/** The parsers for the chat and multiplayer protocol. The main parser is `message`.

 * # Protocol

 * All messages consist of `\n`-separated strings. The end of a message is

 * indicated by a double newline - `\n\n`.

 *

 * For example, a nullary command like PING will be actually sent as `PING\n\n`.

 * A unary command, such as `START_GAME nick` will be actually sent as `START_GAME\nnick\n\n`.

 */

use nom::{

    branch::alt,

    bytes::complete::{tag, tag_no_case, take_until, take_while},

    character::complete::{newline, not_line_ending},

    combinator::{map, peek},

    error::{ErrorKind, ParseError},

    multi::separated_list0,

    sequence::{delimited, pair, preceded, terminated, tuple},

    Err, IResult,

};

use std::{

    num::ParseIntError,

    str,

    str::{FromStr, Utf8Error},

};

use crate::types::{GameCfg, HedgehogInfo, ServerVar, TeamInfo, VoteType};

#[derive(Debug, PartialEq)]

pub struct HwProtocolError {}

impl HwProtocolError {

    pub fn new() -> Self {

        HwProtocolError {}

    }

}

impl<I> ParseError<I> for HwProtocolError {

    fn from_error_kind(_input: I, _kind: ErrorKind) -> Self {

        HwProtocolError::new()

    }

    fn append(_input: I, _kind: ErrorKind, _other: Self) -> Self {

        HwProtocolError::new()

    }

}

impl From<Utf8Error> for HwProtocolError {

    fn from(_: Utf8Error) -> Self {

        HwProtocolError::new()

    }

}

impl From<ParseIntError> for HwProtocolError {

    fn from(_: ParseIntError) -> Self {

        HwProtocolError::new()

    }

}

pub type HwResult<'a, O> = IResult<&'a [u8], O, HwProtocolError>;

fn end_of_message(input: &[u8]) -> HwResult<&[u8]> {

    tag("\n\n")(input)

}

fn convert_utf8(input: &[u8]) -> HwResult<&str> {

    match str::from_utf8(input) {

        Ok(str) => Ok((b"", str)),

        Err(utf_err) => Result::Err(Err::Failure(utf_err.into())),

    }

}

fn convert_from_str<T>(str: &str) -> HwResult<T>

where

    T: FromStr<Err = ParseIntError>,

{

    match T::from_str(str) {

        Ok(x) => Ok((b"", x)),

        Err(format_err) => Result::Err(Err::Failure(format_err.into())),

    }

}

fn str_line(input: &[u8]) -> HwResult<&str> {

    let (i, text) = not_line_ending(<&[u8]>::clone(&input))?;

    if i != input {

        Ok((i, convert_utf8(text)?.1))

    } else {

        Err(Err::Error(HwProtocolError::new()))

    }

}

fn a_line(input: &[u8]) -> HwResult<String> {

    map(str_line, String::from)(input)

}

fn cmd_arg(input: &[u8]) -> HwResult<String> {

    let delimiters = b" \n";

    let (i, str) = take_while(move |c| !delimiters.contains(&c))(<&[u8]>::clone(&input))?;

    if i != input {

        Ok((i, convert_utf8(str)?.1.to_string()))

    } else {

        Err(Err::Error(HwProtocolError::new()))

    }

}

fn u8_line(input: &[u8]) -> HwResult<u8> {

    let (i, str) = str_line(input)?;

    Ok((i, convert_from_str(str)?.1))

}

fn u16_line(input: &[u8]) -> HwResult<u16> {

    let (i, str) = str_line(input)?;

    Ok((i, convert_from_str(str)?.1))

}

fn u32_line(input: &[u8]) -> HwResult<u32> {

    let (i, str) = str_line(input)?;

    Ok((i, convert_from_str(str)?.1))

}

fn yes_no_line(input: &[u8]) -> HwResult<bool> {

    alt((

        map(tag_no_case(b"YES"), |_| true),

        map(tag_no_case(b"NO"), |_| false),

    ))(input)

}

fn opt_arg<'a>(input: &'a [u8]) -> HwResult<'a, Option<String>> {

    alt((

        map(peek(end_of_message), |_| None),

        map(preceded(tag("\n"), a_line), Some),

    ))(input)

}

fn spaces(input: &[u8]) -> HwResult<&[u8]> {

    preceded(tag(" "), take_while(|c| c == b' '))(input)

