import ctypes

"""
Quick and dirty wrapper for ALSA.
"""

c_void_pp = ctypes.POINTER(ctypes.c_void_p)
_alsa = ctypes.cdll.LoadLibrary("libasound.so.2")

_alsa.snd_pcm_open.restype = ctypes.c_int
_alsa.snd_pcm_open.argtypes = [c_void_pp, ctypes.c_char_p, ctypes.c_int, ctypes.c_int]

_alsa.snd_pcm_set_params.restype = ctypes.c_int
_alsa.snd_pcm_set_params.argtypes = [ctypes.c_void_p, ctypes.c_int, ctypes.c_int, ctypes.c_uint, ctypes.c_uint, ctypes.c_int, ctypes.c_uint]
SND_PCM_FORMAT_S16_LE = 2
SND_PCM_ACCESS_RW_INTERLEAVED = 3

# snd_pcm_sframes_t snd_pcm_writei(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size);
_alsa.snd_pcm_writei.restype = ctypes.c_long
_alsa.snd_pcm_writei.argtypes = [ctypes.c_void_p, ctypes.c_void_p, ctypes.c_ulong]

# int snd_pcm_drain(snd_pcm_t *pcm);
_alsa.snd_pcm_drain.restype = ctypes.c_int
_alsa.snd_pcm_drain.argtypes = [ctypes.c_void_p]


class Alsa:
    def __init__(self, sample_rate, latency):
        self.sample_rate = sample_rate
        self.handle = ctypes.c_void_p()
        ret = _alsa.snd_pcm_open(ctypes.byref(self.handle), b"default", 0, 0)
        assert ret >= 0, "snd_pcm_open failed"
        ret = _alsa.snd_pcm_set_params(self.handle, SND_PCM_FORMAT_S16_LE, SND_PCM_ACCESS_RW_INTERLEAVED, 1, sample_rate, 1, latency)

    def write(self, samples):
        BufferType = ctypes.c_int16 * len(samples)
        buf = BufferType(*samples)
        ret = _alsa.snd_pcm_writei(self.handle, buf, len(samples))
        assert ret == len(samples), "snd_pcm_writei failed"
        return ret

    def drain(self):
        ret = _alsa.snd_pcm_drain(self.handle)
        assert ret >= 0


#_alsa.snd_seq_open.argtypes = [c_void_pp, ctypes.c_char_p, ctypes.c_int, ctypes.c_int]

class AlsaSeq:
    def __init__(self):
        self.handle = ctypes.c_void_p()
        ret = _alsa.snd_seq_open(ctypes.byref(self.handle), b"default", 2, 0)
        if ret < 0:
            raise RuntimeError("snd_seq_open failed")
        ret = _alsa.snd_seq_set_client_name(self.handle, b"Midi Listener");
        assert ret >= 0, "snd_seq_set_client_name failed"
        self.port = _alsa.snd_seq_create_simple_port(self.handle, b"listen:in", 2 | 64, 1 << 20)
        assert self.port >= 0, "snd_seq_create_simple_port failed"
        print(self.handle, self.port)
        err = _alsa.snd_seq_connect_from(self.handle, self.port, 20, 0)
        assert err >= 0, "snd_seq_connect_from failed"

    def get_event(self):
        evt = ctypes.c_void_p()
        err = _alsa.snd_seq_event_input(self.handle, ctypes.byref(evt))
        assert err >= 0, "snd_seq_event_input failed"
        return evt

if __name__ == "__main__":
    seq = AlsaSeq()
    while True:
        evt = seq.get_event()
        print(evt)