#!/bin/bash

# LVM Migration Troubleshooting Script
# Helps diagnose issues with the migration process

set -e

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

log() { echo -e "${BLUE}[$(date '+%H:%M:%S')]${NC} $1"; }
error() { echo -e "${RED}[ERROR]${NC} $1" >&2; }
success() { echo -e "${GREEN}[SUCCESS]${NC} $1"; }
warning() { echo -e "${YELLOW}[WARNING]${NC} $1"; }

echo -e "${GREEN}=== LVM Migration Troubleshooting ===${NC}"
echo

# Check basic system requirements
check_system() {
    log "Checking system requirements..."
    
    # Check if running as root
    if [ "$EUID" -ne 0 ]; then
        error "This script must be run as root. Use: sudo $0"
        return 1
    fi
    
    # Check if running from live system
    local root_device=$(df / | tail -1 | awk '{print $1}')
    if [[ "$root_device" == *"loop"* ]] || [[ "$root_device" == *"overlay"* ]] || [[ "$root_device" == *"tmpfs"* ]]; then
        success "Running from live system"
    else
        warning "Not running from live system - migration may fail"
    fi
    
    # Check available tools
    local tools=("lvm" "cryptsetup" "rsync" "parted" "pv" "grub-install" "mkfs.ext4" "mkfs.fat" "bc" "wipefs")
    local missing=()
    
    for tool in "${tools[@]}"; do
        if command -v "$tool" >/dev/null 2>&1; then
            success "Tool available: $tool"
        else
            missing+=("$tool")
        fi
    done
    
    if [ ${#missing[@]} -gt 0 ]; then
        error "Missing tools: ${missing[*]}"
        echo "Run: sudo ./emergency_install.sh to install missing packages"
        return 1
    fi
}

# Check drives
check_drives() {
    log "Checking available drives..."
    
    echo "All block devices:"
    lsblk -dpno NAME,SIZE,MODEL,VENDOR
    echo
    
    # Look for likely candidates
    local internal_drives=($(lsblk -dpno NAME | grep -E "nvme|sda"))
    local usb_drives=()
    
    # Check for USB drives
    for drive in $(lsblk -dpno NAME); do
        if udevadm info --query=property --name="$drive" | grep -q "ID_BUS=usb"; then
            usb_drives+=("$drive")
        fi
    done
    
    echo "Likely internal drives:"
    for drive in "${internal_drives[@]}"; do
        local info=$(lsblk -dpno NAME,SIZE,MODEL "$drive")
        echo "  $info"
    done
    
    echo "USB drives (external/migration stick):"
    for drive in "${usb_drives[@]}"; do
        local info=$(lsblk -dpno NAME,SIZE,MODEL "$drive")  
        echo "  $info"
    done
}

# Check LVM status
check_lvm() {
    log "Checking LVM status..."
    
    echo "Physical volumes:"
    pvs 2>/dev/null || echo "No physical volumes found"
    
    echo "Volume groups:"
    vgs 2>/dev/null || echo "No volume groups found"
    
    echo "Logical volumes:"
    lvs 2>/dev/null || echo "No logical volumes found"
    
    # Check for existing system-vg
    if vgs system-vg 2>/dev/null; then
        warning "system-vg already exists - migration may have partially completed"
        echo "To restart migration, you may need to:"
        echo "  vgremove -f system-vg"
        echo "  pvremove /dev/sdaX"
    fi
}

# Check filesystem space and usage
check_filesystems() {
    log "Checking current filesystem usage..."
    
    echo "Current mounts and usage:"
    df -h | grep -E "/$|/home$|/boot$"
    
    echo
    echo "System memory:"
    free -h
}

# Test LVM commands
test_lvm_commands() {
    log "Testing LVM command availability..."
    
    # Test basic LVM commands
    lvm version || error "LVM not working"
    
    # Test if we can create a test PV (on a loop device)
    log "Testing LVM functionality with loop device..."
    
    # Create a small test file
    dd if=/dev/zero of=/tmp/lvm-test.img bs=1M count=100 2>/dev/null
    local loop_device=$(losetup -f --show /tmp/lvm-test.img)
    
    if pvcreate "$loop_device" 2>/dev/null; then
        success "LVM pvcreate works"
        
        if vgcreate test-vg "$loop_device" 2>/dev/null; then
            success "LVM vgcreate works"
            
            if lvcreate -L 50M -n test-lv test-vg 2>/dev/null; then
                success "LVM lvcreate works"
                success "All LVM commands working correctly"
            else
                error "LVM lvcreate failed"
            fi
            
            # Cleanup
            lvremove -f test-vg/test-lv 2>/dev/null || true
            vgremove -f test-vg 2>/dev/null || true
        else
            error "LVM vgcreate failed"
        fi
        
        pvremove -f "$loop_device" 2>/dev/null || true
    else
        error "LVM pvcreate failed"
    fi
    
    # Cleanup
    losetup -d "$loop_device" 2>/dev/null || true
    rm -f /tmp/lvm-test.img
}

# Generate report
generate_report() {
    echo
    echo -e "${BLUE}=== Troubleshooting Report ===${NC}"
    echo "Generated: $(date)"
    echo "System: $(hostname)"
    
    if check_system && check_drives && check_lvm && check_filesystems && test_lvm_commands; then
        echo
        success "All checks passed - system should be ready for migration"
        echo
        echo "To run migration:"
        echo "1. sudo ./migrate_to_lvm.sh"
        echo "2. Follow the interactive prompts"
        echo "3. Carefully select source and target drives"
    else
        echo
        error "Some checks failed - see messages above"
        echo
        echo "Common solutions:"
        echo "• Run: sudo ./emergency_install.sh (for missing packages)"
        echo "• Reboot from live USB (if not in live system)" 
        echo "• Check drive connections (if drives not detected)"
        echo "• Remove existing LVM setup (if system-vg exists)"
    fi
}

# Main execution
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    generate_report
fi