gtp 0.1.2

// Copyright (c) 2019 Weird Constructor <weirdconstructor@gmail.com>
// This is a part of gtp-rs. See README.md and COPYING for details.

/*!

A GTP (Go Text Protocol) controller implementation for Rust
===========================================================

This crate implements a parser, serializer for the Go Text Protocol and an
abstraction for an GTP engine controller.  You may just use the protocol
handling parts if you have an alternative GTP engine controller implementation.
But you are free to use the one provided by this crate.

See also:

* [GTP (Go Text Protocol)](https://www.lysator.liu.se/~gunnar/gtp/)

# Usage

A short overview of the API of this crate.

## Talking with a GTP engine

This is the basic usage on how to communicate with a GTP
engine like `GNU Go`, `Leela Zero` or `KataGo`:

```
use std::time::Duration;
use gtp::Command;
use gtp::controller::Engine;

let mut ctrl = Engine::new("/usr/bin/gnugo", &["--mode", "gtp"]);
assert!(ctrl.start().is_ok());

ctrl.send(Command::cmd("name", |e| e));
let resp = ctrl.wait_response(Duration::from_millis(500)).unwrap();
let ev = resp.entities(|ep| ep.s().s()).unwrap();
assert_eq!(ev[0].to_string(), "GNU");
assert_eq!(ev[1].to_string(), "Go");
assert_eq!(resp.text(), "GNU Go");
```

## Encoding GTP commands and Decoding GTP responses

Sending commands:

```
use gtp;
let mut c = gtp::Command::new("list_commands");
assert_eq!(c.to_string(), "list_commands\n");
```

Sending commands with entities:

```
use gtp::Command;
assert_eq!(Command::new("clear_board").to_string(), "clear_board\n");
assert_eq!(Command::new_with_args("boardsize", |eb| eb.i(19)).to_string(),
           "boardsize 19\n");
```

Receiving Responses:

```
let mut rp = gtp::ResponseParser::new();
rp.feed("= o");
rp.feed("k\n\n");
rp.feed("= A\nB\nC\n\n= white b3 b T19\n\n");

assert_eq!(rp.get_response().unwrap().text(), "ok");
assert_eq!(rp.get_response().unwrap().text(), "A\nB\nC");

// And processing entities in the response:
let ents = rp.get_response().unwrap()
             .entities(|ep| ep.color().vertex().mv()).unwrap();
assert_eq!(ents[0].to_string(), "w");
assert_eq!(ents[1].to_string(), "B3");
assert_eq!(ents[2].to_string(), "b T19");

// And processing entities in the response more complicatedly:
rp.feed("= white b3\n\n");

let mut ep = gtp::EntityParser::new(&rp.get_response().unwrap().text());
let res = ep.mv().result().unwrap();
assert_eq!(res[0].to_string(), "w B3");

match res[0] {
    gtp::Entity::Move((color, (h, v))) => {
        assert_eq!(color, gtp::Color::W);
        assert_eq!(h, 2);
        assert_eq!(v, 3);
    },
    _ => {},
}
```

# License

This project is licensed under the GNU General Public License Version 3 or
later.

## Why GPL?

Picking a license for my code bothered me for a long time. I read many
discussions about this topic. Read the license explanations. And discussed
this matter with other developers.

First about _why I write code for free_ at all:

- It's my passion to write computer programs. In my free time I can
write the code I want, when I want and the way I want. I can freely
allocate my time and freely choose the projects I want to work on.
- To help a friend or member of my family.
- To solve a problem I have.

Those are the reasons why I write code for free. Now the reasons
_why I publish the code_, when I could as well keep it to myself:

- So that it may bring value to users and the free software community.
- Show my work as an artist.
- To get into contact with other developers.
- And it's a nice change to put some more polish on my private projects.

