#!/bin/sh

# 0. Check whether we're on a console
TTY=$(/usr/bin/tty)
case "$TTY" in
	/dev/console|/dev/vc*|/dev/tty[0-9]*)
		;;
	*)
		echo "unicode_start skipped on $TTY" >&2
		exit 0
		;;
esac

# Enables Unicode processing in the current console.
#
# 1. The input side: the keyboard driver.

# Set the keyboard driver in Unicode mode. (Default is ASCII mode.)
# This really does nothing with the way normal keys are handled in
# the kernel. All it does is:
# - It is necessary for `dumpkeys' in order to not drop U+XXXX
#   entries from the keymaps.
# - It is necessary for `loadkeys' in order to avoid warnings.
# - Unicode characters typed as Alt-x1 ... Alt-xn (where x1,...,xn
#   are digits on the numeric keypad) will be emitted in UTF-8.

kbd_mode -u

# Change the keyboard mapping in such a way that the non-ASCII keys
# produce UTF-8 encoded multibyte sequences, instead of single bytes
# >= 0x80 in a legacy 8-bit encoding.

# Non-root users are allowed to change the unicode mode of their console, but
# not the global keymap. root will have to load the keymap in unicode mode
# explicitly.

uid="$(id -u 2>/dev/null)" ||:
if [ "$uid" = 0 ]; then
	# There is no way of reverting the effect of "dumpkeys | loadkeys --unicode",
	# the memory of the earlier keymap is lost. Therefore, try
	# to save a copy of the original keymap to be able to reload it in unicode_stop.
	# (see also http://mail.nl.linux.org/linux-utf8/2003-08/msg00053.html):

	[ -n "$HOME" ] && [ "$HOME" != '/' ] ||
		HOME='/root'

	if [ -d "$HOME" ] && [ -w "$HOME" ]; then
		[ -d "$HOME/.kbd" ] ||
			mkdir -- "$HOME/.kbd"

		[ ! -w "$HOME/.kbd" ] ||
			dumpkeys > "$HOME/.kbd/.keymap_sv"
	fi

	# redirect stderr and stdout of loadkeys to /dev/null to avoid the confusing
	# "plus before udiaeresis ignored" warnings.

	dumpkeys | loadkeys --unicode > /dev/null 2>&1
fi

# 2. The output side: the console screen.

# Tell the console output driver that the bytes arriving are UTF-8
# encoded multibyte sequences.
if [ -t 1 ] && [ -t 2 ]; then
	printf '\033%%G'
fi
stty iutf8

# Tell the graphics card how to display Unicode characters not
# contained in the IBM 437 character set (on PCs). The font should
# have a Unicode map attached, or explicitly specified, e.g.,
# by giving `def.uni' as a second argument.

case "$#" in
	2)
		setfont "$1" -u "$2"
		;;
	1)
		setfont "$1"
		;;
	0)
		;;
	*)
		echo "usage: unicode_start [font [unicode map]]"
		;;
esac
