use std::{

    cmp::PartialEq,

    collections::HashMap,

    fmt::{Formatter, LowerHex},

    iter::Iterator,

};

use self::{

    actions::{Destination, DestinationGroup, PendingMessage},

    inanteroom::LoginResult,

    strings::*,

};

use crate::{

    core::{

        anteroom::HwAnteroom,

        room::RoomSave,

        server::HwServer,

        types::{ClientId, GameCfg, Replay, RoomId, TeamInfo},

    },

    protocol::messages::{

        global_chat, server_chat, HwProtocolMessage, HwProtocolMessage::EngineMessage,

        HwServerMessage, HwServerMessage::*,

    },

    utils,

};

use base64::encode;

use log::*;

use rand::{thread_rng, RngCore};

mod actions;

mod checker;

mod common;

mod inanteroom;

mod inlobby;

mod inroom;

mod strings;

#[derive(PartialEq, Debug)]

pub struct Sha1Digest([u8; 20]);

impl Sha1Digest {

    pub fn new(digest: [u8; 20]) -> Self {

        Self(digest)

    }

}

impl LowerHex for Sha1Digest {

    fn fmt(&self, f: &mut Formatter) -> Result<(), std::fmt::Error> {

        for byte in &self.0 {

            write!(f, "{:02x}", byte)?;

        }

        Ok(())

    }

}

impl PartialEq<&str> for Sha1Digest {

    fn eq(&self, other: &&str) -> bool {

        if other.len() != self.0.len() * 2 {

            false

        } else {

            #[inline]

            fn convert(c: u8) -> u8 {

                if c > b'9' {

                    c.wrapping_sub(b'a').saturating_add(10)

                } else {

                    c.wrapping_sub(b'0')

                }

            }

            other

                .as_bytes()

                .chunks_exact(2)

                .zip(&self.0)

                .all(|(chars, byte)| {

                    if let [hi, lo] = chars {

                        convert(*lo) == byte & 0x0f && convert(*hi) == (byte & 0xf0) >> 4

                    } else {

                        unreachable!()

                    }

                })

        }

    }

}

pub struct ServerState {

    pub server: HwServer,

    pub anteroom: HwAnteroom,

}

impl ServerState {

    pub fn new(clients_limit: usize, rooms_limit: usize) -> Self {

        Self {

            server: HwServer::new(clients_limit, rooms_limit),

            anteroom: HwAnteroom::new(clients_limit),

        }

    }

}

#[derive(Debug)]

pub struct AccountInfo {

    pub is_registered: bool,

    pub is_admin: bool,

    pub is_contributor: bool,

    pub server_hash: Sha1Digest,

}

pub enum IoTask {

    CheckRegistered {

        nick: String,

    },

    GetAccount {

        nick: String,

        protocol: u16,

        password_hash: String,

        client_salt: String,

        server_salt: String,

    },

    GetCheckerAccount {

        nick: String,

        password: String,

    },

    GetReplay {

        id: u32,

    },

    SaveRoom {

        room_id: RoomId,

        filename: String,

        contents: String,

    },

    LoadRoom {

        room_id: RoomId,

        filename: String,

    },

}

#[derive(Debug)]

pub enum IoResult {

    AccountRegistered(bool),

    Account(Option<AccountInfo>),

    CheckerAccount { is_registered: bool },

    Replay(Option<Replay>),

    SaveRoom(RoomId, bool),

    LoadRoom(RoomId, Option<String>),

}

pub struct Response {

    client_id: ClientId,

    messages: Vec<PendingMessage>,

    io_tasks: Vec<IoTask>,

    removed_clients: Vec<ClientId>,

}

impl Response {

    pub fn new(client_id: ClientId) -> Self {

        Self {

            client_id,

            messages: vec![],

            io_tasks: vec![],

            removed_clients: vec![],

        }

    }

    #[inline]

    pub fn is_empty(&self) -> bool {

        self.messages.is_empty() && self.removed_clients.is_empty() && self.io_tasks.is_empty()

    }

    #[inline]

    pub fn len(&self) -> usize {

        self.messages.len()

    }

    #[inline]

    pub fn client_id(&self) -> ClientId {

        self.client_id

    }

    #[inline]

    pub fn add(&mut self, message: PendingMessage) {

        self.messages.push(message)

    }

    #[inline]

    pub fn warn(&mut self, message: &str) {

        self.add(Warning(message.to_string()).send_self());

    }

    #[inline]

    pub fn error(&mut self, message: &str) {

        self.add(Error(message.to_string()).send_self());

    }

    #[inline]

    pub fn request_io(&mut self, task: IoTask) {

        self.io_tasks.push(task)

    }

    pub fn extract_messages<'a, 'b: 'a>(

        &'b mut self,

        server: &'a HwServer,

    ) -> impl Iterator<Item = (Vec<ClientId>, HwServerMessage)> + 'a {

        let client_id = self.client_id;

        self.messages.drain(..).map(move |m| {

            let ids = get_recipients(server, client_id, m.destination);

            (ids, m.message)

        })

    }

    pub fn remove_client(&mut self, client_id: ClientId) {

        self.removed_clients.push(client_id);

    }

    pub fn extract_removed_clients(&mut self) -> impl Iterator<Item = ClientId> + '_ {

        self.removed_clients.drain(..)