Most of those reasons don't yet justify GPL. The main point of the GPL, as far
as I understand: The GPL makes sure the software stays free software until
eternity. That the user of the software always stays in control. That the users
have _at least the means_ to adapt the software to new platforms or use cases.
Even if the original authors don't maintain the software anymore.
It ultimately prevents _"vendor lock in"_. I really dislike vendor lock in,
especially as developer. Especially as developer I want and need to stay
in control of the computers I use.

Another point is, that my work has a value. If I give away my work without
_any_ strings attached, I effectively work for free. Work for free for
companies. I would compromise the price I can demand for my skill, workforce
and time.

This makes two reasons for me to choose the GPL:

1. I do not want to support vendor lock in scenarios. At least not for free.
   I want to prevent those when I have a choice.
   And before you ask, yes I work for a company that sells closed source
   software. I am not happy about the closed source fact.
   But it pays my bills and gives me the freedom to write free software
   in my free time.
2. I don't want to low ball my own wage and prices by giving away free software
   with no strings attached (for companies).

## If you need a permissive or private license (MIT)

Please contact me if you need a different license and really want to use
my code. As long as I am the only author, I can change the license.
We might find an agreement.

# Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in gtp-rs by you, shall be licensed as GPLv3 or later,
without any additional terms or conditions.

# Authors

* Weird Constructor <weirdconstructor@gmail.com>
  (You may find me as `WeirdConstructor` on the Rust Discord.)

*/

pub mod controller;
pub mod detached_command;

/// The color of a move
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Color {
    W,
    B,
}

/// Helper class for constructing an Entity data structure.
///
/// Use it like this:
/// ```
/// use gtp;
/// let mut eb = gtp::EntityBuilder::new();
/// eb.v((19, 19));
/// assert_eq!(eb.build().to_string(), "T19");
/// ```
///
/// Alternatively you can use the [`entity`](fn.entity.html) function:
///
/// ```
/// use gtp;
/// let ent = gtp::entity(|eb| eb.v((19, 19)));
/// assert_eq!(ent.to_string(), "T19");
/// ```
#[derive(Debug, Clone, PartialEq, Default)]
pub struct EntityBuilder {
    list:    Vec<Entity>,
    current: Option<Entity>,
}

/// Entity building helper function.
///
/// If no entity was constructed in the callback an entity
/// with an empty string is returned.
///
/// ```
/// use gtp;
/// assert_eq!(gtp::entity(|eb| eb.v_pass()).to_string(), "pass");
/// ```
pub fn entity<T>(f: T) -> Entity
    where T: Fn(&mut EntityBuilder) -> &mut EntityBuilder {
    let mut b = EntityBuilder::new();
    f(&mut b);
    if b.has_any() {
        b.build()
    } else {
        Entity::String(String::from(""))
    }
}

impl EntityBuilder {
    /// Constructs a new entity builder.
    ///
    /// Please note there are helper functions like [`entity`](fn.entity.html)
    /// Or [`args` of Command](struct.Command.html#method.args).
    pub fn new() -> EntityBuilder {
        EntityBuilder::default()
    }

    pub fn i(&mut self, i: u32) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Int(i));
        self
    }

    pub fn f(&mut self, f: f32) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Float(f));
        self
    }

    pub fn s(&mut self, s: &str) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::String(s.to_string()));
        self
    }

    pub fn v_pass(&mut self) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Vertex((0, 0)));
        self
    }

    pub fn v(&mut self, v: (i32, i32)) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Vertex(v));
        self
    }

    pub fn w(&mut self) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Color(Color::W));
        self
    }

    pub fn b(&mut self) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Color(Color::B));
        self
    }

    pub fn bool(&mut self, b: bool) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Boolean(b));
        self
    }

    pub fn color(&mut self, b: bool) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Color(if b { Color::W } else { Color::B }));
        self
    }

    pub fn mv_w(&mut self, v: (i32, i32)) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Move((Color::W, v)));
        self
    }

    pub fn mv_b(&mut self, v: (i32, i32)) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Move((Color::B, v)));
        self
    }

    pub fn mv(&mut self, color: bool, v: (i32, i32)) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::Move((if color { Color::W } else { Color::B }, v)));
        self
    }

    pub fn list(&mut self) -> &mut Self {
        if self.current.is_some() { self.list.push(self.current.take().unwrap()); }

        self.current = Some(Entity::List(self.list.clone()));
        self.list = Vec::new();
        self
    }

    pub fn has_any(&self) -> bool { self.current.is_some() }

    pub fn build(&self) -> Entity {
        self.current.clone().expect("Did not setup any entitiy in EntityBuilder!")
    }
}

