turn-up-arch/src/turnup/turnupd.py

#!/usr/bin/env python3
"""
turnupd — Turn Up mixer daemon for Linux

Bridges a USB serial device (knobs + buttons) to PipeWire/PulseAudio via
pulsectl, mapping hardware inputs to per-sink, per-source, and per-app
volume control as well as mute toggles and arbitrary shell commands.

LED feedback: after every knob move the device's RGB LEDs are updated to
reflect the current volume using the per-knob (or global) colour scheme
from config.
"""

import logging
import signal
import subprocess
import sys
import time

import pulsectl
import serial

from turnup.config import get_knob_led_cfg, get_led_color, load_config

logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
    datefmt="%H:%M:%S",
)
log = logging.getLogger("turnupd")

# Maximum raw ADC value reported by the hardware.
KNOB_MAX: int = 1012
# Maximum output volume multiplier (1.5 = 150 %).
VOLUME_MAX: float = 1.5
# Number of physical knobs (and therefore LED groups).
NUM_KNOBS: int = 5
# Number of LEDs per knob.
LEDS_PER_KNOB: int = 3


# ── Protocol parser ────────────────────────────────────────────────────────────

def parse_messages(buf: bytearray) -> tuple[list[dict], bytearray]:
    """Parse framed messages out of *buf* and return ``(messages, remainder)``."""
    messages: list[dict] = []
    i = 0
    while i < len(buf):
        if buf[i] != 0xFE:
            i += 1
            continue

        remaining = len(buf) - i

        if remaining >= 3 and buf[i + 1] == 0x02 and buf[i + 2] == 0xFF:
            messages.append({"type": "heartbeat"})
            i += 3

        elif (
            remaining >= 4
            and buf[i + 1] in (0x06, 0x07)
            and buf[i + 3] == 0xFF
        ):
            messages.append({
                "type": "button",
                "action": "press" if buf[i + 1] == 0x06 else "release",
                "id": buf[i + 2],
            })
            i += 4

        elif (
            remaining >= 6
            and buf[i + 1] == 0x03
            and buf[i + 5] == 0xFF
        ):
            messages.append({
                "type": "knob",
                "id": buf[i + 2],
                "value": (buf[i + 3] << 8) | buf[i + 4],
            })
            i += 6

        else:
            i += 1

    return messages, bytearray(buf[i:])


def knob_to_volume(value: int) -> float:
    """Convert a raw knob value (0–``KNOB_MAX``) to a sink volume (0.0–1.5)."""
    return round((value / KNOB_MAX) * VOLUME_MAX, 4)


def knob_to_norm(value: int) -> float:
    """Convert a raw knob value (0–``KNOB_MAX``) to a normalised float (0.0–1.0)."""
    return round(value / KNOB_MAX, 4)


# ── LED control ────────────────────────────────────────────────────────────────

def build_led_packet(colors: list[tuple[int, int, int]]) -> bytes:
    """Build the 47-byte LED packet for all 5 knobs.

    Frame format: ``FE 05 [R G B * LEDS_PER_KNOB] * NUM_KNOBS FF``
    """
    assert len(colors) == NUM_KNOBS
    payload = bytearray([0xFE, 0x05])
    for r, g, b in colors:
        payload += bytes([r, g, b]) * LEDS_PER_KNOB
    payload.append(0xFF)
    return bytes(payload)


def send_leds(ser: serial.Serial, colors: list[tuple[int, int, int]]) -> None:
    """Write an LED packet to the open serial port, swallowing any I/O errors."""
    try:
        ser.write(build_led_packet(colors))
    except serial.SerialException as exc:
        log.warning("LED write failed: %s", exc)


def all_led_colors(
    config: dict, knob_norms: list[float]
) -> list[tuple[int, int, int]]:
    """Return one ``(r, g, b)`` per knob based on each knob's LED config."""
    return [
        get_led_color(get_knob_led_cfg(config, i), knob_norms[i])
        for i in range(NUM_KNOBS)
    ]


# ── PulseAudio / PipeWire controller ──────────────────────────────────────────

class PulseController:
    """Thin wrapper around :class:`pulsectl.Pulse` for volume and mute control."""

    def __init__(self) -> None:
        self._pulse = pulsectl.Pulse("turnupd")

    def close(self) -> None:
        self._pulse.close()

    def set_sink_volume(self, sink_name: str, volume: float) -> None:
        volume = max(0.0, min(VOLUME_MAX, volume))
        try:
            if sink_name == "default":
                info = self._pulse.server_info()
                sink = self._pulse.get_sink_by_name(info.default_sink_name)
            else:
                sink = self._pulse.get_sink_by_name(sink_name)
            self._pulse.volume_set_all_chans(sink, volume)
        except Exception as exc:
            log.warning("set_sink_volume(%r) failed: %s", sink_name, exc)

    def toggle_mute_sink(self, sink_name: str) -> None:
        try:
            if sink_name == "default":
                info = self._pulse.server_info()
                sink = self._pulse.get_sink_by_name(info.default_sink_name)
            else:
                sink = self._pulse.get_sink_by_name(sink_name)
            self._pulse.mute(sink, not sink.mute)
            log.info("Sink %r mute toggled", sink_name)
        except Exception as exc:
            log.warning("toggle_mute_sink(%r) failed: %s", sink_name, exc)

