,
    pub account: Account,
}

pub struct Events {
    pub tx: Sender<Event>,
    rx: Receiver<Event>,

    mail: Sender<Mail>,
    warden: Sender<GameEvent>,
    queue: Option<PvpRequest>,

    clients: HashMap<Id, WsClient>,
}

#[derive(Debug,Clone)]
pub enum Event {
    // ws lifecycle
    Connect(Id, Option<Account>, Sender<RpcMessage>),
    Disconnect(Id),
    Subscribe(Id, Uuid),
    Unsubscribe(Id, Uuid),

    // notifications
    Push(Uuid, RpcMessage),

    // client events
    Queue(PvpRequest),
}

struct WsClient {
    id: Id,
    tx: Sender<RpcMessage>,
    subs: HashSet<Uuid>,
}

impl Events {
    pub fn new(tx: Sender<Event>, rx: Receiver<Event>, warden: Sender<GameEvent>, mail: Sender<Mail>) -> Events {
        Events {
            tx,
            rx,
            warden,
            mail,
            queue: None,
            clients: HashMap::new(),
        }
    }

    pub fn listen(mut self) -> Result<(), Error> {
        loop {
            match self.rx.recv() {
                Ok(m) => {
                    match self.event(m) {
                        Ok(()) => (), // :)
                        Err(e) => {
                            warn!("err={:?}", e);
                        }
                    }
                },

                Err(e) => {
                    return Err(format_err!("events error err={:?}", e));
                },
            };
        }
    }

    fn get_client(&mut self, id: Id) -> Result<&mut WsClient, Error> {
        match self.clients.get_mut(&id) {
            Some(c) => Ok(c),
            None => Err(format_err!("connection not found id={:?}", id)),
        }
    }

    fn remove_client(&mut self, id: Id) {
        self.clients.remove(&id);
    }

    fn event(&mut self, msg: Event) -> Result<(), Error> {
        match msg {
            Event::Connect(id, account, tx) => {
                info!("connect id={:?} account={:?}", id, account);

                let client = WsClient { id, tx, subs: HashSet::new() };
                self.clients.insert(id, client);

                info!("clients={:?}", self.clients.len());
                Ok(())
            },

            Event::Disconnect(id) => {
                info!("disconnect id={:?}", id);

                self.clients.remove(&id);

                info!("clients={:?}", self.clients.len());
                Ok(())
            },

            Event::Subscribe(id, obj) => {
                info!("subscribe id={:?} object={:?}", id, obj);

                match self.clients.get_mut(&id) {
                    Some(client) => {
                        client.subs.insert(obj);
                        info!("client subscriptions={:?}", client.subs.len());
                        Ok(())
                    },
                    None => return Err(format_err!("unknown client {:?}", id))
                }
            },

            Event::Unsubscribe(id, obj) => {
                info!("unsubscribe id={:?} object={:?}", id, obj);

                match self.clients.get_mut(&id) {
                    Some(mut client) => {
                        client.subs.remove(&obj);
                        info!("unsubscribe subscriptions removed={:?}", client.subs.len());
                        Ok(())
                    },
                    None => return Err(format_err!("unknown client {:?}", id))
                }
            },

            Event::Push(id, msg) => {
                info!("push id={:?}", id);

                let mut subs = 0;
                let mut dead = vec![];

                for (client_id, client) in self.clients.iter() {
                    if client.subs.contains(&id) {
                        subs += 1;
                        match client.tx.send(msg.clone()) {
                            Ok(_) => (),
                            Err(e) => {
                                warn!("unable to send msg to client err={:?}", e);
                                dead.push(*client_id);
                            },
                        };
                    }
                }

                if !dead.is_empty() {
                    info!("dead connections={:?}", dead.len());
                    dead.iter().for_each(|id| self.remove_client(*id));
                }

                info!("push subscribers={:?}", subs);

                Ok(())
            },

            Event::Queue(req) => {
                info!("queue id={:?} account={:?}", req.id, req.account);

                self.queue = match self.queue {
                    Some(ref q_req) => {
                        info!("game queue pair found a={:?} b={:?}", req.account, q_req.account);
                        self.warden.send(GameEvent::Match((req, q_req.clone())))?;
                        None
                    },
                    None => {
                        info!("joined game queue id={:?} account={:?}", req.id, req.account);
                        Some(req)
                    },
                };

                Ok(())
            },

        }
    }
}