#!/bin/sh

set -C -f
IFS="$(printf '%b_' '\n')"
IFS="${IFS%_}"

PREVIEW_DIR="${XDG_CACHE_HOME:-$HOME/.cache}/lf"
PREVIEW_WIDTH=600 # px

# TODO: Render in the original width when it's smaller than PREVIEW_WIDTH

# PrefixGen: generates a hash prefix for the given file
# This is a unique identifier for the file to preview
PrefixGen() {
	sha256sum "$(readlink -f "$1")" | cut -d' ' -f1
}

# SuffixGen: generates a hash suffix for the given file
# This suffix is used to determine if the preview is outdated
SuffixGen() {
	stat -Lc "%Y" "$1"
}

# Prevent recursive thumbnails (if the file ends in .six)
[ "${1##*.}" = "six" ] && cat "$1" && exit 1

case "$(file --dereference --brief --mime-type -- "$1")" in
text/html)
	lynx -width="$4" -display_charset=utf-8 -dump "$1"
	;;
text/troff)
	man ./ "$1" | col -b
	;;
text/* | */xml | application/json | application/x-ndjson)
	bat --terminal-width "$(($4 - 2))" -f "$1"
	;;
audio/* | application/octet-stream)
	mediainfo "$1" || exit 1
	;;
image/vnd.djvu)
	prefix="$(PrefixGen "$1")"
	suffix="$(SuffixGen "$1")"
	filename="$prefix-$suffix"
	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
		rm -f "$PREVIEW_DIR/$prefix-*"
		djvused "$1" -e 'select 1; save-page-with /dev/stdout' |
			convert djvu:- png:- |
			img2sixel -S -E size -q high -w $PREVIEW_WIDTH -o "$PREVIEW_DIR/$filename.six"
	}
	cat "$PREVIEW_DIR/$filename.six"
	;;
image/*)
	prefix="$(PrefixGen "$1")"
	suffix="$(SuffixGen "$1")"
	filename="$prefix-$suffix"
	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
		rm -f "$PREVIEW_DIR/$prefix-*"
		img2sixel -S -E size -q high -w $PREVIEW_WIDTH "$1" -o "$PREVIEW_DIR/$filename.six"
	}
	cat "$PREVIEW_DIR/$filename.six"
	;;
*/pdf)
	prefix="$(PrefixGen "$1")"
	suffix="$(SuffixGen "$1")"
	filename="$prefix-$suffix"
	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
		rm -f "$PREVIEW_DIR/$prefix-*"
		pdftocairo -singlefile -scale-to-x $PREVIEW_WIDTH -scale-to-y -1 -png "$1" - |
			img2sixel -S -E size -q high -o "$PREVIEW_DIR/$filename.six"
	}
	cat "$PREVIEW_DIR/$filename.six"
	;;
video/*)
	prefix="$(PrefixGen "$1")"
	suffix="$(SuffixGen "$1")"
	filename="$prefix-$suffix"
	# XXX: thumbnail seems to get re-generated every time the file is selected
	[ ! -f "$PREVIEW_DIR/$filename.six" ] && {
		rm -f "$PREVIEW_DIR/$prefix-*"
		ffmpegthumbnailer -i "$1" -s 0 -c png -f -o - |
			img2sixel -S -E size -q high -w $PREVIEW_WIDTH -o "$PREVIEW_DIR/$filename.six"
	}
	cat "$PREVIEW_DIR/$filename.six"
	;;
application/*zip)
	atool --list -- "$1"
	;;
*opendocument*)
	odt2txt "$1"
	;;
application/pgp-encrypted)
	gpg -d -- "$1"
	;;
esac

exit 1