    def set_source_volume(self, source_name: str, volume: float) -> None:
        volume = max(0.0, min(1.0, volume))
        try:
            if source_name == "default":
                info = self._pulse.server_info()
                source = self._pulse.get_source_by_name(info.default_source_name)
            else:
                source = self._pulse.get_source_by_name(source_name)
            self._pulse.volume_set_all_chans(source, volume)
        except Exception as exc:
            log.warning("set_source_volume(%r) failed: %s", source_name, exc)

    def toggle_mute_source(self, source_name: str) -> None:
        try:
            if source_name == "default":
                info = self._pulse.server_info()
                source = self._pulse.get_source_by_name(info.default_source_name)
            else:
                source = self._pulse.get_source_by_name(source_name)
            self._pulse.mute(source, not source.mute)
            log.info("Source %r mute toggled", source_name)
        except Exception as exc:
            log.warning("toggle_mute_source(%r) failed: %s", source_name, exc)

    def set_app_volume(self, app_name: str, volume: float) -> None:
        volume = max(0.0, min(VOLUME_MAX, volume))
        needle = app_name.lower()
        try:
            for inp in self._pulse.sink_input_list():
                name   = inp.proplist.get("application.name", "")
                binary = inp.proplist.get("application.process.binary", "")
                if needle in name.lower() or needle in binary.lower():
                    self._pulse.volume_set_all_chans(inp, volume)
                    return
            log.debug("App %r not found in sink inputs", app_name)
        except Exception as exc:
            log.warning("set_app_volume(%r) failed: %s", app_name, exc)


# ── Event handlers ─────────────────────────────────────────────────────────────

def handle_knob(
    knob_id: int,
    value: int,
    config: dict,
    pulse: PulseController,
    ser: serial.Serial,
    knob_norms: list[float],
) -> None:
    """Dispatch a knob event, update PulseAudio, then refresh the LEDs."""
    knob_cfg = config.get("knobs", {}).get(str(knob_id))
    if not knob_cfg:
        return

    action = knob_cfg.get("action", "sink_volume")
    target = knob_cfg.get("target", "default")
    norm   = knob_to_norm(value)

    if action == "sink_volume":
        vol = knob_to_volume(value)
        pulse.set_sink_volume(target, vol)
        log.info("Knob %d → sink %r = %.2f", knob_id, target, vol)

    elif action == "source_volume":
        pulse.set_source_volume(target, norm)
        log.info("Knob %d → source %r = %.2f", knob_id, target, norm)

    elif action == "app_volume":
        vol = knob_to_volume(value)
        pulse.set_app_volume(target, vol)
        log.info("Knob %d → app %r = %.2f", knob_id, target, vol)

    elif action == "group_volume":
        vol = knob_to_volume(value)
        for t in knob_cfg.get("targets", []):
            pulse.set_app_volume(t, vol)
        log.info("Knob %d → group %s = %.2f", knob_id, knob_cfg.get("targets"), vol)

    knob_norms[knob_id] = norm
    send_leds(ser, all_led_colors(config, knob_norms))


def handle_button(
    button_id: int, action: str, config: dict, pulse: PulseController
) -> None:
    """Dispatch a button press event."""
    if action != "press":
        return

    btn_cfg = config.get("buttons", {}).get(str(button_id))
    if not btn_cfg:
        return

    btn_action = btn_cfg.get("action", "")
    target     = btn_cfg.get("target", "default")

    if btn_action == "mute_sink":
        pulse.toggle_mute_sink(target)
    elif btn_action == "mute_source":
        pulse.toggle_mute_source(target)
    elif btn_action == "command":
        try:
            subprocess.Popen(target, shell=True)  # noqa: S602
            log.info("Button %d → command %r", button_id, target)
        except Exception as exc:
            log.warning("Button %d command failed: %s", button_id, exc)


# ── Main loop ──────────────────────────────────────────────────────────────────

def main() -> None:
    config = load_config()
    port: str = config.get("port", "/dev/ttyACM0")
    baud: int = config.get("baud", 115200)

    log.info("Turn Up daemon starting — %s @ %d baud", port, baud)

    pulse      = PulseController()
    knob_norms = [0.0] * NUM_KNOBS
    buf        = bytearray()

    def _shutdown(sig: int, _frame: object) -> None:
        log.info("Received signal %d — shutting down", sig)
        pulse.close()
        sys.exit(0)

    signal.signal(signal.SIGINT,  _shutdown)
    signal.signal(signal.SIGTERM, _shutdown)

    while True:
        try:
            with serial.Serial(port, baud, timeout=0.1) as ser:
                log.info("Connected to %s", port)
                buf.clear()
                send_leds(ser, all_led_colors(config, knob_norms))

                while True:
                    data = ser.read(64)
                    if not data:
                        continue
                    buf.extend(data)
                    messages, buf = parse_messages(buf)
                    for msg in messages:
                        if msg["type"] == "knob":
                            handle_knob(
                                msg["id"], msg["value"],
                                config, pulse, ser, knob_norms,
                            )
                        elif msg["type"] == "button":
                            handle_button(
                                msg["id"], msg["action"], config, pulse
                            )

        except serial.SerialException as exc:
            log.warning("Serial error: %s — retrying in 3 s", exc)
            time.sleep(3)
        except Exception as exc:  # noqa: BLE001
            log.error("Unexpected error: %s — retrying in 3 s", exc)
            time.sleep(3)


if __name__ == "__main__":
    main()