#[derive(Debug, Clone, PartialEq)]
pub enum Entity {
    Int(u32),
    Float(f32),
    String(String),
    Vertex((i32, i32)),
    Color(Color),
    Move((Color, (i32, i32))),
    Boolean(bool),
    List(Vec<Entity>),
}

fn gen_move_char(i: u32) -> char {
    let c = if i <= 8 {
        ('A' as u32) + (i - 1)
    } else {
        ('A' as u32) + i
    };
    if let Some(c) = std::char::from_u32(c) {
        c
    } else {
        'Z'
    }
}

impl std::fmt::Display for Entity {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        match self {
            Entity::Int(i)      => write!(f, "{}", i),
            Entity::Float(n)    => write!(f, "{}", n),
            Entity::String(s)   => write!(f, "{}", s),
            Entity::Vertex((h, v)) => {
                let mut s = String::from("");
                if *h <= 0 || *v <= 0 {
                    s += &"pass".to_string();
                } else {
                    s += &format!("{}", gen_move_char(*h as u32));
                    s += &format!("{}", v);
                }
                write!(f, "{}", s)
            },
            Entity::Color(Color::W) => write!(f, "w"),
            Entity::Color(Color::B) => write!(f, "b"),
            Entity::Move((Color::W, (h, v))) => {
                let mut s = String::from("");
                if *h <= 0 || *v <= 0 {
                    s += &"w pass".to_string();
                } else {
                    s += &format!("w {}", gen_move_char(*h as u32));
                    s += &format!("{}", v);
                }
                write!(f, "{}", s)
            },
            Entity::Move((Color::B, (h, v))) => {
                let mut s = String::from("");
                if *h <= 0 || *v <= 0 {
                    s += &"b pass".to_string();
                } else {
                    s += &format!("b {}", gen_move_char(*h as u32));
                    s += &format!("{}", v);
                }
                write!(f, "{}", s)
            },
            Entity::Boolean(true) => write!(f, "true"),
            Entity::Boolean(false) => write!(f, "false"),
            Entity::List(vec) => {

                let mut s = String::from("");
                if vec.is_empty() { return write!(f, ""); }

                // Try to handle at least 2 dimensional lists
                // on output correctly:
                let sep = if let Entity::List(_) = vec[0] {
                    "\n"
                } else {
                    " "
                };

                for (i, e) in vec.iter().enumerate() {
                    if i > 0 { s += sep; }
                    s += &e.to_string();
                }
                write!(f, "{}", s)
            }
        }
    }
}

#[derive(Debug, Clone, PartialEq)]
pub struct EntityParser {
    buffer:         String,
    entities:       Vec<Entity>,
    parse_error:    bool,
}

impl std::iter::Iterator for EntityParser {
    type Item = String;

    fn next(&mut self) -> Option<String> {
        self.buffer = self.buffer.chars().skip_while(|c| *c == ' ' || *c == '\n').collect();

        let mut s = String::from("");
        let mut skip_count = 0;
        for c in self.buffer.chars() {
            skip_count += 1;
            if c == ' ' || c == '\n' { break; }
            s.push(c);
        }

        self.buffer = self.buffer.chars().skip(skip_count).collect();

        if s.is_empty() { None } else { Some(s) }
    }

}

impl EntityParser {
    pub fn new(s: &str) -> Self {
        EntityParser {
            buffer:     String::from(s),
            entities:   Vec::new(),
            parse_error: false,
        }
    }

    pub fn result(&self) -> Option<Vec<Entity>> {
        if self.parse_error { return None; }
        Some(self.entities.clone())
    }

