status-indicators/coremidi.py

"""Minimal CoreMIDI access through ctypes (no PyObjC, stdlib only).

Two things the status panel needs that Companion cannot see:

* sessions()  - the live Network MIDI (RTP-MIDI) sessions on this Mac and the
                peers currently joined to each, read from the network driver's
                "apple.midirtp.session" entity property.
* Listener    - timestamps the last message that arrived on a named MIDI
                source, so a tile can say "last MIDI 3s ago".
* connect_peer() - re-add a peer to a named session, the way Audio MIDI Setup's
                "Connect" does (macOS's MIDINetworkSession API only reaches the
                default session, not named ones like "NA Tracks").
"""
import ctypes
import ctypes.util
import plistlib
import threading
import time

_cm = ctypes.CDLL(ctypes.util.find_library("CoreMIDI"))
_cf = ctypes.CDLL(ctypes.util.find_library("CoreFoundation"))

_U32 = ctypes.c_uint32
_UTF8 = 0x08000100

_cm.MIDIGetNumberOfDevices.restype = ctypes.c_ulong
_cm.MIDIGetDevice.restype = _U32
_cm.MIDIGetDevice.argtypes = [ctypes.c_ulong]
_cm.MIDIDeviceGetNumberOfEntities.restype = ctypes.c_ulong
_cm.MIDIDeviceGetNumberOfEntities.argtypes = [_U32]
_cm.MIDIDeviceGetEntity.restype = _U32
_cm.MIDIDeviceGetEntity.argtypes = [_U32, ctypes.c_ulong]
_cm.MIDIGetNumberOfSources.restype = ctypes.c_ulong
_cm.MIDIGetSource.restype = _U32
_cm.MIDIGetSource.argtypes = [ctypes.c_ulong]
_cm.MIDIObjectGetStringProperty.argtypes = [_U32, ctypes.c_void_p, ctypes.POINTER(ctypes.c_void_p)]
_cm.MIDIObjectGetDictionaryProperty.argtypes = [_U32, ctypes.c_void_p, ctypes.POINTER(ctypes.c_void_p)]
_cm.MIDIObjectGetIntegerProperty.argtypes = [_U32, ctypes.c_void_p, ctypes.POINTER(ctypes.c_int32)]
_cm.MIDIObjectSetDictionaryProperty.argtypes = [_U32, ctypes.c_void_p, ctypes.c_void_p]

_cf.CFStringCreateWithCString.restype = ctypes.c_void_p
_cf.CFStringCreateWithCString.argtypes = [ctypes.c_void_p, ctypes.c_char_p, _U32]
_cf.CFStringGetCString.argtypes = [ctypes.c_void_p, ctypes.c_char_p, ctypes.c_long, _U32]
_cf.CFRelease.argtypes = [ctypes.c_void_p]
_cf.CFPropertyListCreateData.restype = ctypes.c_void_p
_cf.CFPropertyListCreateData.argtypes = [ctypes.c_void_p, ctypes.c_void_p, ctypes.c_long, ctypes.c_ulong, ctypes.c_void_p]
_cf.CFDataGetLength.restype = ctypes.c_long
_cf.CFDataGetLength.argtypes = [ctypes.c_void_p]
_cf.CFDataGetBytePtr.restype = ctypes.c_void_p
_cf.CFDataGetBytePtr.argtypes = [ctypes.c_void_p]
_cf.CFDataCreate.restype = ctypes.c_void_p
_cf.CFDataCreate.argtypes = [ctypes.c_void_p, ctypes.c_char_p, ctypes.c_long]
_cf.CFPropertyListCreateWithData.restype = ctypes.c_void_p
_cf.CFPropertyListCreateWithData.argtypes = [ctypes.c_void_p, ctypes.c_void_p, ctypes.c_ulong,
                                             ctypes.c_void_p, ctypes.c_void_p]

# One lock around every CoreMIDI call: concurrent first calls from two threads
# (session reads vs. MIDIClientCreate) intermittently fail with -2.
_lock = threading.RLock()


def _cfstr(s):
    return _cf.CFStringCreateWithCString(None, s.encode("utf-8"), _UTF8)


def _string_prop(obj, key):
    out = ctypes.c_void_p()
    k = _cfstr(key)
    err = _cm.MIDIObjectGetStringProperty(obj, k, ctypes.byref(out))
    _cf.CFRelease(k)
    if err or not out.value:
        return None
    buf = ctypes.create_string_buffer(1024)
    _cf.CFStringGetCString(out, buf, 1024, _UTF8)
    _cf.CFRelease(out)
    return buf.value.decode("utf-8", "replace")


