#! /bin/bash

# A script to fade ALSA volume when pausing or start playing music
# in music player that support MPRIS.
# Using playerctl and amixer.

# Get ALSA volume value and calculate step
export VOLUMEALSA=$(amixer get Master | grep % | awk '{ print $3 }')
export VOLUMESTEP=$(expr $VOLUMEALSA / 10)

# Commands
export VOLUMEZERO="amixer set Master 0"
export VOLUMERESET="amixer set Master $VOLUMEALSA"
export MPRISSTATUS="$(playerctl status)"

if [ $MPRISSTATUS = "Playing" ]; then
  # Fading down and pausing.
  $VOLUMERESET &&
  for a in 1 2 3 4 5 6 7 8 9 10;
  do amixer set Master $VOLUMESTEP- && sleep 0.1; done &&
  $VOLUMEZERO && playerctl pause && sleep 0.5 && $VOLUMERESET
else
  # Playing and fading up.
  if [ $MPRISSTATUS = "Paused" ]; then
    $VOLUMEZERO && playerctl play &&
    for a in 1 2 3 4 5 6 7 8 9 10;
    do amixer set Master $VOLUMESTEP+ && sleep 0.1; done &&
    $VOLUMERESET
  else
    echo "MPRIS server or your music player is not running."
  fi
fi

echo $MPRISSTATUS