    pub fn is_eof(&self) -> bool { self.buffer.is_empty() }
    pub fn had_parse_error(&self) -> bool { self.parse_error }

    pub fn s(&mut self) -> &mut Self {
        let s = self.next().unwrap_or_else(|| String::from(""));
        if s.is_empty() { self.parse_error = true; return self; }
        self.entities.push(Entity::String(s));
        self
    }

    pub fn i(&mut self) -> &mut Self {
        let s = self.next().unwrap_or_else(|| String::from(""));
        if let Ok(i) = s.parse::<u32>() {
            self.entities.push(Entity::Int(i));
        } else {
            self.parse_error = true;
        }
        self
    }

    pub fn f(&mut self) -> &mut Self {
        let s = self.next().unwrap_or_else(|| String::from(""));
        if let Ok(f) = s.parse::<f32>() {
            self.entities.push(Entity::Float(f));
        } else {
            self.parse_error = true;
        }
        self
    }

    pub fn color(&mut self) -> &mut Self {
        let s = self.next().unwrap_or_else(|| String::from(""));
        let s = s.to_lowercase();
        if s == "w" || s == "white" { self.entities.push(Entity::Color(Color::W)); return self; }
        if s == "b" || s == "black" { self.entities.push(Entity::Color(Color::B)); return self; }
        self.parse_error = true;
        self
    }

    pub fn vertex(&mut self) -> &mut Self {
        let s = self.next().unwrap_or_else(|| String::from(""));
        let s = s.to_uppercase();
        if s == "PASS" { self.entities.push(Entity::Vertex((0, 0))); return self; }
        if s.len() < 2 || s.len() > 3 {
            self.parse_error = true;
            return self;
        }

        let h = s.chars().nth(0).unwrap();
        if !h.is_ascii_alphabetic() {
            self.parse_error = true;
            return self;
        }
        let h = h as u32;
        let mut h = (h - ('A' as u32)) + 1;
        if h > 8 { h -= 1; }

        let v : String = s.chars().skip(1).collect();
        if let Ok(v) = i32::from_str_radix(&v, 10) {
            self.entities.push(Entity::Vertex((h as i32, v)));
        } else {
            self.parse_error = true;
        }

        self
    }

    pub fn mv(&mut self) -> &mut Self {
        self.color();
        if self.parse_error { return self; }
        self.vertex();
        if self.parse_error { self.entities.pop(); }

        let m = self.entities.pop().unwrap();
        let c = self.entities.pop().unwrap();

        if let Entity::Vertex((h, v)) = m {
            if let Entity::Color(c) = c {
                self.entities.push(Entity::Move((c, (h, v))));
                return self;
            }
        }

        self.parse_error = true;
        self
    }

    pub fn bool(&mut self) -> &mut Self {
        let s = self.next().unwrap_or_else(|| String::from(""));
        let s = s.to_uppercase();
        if s == "TRUE" { self.entities.push(Entity::Boolean(true)); return self; }
        if s == "FALSE" { self.entities.push(Entity::Boolean(false)); return self; }
        self.parse_error = true;
        self
    }
}

/// Representation of a GTP controller to engine command.
#[derive(Debug, Clone, PartialEq)]
pub struct Command {
    id:     Option<u32>,
    name:   String,
    args:   Option<Entity>,
}

impl Command {
    /// Constructs a new GTP controller command to be sent to the
    /// GTP engine.
    ///
    /// ```
    /// use gtp;
    ///
    /// let mut c = gtp::Command::new("list_commands");
    /// c.args(|eb| eb.i(10).f(10.20).s("OK").list());
    /// // send with:
    /// let gtp_bytes = c.to_bytes();
    /// // or if you need the string:
    /// let gtp_str = c.to_string();
    /// ```
    pub fn new(name: &str) -> Command {
        Command {
            name: String::from(name),
            id:   None,
            args: None,
        }
    }

