#!/usr/bin/env bash
# Desktop notification with cover art on song change. Run by ncmpcpp's
# execute_on_song_change, so it only fires while ncmpcpp is open.
#
# mopidy: Mopidy-MPD has no albumart command, so the cover comes from the
# Subsonic server behind Mopidy-Subidy. url and username are read from
# mopidy.conf, the password from the untracked secrets.conf.
# Usage: song-notify [subidy:song:<id>]   (defaults to the current song)

set -u

conf=~/.config/mopidy/mopidy.conf
secrets=~/.config/mopidy/secrets.conf
cache=${XDG_CACHE_HOME:-$HOME/.cache}/ncmpcpp/covers

fmt='%file%\t%artist%\t%title%\t%album%'
if [ $# -gt 0 ]; then
  line=$(mpc -f "$fmt" playlist 2>/dev/null |
    awk -F'\t' -v u="$1" '$1 == u { print; exit }')
else
  line=$(mpc -f "$fmt" current 2>/dev/null)
fi
IFS=$'\t' read -r uri artist title album <<<"$line"
[ -n "$uri" ] || exit 0

# Value of key in [subidy] of an ini file.
ini() {
  awk -F' *= *' -v k="$2" '
    /^\[/ { s = ($0 == "[subidy]") }
    s && $1 == k { print $2; exit }' "$1"
}

cover=
id=${uri#subidy:song:}
if [ "$id" != "$uri" ] && [ -r "$secrets" ]; then
  url=$(ini "$conf" url)
  user=$(ini "$conf" username)
  pass=$(ini "$secrets" password)
  salt=$(head -c 8 /dev/urandom | od -An -tx1 | tr -d ' \n')
  token=$(printf '%s%s' "$pass" "$salt" | md5sum | cut -d' ' -f1)
  auth="u=$user&t=$token&s=$salt&v=1.16.1&c=ncmpcpp"

  art=$(curl -fsS --max-time 5 "$url/rest/getSong.view?$auth&f=json&id=$id" |
    jq -r '."subsonic-response".song.coverArt // empty')
  if [ -n "$art" ]; then
    cover=$cache/${art////_}
    if [ ! -s "$cover" ]; then
      mkdir -p "$cache"
      curl -fsS --max-time 10 -o "$cover" \
        "$url/rest/getCoverArt.view?$auth&id=$art&size=256" || cover=
    fi
  fi
fi

notify-send -a ncmpcpp ${cover:+-i "$cover"} \
  -h string:x-canonical-private-synchronous:ncmpcpp \
  "${title:-$uri}" "${artist:-}${album:+ — $album}"