    }

    pub fn extract_io_tasks(&mut self) -> impl Iterator<Item = IoTask> + '_ {

        self.io_tasks.drain(..)

    }

}

impl Extend<PendingMessage> for Response {

    fn extend<T: IntoIterator<Item = PendingMessage>>(&mut self, iter: T) {

        for msg in iter {

            self.add(msg)

        }

    }

}

fn get_recipients(

    server: &HwServer,

    client_id: ClientId,

    destination: Destination,

) -> Vec<ClientId> {

    match destination {

        Destination::ToSelf => vec![client_id],

        Destination::ToId(id) => vec![id],

        Destination::ToIds(ids) => ids,

        Destination::ToAll { group, skip_self } => {

            let mut ids: Vec<_> = match group {

                DestinationGroup::All => server.iter_client_ids().collect(),

                DestinationGroup::Lobby => server.lobby_client_ids().collect(),

                DestinationGroup::Protocol(proto) => server.protocol_client_ids(proto).collect(),

                DestinationGroup::Room(id) => server.room_client_ids(id).collect(),

            };

            if skip_self {

                if let Some(index) = ids.iter().position(|id| *id == client_id) {

                    ids.remove(index);

                }

            }

            ids

        }

    }

}

pub fn handle(

    state: &mut ServerState,

    client_id: ClientId,

    response: &mut Response,

    message: HwProtocolMessage,

) {

    match message {

        HwProtocolMessage::Ping => response.add(Pong.send_self()),

        HwProtocolMessage::Pong => (),

        _ => {

            if state.anteroom.clients.contains(client_id) {

                match inanteroom::handle(state, client_id, response, message) {

                    LoginResult::Unchanged => (),

                    LoginResult::Complete => {

                        if let Some(client) = state.anteroom.remove_client(client_id) {

                            state.server.add_client(client_id, client);

                        }

                    }

                    LoginResult::Exit => {

                        state.anteroom.remove_client(client_id);

                        response.remove_client(client_id);

                    }

                }

            } else if state.server.has_client(client_id) {

                match message {

                    HwProtocolMessage::Quit(Some(msg)) => {

                        common::remove_client(

                            &mut state.server,

                            response,

                            "User quit: ".to_string() + &msg,

                        );

                    }

                    HwProtocolMessage::Quit(None) => {

                        common::remove_client(&mut state.server, response, "User quit".to_string());

                    }

                    HwProtocolMessage::Info(nick) => {

                        if let Some(client) = state.server.find_client(&nick) {

                            let admin_sign = if client.is_admin() { "@" } else { "" };

                            let master_sign = if client.is_master() { "+" } else { "" };

                            let room_info = match client.room_id {

                                Some(room_id) => {

                                    let room = state.server.room(room_id);

                                    let status = match room.game_info {

                                        Some(_) if client.teams_in_game == 0 => "(spectating)",

                                        Some(_) => "(playing)",

                                        None => "",

                                    };

                                    format!(

                                        "[{}{}room {}]{}",

                                        admin_sign, master_sign, room.name, status

                                    )

                                }

                                None => format!("[{}lobby]", admin_sign),

                            };

                            let info = vec![

                                client.nick.clone(),

                                "[]".to_string(),

                                utils::protocol_version_string(client.protocol_number).to_string(),

                                room_info,

                            ];

                            response.add(Info(info).send_self())

                        } else {

                            response.add(server_chat(USER_OFFLINE.to_string()).send_self())

                        }

                    }

                    HwProtocolMessage::ToggleServerRegisteredOnly => {

                        if !state.server.is_admin(client_id) {

                            response.warn(ACCESS_DENIED);

                        } else {

                            state

                                .server

                                .set_is_registered_only(!state.server.is_registered_only());

                            let msg = if state.server.is_registered_only() {

                                REGISTERED_ONLY_ENABLED

                            } else {

                                REGISTERED_ONLY_DISABLED

                            };

                            response.add(server_chat(msg.to_string()).send_all());

                        }

                    }

                    HwProtocolMessage::Global(msg) => {

                        if !state.server.is_admin(client_id) {

                            response.warn(ACCESS_DENIED);

