hmp3-ng-2.16.0: Syntax.hs

-- 
-- Copyright (c) 2005-2008 Don Stewart - http://www.cse.unsw.edu.au/~dons
-- Copyright (c) 2019-2024 Galen Huntington
-- 
-- This program is free software; you can redistribute it and/or
-- modify it under the terms of the GNU General Public License as
-- published by the Free Software Foundation; either version 2 of
-- the License, or (at your option) any later version.
-- 
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-- General Public License for more details.
-- 
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
-- 

--
-- abstract syntax for mpg123/321 'remote control' commands, so we get
-- type safe messaging, and parsing of results
--

module Syntax where

import Base

import qualified Data.ByteString.Char8 as P

------------------------------------------------------------------------
--
-- Values we may print out:

-- Loads and starts playing <file>
--
newtype Load = Load ByteString

instance Pretty Load where
    ppr (Load f) = mconcat ["LOAD ", f]

-- If '+' or '-' is specified, jumps <frames> frames forward, or backwards,
-- respectively, in the the mp3 file.  If neither is specifies, jumps to
-- absolute frame <frames> in the mp3 file.
newtype Jump = Jump Int

instance Pretty Jump where
    ppr (Jump i) = mconcat ["JUMP ", P.pack . show $ i]

-- Pauses the playback of the mp3 file; if already paused, restarts playback.
data Pause = Pause

instance Pretty Pause where
    ppr Pause = "PAUSE"

-- Quits mpg123.
data Quit = Quit

instance Pretty Quit where
    ppr Quit = "QUIT"

------------------------------------------------------------------------
--
-- Values we may have to read back in

-- mpg123 tagline. Output at startup.
data Tag = Tag

-- Track info if ID fields are in the file, otherwise file name.
newtype File = File (Either ByteString Id3)

-- ID3 info 
data Id3 = Id3
        { id3title  :: !ByteString
        , id3artist :: !ByteString
        , id3album  :: !ByteString
        , id3str    :: !ByteString
        }

--      , year   :: Maybe ByteString
--      , genre  :: Maybe ByteString }



-- Outputs information about the mp3 file after loading.
-- <a>: version of the mp3 file. Currently always 1.0 with madlib, but don't 
--      depend on it, particularly if you intend portability to mpg123 as well.
--      Float/string.
-- <b>: layer: 1, 2, or 3. Integer.
-- <c>: Samplerate. Integer.
-- <d>: Mode string. String.
-- <e>: Mode extension. Integer.
-- <f>: Bytes per frame (estimate, particularly if the stream is VBR). Integer.
-- <g>: Number of channels (1 or 2, usually). Integer.
-- <h>: Is stream copyrighted? (1 or 0). Integer.
-- <i>: Is stream CRC protected? (1 or 0). Integer.
-- <j>: Emphasis. Integer.
-- <k>: Bitrate, in kbps. (i.e., 128.) Integer.
-- <l>: Extension. Integer.
newtype Info = Info {
                userinfo      :: ByteString  -- user friendly string
           --   version       :: !ByteString,
           --   layer         :: !Int,     -- 1,2 or 3
           --   sampleRate    :: !Int,
           --   playMode      :: !ByteString,
           --   modeExtns     :: !Int,
           --   bytesPerFrame :: !Int,
           --   channelCount  :: !Int,
           --   copyrighted   :: !Bool,
           --   checksummed   :: !Bool,
           --   emphasis      :: !Int,
           --   bitrate       :: !Int,
           --   extension     :: !Int 
            }

-- @F <current-frame> <frames-remaining> <current-time> <time-remaining>
-- Frame decoding status updates (once per frame).
-- Current-frame and frames-remaining are integers; current-time and
-- time-remaining floating point numbers with two decimal places.
--
-- Only 1 frame a second is actually read, so make sure it's lazy so
-- there's no need to evaluate all the others. 
-- 
data Frame = Frame {
                currentFrame   :: !Int,
                framesLeft     :: !Int,
                currentTime    :: !(Fixed E2),
                timeLeft       :: !(Fixed E2)
             }

-- @P {0, 1, 2}
-- Stop/pause status.
-- 0 - playing has stopped. When 'STOP' is entered, or the mp3 file is finished.
-- 1 - Playing is paused. Enter 'PAUSE' or 'P' to continue.
-- 2 - Playing has begun again.
data Status = Stopped
            | Paused
            | Playing
    deriving stock (Eq, Show)

data Mode = Normal | Loop | Random
    deriving stock (Eq, Bounded, Enum, Show, Read)

------------------------------------------------------------------------

--
-- a pretty printing class
--
class Pretty a where
    ppr :: a -> ByteString

--
-- And a wrapper type 
--
data Msg = T {-# UNPACK #-} !Tag
         | F                !File
         | I {-# UNPACK #-} !Info
         | R {-# UNPACK #-} !Frame
         | S                !Status