#!/bin/bash
# curl --silent http://pvserver:password@pvwr01.example/index.fhtml
#  | html2text | grep --max-count=1 'aktuell.*Gesamtenergie'
#  aktuell    50   WGesamtenergie 23257   kWh                            

# catch errors

set -u
set -e

# preliminaries

HOSTNAME="$1"
shift
REPEAT="$1"
shift
READINGS="$*"
USERNAME="pvserver"
PASSWORD="password"
URL="http://${USERNAME}:${PASSWORD}@${HOSTNAME}/index.fhtml"
REGEXP="aktuell.*Gesamtenergie"

# SC2034
for repeat in $(seq 1 "${REPEAT}"); do
        NOW="$(date +%s)"

        CURLOUT="$(curl --silent "${URL}" | html2text | grep --max-count=1 "${REGEXP}")"

        # pull requested readings from curl output

        for READING in $READINGS; do
                case "$READING" in
                  "Gesamtenergie"|"aktuell")
                        OUTPUT="$(printf "%s\\n" "${CURLOUT}" | sed -n "/.*${READING}[[:space:]]\\+\\([[:digit:]]\\+\\).*/{s//\\1/;p;q;}")"
                        # PVWR prints "x x x" in the dark, that is parsed
                        # into the empty string by the sed regexp, make
                        # that zero here
                        printf "%d: %s = %d\\n" "${NOW}" "${READING}" "${OUTPUT:-0}"
                        ;;
                  *)
                        # we don't have what the user asked for, print error message
                        printf >&2 "no reading %s\\n" "${READING}"
                        exit 1
                        ;;
                esac
        done
        if [ "${repeat}" != "${REPEAT}" ]; then
                sleep 30
        fi
done