#!/system/xbin/bash
#
# Copyright (C) 2017 Jeremy Rand <jeremy@veclabs.net>
# Partially based on code by Wolfgang Wiedmeyer <wolfgit@wiedmeyer.de> and Filippo Fil Bergamo
#
# This file is part of "Replicant Renderer Switcher", a set of shell scripts to switch between
# the Android Software Renderer and the llvmpipe renderer in Replicant.
#
# Replicant Renderer Switcher 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.
#
# Replicant Renderer Switcher 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 -euf -o pipefail

usage()
{
	echo "Usage: graphics.sh [faster|compatible]"
	echo "Examples:"
	echo "graphics.sh faster"
	echo "|-> Uses Android's libagl"
	echo "    which is faster"
	echo "    but some applications"
	echo "    like icecat won't work"
	echo "graphics.sh compatible"
	echo "|-> Uses llvmpipe"
	echo "    which is slower"
	echo "    but more compatible"
	exit 1
}

check_permissions()
{
	new_renderer="$1"

	root_access="$(getprop persist.sys.root_access)"
	uid="$(id -u)"

	# 0: Root access: Disabled, 2: Root access: ADB only
	#    For both the terminal application and ADB we have something
	#    like that:
	#        shell@i9100:/ $ su
	#        255|shell@i9100:/ $
	# 1: Root access: Apps only
	#    From ADB:
	#        shell@i9100:/ $ su
	#        Permission denied
	#        1|shell@i9100:/ $
	#    From the terminal application
	#        u0_a51@i9100:/ $ su
	#        root@i9100:/ #
	if [ "${uid}" != "0" ] ; then
	    echo ""
	    echo "This script requires root."
	    echo "To give it root:"
	    case "${root_access}" in
		"0"|"1"|"2")
		    echo "- Go in Settings"
		    echo "- Go in Developer options"
		    echo "- Select Root access"
		    echo "- Set it to \"Apps and ADB\""
		    ;;
	    esac
	    echo "- Run these 2 commands:"
	    echo "  su"
	    echo "  graphics.sh ${new_renderer}"
	    exit 1
	fi
}

graphics()
{
    new_renderer="$1" # libagl || llvmpipe

    check_permissions "${new_renderer}"

    grep -q "ro.libagl=0" /system/build.prop && \
	old_renderer="llvmpipe" || old_renderer="libagl"

    if [ "${old_renderer}" == "${new_renderer}" ] ; then
	if [ "${old_renderer}" = "libagl" ] ; then
	    echo "Android software renderer is already enabled!"
	else
	    echo "${old_renderer} renderer is already enabled!"
	fi
	exit 1
    fi

    echo "Remounting system partition as writable..."
    mount -o rw,remount /system

    if [ "${new_renderer}" == "libagl" ] ; then
	echo "Enabling Android software renderer..."
	sed "s/ro.libagl=0/ro.libagl=1/" -i /system/build.prop
    else
	echo "Enabling ${new_renderer}..."
	sed "s/ro.libagl=1/ro.libagl=0/" -i /system/build.prop
    fi

    echo "Syncing filesystem..."
    sync
    sync

    echo "Remounting system partition as read-only..."
    mount -o ro,remount /system

    echo "Syncing filesystem..."
    sync
    sync

    if [ "${new_renderer}" == "libagl" ] ; then
	echo "Android software renderer will be enabled after we reboot now..."
    else
	echo "${new_renderer} will be enabled after we reboot now..."
    fi

    # https://android.stackexchange.com/a/139139
    am start -a android.intent.action.REBOOT
}

if [ $# -ne 1 ] ; then
	usage
fi

if [ "$1" = "faster" ] ; then
    graphics libagl
elif [ "$1" = "compatible" ] ;then
    graphics llvmpipe
else
	usage
fi