use crate::leaderboard::{InMemoryLeaderboard, Leaderboard};
use crate::player::Player;
use board_network::protocol::{ClientMessage, ServerMessage};
use board_shared::board::Board;
use board_shared::deck::RngDeck;
use board_shared::expr::is_valid_guess;
use board_shared::game::Hand;
use board_shared::position::Position2d;
use board_shared::score::calc_score;
use board_shared::tile::Tile;
use futures::channel::mpsc::{UnboundedReceiver, UnboundedSender};
use futures::executor::block_on;
use futures::StreamExt;
use rand::distributions::{Alphanumeric, DistString};
use std::collections::hash_map::Entry;
use std::collections::HashMap;
use std::fmt;
use std::net::SocketAddr;
use std::sync::{Arc, Mutex};

type TaggedClientMessage = (SocketAddr, ClientMessage);

pub struct Room {
    pub name: String,
    pub connections: HashMap<SocketAddr, usize>,
    pub players: Vec<Player>,
    pub active_player: usize,
    pub has_started: bool,
    pub board: Board,
    pub validated_board: Board,
    pub deck: RngDeck,
    pub leaderboard: Arc<dyn Leaderboard>,
    pub successive_skipped_turns: usize,
}

impl Room {
    pub fn with_leaderboard(leaderboard: Arc<dyn Leaderboard>) -> Self {
        Self {
            leaderboard,
            ..Self::default()
        }
    }

    pub fn add_player(
        &mut self,
        addr: SocketAddr,
        player_name: String,
        tx: UnboundedSender<ServerMessage>,
    ) -> anyhow::Result<()> {
        // If the player name matches an existing player, but with a dropped connection,
        // then replace this player.
        let mut player_index = None;
        for (i, p) in self.players.iter().enumerate() {
            if p.name == player_name && p.ws.is_none() {
                player_index = Some(i);
                break;
            }
        }

        let mut is_new_player = false;
        if let Some(i) = player_index {
            // Reclaim the player's spot
            self.broadcast(ServerMessage::PlayerReconnected(i));
            self.players[i].ws = Some(tx.clone());
        } else {
            self.broadcast(ServerMessage::PlayerConnected(player_name.clone()));
            player_index = Some(self.players.len());
            is_new_player = true;

            self.players.push(Player {
                name: player_name,
                score: 0,
                hand: Hand::default(),
                ws: Some(tx.clone()),
            });
        }

        let player_index = player_index.expect("A player index should have been attributed");
        self.connections.insert(addr, player_index);

        // Send the player the current state of the room
        tx.unbounded_send(ServerMessage::JoinedRoom {
            room_name: self.name.clone(),
            players: self
                .players
                .iter()
                .map(|p| (p.name.clone(), p.score, p.ws.is_some()))
                .collect(),
            board: self.board.clone(),
            active_player: self.active_player,
            has_started: self.has_started,
        })?;

        if self.has_started && is_new_player {
            self.players[player_index]
                .hand
                .complete(&mut self.deck)
                .ok();
            self.sync_hand(player_index);
        }

        Ok(())
    }

    pub fn next_player(&mut self) {
        if self.connections.is_empty() {
            return;
        }

        if self.successive_skipped_turns >= self.players.len() {
            self.on_game_over();
            return;
        }

        loop {
            self.active_player = (self.active_player + 1) % self.players.len();
            if self.players[self.active_player].ws.is_some() {
                break;
            }
        }