def _dict_prop(obj, key):
    out = ctypes.c_void_p()
    k = _cfstr(key)
    err = _cm.MIDIObjectGetDictionaryProperty(obj, k, ctypes.byref(out))
    _cf.CFRelease(k)
    if err or not out.value:
        return None
    data = _cf.CFPropertyListCreateData(None, out, 100, 0, None)  # 100 = XML format
    raw = ctypes.string_at(_cf.CFDataGetBytePtr(data), _cf.CFDataGetLength(data))
    _cf.CFRelease(data)
    _cf.CFRelease(out)
    return plistlib.loads(raw)


def _set_dict_prop(obj, key, value):
    raw = plistlib.dumps(value)
    data = _cf.CFDataCreate(None, raw, len(raw))
    plist = _cf.CFPropertyListCreateWithData(None, data, 0, None, None)
    _cf.CFRelease(data)
    if not plist:
        raise OSError("could not build the property list")
    k = _cfstr(key)
    err = _cm.MIDIObjectSetDictionaryProperty(obj, k, plist)
    _cf.CFRelease(k)
    _cf.CFRelease(plist)
    return err


def _session_entities():
    """[(entity, its "apple.midirtp.session" dict)] for every network MIDI session on this Mac."""
    out = []
    for i in range(_cm.MIDIGetNumberOfDevices()):
        dev = _cm.MIDIGetDevice(i)
        if _string_prop(dev, "driver") != "com.apple.AppleMIDINetworkDriver":
            continue
        for j in range(_cm.MIDIDeviceGetNumberOfEntities(dev)):
            ent = _cm.MIDIDeviceGetEntity(dev, j)
            sess = _dict_prop(ent, "apple.midirtp.session")
            if sess is not None:
                out.append((ent, sess))
    return out


def with_peer(sess, peer_name, address):
    """The session settings with this peer added, or None if it is already in the session.
    Peers already there are passed back exactly as read, so they are left alone."""
    peers = list(sess.get("peers", []))
    if any(p.get("name") == peer_name or p.get("address") == address for p in peers):
        return None
    new = dict(sess)
    new["peers"] = peers + [{"address": address, "name": peer_name}]
    return new


def connect_peer(session_name, peer_name, address):
    """Ask macOS to connect `peer_name` at `address` ("10.1.10.206:5004") to the named session,
    like Audio MIDI Setup's Connect. Returns "already" (it is in the session) or "asked"."""
    with _lock:
        for ent, sess in _session_entities():
            if (sess.get("dns-sd-name") or _string_prop(ent, "name")) != session_name:
                continue
            new = with_peer(sess, peer_name, address)
            if new is None:
                return "already"
            err = _set_dict_prop(ent, "apple.midirtp.session", new)
            if err:
                raise OSError("MIDIObjectSetDictionaryProperty failed: %d" % err)
            return "asked"
    raise LookupError("no network MIDI session named %r on this Mac" % session_name)


def sessions():
    """{session name: {"port": int, "peers": [{"name", "address", "state"}]}}"""
    found = {}
    with _lock:
        for i in range(_cm.MIDIGetNumberOfDevices()):
            dev = _cm.MIDIGetDevice(i)
            if _string_prop(dev, "driver") != "com.apple.AppleMIDINetworkDriver":
                continue
            for j in range(_cm.MIDIDeviceGetNumberOfEntities(dev)):
                ent = _cm.MIDIDeviceGetEntity(dev, j)
                sess = _dict_prop(ent, "apple.midirtp.session")
                if sess is None:
                    continue
                name = sess.get("dns-sd-name") or _string_prop(ent, "name") or "?"
                found[name] = {
                    "port": sess.get("port"),
                    "peers": [
                        {"name": p.get("name", ""), "address": p.get("address", ""), "state": p.get("state", "")}
                        for p in sess.get("peers", [])
                    ],
                }
    return found


def source_names():
    with _lock:
        return [_string_prop(_cm.MIDIGetSource(i), "displayName") or "" for i in range(_cm.MIDIGetNumberOfSources())]


# --- Listener -----------------------------------------------------------

class _MIDIPacket(ctypes.Structure):
    _pack_ = 4
    _fields_ = [("timeStamp", ctypes.c_uint64), ("length", ctypes.c_uint16), ("data", ctypes.c_ubyte * 256)]


class _MIDIPacketList(ctypes.Structure):
    _pack_ = 4
    _fields_ = [("numPackets", ctypes.c_uint32), ("packet", _MIDIPacket * 1)]


_READPROC = ctypes.CFUNCTYPE(None, ctypes.POINTER(_MIDIPacketList), ctypes.c_void_p, ctypes.c_void_p)