    /// Builds a new GTP engine command ready with the arguments:
    ///
    /// ```
    /// use gtp;
    /// assert_eq!(
    ///     gtp::Command::new_with_args("boardsize", |eb| eb.i(9)).to_string(),
    ///     "boardsize 9\n");
    /// ```
    pub fn new_with_args<T>(name: &str, args: T) -> Command
        where T: Fn(&mut EntityBuilder) -> &mut EntityBuilder {
        let mut cmd = Self::new(name);
        cmd.args(args);
        cmd
    }

    /// Shorthand for `Command::new_with_args`.
    pub fn cmd<T>(name: &str, args: T) -> Command
        where T: Fn(&mut EntityBuilder) -> &mut EntityBuilder {
        Command::new_with_args(name, args)
    }

    /// Sets the ID of the command.
    ///
    /// ```
    /// use gtp;
    ///
    /// let mut c = gtp::Command::new("list_commands");
    /// c.set_id(12);
    /// assert_eq!(c.to_string(), "12 list_commands\n");
    /// ```
    pub fn set_id(&mut self, id: u32) {
        self.id = Some(id);
    }

    /// Helper function to construct Entity arguments for this Command.
    ///
    /// ```
    /// use gtp;
    ///
    /// let mut c = gtp::Command::new("list_commands");
    /// c.args(|eb| eb.i(10).f(10.20).s("OK").list());
    /// assert_eq!(c.to_string(), "list_commands 10 10.2 OK\n");
    /// ```
    pub fn args<T>(&mut self, f: T)
        where T: Fn(&mut EntityBuilder) -> &mut EntityBuilder {
        let mut b = EntityBuilder::new();
        f(&mut b);
        if b.has_any() {
            self.set_args(&b.build());
        }
    }


    /// Function to set Entity arguments:
    ///
    /// ```
    /// use gtp;
    ///
    /// let mut c = gtp::Command::new("list_commands");
    /// c.set_args(&gtp::entity(|eb| eb.v((19, 19))));
    /// ```
    pub fn set_args(&mut self, args: &Entity) {
        self.args = Some(args.clone());
    }

    /// Generates a String representation of the GTP command.
    pub fn to_string(&self) -> String {
        let mut out = String::from("");
        if self.id.is_some() {
            out += &format!("{}", self.id.unwrap());
            out += " ";
        }
        out += &self.name;

        if self.args.is_some() {
            out += " ";
            out += &self.args.as_ref().unwrap().to_string();
        }
        out += "\n";
        out
    }

    /// Generates a byte vector representation of the GTP command,
    /// ready to be sent to another process.
    #[allow(dead_code)]
    pub fn to_bytes(&self) -> Vec<u8> {
        Vec::from(self.to_string().as_bytes())
    }
}

/// Represents a GTP response from the GTP engine.
#[derive(Debug, Clone, PartialEq)]
pub enum Response {
    Error((Option<u32>, String)),
    Result((Option<u32>, String)),
}

#[derive(Debug)]
pub enum ResponseParseError {
    NoInput,
    BadEntityInput,
    BadResponse
}

impl Response {
    /// Returns the complete response text, which you may feed into EntityParser.
    ///
    /// See also the `Response::entities` method.
    pub fn text(&self) -> String {
        match self {
            Response::Error((_, t))  => t.clone(),
            Response::Result((_, t)) => t.clone(),
        }
    }

    /// Returns the ID of the response. Returns 0 if no
    /// ID was submitted.
    pub fn id_0(&self) -> u32 {
        match self {
            Response::Error((None, _))          => 0,
            Response::Result((None, _))         => 0,
            Response::Error((Some(id), _))      => *id,
            Response::Result((Some(id), _))     => *id,
        }
    }