        self.broadcast(ServerMessage::PlayerTurn(self.active_player));
    }

    pub fn on_message(&mut self, addr: SocketAddr, msg: ClientMessage) -> bool {
        match msg {
            ClientMessage::Disconnected => self.on_client_disconnected(addr),
            ClientMessage::CreateRoom(_) | ClientMessage::JoinRoom(_, _) => {
                eprintln!("[{}] Illegal client message {:?}", self.name, msg);
            }
            ClientMessage::StartGame => self.on_start_game(),
            ClientMessage::TileUse(pos, tile_idx) => {
                if let Some(p) = self.connections.get(&addr) {
                    if *p == self.active_player {
                        self.on_tile_use(pos.into(), tile_idx);
                    }
                }
            }
            ClientMessage::TilePlaceEqual(pos) => {
                if let Some(p) = self.connections.get(&addr) {
                    if *p == self.active_player {
                        self.on_tile_place(pos.into(), Tile::Equals);
                    }
                }
            }
            ClientMessage::TileTake(pos) => {
                if let Some(p) = self.connections.get(&addr) {
                    if *p == self.active_player {
                        self.on_tile_take(pos.into());
                    }
                }
            }
            ClientMessage::Validate => {
                if let Some(p) = self.connections.get(&addr) {
                    if *p == self.active_player {
                        self.on_validate();
                    }
                }
            }
        }
        !self.connections.is_empty()
    }

    fn on_start_game(&mut self) {
        if self.has_started {
            return;
        }

        self.has_started = true;
        self.deck = RngDeck::new_complete();

        for p in &mut self.players {
            p.hand
                .complete(&mut self.deck)
                .expect("Not enough tiles in deck");
        }

        for i in 0..self.players.len() {
            self.sync_hand(i);
        }

        self.broadcast(ServerMessage::PlayerTurn(self.active_player));
    }

    fn on_tile_use(&mut self, pos: Position2d, tile_idx: usize) {
        let hand = &mut self.players[self.active_player].hand;
        if let Some(tile) = hand.remove(tile_idx) {
            self.on_tile_place(pos, tile);
            self.sync_hand(self.active_player);
        } else {
            self.send(
                self.active_player,
                ServerMessage::TurnRejected("Invalid tile index".to_string()),
            );
        }
    }

    fn on_tile_place(&mut self, pos: Position2d, tile: Tile) {
        self.board.set(pos.x, pos.y, tile);
        self.broadcast(ServerMessage::TilePlaced(pos.into(), tile.into()));
    }

    fn on_tile_take(&mut self, pos: Position2d) {
        if self.board.get(pos.x, pos.y) == self.validated_board.get(pos.x, pos.y) {
            self.send(
                self.active_player,
                ServerMessage::TurnRejected("Cannot take already validated tile.".to_string()),
            );
        } else if let Some(tile) = self.board.take(pos.x, pos.y) {
            self.players[self.active_player].hand.push(tile);
            self.sync_hand(self.active_player);
            self.broadcast(ServerMessage::TileRemoved(pos.into()));
        }
    }

    fn on_validate(&mut self) {
        let diff = self.board.difference(&self.validated_board);
        if diff.is_empty() {
            self.successive_skipped_turns += 1;
            self.next_player();
            return;
        }
        if !Board::has_alignment(&diff) || !self.board.is_unique_chain(&diff) {
            self.reset_player_moves();
            self.send(
                self.active_player,
                ServerMessage::TurnRejected("Move is not aligned".to_string()),
            );
            return;
        }
        let is_valid = self
            .board
            .find_chains(&diff)
            .iter()
            .all(|chain| is_valid_guess(&self.board, chain) == Ok(true));

        if is_valid {
            self.players[self.active_player]
                .hand
                .complete(&mut self.deck)
                .ok();
            self.on_validated_move(self.active_player, &diff);
            self.next_player();
        } else {
            self.send(
                self.active_player,
                ServerMessage::TurnRejected("Invalid expressions found".to_string()),
            );
        }
    }

    fn on_validated_move(&mut self, player_id: usize, diff: &[Position2d]) {
        let tiles_placed = diff
            .iter()
            .map(|&pos| {
                self.board
                    .get(pos.x, pos.y)
                    .expect("A placed tile should not be empty.")
            })
            .collect::<Vec<Tile>>();
        self.sync_hand(player_id);
        self.players[player_id].score += calc_score(&tiles_placed);
        self.broadcast(ServerMessage::SyncScore(
            player_id,
            self.players[player_id].score,
        ));
        self.validated_board = self.board.clone();
        self.successive_skipped_turns = 0;
    }

