#!/bin/sh
# vim:sw=4:ts=4:et

# Copied and modified from:
# https://github.com/nginxinc/docker-nginx-unprivileged/blob/1.25.2/entrypoint/10-listen-on-ipv6-by-default.sh

set -e

entrypoint_log() {
    if [ -z "${NGINX_ENTRYPOINT_QUIET_LOGS:-}" ]; then
        echo "$@"
    fi
}

ME=$(basename $0)
DEFAULT_CONF_FILE="etc/nginx/templates/default.conf.template"

# check if we have ipv6 available
if [ ! -f "/proc/net/if_inet6" ]; then
    entrypoint_log "$ME: info: ipv6 not available"
    exit 0
fi

if [ ! -f "/$DEFAULT_CONF_FILE" ]; then
    entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE is not a file or does not exist"
    exit 0
fi

# check if the file can be modified, e.g. not on a r/o filesystem
touch /$DEFAULT_CONF_FILE 2>/dev/null || { entrypoint_log "$ME: info: can not modify /$DEFAULT_CONF_FILE (read-only file system?)"; exit 0; }

# check if the file is already modified, e.g. on a container restart
grep -q "listen  \[::]\:8080;" /$DEFAULT_CONF_FILE && { entrypoint_log "$ME: info: IPv6 listen already enabled"; exit 0; }

if [ -f "/etc/os-release" ]; then
    . /etc/os-release
else
    entrypoint_log "$ME: info: can not guess the operating system"
    exit 0
fi

# Modified from original by nscuro:
#   Do not check whether the default configuration file has been changed vs
#   what is packaged with the distribution's installation. We customized the
#   file and want the changes the applied regardless.

#entrypoint_log "$ME: info: Getting the checksum of /$DEFAULT_CONF_FILE"
#
#case "$ID" in
#    "debian")
#        CHECKSUM=$(dpkg-query --show --showformat='${Conffiles}\n' nginx | grep $DEFAULT_CONF_FILE | cut -d' ' -f 3)
#        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | md5sum -c - >/dev/null 2>&1 || {
#            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
#            exit 0
#        }
#        ;;
#    "alpine")
#        CHECKSUM=$(apk manifest nginx 2>/dev/null| grep $DEFAULT_CONF_FILE | cut -d' ' -f 1 | cut -d ':' -f 2)
#        echo "$CHECKSUM  /$DEFAULT_CONF_FILE" | sha1sum -c - >/dev/null 2>&1 || {
#            entrypoint_log "$ME: info: /$DEFAULT_CONF_FILE differs from the packaged version"
#            exit 0
#        }
#        ;;
#    *)
#        entrypoint_log "$ME: info: Unsupported distribution"
#        exit 0
#        ;;
#esac

# enable ipv6 on default.conf listen sockets
sed -i -E 's,listen      8080;,listen      8080;\n  listen  [::]:8080;,' /$DEFAULT_CONF_FILE

entrypoint_log "$ME: info: Enabled listen on IPv6 in /$DEFAULT_CONF_FILE"

exit 0
