#! /bin/sh
# TODO: replace tzconfig with this program
set -e

. /usr/share/debconf/confmodule

TEXTDOMAIN=base-config
export TEXTDOMAIN

NEWLINE="
"
TAB="	"

# The ZONEMAPPING file is used to map between the mangled
# choices and the raw timezones.
ZONEMAPPING=$(tempfile)

NONINTERACTIVE=""

# Given a country code, returns a debconf choices list describing the zones
# in that country.
mangle_zones_in_country () {
	code="$1"
	cat < /dev/null > "$ZONEMAPPING" # truncate
	# Get a list of the time zones for their country,
	# and use it as the choices list in the debconf
	# question.
	OLDIFS="$IFS"
	IFS="$NEWLINE"
	RET=""
	for line in $(grep -i "^$code$TAB" /usr/share/zoneinfo/zone.tab); do
		zone=$(echo "$line" | cut -d "$TAB" -f 3)
		comment=$(echo "$line" | cut -d "$TAB" -f 4 | sed "s/, /; /g")
		# Mangle the time zone for display.
		if [ -z "$comment" ]; then
			choice="$zone"
		else
			choice="$zone ($comment)"
		fi
		# This gettext is freaky, since the text is
		# completly dynamic. To construct the po file entries
		# for this, extract all the time zones and comments 
		# from zone.tab and mangle the same way it's done above.
		choice=$(gettext "$choice")
		echo "$choice$TAB$zone" >> "$ZONEMAPPING"
		if [ -z "$RET" ]; then
			RET="$choice"
		else
			RET="$RET, $choice"
		fi
	done
	IFS="$OLDIFS"
	echo "$RET"
}

# Given a country code, returns a good default timezone for that country,
# in the same form used by the other functions. Should be called after
# mangle_zones_in_country
default_for_country () {
	code="$1"
	
	case "$code" in
	AU)
		best="Australia/Sydney"
	;;
	*)
		# Default to first listed. (Which happens to be correct for
		# most of them.)
		best=$(grep -i "^$code$TAB" /usr/share/zoneinfo/zone.tab |
			head -n 1 | cut -d "$TAB" -f 3)
	;;
	esac

	# Get mangled form.
	grep "$TAB$best\$" "$ZONEMAPPING" | cut -d "$TAB" -f 1
}

# Given a choice from the list constructed by mangle_zones_in_country,
# returns the time zone.
demangle_zone () {
	CHOICE="$1"

	# Map from a possibly translated choice back the the C version.
	zone=$(grep "^$CHOICE$TAB" "$ZONEMAPPING" | cut -d "$TAB" -f 2)
	if [ -z "$zone" ]; then
		echo "$0 internal error: cannot find \"$CHOICE\" in $ZONEMAPPING" >&2
		exit 1
	fi
	echo "$zone"
}

while getopts "gUc:yN" o; do
	case $o in
	g) ASKUTC=1 ;;
	y) CHANGE=1 ;;
	c) COUNTRY=$OPTARG ;;
	U) NOTUTC=1 ;;
	N) NONINTERACTIVE=1 ;;
	*) exit 1   ;;
	esac
done

# s390 arch has no hwclock support; if there is no hwclock just diaable
# that code path in general
if [ ! -e /sbin/hwclock ]; then
	ASKUTC=""
fi

# Set up debconf.
db_capb backup
db_settitle tzconfig/title

# Feed current timezone in to question.
if [ -f /etc/timezone ]; then
	db_subst tzconfig/change_timezone timezone `cat /etc/timezone`
elif [ -L /etc/localtime ]; then
	db_subst tzconfig/change_timezone timezone \
		$(readlink /etc/localtime | sed 's%^/usr/share/zoneinfo/%%')	
fi

# Let's use a state machine to let the user jump back to earlier questions.
STATE=1
LASTSTATE=7
while [ "$STATE" -le $LASTSTATE ]; do
	case "$STATE" in
	1)
		if [ "$ASKUTC" ]; then
			if [ ! "$NOTUTC" ]; then
				# Source rcS to get the current setting,
				# and use that to control the default.
				if [ -e /etc/default/rcS ]; then
					. /etc/default/rcS || true
				fi
				if [ "$UTC" = yes ]; then
					db_set tzconfig/gmt true
				else
					db_set tzconfig/gmt false
				fi
			else
				db_fget tzconfig/gmt seen
				if [ "$RET" = false ] || [ ! "$NONINTERACTIVE" ]; then
					db_set tzconfig/gmt false
				fi
			fi