    fn on_game_over(&mut self) {
        self.broadcast(ServerMessage::GameOver);
        block_on(self.update_global_leaderboard());
    }

    fn reset_player_moves(&mut self) {
        let diff = self.board.difference(&self.validated_board);
        for pos in diff {
            self.broadcast(ServerMessage::TileRemoved(pos.into()));
        }
        self.board = self.validated_board.clone();
        self.sync_hand(self.active_player);
    }

    async fn update_global_leaderboard(&mut self) {
        for player in &self.players {
            self.leaderboard
                .add_score(&player.name, player.score)
                .await
                .ok();
        }
    }

    fn on_client_disconnected(&mut self, addr: SocketAddr) {
        if let Some(p) = self.connections.remove(&addr) {
            self.players[p].ws = None;
            self.broadcast(ServerMessage::PlayerDisconnected(p));
        }
    }

    fn broadcast(&self, s: ServerMessage) {
        for c in self.connections.values() {
            if let Some(ws) = &self.players[*c].ws {
                if let Err(e) = ws.unbounded_send(s.clone()) {
                    eprintln!(
                        "[{}] Failed to send broadcast to {}: {e}",
                        self.name, self.players[*c].name
                    );
                }
            }
        }
    }

    fn send(&self, player_id: usize, s: ServerMessage) {
        if let Some(p) = self.players[player_id].ws.as_ref() {
            if let Err(e) = p.unbounded_send(s) {
                eprintln!(
                    "[{}] Failed to send message to {}: {e}",
                    self.name, self.players[player_id].name
                );
            }
        } else {
            eprintln!("[{}] Tried sending message to inactive player", self.name);
        }
    }

    fn sync_hand(&mut self, player_id: usize) {
        self.send(
            player_id,
            ServerMessage::SyncHand(self.players[player_id].hand.tiles.clone()),
        );
    }
}

impl Default for Room {
    fn default() -> Self {
        Self {
            name: String::new(),
            connections: Default::default(),
            players: vec![],
            active_player: 0,
            has_started: false,
            board: Default::default(),
            validated_board: Default::default(),
            deck: Default::default(),
            leaderboard: Arc::new(InMemoryLeaderboard::default()),
            successive_skipped_turns: 0,
        }
    }
}

impl fmt::Debug for Room {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Room")
            .field("name", &self.name)
            .field("connections", &self.connections)
            .field("players", &self.players)
            .field("active_player", &self.active_player)
            .field("has_started", &self.has_started)
            .field("board", &self.board)
            .field("validated_board", &self.validated_board)
            .field("deck", &self.deck)
            .field("skipped_successive_turns", &self.successive_skipped_turns)
            .finish()
    }
}

type RoomPtr = Arc<Mutex<Room>>;

#[derive(Clone)]
pub struct RoomHandle {
    pub write: UnboundedSender<TaggedClientMessage>,
    pub room: RoomPtr,
}

impl RoomHandle {
    pub async fn run_room(&mut self, mut read: UnboundedReceiver<TaggedClientMessage>) {
        while let Some((addr, msg)) = read.next().await {
            if !self.room.lock().unwrap().on_message(addr, msg) {
                break;
            }
        }
    }
}

pub type Rooms = HashMap<String, RoomHandle>;

pub fn generate_room_name(rooms: &mut Rooms, room: RoomHandle) -> String {
    let mut rng = rand::thread_rng();
    loop {
        let name = Alphanumeric.sample_string(&mut rng, 5);
        if let Entry::Vacant(v) = rooms.entry(name.clone()) {
            room.room.lock().unwrap().name = name.clone();
            v.insert(room);
            return name;
        }
    }
}