#!/bin/bash

TARGET_DIR="/local_testdata/test-destination"

THRESHOLD=60
TARGET_USAGE=50

SLEEP_INTERVAL=2
DELETE_BATCH=200
SAFE_MINUTES=5

echo "[$(date)] Blackhole Monitor gestartet für $TARGET_DIR"

while true; do

    CURRENT_USAGE=$(df -P "$TARGET_DIR" | awk 'NR==2 {print $5}' | tr -d '%')

    if (( CURRENT_USAGE > THRESHOLD )); then
        echo "[$(date)] Disk usage ${CURRENT_USAGE}% -> starte Cleanup"

        while (( CURRENT_USAGE > TARGET_USAGE )); do

            find "$TARGET_DIR" \
                -type f \
                -mmin +$SAFE_MINUTES \
                -print0 \
            | head -z -n $DELETE_BATCH \
            | xargs -0 -r rm -f

            CURRENT_USAGE=$(df -P "$TARGET_DIR" | awk 'NR==2 {print $5}' | tr -d '%')

            echo "[$(date)] aktuelle Auslastung: ${CURRENT_USAGE}%"

            if ! find "$TARGET_DIR" -type f -mmin +$SAFE_MINUTES | head -n 1 | grep -q .; then
                echo "[$(date)] Keine alten Dateien mehr zum Löschen"
                break
            fi

        done

        echo "[$(date)] Cleanup beendet"
    fi

    sleep "$SLEEP_INTERVAL"
done