#!/bin/bash

# Fix System Data Growth When Deleting Files
# This happens when APFS snapshots preserve deleted files

set -e

echo "=== Fix System Data Growth ==="
echo ""
echo "When you delete files but 'System Data' grows, it means:"
echo "  - APFS snapshots are preserving deleted files"
echo "  - Time Machine local snapshots are holding space"
echo "  - The deleted data is being kept for backup purposes"
echo ""

FREE_SPACE_BEFORE=$(df / | tail -1 | awk '{print $4}')
FREE_SPACE_GB_BEFORE=$(echo "scale=2; $FREE_SPACE_BEFORE / 1024 / 1024" | bc)
echo "Current free space: ${FREE_SPACE_GB_BEFORE}GB"
echo ""

# Check for snapshots
echo "📸 Checking for snapshots..."
TM_SNAPSHOTS=$(tmutil listlocalsnapshots / 2>/dev/null | grep -v "Snapshots for disk" | grep -v "^$")
SNAP_COUNT=$(echo "$TM_SNAPSHOTS" | grep -v "^$" | wc -l | tr -d ' ')

if [ "$SNAP_COUNT" -gt 0 ]; then
    echo "   Found $SNAP_COUNT Time Machine snapshot(s):"
    echo "$TM_SNAPSHOTS" | sed 's/^/     - /'
else
    echo "   No Time Machine snapshots found"
fi

APFS_SNAPS=$(diskutil apfs listSnapshots / 2>/dev/null | grep -c "Name:" || echo "0")
echo "   Found $APFS_SNAPS APFS snapshot(s)"
echo ""

if [ "$SNAP_COUNT" -eq 0 ] && [ "$APFS_SNAPS" -le 1 ]; then
    echo "⚠️  No obvious snapshots, but System Data is still growing."
    echo "   This may be due to:"
    echo "   - Time Machine preparing for backup"
    echo "   - System cache growth"
    echo "   - Other system processes"
    echo ""
fi

echo "🔧 Solution: Disable local snapshots and clean up"
echo ""
read -p "Proceed with cleanup? (y/n) " -n 1 -r
echo ""
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
    exit 0
fi

echo ""
echo "Step 1: Stop Time Machine backup (if running)..."
sudo tmutil stopbackup 2>/dev/null || true
sleep 2
echo "   ✓ Stopped"
echo ""

echo "Step 2: Delete all local snapshots..."
if [ "$SNAP_COUNT" -gt 0 ]; then
    echo "$TM_SNAPSHOTS" | while read snapshot; do
        if [ -n "$snapshot" ]; then
            SNAP_DATE=$(echo "$snapshot" | sed 's/.*\.\([0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}-[0-9]\{6\}\)\.backup/\1/')
            if [ -n "$SNAP_DATE" ]; then
                echo "   Deleting: $snapshot"
                sudo tmutil deletelocalsnapshots "$SNAP_DATE" 2>/dev/null && \
                    echo "     ✅ Deleted" || \
                    echo "     ⚠️  Could not delete (may be in use)"
            fi
        fi
    done
else
    echo "   No snapshots to delete"
fi
echo ""

echo "Step 3: Aggressively thin all snapshots..."
sudo tmutil thinlocalsnapshots / 1000000000 1 2>&1 || true
echo "   ✓ Thinned"
echo ""

echo "Step 4: Disable local snapshots (prevents new ones)..."
# Note: tmutil disablelocal doesn't exist in newer macOS, so we'll use a workaround
# We'll remove Time Machine destination temporarily
echo "   ⚠️  To prevent snapshots, you need to:"
echo "      1. Remove Time Machine destination in System Settings"
echo "      2. Or wait for successful backup to clear snapshots"
echo ""

echo "Step 5: Purge system memory and caches..."
if command -v purge &> /dev/null; then
    sudo purge
    echo "   ✓ Purged"
else
    echo "   ⚠️  Purge command not available"
fi
echo ""

echo "Step 6: Clean user caches..."
rm -rf ~/Library/Caches/* 2>/dev/null || true
echo "   ✓ Cleaned"
echo ""

echo "⏳ Waiting for system to update..."
sleep 5

# Check results
FREE_SPACE_AFTER=$(df / | tail -1 | awk '{print $4}')
FREE_SPACE_GB_AFTER=$(echo "scale=2; $FREE_SPACE_AFTER / 1024 / 1024" | bc)
FREED_GB=$(echo "scale=2; $FREE_SPACE_GB_AFTER - $FREE_SPACE_GB_BEFORE" | bc)

echo ""
echo "=== Results ==="
echo "   Before: ${FREE_SPACE_GB_BEFORE}GB free"
echo "   After:  ${FREE_SPACE_GB_AFTER}GB free"
if (( $(echo "$FREED_GB > 0" | bc -l) )); then
    echo "   ✅ Freed: ${FREED_GB}GB"
else
    echo "   ⚠️  No space freed yet"
fi
echo ""

echo "=== Critical Next Steps ==="
echo ""
echo "To STOP System Data from growing when you delete files:"
echo ""
echo "1. **Remove Time Machine destination temporarily**:"
echo "   System Settings → Time Machine → Remove backup disk"
echo "   This prevents new snapshots from being created"
echo ""
echo "2. **Wait 10-15 minutes** after deleting files before checking space"
echo "   macOS needs time to release snapshot space"
echo ""
echo "3. **After freeing space, fix Time Machine connection**:"
echo "   - Clear credentials in Keychain Access"
echo "   - Re-add Time Machine destination"
echo "   - Ensure it can successfully connect"
echo ""
echo "4. **Alternative: Use 'Optimize Storage' in System Settings**:"
echo "   Apple Menu → About This Mac → Storage → Optimize"
echo "   This can help release snapshot space"
echo ""
echo "5. **If System Data keeps growing**:"
echo "   - Restart your Mac (releases snapshots)"
echo "   - Or remove Time Machine until you have more free space"
echo ""

if (( $(echo "$FREE_SPACE_GB_AFTER < 5" | bc -l) )); then
    echo "⚠️  Still critically low on space!"
    echo ""
    echo "   You need to free more space before Time Machine can work."
    echo "   Consider:"
    echo "   - Moving large files to NAS"
    echo "   - Removing unused applications"
    echo "   - Cleaning Downloads folder"
    echo ""
fi

echo ""