    /// Parses entities from a Response
    ///
    /// ```
    /// let mut rp = gtp::ResponseParser::new();
    /// rp.feed("= 10 w H6\n\n");
    /// let entity_vec =
    ///     rp.get_response().unwrap()
    ///       .entities(|ep| ep.i().mv())
    ///       .unwrap();
    /// assert_eq!(format!("{:?}", entity_vec),
    ///            "[Int(10), Move((W, (8, 6)))]");
    ///
    /// if let gtp::Entity::Int(i) = entity_vec[0] {
    ///     assert_eq!(i, 10);
    /// }
    /// ```
    ///
    /// Here is an example for how to read a variable length list:
    ///
    /// ```
    /// let mut rp = gtp::ResponseParser::new();
    /// rp.feed("= A\nB\nC\nD\nE\n\n");
    /// let entity_vec =
    ///     rp.get_response().unwrap()
    ///       .entities(|ep| { while !ep.is_eof() { ep.s(); }; ep })
    ///       .unwrap();
    /// assert_eq!(format!("{:?}", entity_vec),
    ///            "[String(\"A\"), String(\"B\"), String(\"C\"), String(\"D\"), String(\"E\")]");
    /// ```
    pub fn entities<T>(&self, parse_fn: T) -> Result<Vec<Entity>, ResponseParseError>
        where T: Fn(&mut EntityParser) -> &mut EntityParser  {

        let response = match self {
            Response::Result((_, res)) => res.to_string(),
            Response::Error((_, res))  => res.to_string(),
        };

        let mut ep = EntityParser::new(&response);
        parse_fn(&mut ep);
        if ep.had_parse_error() {
            return Err(ResponseParseError::BadEntityInput);
        }
        Ok(ep.result().unwrap())
    }
}

/// A parser for a GTP response.
#[derive(Debug, Clone, PartialEq, Default)]
pub struct ResponseParser {
    buffer:     String,
}

/// Error for the ResponseParser.
#[derive(Debug, Clone, PartialEq)]
pub enum ResponseError {
    IncompleteResponse,
    BadResponse(String),
}

fn refine_input(s: String) -> String {
    let mut ret : String =
        s.chars()
         .filter(|c| *c != '\r')
         .map(|c| if c == '\x09' { ' ' } else { c })
         .skip_while(|c| *c == '\n' || *c == ' ' || *c == '\x09')
         .collect();

    loop {
        let comment_pos = ret.find('#');
        if comment_pos.is_some() {
            let end_comment_pos = (&ret[comment_pos.unwrap()..]).find('\n');
            if end_comment_pos.is_some() {
                ret = String::from(&ret[..comment_pos.unwrap()])
                      + &ret[comment_pos.unwrap() + end_comment_pos.unwrap() + 1..];
            } else {
                break;
            }
        } else {
            break;
        }
    }

    ret
}

impl ResponseParser {
    /// Constructs a new GTP engine response parser.
    ///
    /// ```
    /// let mut rp = gtp::ResponseParser::new();
    /// rp.feed("= ok\n\n");
    /// let s = rp.get_response().unwrap();
    /// assert_eq!(format!("{:?}", s), "Result((None, \"ok\"))");
    /// ```
    pub fn new() -> ResponseParser {
        ResponseParser::default()
    }

    /// Feed the response text to the parser.
    pub fn feed(&mut self, s: &str) {
        self.buffer += s;
    }

    /// Tries to read the response from the until now feeded input.
    ///
    /// Returns `Ok(None)` if no response is available yet.
    /// Returns an error if the response is malformed.
    /// Returns the Ok([`Response`](enum.Response.html)) if one could be read.
    #[allow(unused_assignments, clippy::collapsible_if)]
    pub fn get_response(&mut self) -> Result<Response, ResponseError> {
        self.buffer = refine_input(self.buffer.to_string());
        if self.buffer.is_empty() { return Err(ResponseError::IncompleteResponse); }

        let is_error = self.buffer.chars().nth(0).unwrap() != '=';

        let mut id_str   = String::from("");
        let mut response = String::from("");

        let mut read_id =
            !(   self.buffer.len() > 1
              && self.buffer.chars().nth(1).unwrap() == ' ');

        let mut found_start      = false;
        let mut found_end        = false;
        let mut last_was_newline = false;
        let mut skip_count       = 1;

