#!/bin/bash

# Free System Data (351GB)
# Most of this is purgeable space held by snapshots

set -e

echo "=== Free System Data (351GB) ==="
echo ""
echo "System Data is 351GB, but visible components only add up to ~20GB."
echo "This means ~330GB is PURGEABLE SPACE held by snapshots."
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 ""

echo "🔧 Step 1: Aggressively thin all snapshots..."
sudo tmutil thinlocalsnapshots / 1000000000 1 2>&1
echo "   ✓ Completed"
echo ""

echo "🔧 Step 2: 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 3: Remove Time Machine destination (CRITICAL)"
echo ""
echo "   ⚠️  IMPORTANT: You MUST remove Time Machine destination to"
echo "      prevent new snapshots from being created!"
echo ""
echo "   Do this now:"
echo "   1. System Settings → General → Time Machine"
echo "   2. Click '-' to remove backup disk"
echo "   3. Confirm removal"
echo ""
read -p "   Have you removed Time Machine destination? (y/n) " -n 1 -r
echo ""
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
    echo "   ⚠️  Please remove it first, then run this script again."
    exit 1
fi

echo ""
echo "🔧 Step 4: Wait for system to release purgeable space..."
echo "   This may take a few minutes..."
sleep 10

echo ""
echo "🔧 Step 5: Try to delete stuck snapshot..."
SNAPSHOT=$(tmutil listlocalsnapshots / 2>/dev/null | grep -v "Snapshots for disk" | grep -v "^$" | head -1)
if [ -n "$SNAPSHOT" ]; then
    SNAP_DATE=$(echo "$SNAPSHOT" | sed 's/.*\.\([0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}-[0-9]\{6\}\)\.backup/\1/')
    echo "   Attempting to delete: $SNAPSHOT"
    if sudo tmutil deletelocalsnapshots "$SNAP_DATE" 2>/dev/null; then
        echo "   ✅ Deleted!"
    else
        echo "   ⚠️  Still stuck (ghost entry - will clear on restart)"
    fi
else
    echo "   ✅ No snapshots found"
fi

echo ""
echo "⏳ Waiting for space to be released..."
sleep 10

# 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 > 100" | bc -l) )); then
    echo "   ✅ Successfully freed: ${FREED_GB}GB!"
elif (( $(echo "$FREED_GB > 0" | bc -l) )); then
    echo "   ✅ Freed: ${FREED_GB}GB"
    echo "   (More space may be released over time)"
else
    echo "   ⚠️  No space freed yet"
fi
echo ""

if (( $(echo "$FREE_SPACE_GB_AFTER < 50" | bc -l) )); then
    echo "⚠️  Still low on space. Additional steps:"
    echo ""
    echo "1. **Restart your Mac** - This is the most effective way"
    echo "   to release purgeable space from snapshots."
    echo ""
    echo "2. Use macOS Storage Management:"
    echo "   Apple Menu → About This Mac → Storage → Manage"
    echo "   Click 'Optimize' to release purgeable space"
    echo ""
    echo "3. Wait 15-30 minutes - macOS may need time to"
    echo "   release the purgeable space"
    echo ""
    echo "4. The 351GB in System Data is mostly purgeable space"
    echo "   that will be released when snapshots are cleared."
    echo ""
fi

echo ""