#!/bin/sh
#
# gst-screencast - screencasting of a window using GStreamer
#
# Copyright (C) 2015-2017  Antonio Ospite <ao2@ao2.it>
#
# 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 2 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 <http://www.gnu.org/licenses/>.

set -e

usage() {
  cat <<EOF
usage: $(basename $0) [OPTIONS] <output_file> [<ximagesrc_options>]

Screencast script based on GStreamer.

Options:
  --audio         record audio from pulsesrc
  --frame         include the window manager border, without the shadows
  --pointer       capture the mouse pointer
  --single-shot   capture a single snapshot as a PNG instead of a video
  -h, --help      display this usage message and exit

EOF
}

CAPTURE_AUDIO=0
WINDOW_FRAME=0
SHOW_POINTER=0
SINGLE_SHOT=0

while [ $# -gt 0 ];
do
  case "$1" in
    -h|--help)
      usage
      exit 0
      ;;
    --audio)
      CAPTURE_AUDIO=1
      ;;
    --frame)
      WINDOW_FRAME=1
      ;;
    --pointer)
      SHOW_POINTER=1
      ;;
    --single-shot)
      SINGLE_SHOT=1
      ;;
    -*)
      echo "Error: Unknown option '${1}'" 1>&2
      ;;
    *)
      break;
  esac
  shift
done

[ "x" = "x$1" ] && { usage 1>&2; exit 1; }

[ -f "$1" ] && { echo "Error: file '${1}' already exists!" 1>&2; exit 2; }

FILENAME="$1"
shift

if [ "x" = "x$1" ];
then
  SHADOW_SIZE=0
  SHADOW_X_OFFSET=0
  SHADOW_Y_OFFSET=0
  if [ $WINDOW_FRAME -eq 1 ];
  then
    XWININFO_OPTIONS="-frame"

    # XXX the values below are still hardcoded, they may be different
    # depending on the theme and the window manager.
    SHADOW_SIZE=26
    SHADOW_X_OFFSET=0
    SHADOW_Y_OFFSET=3
  fi

  WIN_INFO="$(xwininfo $XWININFO_OPTIONS)"

  X=$(echo "$WIN_INFO" | sed -n -e "/^[[:space:]]*Absolute upper-left X:[[:space:]]*/s///p")
  Y=$(echo "$WIN_INFO" | sed -n -e "/^[[:space:]]*Absolute upper-left Y:[[:space:]]*/s///p")
  WIDTH=$(echo "$WIN_INFO" | sed -n -e "/^[[:space:]]*Width:[[:space:]]*/s///p")
  HEIGHT=$(echo "$WIN_INFO" | sed -n -e "/^[[:space:]]*Height:[[:space:]]*/s///p")

  XIMAGESRC_ARGS="startx=$(($X + $SHADOW_SIZE - $SHADOW_X_OFFSET)) starty=$(($Y + $SHADOW_SIZE - $SHADOW_Y_OFFSET)) endx=$(($X + $WIDTH - 1 - $SHADOW_SIZE - $SHADOW_X_OFFSET)) endy=$(($Y + $HEIGHT - 1 - $SHADOW_SIZE - $SHADOW_Y_OFFSET))"
else
  XIMAGESRC_ARGS="$@"
fi

if [ $SINGLE_SHOT -eq 1 ];
then
  gst-launch-1.0 -v \
    ximagesrc use-damage=0 show-pointer=$SHOW_POINTER $XIMAGESRC_ARGS num-buffers=1 ! \
    videoconvert ! pngenc ! filesink location="$FILENAME"
else
  VIDEO_CODEC="video/x-raw,format=I420 ! jpegenc quality=90"

  if [ $CAPTURE_AUDIO -eq 1 ];
  then
    # Record from everything
    if ! pactl list short sinks | grep -q module-null-sink;
    then

      PA_IDS=$(pactl load-module module-null-sink)
      trap 'exit 1' INT
      trap 'trap INT; for pa_id in $PA_IDS; do pactl unload-module "$pa_id"; done' EXIT

      SOURCES=$(pactl list short sources | cut -f 2 | grep -v "^null\.monitor$")
      for source in $SOURCES;
      do
        MODULE_ID=$(pactl load-module module-loopback latency_msec=1 source="$source" sink=null)
        PA_IDS="$MODULE_ID $PA_IDS"
      done

      pactl set-sink-mute null 0
    fi

    AUDIO_PIPELINE="pulsesrc device=null.monitor ! audioconvert ! audio/x-raw,rate=44100,channels=2 ! vorbisenc ! queue ! mux."
  fi

  gst-launch-1.0 -v -e \
    matroskamux name=mux ! filesink location="$FILENAME" \
    ximagesrc use-damage=0 show-pointer=$SHOW_POINTER $XIMAGESRC_ARGS ! video/x-raw,framerate=25/1 ! \
    videoconvert ! videorate ! $VIDEO_CODEC ! queue ! mux. \
    $AUDIO_PIPELINE
fi