#!/usr/bin/env nix-shell
#!nix-shell -i python3 -p "python3.withPackages (ps: [  ])" -p wireplumber
# vim: set filetype=python :

import logging
import os
import subprocess

logger = logging.getLogger(__name__)

class PwMonConsumer:
    last_volume: float | None = None
    last_mute: bool | None = None
    last_effective_volume: float | None = None

    # parser state:
    in_changed: bool = False
    in_node: bool = False
    in_vol: bool = False
    in_mute: bool = False

    def feed_line(self, line: str) -> float | None:
        """ consume a line and *maybe* return the volume """

        logger.debug("got pw-mon line: %s", line.rstrip())
        line = line.strip()

        if line.startswith("changed:"):
            self.in_changed = True
        elif line.startswith("added:") or line.startswith("removed:"):
            self.in_changed = False
        elif line.startswith("type: "):
            self.in_node = line.startswith("type: PipeWire:Interface:Node")
            logger.debug("parsed `type:` %s %d", line, self.in_node)
        elif line.startswith("Prop: "):
            # which of the *Volumes params we read is unclear.
            # alternative to this is to just detect the change, and then cal wpctl get-volume @DEFAULT_AUDIO_SINK@
            self.in_vol = line.startswith("Prop: key Spa:Pod:Object:Param:Props:channelVolumes")
            self.in_mute = line.startswith("Prop: key Spa:Pod:Object:Param:Props:softMute")
            logger.debug("parsed `Prop:` %s %d", line, self.in_vol)
        elif line.startswith("Float ") and self.in_changed and self.in_node and self.in_vol:
            value = float(line[len("Float "):])
            self.feed_volume(value)
        elif line.startswith("Bool ") and self.in_changed and self.in_node and self.in_mute:
            value = line[len("Bool "):] == "true"
            self.feed_mute(value)

    def feed_volume(self, new: float) -> None:
        logger.debug("feed volume: %f -> %f", self.last_volume or 0.0, new)
        self.last_volume = new
        self.check_effective_volume()

    def feed_mute(self, new: bool) -> None:
        logger.debug("feed mute: %d -> %d", self.last_mute or False, new)
        self.last_mute = new
        self.check_effective_volume()

    def check_effective_volume(self) -> None:
        eff_volume = 0.0 if self.last_mute else self.last_volume
        if eff_volume != self.last_effective_volume:
            logger.info("new effective volume: %f", eff_volume)
            self.on_new_volume(eff_volume)
            self.last_effective_volume = eff_volume


class PwMonWobConsumer(PwMonConsumer):
    def __init__(self):
        self.sock_name = os.path.join(
            os.environ.get("XDG_RUNTIME_DIR", "/run"),
            os.environ.get("WOBSOCK_NAME", "wob.sock"),
        )
        self.wob_sock = open(self.sock_name, "w")

    def on_new_volume(self, vol: float) -> None:
        # pipewire volume is between 0 and 3.375.
        # wob is between 0 - 1, or 1 - 2 if overdriven.
        # idk where vol ** (1/3) comes from, but it precisely matches what wpctl shows,
        # getting the range to 0.00 - 1.50 with precise 0.05 increments.
        int_vol = int(round(vol ** 0.3333 * 100))
        logger.info("writing to %s: %d", self.sock_name, int_vol)
        self.wob_sock.write(f"{int_vol}\n")
        self.wob_sock.flush()


def main() -> None:
    logging.basicConfig()
    logging.getLogger().setLevel(logging.INFO)
    if os.environ.get("WOB_VERBOSE", "") == "1":
        logging.getLogger().setLevel(logging.DEBUG)

    consumer = PwMonWobConsumer()
    proc = subprocess.Popen(["pw-mon"], stdout=subprocess.PIPE)
    for line in iter(proc.stdout.readline, b''):
        consumer.feed_line(line.decode("utf-8"))

if __name__ == "__main__":
    main()