#!/usr/bin/env bash
#
# The purpose of this script is to demonstrate how to preview a file or an
# image in the preview window of fzf.
#
# Dependencies:
# - https://github.com/sharkdp/bat
# - https://github.com/hpjansson/chafa
# - https://iterm2.com/utilities/imgcat

if [[ $# -ne 1 ]]; then
	echo >&2 "usage: $0 FILENAME"
	exit 1
fi

file=${1/#\~\//$HOME/}
type=$(file --dereference --mime -- "$file")

if [[ ! $type =~ image/ ]]; then
	if [[ $type =~ =binary ]]; then
		file "$1"
		exit
	fi

	# Sometimes bat is installed as batcat.
	if command -v batcat >/dev/null; then
		batname="batcat"
	elif command -v bat >/dev/null; then
		batname="bat"
	else
		cat "$1"
		exit
	fi

	${batname} --style="${BAT_STYLE:-numbers}" --color=always --pager=never -- "$file"
	exit
fi

dim=${FZF_PREVIEW_COLUMNS}x${FZF_PREVIEW_LINES}
if [[ $dim = x ]]; then
	dim=$(stty size </dev/tty | awk '{print $2 "x" $1}')
elif ! [[ $KITTY_WINDOW_ID ]] && ((FZF_PREVIEW_TOP + FZF_PREVIEW_LINES == $(stty size </dev/tty | awk '{print $1}'))); then
	# Avoid scrolling issue when the Sixel image touches the bottom of the screen
	# * https://github.com/junegunn/fzf/issues/2544
	dim=${FZF_PREVIEW_COLUMNS}x$((FZF_PREVIEW_LINES - 1))
fi

# 1. Use kitty icat on kitty terminal
if [[ $KITTY_WINDOW_ID ]]; then
	# 1. 'memory' is the fastest option but if you want the image to be scrollable,
	#    you have to use 'stream'.
	#
	# 2. The last line of the output is the ANSI reset code without newline.
	#    This confuses fzf and makes it render scroll offset indicator.
	#    So we remove the last line and append the reset code to its previous line.
	kitty icat --clear --transfer-mode=memory --stdin=no --place="$dim@0x0" "$file" | sed '$d' | sed $'$s/$/\e[m/'

# 2. Use chafa with Sixel output
elif command -v chafa >/dev/null; then
	chafa -f sixel -s "$dim" "$file"
	# Add a new line character so that fzf can display multiple images in the preview window
	echo

# 3. If chafa is not found but imgcat is available, use it on iTerm2
elif command -v imgcat >/dev/null; then
	# NOTE: We should use https://iterm2.com/utilities/it2check to check if the
	# user is running iTerm2. But for the sake of simplicity, we just assume
	# that's the case here.
	imgcat -W "${dim%%x*}" -H "${dim##*x}" "$file"

# 4. Cannot find any suitable method to preview the image
else
	file "$file"
fi