}

fn opt_space_arg<'a>(input: &'a [u8]) -> HwResult<'a, Option<String>> {

    alt((

        map(peek(end_of_message), |_| None),

        map(preceded(spaces, a_line), Some),

    ))(input)

}

fn hedgehog_array(input: &[u8]) -> HwResult<[HedgehogInfo; 8]> {

    fn hedgehog_line(input: &[u8]) -> HwResult<HedgehogInfo> {

        map(

            tuple((terminated(a_line, newline), a_line)),

            |(name, hat)| HedgehogInfo { name, hat },

        )(input)

    }

    let (i, (h1, h2, h3, h4, h5, h6, h7, h8)) = tuple((

        terminated(hedgehog_line, newline),

        terminated(hedgehog_line, newline),

        terminated(hedgehog_line, newline),

        terminated(hedgehog_line, newline),

        terminated(hedgehog_line, newline),

        terminated(hedgehog_line, newline),

        terminated(hedgehog_line, newline),

        hedgehog_line,

    ))(input)?;

    Ok((i, [h1, h2, h3, h4, h5, h6, h7, h8]))

}

fn voting(input: &[u8]) -> HwResult<VoteType> {

    alt((

        map(tag_no_case("PAUSE"), |_| VoteType::Pause),

        map(tag_no_case("NEWSEED"), |_| VoteType::NewSeed),

        map(

            preceded(pair(tag_no_case("KICK"), spaces), a_line),

            VoteType::Kick,

        ),

        map(

            preceded(pair(tag_no_case("HEDGEHOGS"), spaces), u8_line),

            VoteType::HedgehogsPerTeam,

        ),

        map(preceded(tag_no_case("MAP"), opt_space_arg), VoteType::Map),

    ))(input)

}

fn no_arg_message(input: &[u8]) -> HwResult<HwProtocolMessage> {

    fn message<'a>(

        name: &'a str,

        msg: HwProtocolMessage,

    ) -> impl Fn(&'a [u8]) -> HwResult<'a, HwProtocolMessage> {

        move |i| map(tag(name), |_| msg.clone())(i)

    }

    alt((

        message("PING", Ping),

        message("PONG", Pong),

        message("LIST", List),

        message("BANLIST", BanList),

        message("GET_SERVER_VAR", GetServerVar),

        message("TOGGLE_READY", ToggleReady),

        message("START_GAME", StartGame),

        message("TOGGLE_RESTRICT_JOINS", ToggleRestrictJoin),

        message("TOGGLE_RESTRICT_TEAMS", ToggleRestrictTeams),

        message("TOGGLE_REGISTERED_ONLY", ToggleRegisteredOnly),

    ))(input)

}

fn single_arg_message(input: &[u8]) -> HwResult<HwProtocolMessage> {

    fn message<'a, T, F, G>(

        name: &'a str,

        parser: F,

        constructor: G,

    ) -> impl FnMut(&'a [u8]) -> HwResult<'a, HwProtocolMessage>

    where

        F: Fn(&[u8]) -> HwResult<T>,

        G: Fn(T) -> HwProtocolMessage,

    {

        map(preceded(tag(name), parser), constructor)

    }

    alt((

        message("NICK\n", a_line, Nick),

        message("INFO\n", a_line, Info),

        message("CHAT\n", a_line, Chat),

        message("PART", opt_arg, Part),

        message("FOLLOW\n", a_line, Follow),

        message("KICK\n", a_line, Kick),

        message("UNBAN\n", a_line, Unban),

        message("EM\n", a_line, EngineMessage),

        message("TEAMCHAT\n", a_line, TeamChat),

        message("ROOM_NAME\n", a_line, RoomName),

        message("REMOVE_TEAM\n", a_line, RemoveTeam),

        message("ROUNDFINISHED", opt_arg, |_| RoundFinished),

        message("PROTO\n", u16_line, Proto),

        message("QUIT", opt_arg, Quit),

    ))(input)

}

fn cmd_message<'a>(input: &'a [u8]) -> HwResult<'a, HwProtocolMessage> {

    fn cmd_no_arg<'a>(

        name: &'a str,

        msg: HwProtocolMessage,

    ) -> impl Fn(&'a [u8]) -> HwResult<'a, HwProtocolMessage> {

        move |i| map(tag_no_case(name), |_| msg.clone())(i)