        for c in self.buffer.chars().skip(1) {
            skip_count += 1;

            if read_id {
                match c {
                    c if c.is_ascii_digit() => {
                        id_str.push(c);
                    },
                    ' ' => {
                        found_start = true;
                        read_id     = false;
                    },
                    _ => { return Err(ResponseError::BadResponse(self.buffer.to_string())); }
                }
            } else if !found_start {
                if c == ' ' {
                    found_start = true;
                } else {
                    return Err(ResponseError::BadResponse(self.buffer.to_string()));
                }
            } else {
                if c == '\n' {
                    if last_was_newline {
                        found_end = true;
                        break;
                    } else {
                        last_was_newline = true;
                    }
                } else {
                    if last_was_newline {
                        response.push('\n');
                    }
                    last_was_newline = false;
                    response.push(c);
                }
            }
        }

        if found_end {
            self.buffer = self.buffer.chars().skip(skip_count).collect();
        } else {
            return Err(ResponseError::IncompleteResponse);
        }

        let id = if !id_str.is_empty() {
            if let Ok(cn) = u32::from_str_radix(&id_str, 10) {
                Some(cn)
            } else {
                None
            }
        } else {
            None
        };

        if is_error {
            Ok(Response::Error((id, response)))
        } else {
            Ok(Response::Result((id, response)))
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn check_printing() {
        assert_eq!(Entity::Int(10).to_string(),                      "10");
        assert_eq!(Entity::Float(10.12).to_string(),                 "10.12");
        assert_eq!(Entity::String(String::from("Test")).to_string(), "Test");
        assert_eq!(Entity::Vertex((-1, -1)).to_string(),             "pass");
        assert_eq!(Entity::Vertex((1, 1)).to_string(),               "A1");
        assert_eq!(Entity::Vertex((19, 19)).to_string(),             "T19");
        assert_eq!(Entity::Vertex((8, 19)).to_string(),              "H19");
        assert_eq!(Entity::Vertex((9, 19)).to_string(),              "J19");
        assert_eq!(Entity::Color(Color::W).to_string(),              "w");
        assert_eq!(Entity::Color(Color::B).to_string(),              "b");
        assert_eq!(Entity::Move((Color::B, (0, 0))).to_string(),     "b pass");
        assert_eq!(Entity::Move((Color::W, (0, 0))).to_string(),     "w pass");
        assert_eq!(Entity::Move((Color::B, (8, 1))).to_string(),     "b H1");
        assert_eq!(Entity::Move((Color::W, (9, 1))).to_string(),     "w J1");
        assert_eq!(Entity::Move((Color::B, (19, 1))).to_string(),    "b T1");
        assert_eq!(Entity::Move((Color::W, (19, 19))).to_string(),   "w T19");
        assert_eq!(Entity::Boolean(true).to_string(),                "true");
        assert_eq!(Entity::Boolean(false).to_string(),               "false");
        assert_eq!(Entity::List(vec![Entity::Int(1), Entity::Int(2)]).to_string(),
                   "1 2");
        assert_eq!(Entity::List(vec![
                        Entity::List(vec![Entity::Int(1), Entity::Int(2)]),
                        Entity::List(vec![Entity::Int(3), Entity::Int(4)])]).to_string(),
                   "1 2\n3 4");
    }

