#! /usr/bin/env sh

# Mirai Nikki Bot a video frame posting bot for Pleroma
# Copyright (C) 2022 Anon
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# ISSUES:
# - https://github.com/mpv-player/mpv/issues/5498
#     MPV has an issue when outputting to jpg.
#     Colors look washed out and faded compared to png screenshots.
#     As a workaround this script will output to png then convert to jpg.
#
# - https://trac.ffmpeg.org/ticket/2391
#     I want to just use ffmpeg for this script, however it
#     does not support dvd subtitles. For now, I have to
#     rely on mpv to render dvdsubs correctly :(

# TODO:
# - Tidy up this script and add some safety checks
# - Add some logic to the bot to detect if this script failed
# - Research more mpv options to avoid having to use mpv + convert

# Requiered args supplied by the bot
INPUT_PATH="$1"
OUTPUT_PATH="$2"
PICKED_FRAME="$3"

PNG_PATH="${OUTPUT_PATH%.*}.png"

echo "$INPUT_PATH"
echo "$OUTPUT_PATH"
echo "$PICKED_FRAME"

mkdir -p "$(dirname "$OUTPUT_PATH")"

mpv "$INPUT_PATH" --sid=1 "--start=${PICKED_FRAME}" --frames=1 -o "$PNG_PATH"
convert -quality 95 "$PNG_PATH" "$OUTPUT_PATH"

rm -fv "$PNG_PATH"