#!/usr/bin/env bash

set -e

# === Konfiguration ===
TEST_DIR="${1:-./disk_test}"
TEST_FILE="$TEST_DIR/testfile.bin"
FILE_SIZE_MB=1024
BLOCK_SIZE_SEQ=1M
BLOCK_SIZE_4K=4K
COUNT_4K=262144 # 4K * 262144 = 1GB
JSON_FILE="disk_benchmark_$(date +%Y%m%d_%H%M%S).json"

mkdir -p "$TEST_DIR"

clear_cache() {
sync
if [ "$EUID" -eq 0 ]; then
echo 3 > /proc/sys/vm/drop_caches
fi
}

measure_time() {
START=$(date +%s.%N)
eval "$1"
END=$(date +%s.%N)
awk "BEGIN {print $END - $START}"
}

echo "Starte Benchmark im Verzeichnis: $TEST_DIR"
echo

# =============================
# Sequential Write
# =============================
echo "Teste Sequential Write..."
clear_cache
TIME_SEQ_WRITE=$(measure_time \
"dd if=/dev/zero of=$TEST_FILE bs=$BLOCK_SIZE_SEQ count=$FILE_SIZE_MB conv=fdatasync status=none")

SEQ_WRITE_MBPS=$(awk "BEGIN {printf "%.2f", $FILE_SIZE_MB / $TIME_SEQ_WRITE}")

# =============================
# Sequential Read
# =============================
echo "Teste Sequential Read..."
clear_cache
TIME_SEQ_READ=$(measure_time \
"dd if=$TEST_FILE of=/dev/null bs=$BLOCK_SIZE_SEQ status=none")

SEQ_READ_MBPS=$(awk "BEGIN {printf "%.2f", $FILE_SIZE_MB / $TIME_SEQ_READ}")

# =============================
# 4K Random Write
# =============================
echo "Teste 4K Random Write..."
clear_cache
TIME_4K_WRITE=$(measure_time \
"dd if=/dev/urandom of=$TEST_FILE bs=$BLOCK_SIZE_4K count=$COUNT_4K conv=fdatasync status=none")

TOTAL_MB_4K=$(awk "BEGIN {print ($COUNT_4K * 4) / 1024}")
WRITE_4K_MBPS=$(awk "BEGIN {printf "%.2f", $TOTAL_MB_4K / $TIME_4K_WRITE}")
WRITE_4K_IOPS=$(awk "BEGIN {printf "%.0f", $COUNT_4K / $TIME_4K_WRITE}")

# =============================
# 4K Random Read
# =============================
echo "Teste 4K Random Read..."
clear_cache
TIME_4K_READ=$(measure_time \
"dd if=$TEST_FILE of=/dev/null bs=$BLOCK_SIZE_4K status=none")

READ_4K_MBPS=$(awk "BEGIN {printf "%.2f", $TOTAL_MB_4K / $TIME_4K_READ}")
READ_4K_IOPS=$(awk "BEGIN {printf "%.0f", $COUNT_4K / $TIME_4K_READ}")

rm -f "$TEST_FILE"

TIMESTAMP=$(date -Iseconds)
HOSTNAME=$(hostname)
KERNEL=$(uname -r)

echo
echo "===== Ergebnisse ====="
echo "Seq Write: $SEQ_WRITE_MBPS MB/s"
echo "Seq Read: $SEQ_READ_MBPS MB/s"
echo "4K Write: $WRITE_4K_MBPS MB/s ($WRITE_4K_IOPS IOPS)"
echo "4K Read: $READ_4K_MBPS MB/s ($READ_4K_IOPS IOPS)"

cat <<EOF > "$JSON_FILE"
{
"timestamp": "$TIMESTAMP",
"hostname": "$HOSTNAME",
"kernel": "$KERNEL",
"test_directory": "$TEST_DIR",
"results": {
"sequential_write_mb_s": $SEQ_WRITE_MBPS,
"sequential_read_mb_s": $SEQ_READ_MBPS,
"random_4k_write_mb_s": $WRITE_4K_MBPS,
"random_4k_write_iops": $WRITE_4K_IOPS,
"random_4k_read_mb_s": $READ_4K_MBPS,
"random_4k_read_iops": $READ_4K_IOPS
}
}
EOF

echo
echo "Ergebnisse gespeichert in: $JSON_FILE"

chmod +x disk_benchmark.sh
./disk_benchmark.sh