    #[test]
    fn check_entity_builder() {
        assert_eq!(entity(|eb| eb.i(10)).to_string(),           "10");
        assert_eq!(entity(|eb| eb.f(10.12)).to_string(),        "10.12");
        assert_eq!(entity(|eb| eb.s("ok")).to_string(),         "ok");
        assert_eq!(entity(|eb| eb.v_pass()).to_string(),        "pass");
        assert_eq!(entity(|eb| eb.v((19, 19))).to_string(),     "T19");
        assert_eq!(entity(|eb| eb.bool(false)).to_string(),     "false");
        assert_eq!(entity(|eb| eb.w()).to_string(),             "w");
        assert_eq!(entity(|eb| eb.b()).to_string(),             "b");
        assert_eq!(entity(|eb| eb.color(true)).to_string(),     "w");
        assert_eq!(entity(|eb| eb.color(false)).to_string(),    "b");
        assert_eq!(entity(|eb| eb.mv_w((8, 8))).to_string(),    "w H8");
        assert_eq!(entity(|eb| eb.mv_b((8, 8))).to_string(),    "b H8");
        assert_eq!(entity(|eb| eb.mv(true, (8, 8))).to_string(),"w H8");
        assert_eq!(entity(|eb| eb.mv_w((8, 8)).mv_b((9, 9)).list()).to_string(),
                   "w H8 b J9");
    }

    #[test]
    fn check_entity_parser() {
        let mut ep = EntityParser::new("10 10.2 ok WHite t19 false");
        ep.i().f().s().mv().bool();
        let res = ep.result().unwrap();
        assert_eq!(res[0].to_string(), "10");
        assert_eq!(res[1].to_string(), "10.2");
        assert_eq!(res[2].to_string(), "ok");
        assert_eq!(res[3].to_string(), "w T19");
        assert_eq!(res[4].to_string(), "false");
    }

    #[test]
    fn check_eof() {
        let mut ep = EntityParser::new("t19 b10 a1 d2");
        while !ep.is_eof() {
            ep.vertex();
        }
        let res = ep.result().unwrap();
        assert_eq!(res[3].to_string(), "D2");
    }

    #[test]
    fn check_build_command() {
        let mut c = Command::new("list_commands");
        c.args(|eb| eb.i(10).f(10.20).s("OK").list());
        assert_eq!(c.to_string(), "list_commands 10 10.2 OK\n");

        assert_eq!(
            Command::new_with_args("boardsize", |eb| eb.i(9)).to_string(),
            "boardsize 9\n");
    }

    #[test]
    fn check_setid_command() {
        let mut c = Command::new("list_commands");
        c.set_id(12);
        assert_eq!(c.to_string(), "12 list_commands\n");
    }

    fn must_parse(s: &str) -> Response {
        let mut rp = ResponseParser::new();
        rp.feed(s);
        let s = rp.get_response().unwrap();
        s
    }

    #[test]
    fn check_parser() {
        {
            let mut rp = ResponseParser::new();
            rp.feed("= ok\n\n");
            let s = rp.get_response().unwrap();
            assert_eq!(format!("{:?}", s), "Result((None, \"ok\"))");
        }

        {
            let mut rp = ResponseParser::new();
            rp.feed("= ok\n\n");
            rp.feed("= \n\n");

            assert_eq!(rp.get_response().unwrap().text(), "ok");
        }

        {
            let mut rp = ResponseParser::new();
            rp.feed("= ok\n");

            assert!(rp.get_response().is_err());
        }

        let res = must_parse("= ok\nfoobar\n\n");
        assert_eq!(res.text(), "ok\nfoobar");

        assert_eq!(format!("{:?}", must_parse("=10 ok\n\n")),
                   "Result((Some(10), \"ok\"))");

        assert_eq!(format!("{:?}", must_parse("#\n=10 ok\n\n")),
                   "Result((Some(10), \"ok\"))");

        assert_eq!(format!("{:?}", must_parse("= ok\n\n")),
                   "Result((None, \"ok\"))");

        assert_eq!(format!("{:?}", must_parse("= \n\n")),
                   "Result((None, \"\"))");

        assert_eq!(format!("{:?}", must_parse("= \na\nb\nc\n\n")),
                   "Result((None, \"\\na\\nb\\nc\"))");

        assert_eq!(format!("{:?}", must_parse("= foo # all ok\n\n\n")),
                   "Result((None, \"foo \"))");

        assert_eq!(format!("{:?}", must_parse("= \na\nb fooo #fewiofw jfw\nc\n\n")),
                   "Result((None, \"\\na\\nb fooo c\"))");
    }

}