                        } else {

                            response.add(global_chat(msg).send_all())

                        }

                    }

                    HwProtocolMessage::SuperPower => {

                        if state.server.enable_super_power(client_id) {

                            response.add(server_chat(SUPER_POWER.to_string()).send_self())

                        } else {

                            response.warn(ACCESS_DENIED);

                        }

                    }

                    HwProtocolMessage::Watch(id) => {

                        #[cfg(feature = "official-server")]

                        {

                            response.request_io(IoTask::GetReplay { id })

                        }

                        #[cfg(not(feature = "official-server"))]

                        {

                            response.warn(REPLAY_NOT_SUPPORTED);

                        }

                    }

                    _ => match state.server.get_room_control(client_id) {

                        None => inlobby::handle(&mut state.server, client_id, response, message),

                        Some(control) => inroom::handle(control, response, message),

                    },

                }

            }

        }

    }

}

pub fn handle_client_accept(

    state: &mut ServerState,

    client_id: ClientId,

    response: &mut Response,

    addr: [u8; 4],

    is_local: bool,

) {

    let ban_reason = Some(addr)

        .filter(|_| !is_local)

        .and_then(|a| state.anteroom.find_ip_ban(a));

    if let Some(reason) = ban_reason {

        response.add(HwServerMessage::Bye(reason).send_self());

        response.remove_client(client_id);

    } else {

        let mut salt = [0u8; 18];

        thread_rng().fill_bytes(&mut salt);

        state

            .anteroom

            .add_client(client_id, encode(&salt), is_local);

        response.add(HwServerMessage::Connected(utils::SERVER_VERSION).send_self());

    }

}

pub fn handle_client_loss(state: &mut ServerState, client_id: ClientId, response: &mut Response) {

    if state.anteroom.remove_client(client_id).is_none() {

        common::remove_client(&mut state.server, response, "Connection reset".to_string());

    }

}

pub fn handle_io_result(

    state: &mut ServerState,

    client_id: ClientId,

    response: &mut Response,

    io_result: IoResult,

) {

    match io_result {

        IoResult::AccountRegistered(is_registered) => {

            if !is_registered && state.server.is_registered_only() {

                response.add(Bye(REGISTRATION_REQUIRED.to_string()).send_self());

                response.remove_client(client_id);

            } else if is_registered {

                let client = &state.anteroom.clients[client_id];

                response.add(AskPassword(client.server_salt.clone()).send_self());

            } else if let Some(client) = state.anteroom.remove_client(client_id) {

                state.server.add_client(client_id, client);

                common::get_lobby_join_data(&state.server, response);

            }

        }

        IoResult::Account(None) => {

            response.add(Bye(AUTHENTICATION_FAILED.to_string()).send_self());

            response.remove_client(client_id);

        }

        IoResult::Account(Some(info)) => {

            response.add(ServerAuth(format!("{:x}", info.server_hash)).send_self());

            if let Some(mut client) = state.anteroom.remove_client(client_id) {

                client.is_registered = info.is_registered;

                client.is_admin = info.is_admin;

                client.is_contributor = info.is_contributor;

                state.server.add_client(client_id, client);

                common::get_lobby_join_data(&state.server, response);

            }

        }

        IoResult::CheckerAccount { is_registered } => {

            if is_registered {

                if let Some(client) = state.anteroom.remove_client(client_id) {

                    state.server.add_client(client_id, client);

                    response.add(LogonPassed.send_self());

                }

            } else {

                response.add(Bye(NO_CHECKER_RIGHTS.to_string()).send_self());

                response.remove_client(client_id);

            }

        }

        IoResult::Replay(Some(replay)) => {

            let client = state.server.client(client_id);

            let protocol = client.protocol_number;

            let start_msg = if protocol < 58 {

                RoomJoined(vec![client.nick.clone()])

            } else {

                ReplayStart

            };

            response.add(start_msg.send_self());

            common::get_room_config_impl(&replay.config, client_id, response);

            common::get_teams(replay.teams.iter(), client_id, response);

            response.add(RunGame.send_self());

            response.add(ForwardEngineMessage(replay.message_log).send_self());

            if protocol < 58 {

                response.add(Kicked.send_self());

            }

        }

        IoResult::Replay(None) => {

            response.warn(REPLAY_LOAD_FAILED);

        }

        IoResult::SaveRoom(_, true) => {

            response.add(server_chat(ROOM_CONFIG_SAVED.to_string()).send_self());

        }

        IoResult::SaveRoom(_, false) => {

            response.warn(ROOM_CONFIG_SAVE_FAILED);

        }

        IoResult::LoadRoom(room_id, Some(contents)) => {

            match state.server.set_room_saves(room_id, &contents) {