_cm.MIDIClientCreate.argtypes = [ctypes.c_void_p, ctypes.c_void_p, ctypes.c_void_p, ctypes.POINTER(_U32)]
_cm.MIDIInputPortCreate.argtypes = [_U32, ctypes.c_void_p, _READPROC, ctypes.c_void_p, ctypes.POINTER(_U32)]
_cm.MIDIPortConnectSource.argtypes = [_U32, _U32, ctypes.c_void_p]
_cm.MIDIPortDisconnectSource.argtypes = [_U32, _U32]

_client = None


def _get_client():
    global _client
    with _lock:
        if _client is None:
            ref = _U32()
            name = _cfstr("status-panel")
            err = _cm.MIDIClientCreate(name, None, None, ctypes.byref(ref))
            _cf.CFRelease(name)
            if err:
                raise OSError("MIDIClientCreate failed: %d" % err)
            _client = ref.value
        return _client


def describe(data):
    """Short human label for a MIDI message: 'NOTE 36', 'CC 7=64', 'PC 5', 'MTC'."""
    if not data:
        return ""
    st = data[0] & 0xF0
    if st == 0x90 and len(data) >= 3 and data[2]:
        return "NOTE %d" % data[1]
    if st in (0x80, 0x90) and len(data) >= 2:
        return "OFF %d" % data[1]
    if st == 0xB0 and len(data) >= 3:
        return "CC %d=%d" % (data[1], data[2])
    if st == 0xC0 and len(data) >= 2:
        return "PC %d" % data[1]
    if data[0] == 0xF1:
        return "MTC"
    if data[0] == 0xF0:
        return "SYSEX"
    return "0x%02X" % data[0]


class Listener:
    """Connects an input port to the named source (re-checked on poll())."""

    def __init__(self, source_name):
        self.source_name = source_name
        self.last_time = None
        self.last_msg = ""
        self.count = 0
        self._endpoint = None
        self._port = None
        self._proc = _READPROC(self._on_packets)  # keep a reference or it is collected

    def _on_packets(self, pktlist, _ref, _src):
        try:
            pl = pktlist.contents
            if pl.numPackets:
                pkt = pl.packet[0]
                n = min(pkt.length, 256)
                data = bytes(pkt.data[:n])
                # Skip active sensing / clock so they do not mask real traffic.
                if data and data[0] not in (0xF8, 0xFE):
                    self.last_msg = describe(data)
                    self.last_time = time.time()
                    self.count += 1
        except Exception:  # never raise into CoreMIDI's thread
            pass

    def _find(self):
        with _lock:
            for i in range(_cm.MIDIGetNumberOfSources()):
                ep = _cm.MIDIGetSource(i)
                if _string_prop(ep, "displayName") == self.source_name or _string_prop(ep, "name") == self.source_name:
                    return ep
        return None

    @property
    def connected(self):
        return self._endpoint is not None

    def poll(self):
        """(Re)connect if the source appeared, disappeared or changed."""
        with _lock:
            self._poll()

    def _poll(self):
        ep = self._find()
        if ep == self._endpoint:
            return
        if self._port is None:
            ref = _U32()
            name = _cfstr("status-panel in")
            err = _cm.MIDIInputPortCreate(_get_client(), name, self._proc, None, ctypes.byref(ref))
            _cf.CFRelease(name)
            if err:
                raise OSError("MIDIInputPortCreate failed: %d" % err)
            self._port = ref.value
        if self._endpoint is not None:
            _cm.MIDIPortDisconnectSource(self._port, self._endpoint)
        self._endpoint = None
        if ep is not None and _cm.MIDIPortConnectSource(self._port, ep, None) == 0:
            self._endpoint = ep


# --- test helper: a virtual source we can send into ----------------------

_cm.MIDISourceCreate.argtypes = [_U32, ctypes.c_void_p, ctypes.POINTER(_U32)]
_cm.MIDIReceived.argtypes = [_U32, ctypes.POINTER(_MIDIPacketList)]
_cm.MIDIEndpointDispose.argtypes = [_U32]


class VirtualSource:
    """Only used by the tests: a source whose messages a Listener can receive."""

    def __init__(self, name):
        ref = _U32()
        cname = _cfstr(name)
        with _lock:
            err = _cm.MIDISourceCreate(_get_client(), cname, ctypes.byref(ref))
        _cf.CFRelease(cname)
        if err:
            raise OSError("MIDISourceCreate failed: %d" % err)
        self.ref = ref.value

    def send(self, data):
        pl = _MIDIPacketList()
        pl.numPackets = 1
        pl.packet[0].timeStamp = 0
        pl.packet[0].length = len(data)
        for i, b in enumerate(data):
            pl.packet[0].data[i] = b
        _cm.MIDIReceived(self.ref, ctypes.byref(pl))

    def close(self):
        _cm.MIDIEndpointDispose(self.ref)