---

#!/usr/bin/env bash

set -u

if [[ $# -ne 4 ]]; then
    echo "Usage: $0 <input_file> <agent_address> <existing_oids_file> <removed_oids_file>"
    exit 1
fi

INPUT_FILE="$1"
AGENT="$2"
EXISTING_FILE="$3"
REMOVED_FILE="$4"

COMMUNITY="public"

> "$EXISTING_FILE"
> "$REMOVED_FILE"

while IFS= read -r oid || [[ -n "$oid" ]]; do
    # Skip empty lines
    [[ -z "$oid" ]] && continue

    result=$(snmpget -v2c -c "$COMMUNITY" "$AGENT" "$oid" 2>&1)

    if grep -qi "No Such Object" <<< "$result"; then
        echo "REMOVE: $oid"
        echo "$oid | $result" >> "$REMOVED_FILE"
    else
        # Keep normal results AND "No Such Instance"
        echo "$oid" >> "$EXISTING_FILE"

        if grep -qi "No Such Instance" <<< "$result"; then
            echo "KEEP:   $oid (object exists, instance absent)"
        else
            echo "KEEP:   $oid"
        fi
    fi
done < "$INPUT_FILE"