previewer

#!/usr/bin/env bash

FILE_PATH="${1}"
FILE_EXTENSION="${FILE_PATH##*.}"
FILE_EXTENSION_LOWER="$(printf "%s" "${FILE_EXTENSION}" | tr '[:upper:]' '[:lower:]')"

PV_WIDTH="${2}"
PV_HEIGHT="${3}"
HORIZONTAL_POS="${4}"
VERTICAL_POS="${5}"

bat() {
  command bat \
    --color=always --paging=never \
    --style=plain \
    --wrap=character \
    --line-range :"${PV_HEIGHT}" \
    --terminal-width="${PV_WIDTH}" "$@"
}

image_previewer() {
  # In Kitty, only lf running in normal terminal, not in tmux or Neovim's builtin terminal, could
  # use kitty image protocal. In other situations, chafa could be used, however, lf running in
  # tmux displays the image with abnormal colors.
  if [[ $KITTY_WINDOW_ID ]]; then
    # In Kitty
    if [[ ! $TERM =~ "tmux" && -z $NVIM ]]; then
      local place="${PV_WIDTH}x${PV_HEIGHT}@${HORIZONTAL_POS}x${VERTICAL_POS}"
      kitty icat --clear --transfer-mode memory --stdin no --align left --place "$place" "$1" < /dev/null > /dev/tty
    elif [[ $TERM =~ "tmux" && -z $NVIM ]]; then
      printf "Preview is not supported here!\n"
      printf "Instead, preview it in FZF (CTRL-F)."
    else
      chafa -f symbols -s "${PV_WIDTH}x${PV_HEIGHT}" --animate off --polite on "$1"
    fi
  elif [[ $WEZTERM_PANE || $ALACRITTY_WINDOW_ID ]]; then
    # In Wezterm or Alacritty
    if [[ ! $TERM =~ "tmux" && -z $NVIM ]]; then
      chafa -s "${PV_WIDTH}x${PV_HEIGHT}" --animate off --polite on "$1"
    elif [[ $TERM =~ "tmux" && -z $NVIM ]]; then
      printf "Preview is not supported here!\n"
      printf "Instead, preview it in FZF (CTRL-F)."
    else
      chafa -f symbols -s "${PV_WIDTH}x${PV_HEIGHT}" --animate off --polite on "$1"
    fi
  else
    printf "Preview is NOT supported!"
  fi
}

handle_extension() {
  case "${FILE_EXTENSION_LOWER}" in
    # Markdown
    md)
      glow -s dark --width "${PV_WIDTH}" -- "${FILE_PATH}" && exit 1;;
    # Archive
    bz2|gz|lz|tar|xz|zip)
      atool --list -- "${FILE_PATH}" && exit 1;;
    rar)
      unrar lt -p- -- "${FILE_PATH}" && exit 1;;
    7z)
      7z l -p -- "${FILE_PATH}" && exit 1;;
    # PDF
    pdf)
      pdftotext -l 10 -nopgbrk -q -- "${FILE_PATH}" - | fmt -w "${PV_WIDTH}" && exit 1;;
    # OpenDocument
    odt|sxw|ods|odp)
      odt2txt "${FILE_PATH}" && exit 1;;
    # XLSX
    xlsx)
      xlsx2csv -- "${FILE_PATH}" | head -n 500 && exit 1;;
    # JSON
    json)
      jq --color-output . "${FILE_PATH}" && exit1 ;;
    # BitTorrent
    torrent)
      transmission-show -- "${FILE_PATH}" && exit 1;;
    # Dmg
    dmg)
      hdiutil imageinfo "${FILE_PATH}" | bat -l yaml && exit 1;;
    # CSV and TSV
    csv|tsv)
      mlr --icsv --opprint -C --key-color darkcyan --value-color grey70 head -n 500 "${FILE_PATH}" && exit 1;;
    # Sqlite3 and sqlite
    sqlite3 | sqlite)
      sqlite3 "${FILE_PATH}" .schema | sed "s/;/;\n/g" | bat -l sql && exit 1;;
    # so and dylib
    so|dylib)
      nm "${FILE_PATH}" && exit 1
      nm -D "${FILE_PATH}" && exit 1
  esac
}

handle_mime() {
  local mimetype="${1}"
  case "${mimetype}" in
    # DOCX, ePub, FB2
    *wordprocessingml.document|*/epub+zip|*/x-fictionbook+xml)
      pandoc -s -t markdown -- "${FILE_PATH}" | glow -s dark --width "${PV_WIDTH}" && exit 1;;
    # Image
    image/*)
      image_previewer "${FILE_PATH}"
      exit 1;;
    # Video
    video/*)
      local thumbnail=$($HOME/.config/lf/vidthumb "${FILE_PATH}")
      image_previewer "$thumbnail"
      exit 1;;
    # Text
    text/* | */xml)
      (bat --style=numbers,changes -- "${FILE_PATH}" \
      || highlight --out-format truecolor --style darkplus --force \
          --line-numbers --line-range=1-"${PV_HEIGHT}" -- "${FILE_PATH}" \
      || cat -- "${FILE_PATH}") && exit 1;;
  esac
}

handle_fallback() {
  # Use file command as the fallback. It outputs the file properties, separated by comma, in a
  # single lone line. In order to fit the width of the preview window, replace each comma with a
  # line break, but leave the commas inside square brackets unchanged.
  file --dereference --brief -- "${FILE_PATH}" | gsed -r ':a; s/(\[[^][]*),([^][]*\])/\1TTEEMMPP\2/g; ta; s/, /\n/g; s/TTEEMMPP/,/g' && exit 1
  exit 1
}

MIMETYPE="$( file --dereference --brief --mime-type -- "${FILE_PATH}" )"
handle_extension
handle_mime "${MIMETYPE}"
handle_fallback

exit 1