#!/usr/bin/env bash

declare usage
usage="Usage:
$(basename "$0") [-h]
$(basename "$0") <FILE> <START_TIME> <DURATION> [FPS]

Creates a gif from a video file.

command line arguments:
<FILE> - the path to the movie we're converting
<START_TIME> - the start time of the finished gif
<DURATION> - duration; the length of the video clip after the start time to convert
Time(s) can be in seconds, or it also accepts the \"hh:mm:ss[.xxx]\" format
[FPS] - (optional) specify an integer fps value. default is 10
For best output, it should be a factor of 100; e.g. 10, 20, 25, 50

e.g. gifme ~/Movies/your-favorite-movie.mp4 00:43:04 5
e.g. gifme ~/Movies/your-favorite-movie.mp4 01:04:02 10.5 25

Note if you want to convert the entire duration for a video file to
a gif, you can provide a duration much higher than the length of the video
e.g. gifme ~/Movies/a-short-video.mkv 0 9999999 10

requires 'imagemagick' and 'ffmpeg'

Modified from: https://github.com/holman/dotfiles/blob/master/bin/movieme
"

# print help if user asked for it
if [[ "$1" =~ ^[-]{1,2}?h(elp)?$ ]]; then
	echo "${usage}"
	exit 0
fi

havecmd -v ffmpeg || exit $?
havecmd -V 'This is typically installed as part of imagemagick' magick || exit $?

# quit if ffmpeg fails
set -e

# reset temp directory
tdir="$(mktemp -d)"

main() {

	# check for command line arguments
	if [[ -z "$3" ]]; then
		printf "You didn't provide enough arguments.
Type 'gifme -h' for additional help.

\$1 - the path to the movie we're converting
\$2 - the start time of the finished gif
\$3 - duration; the length of the video clip after the start time to convert
Time(s) can be in seconds, or it also accepts the \"hh:mm:ss[.xxx]\" format
\$4 - (optional) specify an integer fps value. default is 10
For best output, it should be a factor of 100; e.g. 10, 20, 25, 50
"
		return 1
	fi

	# process fps arg
	readonly fps="${4:-10}"
	readonly convert_delay="$((100 / fps))"

	# generate output filename based on input file
	declare output_filename current_time
	current_time="$(date +%H.%M.%S)"
	output_filename="$(basename "$1")"
	output_filename="${output_filename%.*}" # remove extension
	output_filename="${output_filename}-gifme-${current_time}.gif"

	# create frames
	# i - input
	# f - force image format
	# ss - start time
	# t - time
	# r - fps
	ffmpeg -i "$1" -f image2 -ss "$2" -t "$3" -r "$fps" /tmp/gifme/d-%09d.png
	printf "Converting %d frames to a gif...\n" "$(find /tmp/gifme | wc -l)"
	# convert to gif
	# delay - speed, determined by fps above
	# loop 0 - make gif repeat itself
	magick -delay "${convert_delay}" -loop 0 -limit memory 2GB -limit map 2GB /tmp/gifme/*.png "${output_filename}"
	printf "Created %s successfully\n" "${output_filename}"

}

main "$@"
ret=$?
rm -rf "$tdir"
exit "$ret"