#!/bin/bash

# --- Configuration ---
# Source directory (on the internal macOS SSD).
SOURCE_DIR="$HOME/fio-test-source"
# Destination directory (on your SCSI Target mount point).
DEST_DIR="/Volumes/RAID5-0/copy-test"
# Sequence of file sizes to test.
TEST_SIZES=("16M" "32M" "64M" "128M" "256M" "512M" "1G" "2G" "4G" "5G" "8G" "16G" "20G")

# --- Script Start ---
echo "Starting system-level file copy integrity test..."
echo "================================="

# Create source and destination directories.
mkdir -p "$SOURCE_DIR"
mkdir -p "$DEST_DIR"

# Check if directories were created successfully.
if [ ! -d "$SOURCE_DIR" ] || [ ! -d "$DEST_DIR" ]; then
    echo "Error: Could not create test directories."
    exit 1
fi

# Iterate through all defined sizes.
for size in "${TEST_SIZES[@]}"; do
    echo -e "\n[*] Testing file size: $size"
    SOURCE_FILE="$SOURCE_DIR/testfile_${size}.dat"
    DEST_FILE="$DEST_DIR/testfile_${size}.dat"

    # 1. Create the test file on the source SSD using random data.
    echo "  -> Step 1: Creating $size test file on source SSD..."
    # Convert M/G units to the 'count' parameter for dd.
    count=$(echo "$size" | sed 's/G/ \* 1024/' | sed 's/M//' | bc)
    dd if=/dev/urandom of="$SOURCE_FILE" bs=1m count=$count status=none
    if [ $? -ne 0 ]; then
        echo "  [!!!] Error: Failed to create source file."
        continue
    fi

    # 2. Calculate the checksum of the source file.
    echo "  -> Step 2: Calculating SHA256 checksum of source file..."
    SOURCE_HASH=$(shasum -a 256 "$SOURCE_FILE" | awk '{print $1}')
    echo "     Source Hash: $SOURCE_HASH"

    # 3. Copy the file to the SCSI Target.
    echo "  -> Step 3: Copying file to SCSI Target..."
    cp "$SOURCE_FILE" "$DEST_FILE"
    if [ $? -ne 0 ]; then
        echo "  [!!!] Error: File copy command failed!"
        rm -f "$SOURCE_FILE" "$DEST_FILE"
        continue
    fi

    # 4. Force sync of file system buffers to disk (very important!).
    # This ensures we are verifying the data that was actually written to the physical disk.
    sync
    sleep 1 # Give sync a moment

    # 5. Calculate the checksum of the destination file.
    echo "  -> Step 4: Calculating SHA256 checksum of destination file..."
    DEST_HASH=$(shasum -a 256 "$DEST_FILE" | awk '{print $1}')
    echo "     Destination Hash: $DEST_HASH"

    # 6. Compare the checksums.
    echo "  -> Step 5: Verifying checksums..."
    if [ "$SOURCE_HASH" == "$DEST_HASH" ]; then
        echo "  [OK] SUCCESS: Data integrity verified for $size file."
    else
        echo "  [!!!] FAILURE: Data corruption detected for $size file!"
        echo "--------------------------------------------------"
        echo "Source Hash:      $SOURCE_HASH"
        echo "Destination Hash: $DEST_HASH"
        echo "--------------------------------------------------"
        # Clean up and terminate the script.
        rm -f "$SOURCE_FILE" "$DEST_FILE"
        exit 1
    fi

    # 7. Clean up the files from the current successful test run.
    rm -f "$SOURCE_FILE" "$DEST_FILE"
done

echo "================================="
echo "All system-level copy tests completed successfully!"