use std::str;

macro_rules! eof_slice (

  ($i:expr,) => (

    {

      if ($i).input_len() == 0 {

        Ok(($i, $i))

      } else {

        Err(Error(error_position!($i, ErrorKind::Eof::<u32>)))

      }

    }

  );

);

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

    do_parse!(rest >> (Unknown))

);

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

named!(length_without_timestamp<&[u8], usize>,

    map_opt!(rest_len, |l| if l > 2 { Some(l - 2) } else { None } )

);

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

      | do_parse!(tag!("l") >> ( Left(Release) ))

      | do_parse!(tag!("R") >> ( Right(Press) ))

      | do_parse!(tag!("r") >> ( Right(Release) ))

      | do_parse!(tag!("U") >> ( Up(Press) ))

      | do_parse!(tag!("u") >> ( Up(Release) ))

      | do_parse!(tag!("D") >> ( Down(Press) ))

      | do_parse!(tag!("d") >> ( Down(Release) ))

      | do_parse!(tag!("Z") >> ( Precise(Press) ))

      | do_parse!(tag!("z") >> ( Precise(Release) ))

      | do_parse!(tag!("A") >> ( Attack(Press) ))

      | do_parse!(tag!("a") >> ( Attack(Release) ))

      | do_parse!(tag!("N") >> ( NextTurn ))

      | do_parse!(tag!("j") >> ( LongJump ))

      | do_parse!(tag!("J") >> ( HighJump ))

      | do_parse!(tag!("S") >> ( Switch ))

      | do_parse!(tag!(",") >> ( Skip ))

      | do_parse!(tag!("1") >> ( Timer(1) ))

      | do_parse!(tag!("2") >> ( Timer(2) ))

      | do_parse!(tag!("3") >> ( Timer(3) ))

      | do_parse!(tag!("4") >> ( Timer(4) ))

      | do_parse!(tag!("5") >> ( Timer(5) ))

      | do_parse!(tag!("p") >> x: be_i24 >> y: be_i24 >> ( Put(x, y) ))

      | do_parse!(tag!("P") >> x: be_i24 >> y: be_i24 >> ( CursorMove(x, y) ))

      | do_parse!(tag!("f") >> s: string_tail >> ( SyncedEngineMessage::TeamControlLost(s) ))

      | do_parse!(tag!("g") >> s: string_tail >> ( SyncedEngineMessage::TeamControlGained(s) ))

));

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

));

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

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

));

named!(timestamped_message<&[u8], (SyncedEngineMessage, u16)>,

    do_parse!(msg: length_value!(length_without_timestamp, terminated!(synced_message, eof_slice!()))

        >> timestamp: be_u16

        >> ((msg, timestamp))

    )

);

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

    alt!(

        map!(timestamped_message, |(m, t)| Synced(m, t as u32))

        | do_parse!(tag!("#") >> (Synced(TimeWrap, 65535)))

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

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

        | unrecognized_message

));

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

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

);

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

    length_value!(length_specifier, terminated!(unwrapped_message, eof_slice!())));

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)));

}

#[test]

fn parse_synced_messages() {

    assert_eq!(message(b"\x01#"), Ok((&b""[..], Synced(TimeWrap, 65535))));

}

#[test]

fn parse_unsynced_messages() {

}

#[test]

fn parse_incorrect_messages() {

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

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

    // garbage after correct message

    assert_eq!(message(b"\x04La\x01\x02"), Ok((&b""[..], Unknown)));

}

#[test]

fn parse_config_messages() {

}

#[test]

fn parse_test_general() {

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

}