			# The awk removes info about drift from the 
			# hwclock output.
			db_subst tzconfig/gmt hwtime $(hwclock --show --localtime | awk '{NF-=2; print $0}')
			db_input high tzconfig/gmt || true
		fi
	;;
	2)
		db_fset tzconfig/gmt seen false
	
		if [ ! "$CHANGE" ]; then
			# Show current time zone and ask if it should be changed.
			db_input high tzconfig/change_timezone || true
		fi
	;;
	3)
		db_fset tzconfig/change_timezone seen false
	
		# Jump to end if the user doesn't want the time zone changed.
		db_get tzconfig/change_timezone
		if [ "$RET" = false ] && [ ! "$CHANGE" ]; then
			STATE=$(($LASTSTATE - 2))
		elif [ -n "$COUNTRY" ]; then
			# See if there is a special question for this
			# country.
			COUNTRY=$(echo "$COUNTRY" | tr a-z A-Z)
			if db_get tzconfig/choose_country_zone/$COUNTRY; then
				COUNTRY_ZONE_Q=tzconfig/choose_country_zone/$COUNTRY
				case "$COUNTRY" in
				CA)
					COUNTRY_ZONE_PREFIX=Canada
				;;
				US)
					COUNTRY_ZONE_PREFIX=US
				;;
				BR)
					COUNTRY_ZONE_PREFIX=Brazil
				;;
				esac
			else
				zone_choices=$(mangle_zones_in_country "$COUNTRY")
				if [ -n "$zone_choices" ]; then
					# Always subst into this, it is
					# used below to get the zone, no
					# matter which style of question is
					# displayed.
					db_subst tzconfig/choose_country_zone_multiple \
						choices "$zone_choices"
					db_fget tzconfig/choose_country_zone_multiple seen 
					if [ "$RET" = false ] || [ ! "$NONINTERACTIVE" ]; then
						db_set tzconfig/choose_country_zone_multiple \
							$(default_for_country "$COUNTRY")
					fi
					if echo "$zone_choices" | grep -q ", "; then
						COUNTRY_ZONE_Q=tzconfig/choose_country_zone_multiple
					else
						COUNTRY_ZONE_Q=tzconfig/choose_country_zone_single
						db_subst $COUNTRY_ZONE_Q zone "$zone_choices"
					fi
				fi
			fi
			if [ -n "$COUNTRY_ZONE_Q" ]; then
				db_input high $COUNTRY_ZONE_Q || true
			fi
		fi
	;;
	4)
		if [ -n "$COUNTRY_ZONE_Q" ]; then
			db_fset $COUNTRY_ZONE_Q seen false
			db_get $COUNTRY_ZONE_Q
			if [ "$COUNTRY_ZONE_Q" = tzconfig/choose_country_zone_single ]; then
				if [ "$RET" = "true" ]; then
					SKIP_DRILLDOWN=1
				else
					SKIP_DRILLDOWN=0
				fi
			elif [ "$RET" = other ]; then
				SKIP_DRILLDOWN=0
			else
				SKIP_DRILLDOWN=1
			fi
		else
			SKIP_DRILLDOWN=0
		fi
		
		if [ "$SKIP_DRILLDOWN" = 0 ]; then
			# Show top level divisions (mainly by continent).
			db_input high tzconfig/geographic_area || true
		fi
	;;
	5)
		if [ "$SKIP_DRILLDOWN" = 0 ]; then
			db_fset tzconfig/geographic_area seen false
			
