#!/bin/sh
#
# byobu-ctrl-a - set the ctrl-a behavior
# Copyright (C) 2011 Canonical Ltd.
#
# Authors: Dustin Kirkland <[email protected]>
#
# 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}\" eval \"process x\"" >> "$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