#!/bin/bash
#
# goodsong v2.1
#
# pbrisbin 2009, 2010
#
# http://pbrisbin.com/bin/goodsong
#
# 5/9/2010 patched by TomVincent to add:
#
#  * use of heredoc in message
#  * locateMPDConf()
#  * mpdParam()
#  * default list as an actual playlist
#  
###

message() {
  cat << EOF
usage: goodsong [option]

  options:

        -p, --play        play a random song from list, now

        -b, --build       build a playlist from your list, play it

        -s, --show        display a random song from list

        -f, --find regex  find a song in your list using grep 'regex'

        -S, --smart       select a song from your list; find it in
                          your current playlist or add it; when the
                          current song ends, play it

        -P, --print       print your list with music dir prepended

        -h, --help        display this

        none              append playing song to list

EOF

  exit 1
}

# tvincent 5/9/2010 +
# Return the mpd.conf passed as a parameter to mpd or an expected default
locateMPDConf() {
  # Don't use any command that overrides the "real" mpd binary
  local config="$(pgrep -fl $(which --skip-tilde mpd) | awk '{print $3}')"

  if [[ -z $config ]]; then
    if [[ -r "$HOME/.mpd/mpd.conf" ]]; then
      config="$HOME/.mpd/mpd.conf"
    elif [[ -r '/etc/mpd.conf' ]]; then
      config='/etc/mpd.conf'
    else
      echo 'unable to locate a readable mpd.conf' >&2
      exit 1
    fi
  fi

  echo "$config"
}

# tvincent 5/9/2010 +
# From the given regex ($1), find the relevant mpd.conf parameter
mpdParam() {
  if [[ -z "$1" ]]; then
    echo 'illegal function call: mpdParam()' >&2
    exit 1
  fi

  local mpdconf="$(locateMPDConf)" param

  # locates parameter values where value can be single, double, or
  # un-quoted -- also translate ~ to $HOME
  param="$(sed -r '/^'"$1"' *(\"|'\''|)([^\1]*)\1/!d; s//\2/g; s%~%'"$HOME"'%g' "$mpdconf")"

  echo "$param"
}

# just prints your list with the music dir prepended (for easy piping, etc)
printlist() {
  local mdir="$(mpdParam '^music_directory')"
  sed "s|^|$mdir/|g" "$list"
}

# return playlist position of a random good song
get_pos() {
  local track="$(cat $list | sort -R | head -n 1)" pos

  #pos=$(mpc --format '%position% %file%' playlist | grep "[0-9]*\ $track$" | awk '{print $1}' | head -n 1)
  pos=$(mpc --format '%position% %file%' playlist | awk "/[0-9]* ${track//\//\\/}$/"'{print $1}' | head -n 1)

  if [[ -z "$pos" ]]; then
    mpc add "$track"
    pos=$(mpc playlist | wc -l)
  fi

  echo "$pos"
}

# returns current seconds remaining
get_lag() {
  local time curm curs totm tots lag N

  time="$(mpc | awk '/playing/ {print $3}')"

  if [[ -n "$time" ]]; then
    while IFS=':' read -r curm curs totm tots; do
      cur=$((curm*60+curs))
      tot=$((totm*60+tots))

      lag=$((tot-cur))
    done <<< "${time////:}"

    # adjust lag based on crossfade
    N=$(mpc crossfade | awk '{print $2}')
    [[ -n "$N" ]] && lag=$((lag-N))

    echo "$lag"
  else
    echo "0"
  fi
}

# build a playlist and play it; could probably just use mpc load
# playlist command here at this point...
build_playlist() {
  local IFS=$'\n'

  mpc clear >/dev/null
  while read -r; do
    mpc add "$REPLY"
  done < <(sort -R "$list")
  mpc play
}

# add current song to the list
add_to_list() {
  # is mpd playing?
  mpc | grep -Fq playing || exit 1

  # get song filename
  song="$(mpc --format %file% | head -n 1)"

  # add it -- prevent dupes
  grep -Fqx "$song" "$list" || echo "$song" >> "$list"
}

# queue up a good song for when the current song ends
smart_play() { (sleep $(get_lag) && mpc play $(get_pos) &>/dev/null) & }

# show one random good song
show_one() { sort -R "$list" | head -n 1; }

# play a random good song
play_one() { mpc play $(get_pos); }

# search the list
search_list() { grep -i "$*" "$list"; }

parse_options() {
  case "$1" in
    -h|--help)  message                 ;;
    -s|--show)  show_one                ;;
    -f|--find)  shift; search_list "$*" ;;
    -p|--play)  play_one                ;;
    -b|--build) build_playlist          ;;
    -S|--smart) smart_play              ;;
    -P|--print) printlist               ;;
    *)          add_to_list             ;;
  esac
}

# tvincent 5/9/2010 +
list="$(mpdParam 'playlist_directory')/goodsongs.m3u"
touch "$list" || exit 1

parse_options "$@"