#!/bin/bash
CODENAME=$(lsb_release -sc)
VERSION=$(lsb_release -sr)
URL="https://changelogs.ubuntu.com/meta-release"
TMPFILE=$(mktemp)

if ! curl -fsSL "$URL" -o "$TMPFILE"; then
  echo "Fehler: meta-release Datei konnte nicht geladen werden."
  rm -f "$TMPFILE"
  exit 1
fi

CURRENT_LINE=$(grep -n "^Dist: $CODENAME" "$TMPFILE" | cut -d: -f1 | head -n1)

NEXT_BLOCK_START=$(awk -v line=$CURRENT_LINE 'NR > line && /^Dist:/ {print NR; exit}' "$TMPFILE")

NEXT_VERSION=$(awk "NR>=$NEXT_BLOCK_START && NR<=$NEXT_BLOCK_START+10" "$TMPFILE" | grep "^Version:" | cut -d' ' -f2)
NEXT_CODENAME=$(awk "NR>=$NEXT_BLOCK_START && NR<=$NEXT_BLOCK_START+10" "$TMPFILE" | grep "^Dist:" | cut -d' ' -f2)
RELEASE_DATE_RAW=$(awk "NR>=$NEXT_BLOCK_START && NR<=$NEXT_BLOCK_START+10" "$TMPFILE" | grep "^Date:" | cut -d' ' -f2-)

STATUS=$(grep "^${CODENAME}=" "$TMPFILE" | cut -d= -f2)
rm -f "$TMPFILE"

if [[ -z "$RELEASE_DATE_RAW" ]]; then
  RELEASE_DATE_RAW="1970-01-01"
fi

UPGRADE_DATE=$(date -d "$RELEASE_DATE_RAW +1 month" +"%Y-%m-%d" 2>/dev/null)
TODAY=$(date +"%Y-%m-%d")

DAYS_REMAINING=$(( ( $(date -d "$UPGRADE_DATE" +%s) - $(date -d "$TODAY" +%s) ) / 86400 ))

RELEASE_DATE_FMT=$(LC_TIME=de_DE.UTF-8 date -d "$RELEASE_DATE_RAW" +"%a., %d. %B %Y")
UPGRADE_DATE_FMT=$(LC_TIME=de_DE.UTF-8 date -d "$RELEASE_DATE_RAW +1 month" +"%a., %d. %B %Y")

if [[ "$STATUS" == "1" ]]; then
  echo "Das Upgrade von $CODENAME ($VERSION) auf $NEXT_CODENAME ($NEXT_VERSION) IST FREIGEGEBEN!"
  echo "Das Upgrade von $CODENAME ($VERSION) auf $NEXT_CODENAME ($NEXT_VERSION) IST FREIGEGEBEN!"
  echo "Info:"
  echo "Release:                 $RELEASE_DATE_FMT"
  echo "Upgrade möglich ab:      $UPGRADE_DATE_FMT"
  echo "($DAYS_REMAINING Tage seit Veröffentlichung)"
else
  echo "Das Upgrade von $CODENAME ($VERSION) auf $NEXT_CODENAME ($NEXT_VERSION) wurde noch ***nicht*** freigegeben."
  echo "Info:"
  echo "Release:                 $RELEASE_DATE_FMT"
  echo "Upgrade möglich ab:      $UPGRADE_DATE_FMT ($DAYS_REMAINING Tage verbleibend)"
  exit 0
fi