#!/bin/bash

# Fix Stuck Time Machine Snapshot
# When snapshots can't be deleted due to "Stale NFS file handle" error

set -e

echo "=== Fix Stuck Time Machine Snapshot ==="
echo ""
echo "This script fixes the 'Stale NFS file handle' error that prevents"
echo "snapshot deletion. This happens when Time Machine has a stale"
echo "connection to the backup destination."
echo ""

# Check current situation
echo "📊 Current Status:"
FREE_SPACE=$(df / | tail -1 | awk '{print $4}')
FREE_SPACE_GB=$(echo "scale=2; $FREE_SPACE / 1024 / 1024" | bc)
echo "   Free space: ${FREE_SPACE_GB}GB"
echo ""

SNAPSHOTS=$(tmutil listlocalsnapshots / 2>/dev/null | grep -v "Snapshots for disk" | grep -v "^$")
if [ -n "$SNAPSHOTS" ]; then
    echo "   Stuck snapshots found:"
    echo "$SNAPSHOTS" | sed 's/^/     - /'
else
    echo "   ✓ No snapshots found"
    exit 0
fi

echo ""
echo "🔧 Solution: Temporarily remove Time Machine destination, delete snapshot, then re-add"
echo ""
echo "⚠️  IMPORTANT: This will temporarily disconnect Time Machine from your NAS."
echo "   You'll need to re-add it after the snapshot is deleted."
echo ""

read -p "Do you want to proceed? (y/n) " -n 1 -r
echo ""
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
    echo "Cancelled."
    exit 0
fi

echo ""
echo "Step 1: Removing Time Machine destination..."
echo ""
echo "   Please do this manually:"
echo "   1. Open System Settings → General → Time Machine"
echo "   2. Click the 'Remove' or '-' button next to your backup disk"
echo "   3. Confirm removal"
echo ""
read -p "   Have you removed the 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 2: Waiting for Time Machine to disconnect..."
sleep 5

echo ""
echo "Step 3: Attempting to delete stuck snapshot..."
echo "$SNAPSHOTS" | while read snapshot; do
    if [ -n "$snapshot" ]; then
        # Extract date part
        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: $snapshot"
            if sudo tmutil deletelocalsnapshots "$SNAP_DATE" 2>/dev/null; then
                echo "   ✅ Successfully deleted!"
            else
                echo "   ⚠️  Still stuck. Try restarting your Mac."
                echo "      After restart, run: sudo tmutil deletelocalsnapshots $SNAP_DATE"
            fi
        fi
    fi
done

echo ""
echo "Step 4: Checking disk space..."
sleep 3
NEW_FREE_SPACE=$(df / | tail -1 | awk '{print $4}')
NEW_FREE_SPACE_GB=$(echo "scale=2; $NEW_FREE_SPACE / 1024 / 1024" | bc)
FREED_GB=$(echo "scale=2; $NEW_FREE_SPACE_GB - $FREE_SPACE_GB" | bc)

echo "   New free space: ${NEW_FREE_SPACE_GB}GB"
if (( $(echo "$FREED_GB > 0" | bc -l) )); then
    echo "   ✅ Freed: ${FREED_GB}GB"
else
    echo "   ⚠️  Space not freed yet - may need restart"
fi

echo ""
echo "Step 5: Re-adding Time Machine destination..."
echo ""
echo "   Now re-add your Time Machine backup:"
echo "   1. System Settings → General → Time Machine"
echo "   2. Click 'Add Backup Disk...'"
echo "   3. Select 'Time Machine Folder' on 'DS224plus.local'"
echo "   4. Enter your credentials"
echo ""
echo "   Or use the troubleshooting guide:"
echo "   See: time_machine_troubleshooting.md"
echo ""