use nom::*;

use std::str;

use super::messages::{*, EngineMessage::*, UnsyncedEngineMessage::*, SyncedEngineMessage::*, ConfigEngineMessage::*, KeystrokeAction::*};

named!(length_specifier<&[u8], u16>, alt!(

    verify!(map!(take!(1), |a : &[u8]| a[0] as u16), |l| l < 64)

    | map!(take!(2), |a| (a[0] as u16 - 64) * 256 + a[1] as u16 + 64)

    )

);

named!(unrecognized_message<&[u8], EngineMessage>,

    do_parse!(rest >> (Unknown))

);

named!(string_tail<&[u8], String>, map!(map_res!(rest, str::from_utf8), String::from));

named!(synced_message<&[u8], SyncedEngineMessage>, alt!(

      do_parse!(tag!("+l") >> (Left(Press)))

));

named!(unsynced_message<&[u8], UnsyncedEngineMessage>, alt!(

      do_parse!(tag!("?") >> (Ping))

    | do_parse!(tag!("!") >> (Ping))

    | do_parse!(tag!("esay ") >> s: string_tail  >> (Say(s)))

));

named!(config_message<&[u8], ConfigEngineMessage>, alt!(

    do_parse!(tag!("C") >> (ConfigRequest))

));

named!(empty_message<&[u8], EngineMessage>,

    do_parse!(tag!("\0") >> (Empty))

);

named!(non_empty_message<&[u8], EngineMessage>, length_value!(length_specifier,

    alt!(

          map!(synced_message, |m| Synced(m, 0))

        | map!(unsynced_message, |m| Unsynced(m))

        | map!(config_message, |m| Config(m))

        | unrecognized_message

    )

));

named!(message<&[u8], EngineMessage>, alt!(

      empty_message

    | non_empty_message

    )

);

named!(pub extract_messages<&[u8], Vec<EngineMessage> >, many0!(complete!(message)));

#[test]

fn parse_length() {

    assert_eq!(length_specifier(b"\x01"), Ok((&b""[..], 1)));

    assert_eq!(length_specifier(b"\x00"), Ok((&b""[..], 0)));

    assert_eq!(length_specifier(b"\x3f"), Ok((&b""[..], 63)));

    assert_eq!(length_specifier(b"\x40\x00"), Ok((&b""[..], 64)));

    assert_eq!(length_specifier(b"\xff\xff"), Ok((&b""[..], 49215)));

}

#[test]

fn parse_synced_messages() {

    assert_eq!(message(b"\x04+l\x01\x01"), Ok((&b""[..], Synced(Left(Press), 0))));

}

#[test]

fn parse_unsynced_messages() {

    assert_eq!(message(b"\x0aesay hello"), Ok((&b""[..], Unsynced(Say(String::from("hello"))))));

}

#[test]

fn parse_incorrect_messages() {

    assert_eq!(message(b"\x00"), Ok((&b""[..], Empty)));

    assert_eq!(message(b"\x01\x00"), Ok((&b""[..], Unknown)));

}

#[test]

fn parse_config_messages() {

    assert_eq!(

        message(b"\x01C"),

        Ok((

            &b""[..],

            Config(ConfigRequest)

        ))

    );

}

#[test]

fn parse_test_general() {

    assert_eq!(string_tail(b"abc"), Ok((&b""[..], String::from("abc"))));

}