import ../../core

# alsa API
type 
  OpenMode*{.size: sizeof(culong).} = enum
    SND_PCM_BLOCK = 0x00000000 # added by semicongine, for clarity
    SND_PCM_NONBLOCK = 0x00000001
  StreamMode* {.size: sizeof(cint).} = enum
    SND_PCM_STREAM_PLAYBACK = 0
  AccessMode*{.size: sizeof(cint).} = enum 
    SND_PCM_ACCESS_RW_INTERLEAVED = 3
  PCMFormat*{.size: sizeof(cint).} = enum
    SND_PCM_FORMAT_S16_LE = 2
  snd_pcm_p* = ptr object
  snd_pcm_hw_params_p* = ptr object
  snd_pcm_uframes_t* = culong
  snd_pcm_sframes_t* = clong
{.pragma: alsafunc, importc, cdecl, dynlib: "libasound.so.2" .}
proc snd_pcm_open*(pcm_ref: ptr snd_pcm_p, name: cstring, streamMode: StreamMode, openmode: OpenMode): cint {.alsafunc.}
proc snd_pcm_close*(pcm: snd_pcm_p): cint {.alsafunc.}
proc snd_pcm_hw_params_malloc*(hw_params_ptr: ptr snd_pcm_hw_params_p): cint {.alsafunc.}
proc snd_pcm_hw_params_free*(hw_params: snd_pcm_hw_params_p) {.alsafunc.}
proc snd_pcm_hw_params_any*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p): cint {.alsafunc.}
proc snd_pcm_hw_params_set_access*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p, mode: AccessMode): cint {.alsafunc.}
proc snd_pcm_hw_params_set_format*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p, format: PCMFormat): cint {.alsafunc.}
proc snd_pcm_hw_params_set_channels*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p, val: cuint): cint {.alsafunc.}
proc snd_pcm_hw_params_set_buffer_size*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p, size: snd_pcm_uframes_t): cint {.alsafunc.}
proc snd_pcm_hw_params_set_rate*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p, val: cuint, dir: cint): cint {.alsafunc.}
proc snd_pcm_hw_params*(pcm: snd_pcm_p, params: snd_pcm_hw_params_p): cint {.alsafunc.}
proc snd_pcm_writei*(pcm: snd_pcm_p, buffer: pointer, size: snd_pcm_uframes_t): snd_pcm_sframes_t {.alsafunc.}
proc snd_pcm_recover*(pcm: snd_pcm_p, err: cint, silent: cint): cint {.alsafunc.}

template checkAlsaResult*(call: untyped) =
  let value = call
  if value < 0:
    raise newException(Exception, "Alsa error: " & astToStr(call) &
      " returned " & $value)

# required for engine:

type
  NativeSoundDevice* = object
    handle: snd_pcm_p
    buffers: seq[ptr SoundData]
 
proc openSoundDevice*(sampleRate: uint32, buffers: seq[ptr SoundData]): NativeSoundDevice =
  var hw_params: snd_pcm_hw_params_p = nil
  checkAlsaResult snd_pcm_open(addr result.handle, "default", SND_PCM_STREAM_PLAYBACK, SND_PCM_BLOCK)

  # hw parameters, quiet a bit of hardcoding here
  checkAlsaResult snd_pcm_hw_params_malloc(addr hw_params)
  checkAlsaResult snd_pcm_hw_params_any(result.handle, hw_params)
  checkAlsaResult snd_pcm_hw_params_set_access(result.handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)
  checkAlsaResult snd_pcm_hw_params_set_format(result.handle, hw_params, SND_PCM_FORMAT_S16_LE)
  checkAlsaResult snd_pcm_hw_params_set_rate(result.handle, hw_params, sampleRate, 0)
  checkAlsaResult snd_pcm_hw_params_set_channels(result.handle, hw_params, 2)
  checkAlsaResult snd_pcm_hw_params_set_buffer_size(result.handle, hw_params, snd_pcm_uframes_t(buffers[0][].len))
  checkAlsaResult snd_pcm_hw_params(result.handle, hw_params)
  snd_pcm_hw_params_free(hw_params)
  result.buffers = buffers

proc writeSoundData*(soundDevice: NativeSoundDevice, buffer: int) =
  var ret = snd_pcm_writei(soundDevice.handle, addr soundDevice.buffers[buffer][][0], snd_pcm_uframes_t(soundDevice.buffers[buffer][].len))
  if ret < 0:
    checkAlsaResult snd_pcm_recover(soundDevice.handle, cint(ret), 0)

proc closeSoundDevice*(soundDevice: NativeSoundDevice) =
  discard snd_pcm_close(soundDevice.handle)