#!/bin/sh

HOST="${HOST_TO_CHECK:-example.com}"
INTERVAL="${INTERVAL_SECONDS:-300}"
LOGFILE="/logs/${HOST}.log"

mkdir -p /logs

echo "Monitoring $HOST every $INTERVAL seconds..."

while true; do
  OUTPUT=$(ping -c 1 -W 2 "$HOST" 2>&1)
  EXIT_CODE=$?

  if [ $EXIT_CODE -ne 0 ]; then
    TIMESTAMP=$(date '+%Y-%m-%d %H:%M:%S')

    if echo "$OUTPUT" | grep -q "bad address"; then
      REASON="DNS resolution failed"
    elif echo "$OUTPUT" | grep -q "Network is unreachable"; then
      REASON="No route to network"
    elif echo "$OUTPUT" | grep -q "ping: permission denied"; then
      REASON="ICMP not permitted (try running as root or with CAP_NET_RAW)"
    elif echo "$OUTPUT" | grep -q "100% packet loss"; then
      REASON="Timed out (no response)"
    else
      REASON="Unknown error: $OUTPUT"
    fi

    echo "[$TIMESTAMP] Host unreachable: $HOST — Reason: $REASON" | tee -a "$LOGFILE"
  fi

  sleep "$INTERVAL"
done