#!/usr/bin/env bash
# terminal application launcher for sway, using fzf
# Based on: https://gitlab.com/FlyingWombat/my-scripts/blob/master/sway-launcher
# https://gist.github.com/Biont/40ef59652acf3673520c7a03c9f22d2a
shopt -s nullglob globstar
set -o pipefail
# shellcheck disable=SC2154
trap 's=$?; echo "$0: Error on line "$LINENO": $BASH_COMMAND"; exit $s' ERR
IFS=$'\n\t'

# Defaulting terminal to urxvt, but feel free to either change
# this or override with an environment variable in your sway config
# It would be good to move this to a config file eventually
TERMINAL_COMMAND="${TERMINAL_COMMAND:="urxvt -e"}"
GLYPH_COMMAND="  "
GLYPH_DESKTOP="  "
HIST_FILE="${XDG_CACHE_HOME:-$HOME/.cache}/${0##*/}-history.txt"

# Get locations of desktop application folders according to spec
# https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
IFS=':' read -ra DIRS <<< "${XDG_DATA_HOME-${HOME}/.local/share}:${XDG_DATA_DIRS-/usr/local/share:/usr/share}"

function describe() {
  if [[ $2 == 'command' ]]; then
    title=$1
    readarray arr < <(whatis -l "$1" 2>/dev/null)
    description="${arr[0]}"
    description="${description%*-}"
  else
    title=$(sed -ne '/^Name=/{s/^Name=//;p;q}' "$1")
    description=$(sed -ne '/^Comment=/{s/^Comment=//;p;q}' "$1")
  fi
  echo -e "\033[33m$title\033[0m"
  echo "${description:-No description}"
}

function entries() {
  # shellcheck disable=SC2068
  awk -v pre="$GLYPH_DESKTOP" -F= '
    function desktopFileID(filename){
      sub("^.*applications/", "", filename);
      sub("/", "-", filename);
      return filename
    }
    BEGINFILE{
      application=0;
      block="";
      a=0

      id=desktopFileID(FILENAME)
      if(id in fileIds){
        nextfile;
      }else{
        fileIds[id]=0
      }
    }
    /^\[Desktop Entry\]/{block="entry"}
    /^Type=Application/{application=1}
    /^\[Desktop Action/{
      sub("^\\[Desktop Action ", "");
      sub("\\]$", "");
      block="action";
      a++;
      actions[a,"key"]=$0
    }
    /^Name=/{
    if(block=="action") {
        actions[a,"name"]=$2;
    } else {
        name=$2
    }
    }
    ENDFILE{
      if (application){
          print FILENAME "\034desktop\034\033[33m" pre name "\033[0m";
          if (a>0)
              for (i=1; i<=a; i++)
                  print FILENAME "\034desktop\034\033[33m" pre name "\033[0m (" actions[i, "name"] ")\034" actions[i, "key"]
      }
    }' \
    $@ </dev/null
  # the empty stdin is needed in case no *.desktop files
}

function generate-command() {
  # Define the search pattern that specifies the block to search for within the .desktop file
  PATTERN="^\\\\[Desktop Entry\\\\]"
  if [[ -n $2 ]]; then
    PATTERN="^\\\\[Desktop Action ${2%?}\\\\]"
  fi
  # 1. We see a line starting [Desktop, but we're already searching: deactivate search again
  # 2. We see the specified pattern: start search
  # 3. We see an Exec= line during search: remove field codes and set variable
  # 3. We see a Path= line during search: set variable
  # 4. Finally, build command line
  awk -v pattern="${PATTERN}" -v terminal_command="${TERMINAL_COMMAND}" -F= '
    BEGIN{a=0;exec=0;path=0}
       /^\[Desktop/{
        if(a){
          a=0
        }
       }
      $0 ~ pattern{
       a=1
      }
      /^Terminal=/{
        sub("^Terminal=", "");
        if ($0 == "true") {
          terminal=1
        }
      }
      /^Exec=/{
        if(a && !exec){
          sub("^Exec=", "");
          gsub(" ?%[cDdFfikmNnUuv]", "");
          exec=$0;
        }
      }
      /^Path=/{
        if(a && !path){
          path=$2
        }
       }

    END{
      if(path){
        printf "cd " path " && "
      }
      if (terminal){
        printf terminal_command " "
      }
      print exec
    }' "$1"
}

case "$1" in
describe | entries | generate-command)
  "$@"
  exit
  ;;
esac

touch "$HIST_FILE"
readarray HIST_LINES <"$HIST_FILE"
FZFPIPE=$(mktemp)
PIDFILE=$(mktemp)
trap 'rm "$FZFPIPE" "$PIDFILE"' EXIT INT

# Append Launcher History, removing usage count
(printf '%s' "${HIST_LINES[@]#* }" >>"$FZFPIPE") &

# Load and append Desktop entries
(
for i in "${!DIRS[@]}"; do
  if [[ ! -d "${DIRS[i]}" ]]; then
    unset -v 'DIRS[$i]'
  else
    DIRS[$i]="${DIRS[i]}/applications/**/*.desktop"
  fi
done
# shellcheck disable=SC2068
entries ${DIRS[@]} >>"$FZFPIPE"
) &

# Load and append command list
(
  IFS=:
  read -ra path <<<"$PATH"
  for dir in "${path[@]}"; do
    printf '%s\n' "$dir/"* |
      awk -F / -v pre="$GLYPH_COMMAND" '{print $NF "\034command\034\033[31m" pre "\033[0m" $NF;}'
  done | sort -u >>"$FZFPIPE"
) &

COMMAND_STR=$(
  (
    tail -n +0 -f "$FZFPIPE" &
    echo $! >"$PIDFILE"
  ) |
    fzf +s -x -d '\034' --nth ..3 --with-nth 3 \
      --preview "$0 describe {1} {2}" \
      --preview-window=up:3:wrap --ansi
  (kill -9 "$(<"$PIDFILE")"; exit 0) | tail -n1
) || exit 1

[ -z "$COMMAND_STR" ] && exit 1

# update history
for i in "${!HIST_LINES[@]}"; do
  if [[ "${HIST_LINES[i]}" == *" $COMMAND_STR"$'\n' ]]; then
    HIST_COUNT=${HIST_LINES[i]%% *}
    HIST_LINES[$i]="$((HIST_COUNT + 1)) $COMMAND_STR"$'\n'
    match=1
    break
  fi
done
if ! ((match)); then
  HIST_LINES+=("1 $COMMAND_STR"$'\n')
fi

printf '%s' "${HIST_LINES[@]}" | sort -nr >"$HIST_FILE"

command='echo "nope"'
# shellcheck disable=SC2086
readarray -d $'\034' -t PARAMS <<<${COMMAND_STR}
# COMMAND_STR is "<string>\034<type>"
case ${PARAMS[1]} in
desktop)
  command=$(generate-command "${PARAMS[0]}" "${PARAMS[3]}")
  ;;
command)
  command="$TERMINAL_COMMAND ${PARAMS[0]}"
  ;;
esac

swaymsg exec "'$command'"