    }

    fn cmd_single_arg<'a, T, F, G>(

        name: &'a str,

        parser: F,

        constructor: G,

    ) -> impl FnMut(&'a [u8]) -> HwResult<'a, HwProtocolMessage>

    where

        F: Fn(&'a [u8]) -> HwResult<'a, T>,

        G: Fn(T) -> HwProtocolMessage,

    {

        map(

            preceded(pair(tag_no_case(name), spaces), parser),

            constructor,

        )

    }

    fn cmd_no_arg_message(input: &[u8]) -> HwResult<HwProtocolMessage> {

        alt((

            cmd_no_arg("STATS", Stats),

            cmd_no_arg("FIX", Fix),

            cmd_no_arg("UNFIX", Unfix),

            cmd_no_arg("REGISTERED_ONLY", ToggleServerRegisteredOnly),

            cmd_no_arg("SUPER_POWER", SuperPower),

        ))(input)

    }

    fn cmd_single_arg_message(input: &[u8]) -> HwResult<HwProtocolMessage> {

        alt((

            cmd_single_arg("RESTART_SERVER", |i| tag("YES")(i), |_| RestartServer),

            cmd_single_arg("DELEGATE", a_line, Delegate),

            cmd_single_arg("DELETE", a_line, Delete),

            cmd_single_arg("SAVEROOM", a_line, SaveRoom),

            cmd_single_arg("LOADROOM", a_line, LoadRoom),

            cmd_single_arg("GLOBAL", a_line, Global),

            cmd_single_arg("WATCH", u32_line, Watch),

            cmd_single_arg("VOTE", yes_no_line, Vote),

            cmd_single_arg("FORCE", yes_no_line, ForceVote),

            cmd_single_arg("INFO", a_line, Info),

            cmd_single_arg("MAXTEAMS", u8_line, MaxTeams),

            cmd_single_arg("CALLVOTE", voting, |v| CallVote(Some(v))),

        ))(input)

    }

    preceded(

        tag("CMD\n"),

        alt((

            cmd_no_arg_message,

            cmd_single_arg_message,

            map(tag_no_case("CALLVOTE"), |_| CallVote(None)),

            map(preceded(tag_no_case("GREETING"), opt_space_arg), Greeting),

            map(preceded(tag_no_case("PART"), opt_space_arg), Part),

            map(preceded(tag_no_case("QUIT"), opt_space_arg), Quit),

            map(

                preceded(

                    tag_no_case("SAVE"),

                    pair(preceded(spaces, cmd_arg), preceded(spaces, cmd_arg)),

                ),

                |(n, l)| Save(n, l),

            ),

            map(

                preceded(

                    tag_no_case("RND"),

                    alt((

                        map(peek(end_of_message), |_| vec![]),

                        preceded(spaces, separated_list0(spaces, cmd_arg)),

                    )),

                ),

                Rnd,

            ),

        )),

    )(input)

}

fn config_message<'a>(input: &'a [u8]) -> HwResult<'a, HwProtocolMessage> {

    fn cfg_single_arg<'a, T, F, G>(

        name: &'a str,

        parser: F,

        constructor: G,

    ) -> impl FnMut(&'a [u8]) -> HwResult<'a, GameCfg>

    where

        F: Fn(&[u8]) -> HwResult<T>,

        G: Fn(T) -> GameCfg,

    {

        map(preceded(pair(tag(name), newline), parser), constructor)

    }

    let (i, cfg) = preceded(

        tag("CFG\n"),

        alt((

            cfg_single_arg("THEME", a_line, GameCfg::Theme),

            cfg_single_arg("SCRIPT", a_line, GameCfg::Script),

            cfg_single_arg("MAP", a_line, GameCfg::MapType),

            cfg_single_arg("MAPGEN", u32_line, GameCfg::MapGenerator),

            cfg_single_arg("MAZE_SIZE", u32_line, GameCfg::MazeSize),

            cfg_single_arg("TEMPLATE", u32_line, GameCfg::Template),

            cfg_single_arg("FEATURE_SIZE", u32_line, GameCfg::FeatureSize),

            cfg_single_arg("SEED", a_line, GameCfg::Seed),

            cfg_single_arg("DRAWNMAP", a_line, GameCfg::DrawnMap),

            preceded(pair(tag("AMMO"), newline), |i| {

                let (i, name) = a_line(i)?;

                let (i, value) = opt_arg(i)?;

                Ok((i, GameCfg::Ammo(name, value)))

