#!/bin/bash

# LVM Migration Preview Script
# Shows current status and what the migration will do

set -euo pipefail

# Colors
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
RED='\033[0;31m'
NC='\033[0m'

echo -e "${BLUE}=== LVM Migration Preview ===${NC}"
echo

echo -e "${GREEN}Current Boot Status:${NC}"
echo "Root mounted from: $(findmnt -n -o SOURCE /)"
echo "Boot mounted from: $(findmnt -n -o SOURCE /boot)"
echo "Home mounted from: $(findmnt -n -o SOURCE /home)"
echo

echo -e "${GREEN}Current LVM Structure (External M.2):${NC}"
sudo vgs migration-vg 2>/dev/null || echo "No VG found"
echo
sudo lvs migration-vg 2>/dev/null || echo "No LVs found"
echo

echo -e "${GREEN}Current Drive Layout:${NC}"
echo "External M.2 (sda):"
lsblk /dev/sda
echo
echo "Internal NVMe (nvme0n1):"
lsblk /dev/nvme0n1
echo

echo -e "${GREEN}Available Space Analysis:${NC}"
echo "External VG size: $(sudo vgs --noheadings --units g -o vg_size migration-vg | tr -d ' ')B"
echo "External VG free: $(sudo vgs --noheadings --units g -o vg_free migration-vg | tr -d ' ')B"
echo "Internal drive size: $(lsblk -b -n -o SIZE /dev/nvme0n1 | awk '{printf "%.1fGB", $1/1024/1024/1024}')"
echo

echo -e "${YELLOW}Migration Plan:${NC}"
echo "1. ✅ Wipe internal NVMe drive completely"
echo "2. ✅ Create new GPT partition table"
echo "3. ✅ Create EFI boot partition (512MB)"
echo "4. ✅ Create LVM partition (remaining space)"
echo "5. ✅ Set up LVM with volume group 'internal-vg'"
echo "6. ✅ Create logical volumes matching current structure"
echo "7. ✅ Copy all data from external to internal"
echo "8. ✅ Configure GRUB for LVM boot"
echo "9. ✅ Set up LVM snapshot capabilities"
echo "10. ✅ Reserve 20% space for snapshots"
echo

echo -e "${RED}⚠️  WARNINGS:${NC}"
echo "• This will COMPLETELY WIPE the internal NVMe drive"
echo "• All current data on internal drive will be lost"
echo "• Make sure you're booted from external M.2 (verified above)"
echo "• Ensure external M.2 LED is active/blinking"
echo

echo -e "${GREEN}Snapshot Features After Migration:${NC}"
echo "• lvm-snapshot-manager create     - Create system snapshots"
echo "• lvm-snapshot-manager list       - List existing snapshots"
echo "• lvm-snapshot-manager remove     - Remove snapshots"
echo "• lvm-snapshot-manager merge      - Restore from snapshot"
echo "• snapshot-backup                 - Backup using snapshots"
echo

echo -e "${BLUE}Ready to proceed?${NC}"
echo "Run: sudo ./migrate_lvm_to_internal.sh"
echo
echo -e "${YELLOW}Estimated time: 2-4 hours depending on data size${NC}"