#!/bin/bash

# Explain Why Moving Files Doesn't Free Space

set -e

echo "=== Why Moving Files Doesn't Free Space ==="
echo ""
echo "⚠️  THE PROBLEM:"
echo ""
echo "When you move/delete files, the OS update snapshot preserves them."
echo "This means:"
echo "  - Files are moved to NAS ✅"
echo "  - But space isn't freed on Mac ❌"
echo "  - System Data grows instead 📈"
echo ""

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

echo "📸 The OS Update Snapshot:"
SNAPSHOT=$(diskutil apfs listSnapshots / 2>/dev/null | grep "Name:" | head -1)
if [ -n "$SNAPSHOT" ]; then
    echo "$SNAPSHOT" | sed 's/^/   /'
    echo ""
    echo "   This snapshot:"
    echo "   - Is NOT purgeable"
    echo "   - Preserves all deleted/moved files"
    echo "   - Can't be deleted manually"
    echo "   - Will only clear when you update macOS"
fi
echo ""

echo "🔍 What's Happening:"
echo ""
echo "1. You move files → Files go to NAS ✅"
echo "2. macOS snapshot preserves them → System Data grows 📈"
echo "3. Space isn't freed → Still full ❌"
echo ""

echo "=== THE ONLY SOLUTION ==="
echo ""
echo "You MUST install the macOS update to clear the snapshot."
echo ""
echo "But you need space to install the update (17.64GB needed)."
echo ""
echo "This is a catch-22 situation:"
echo "  - Need space to update"
echo "  - Can't get space because snapshot preserves deleted files"
echo ""

echo "=== WORKAROUND ==="
echo ""
echo "Option 1: Free space from sources that DON'T trigger snapshots:"
echo "  - Clean caches: rm -rf ~/Library/Caches/* (~6GB)"
echo "  - Clean user cache: rm -rf ~/.cache/* (~3GB)"
echo "  - Clean npm: npm cache clean --force (~1GB)"
echo "  Total: ~10GB (still not enough for 17.64GB update)"
echo ""

echo "Option 2: Try downloading update with less space:"
echo "  sudo softwareupdate --download --all"
echo "  (Sometimes works with less than required space)"
echo ""

echo "Option 3: Use external drive temporarily:"
echo "  - Move files to external drive (not NAS)"
echo "  - Install update"
echo "  - Move files back after snapshot clears"
echo ""

echo "Option 4: Contact Apple Support:"
echo "  They may have tools to force-clear the snapshot"
echo ""

echo "=== Current Status ==="
echo ""
echo "Files moved to NAS: ✅ (they're safe)"
echo "Space freed on Mac: ❌ (snapshot preserving them)"
echo "System Data: 📈 (growing because of snapshot)"
echo ""
echo "The files ARE moved, but the space won't be freed"
echo "until the snapshot is cleared by updating macOS."
echo ""