            }),

            preceded(

                pair(tag("SCHEME"), newline),

                map(

                    pair(

                        a_line,

                        alt((

                            map(peek(end_of_message), |_| None),

                            map(preceded(newline, separated_list0(newline, a_line)), Some),

                        )),

                    ),

                    |(name, values)| GameCfg::Scheme(name, values.unwrap_or_default()),

                ),

            ),

        )),

    )(input)?;

    Ok((i, Cfg(cfg)))

}

fn server_var_message(input: &[u8]) -> HwResult<HwProtocolMessage> {

    map(

        preceded(

            tag("SET_SERVER_VAR\n"),

            alt((

                map(preceded(tag("MOTD_NEW\n"), a_line), ServerVar::MOTDNew),

                map(preceded(tag("MOTD_OLD\n"), a_line), ServerVar::MOTDOld),

                map(

                    preceded(tag("LATEST_PROTO\n"), u16_line),

                    ServerVar::LatestProto,

                ),

            )),

        ),

        SetServerVar,

    )(input)

}

fn complex_message(input: &[u8]) -> HwResult<HwProtocolMessage> {

    alt((

        preceded(

            pair(tag("PASSWORD"), newline),

            map(pair(terminated(a_line, newline), a_line), |(pass, salt)| {

                Password(pass, salt)

            }),

        ),

        preceded(

            pair(tag("CHECKER"), newline),

            map(

                tuple((

                    terminated(u16_line, newline),

                    terminated(a_line, newline),

                    a_line,

                )),

                |(protocol, name, pass)| Checker(protocol, name, pass),

            ),

        ),

        preceded(

            pair(tag("CREATE_ROOM"), newline),

            map(pair(a_line, opt_arg), |(name, pass)| CreateRoom(name, pass)),

        ),

        preceded(

            pair(tag("JOIN_ROOM"), newline),

            map(pair(a_line, opt_arg), |(name, pass)| JoinRoom(name, pass)),

        ),

        preceded(

            pair(tag("ADD_TEAM"), newline),

            map(

                tuple((

                    terminated(a_line, newline),

                    terminated(u8_line, newline),

                    terminated(a_line, newline),

                    terminated(a_line, newline),

                    terminated(a_line, newline),

                    terminated(a_line, newline),

                    terminated(u8_line, newline),

                    hedgehog_array,

                )),

                |(name, color, grave, fort, voice_pack, flag, difficulty, hedgehogs)| {

                    AddTeam(Box::new(TeamInfo {

                        owner: String::new(),

                        name,

                        color,

                        grave,

                        fort,

                        voice_pack,

                        flag,

                        difficulty,

                        hedgehogs,

                        hedgehogs_number: 0,

                    }))

                },

            ),

        ),

        preceded(

            pair(tag("HH_NUM"), newline),

            map(

                pair(terminated(a_line, newline), u8_line),

                |(name, count)| SetHedgehogsNumber(name, count),

            ),

        ),

        preceded(

            pair(tag("TEAM_COLOR"), newline),

            map(

                pair(terminated(a_line, newline), u8_line),

                |(name, color)| SetTeamColor(name, color),

            ),

        ),

        preceded(

            pair(tag("BAN"), newline),

            map(

                tuple((

                    terminated(a_line, newline),

                    terminated(a_line, newline),

                    u32_line,

                )),

                |(name, reason, time)| Ban(name, reason, time),

            ),

        ),

        preceded(

            pair(tag("BAN_IP"), newline),

            map(

                tuple((

                    terminated(a_line, newline),

                    terminated(a_line, newline),

                    u32_line,

                )),

                |(ip, reason, time)| BanIp(ip, reason, time),

            ),

        ),

        preceded(

            pair(tag("BAN_NICK"), newline),

            map(

                tuple((

                    terminated(a_line, newline),

                    terminated(a_line, newline),

                    u32_line,

                )),

                |(nick, reason, time)| BanNick(nick, reason, time),

            ),

        ),

    ))(input)

}

pub fn malformed_message(input: &[u8]) -> HwResult<()> {

    map(terminated(take_until(&b"\n\n"[..]), end_of_message), |_| ())(input)

}

pub fn message(input: &[u8]) -> HwResult<HwProtocolMessage> {

    delimited(

        take_while(|c| c == b'\n'),

        alt((

            no_arg_message,

            single_arg_message,

            cmd_message,

            config_message,

            server_var_message,

            complex_message,

        )),

        end_of_message,

    )(input)

}