#!/bin/sh -e
#
# update-langlist maintains the LANGUAGE priority list. It does so in
# a simplified manner, unlike the principal UI for setting the user
# language which provides full control.

first_language=$1
user=$2
renewed_langlist=

[ -n "$first_language" -a -n "$user" ] || exit 0

get_old_langlist() {
    while read line; do
        [ "${line%%:*}" = $user ] && break
    done < /etc/passwd
    if [ -n "$line" ]; then
        OLDIFS=$IFS
        IFS=':'
        i=1
        for homedir in $line; do
            if [ $i -ne 6 ]; then
                i=$(( $i + 1 ))
                continue
            fi
            break
        done
        IFS=$OLDIFS
    fi

    if [ -r "$homedir/.profile" ]; then
        old_langlist=$( grep "^[[:space:]]*export LANGUAGE=" \
                        $homedir/.profile | cut -d '"' -f 2 )
    fi
}

old_langlist=
english=true
if [ ${first_language%%[_@]*} != 'en' ]; then
    get_old_langlist
    english=false
fi

if [ -n "$old_langlist" ] && ! $english; then
    if expr $old_langlist : ".*:$first_language:" > /dev/null ; then
        renewed_langlist=$( echo $old_langlist | sed -r "s/(.+:)($first_language:)/\2\1/" )
    elif [ ${old_langlist%%:*} = $first_language ]; then
        # no change
        renewed_langlist=$old_langlist
    else
        renewed_langlist=$first_language:$old_langlist
    fi
else
    # build fresh list with 'en' as the last element
    # no other languages needed if English was selected
    renewed_langlist=$first_language
    [ $first_language != 'en' ] && renewed_langlist=$renewed_langlist:en
fi

echo $renewed_langlist