#!/bin/sh
#
#    byobu-ctrl-a - set the ctrl-a behavior
#    Copyright (C) 2011 Canonical Ltd.
#
#    Authors: Dustin Kirkland <kirkland@byobu.co>
#
#    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, version 3 of the License.
#
#    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/>.

Usage() {
	cat <<EOF
Usage: ${0##*/} [mode]
   mode is one of 'screen' or 'emacs'
   if not specified, prompt the user
EOF
}

PKG="byobu"
[ -r "$HOME/.byoburc" ] && . "$HOME/.byoburc"
[ -z "${BYOBU_PREFIX}" ] && export BYOBU_PREFIX="/usr" || export BYOBU_PREFIX
. "${BYOBU_PREFIX}/lib/${PKG}/include/common"

bind_to=""
keybindings="$BYOBU_CONFIG_DIR/keybindings"
[ "$BYOBU_BACKEND" = "tmux" ] && keybindings="$keybindings.tmux"
touch "$keybindings"

# If the user has already chosen an escape sequence, then
# presumably they want ctrl-a to operate in emacs mode
case "$BYOBU_BACKEND" in
	"screen")
		if grep -qs "^escape" "$keybindings"; then
			# Check for escape definition in local keybindings config
			bind_to="emacs"
		fi
	;;
	"tmux")
		if grep -qs "^set -g prefix" "$keybindings"e;  then
			# Check for escape definition in local keybindings config
			bind_to="emacs"
		fi
		# Check for some other escape sequence in tmux keys
		if tmux list-keys | grep -qs "^bind-key\s\+[^a]\s\+send-prefix"; then
			bind_to="emacs"
		fi
	;;
esac

case "${1}" in
	-h|--help) Usage; exit 0;;
	screen) bind_to="screen";;
	emacs) bind_to="emacs";;
	"") :;;
	*) { Usage printf "%s\n" "Bad argument $1"; } 1>&2; exit 1;;
esac

if [ "${2}" ]; then
	KEY=$(printf "$2" | $BYOBU_SED 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/')
	key=$(printf "$2" | $BYOBU_SED 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/')
else
	KEY="A"
	key="a"
fi

while [ -z "$bind_to" ]; do
	echo
	echo "Configure Byobu's ctrl-a behavior..."
	echo
	echo "When you press ctrl-a in Byobu, do you want it to operate in:"
	echo "    (1) Screen mode (GNU Screen's default escape sequence)"
	echo "    (2) Emacs mode  (go to beginning of line)"
	echo
	echo "Note that:"
	echo "  - F12 also operates as an escape in Byobu"
	echo "  - You can press F9 and choose your escape character"
	echo "  - You can run 'byobu-ctrl-a' at any time to change your selection"
	echo
	printf "Select [1 or 2]: "
	s=$(head -n1)
	echo
	case "$s" in
		1) bind_to="screen"; break;;
		2) bind_to="emacs"; break;;
	esac
done

case "$bind_to" in
	emacs)
		case "$BYOBU_BACKEND" in
			screen)
				$BYOBU_SED -i -e "/^register x /d" -e "/^bindkey /d" -e "/^escape /d" "$keybindings"
				echo "bindkey \"^${KEY}\"" >> "$keybindings"
				$BYOBU_BACKEND -X at 0 source "$BYOBU_CONFIG_DIR/profile"
			;;
			tmux)
				$BYOBU_SED -i -e "/^set -g prefix/d" -e "/ send-prefix/d" -e "/^unbind-key -n C-${key}/d" "$keybindings"
				echo "set -g prefix F12" >> "$keybindings"
				echo "unbind-key -n C-${key}" >> "$keybindings"
				$BYOBU_BACKEND source "$BYOBU_PREFIX/share/byobu/profiles/tmuxrc"
			;;
		esac
		echo "INFO: ctrl-a will now operate in emacs mode"
	;;
	screen)
		case "$BYOBU_BACKEND" in
			screen)
				$BYOBU_SED -i -e "/^register x /d" -e "/^bindkey \"^\"/d" -e "/^escape /d" "$keybindings"
				echo "escape \"^${KEY}${key}\"" >> "$keybindings"
				echo "register x \"^${KEY}\"" >> "$keybindings"
				echo "bindkey \"^${KEY}\"" >> "$keybindings"
				$BYOBU_BACKEND -X at 0 source "$BYOBU_CONFIG_DIR/profile"
			;;
			tmux)
				$BYOBU_SED -i -e "/^set -g prefix/d" -e "/ send-prefix/d" -e "/^unbind-key -n C-${key}/d" "$keybindings"
				echo "unbind-key -n C-${key}" >> "$keybindings"
				if $BYOBU_BACKEND -V | grep " 1.5"; then
					# tmux 1.5 supports a list of prefixes
					echo "set -g prefix ^${KEY},F12" >> "$keybindings"
				else
					# tmux 1.6 and above supports prefix and prefix2
					echo "set -g prefix ^${KEY}" >> "$keybindings"
					echo "set -g prefix2 ^${KEY}" >> "$keybindings"
				fi
				echo "bind ${key} send-prefix" >> "$keybindings"
				$BYOBU_BACKEND source "$BYOBU_PREFIX/share/byobu/profiles/tmuxrc"
			;;
		esac
		echo "INFO: ctrl-a will now operate in GNU Screen mode"
	;;
	*)
		echo "Error: bad value for binding: $bind_to"
	;;
esac

if [ -z "${2}" ]; then
	echo "To modify this behavior again later, run 'byobu-ctrl-a'"
	echo
fi

# vi: syntax=sh ts=4 noexpandtab