			# Prompt with a list of zones in the selected area.
			# Suckily, we have to map some of the values that were
			# prompted with to the directory names themselves.
			db_get tzconfig/geographic_area
			DIR="$RET"
			case "$DIR" in
			"Atlantic Ocean")		DIR=Atlantic	;;
			"Indian Ocean")			DIR=Indian	;;
			"Pacific Ocean")		DIR=Pacific	;;
			"System V style time zones")	DIR=SystemV	;;
			"None of the above")		DIR=Etc		;;
			esac
			if [ ! -d /usr/share/zoneinfo/$DIR ]; then
				echo "$0 internal error: /usr/share/zoneinfo/$DIR does not exist" >&2
				exit 1
			fi

			# Instantiate zone selection question for area, and
			# populate with available choices.
			db_register tzconfig/select_zone tzconfig/select_zone/$DIR || true
			db_subst tzconfig/select_zone/$DIR choices \
				$(find /usr/share/zoneinfo/$DIR -type f -printf "%f, \n" | \
				  sort | xargs echo | sed 's/,$//')

			db_input high tzconfig/select_zone/$DIR || true
		fi
	;;
	6)
		if [ "$SKIP_DRILLDOWN" = 1 ]; then
			if db_get tzconfig/choose_country_zone/$COUNTRY; then
				timezone="$COUNTRY_ZONE_PREFIX/$RET"
			else
				db_get tzconfig/choose_country_zone_multiple
				timezone=$(demangle_zone "$RET")
			fi
		else
			db_fset tzconfig/select_zone/$DIR seen false
			db_get tzconfig/select_zone/$DIR || true
			timezone="$DIR/$RET"
		fi

		if [ "$timezone" = "/" ] || [ "$timezone" = "" ]; then
			# Skipped timezone selection stage.
			timezone=$(cat /etc/timezone)
		fi

		# Set time zone.
		db_get tzconfig/change_timezone
		if [ "$RET" = true ] || [ "$CHANGE" ]; then
			echo $timezone > /etc/timezone 
			rm -f /etc/localtime && \
				ln -sf /usr/share/zoneinfo/$timezone /etc/localtime
		fi
		
		if [ "$ASKUTC" ]; then
			# Set gmt or not. Only change the file if the value
			# changed. This must only be done after the time zone
			# file is set up.
			db_get tzconfig/gmt
			if [ "$RET" = true ] && [ "$UTC" != yes ]; then
				sed -e 's:^UTC="no":UTC="yes":' -e 's:^UTC=no:UTC=yes:' \
					/etc/default/rcS > /etc/default/rcS.new
				CHANGEUTC=1
			elif [ "$RET" = false ] && [ "$UTC" != no ]; then
				sed -e 's:^UTC="yes":UTC="no":' -e 's:^UTC=yes:UTC=no:' \
					/etc/default/rcS > /etc/default/rcS.new
				CHANGEUTC=1
			fi
			if [ "$CHANGEUTC" ]; then
				mv -f /etc/default/rcS.new /etc/default/rcS
				/etc/init.d/hwclock.sh start >/dev/null </dev/null
			fi
		fi
		
		db_get tzconfig/change_timezone
		if [ "$RET" = true ] || [ "$CHANGE" ]; then
			# Display a final message giving the selected zone
			# and showing the time in that zone (and UTC for
			# comparison) and asking if it looks ok.
			utdate=$(LANG=C LC_ALL=C date -u)
			tzdate=$(LANG=C LC_ALL=C date -d "$utdate")
			db_subst tzconfig/verify_choices timezone "$timezone"
			db_subst tzconfig/verify_choices tzdate "$tzdate"
			db_subst tzconfig/verify_choices utdate $utdate
			db_set tzconfig/verify_choices true
			db_input low tzconfig/verify_choices || true
		fi
	;;
	7)
		db_get tzconfig/change_timezone
		if [ "$RET" = true ] || [ "$CHANGE" ]; then
			db_fset tzconfig/verify_choices seen false
			# Get the result of that last question, and if it
			# is false, loop back to start.
			db_get tzconfig/verify_choices
			if [ "$RET" = false ]; then
				STATE=0
			fi
		fi
	;;
	esac

	if db_go; then
		STATE=$(($STATE + 1))
	else
		STATE=$(($STATE - 1))
	fi

	if [ "$STATE" = 0 ]; then
		# propigate back up out
		exit 30
	fi
done

rm -f "$ZONEMAPPING"