# Dependency checking and validation for Ubuntu uBlue bootupd-alternative Tool
check_dependencies() {
    log_info "Checking dependencies..." "bootupd-alternative"
    
    local missing_deps=()
    
    # Core dependencies
    for dep in mount umount lsblk bc; do
        if ! command -v "$dep" >/dev/null 2>&1; then
            missing_deps+=("$dep")
        fi
    done
    
    # Bootloader-specific dependencies
    local bootloader
    bootloader=$(detect_bootloader)
    
    case "$bootloader" in
        "uefi")
            if ! command -v efibootmgr >/dev/null 2>&1; then
                missing_deps+=("efibootmgr")
            fi
            ;;
        "grub")
            if ! command -v grub-install >/dev/null 2>&1; then
                missing_deps+=("grub-install")
            fi
            if ! command -v grub-mkconfig >/dev/null 2>&1; then
                missing_deps+=("grub-mkconfig")
            fi
            ;;
        "lilo")
            if ! command -v lilo >/dev/null 2>&1; then
                missing_deps+=("lilo")
            fi
            ;;
        "syslinux")
            if ! command -v syslinux >/dev/null 2>&1; then
                missing_deps+=("syslinux")
            fi
            ;;
    esac
    
    # Check for kernel modules
    check_kernel_modules
    
    if [ ${#missing_deps[@]} -ne 0 ]; then
        log_error "Missing dependencies: ${missing_deps[*]}" "bootupd-alternative"
        log_info "Install missing packages with: sudo apt install -y ${missing_deps[*]}" "bootupd-alternative"
        exit 1
    fi
    
    log_success "All dependencies found" "bootupd-alternative"
}

# Check kernel modules
check_kernel_modules() {
    log_info "Checking kernel modules..." "bootupd-alternative"
    
    local missing_modules=()
    
    # Check for squashfs module
    if ! modprobe -n squashfs >/dev/null 2>&1; then
        missing_modules+=("squashfs")
    fi
    
    # Check for overlay module
    if ! modprobe -n overlay >/dev/null 2>&1; then
        missing_modules+=("overlay")
    fi
    
    # Check for loop module
    if ! modprobe -n loop >/dev/null 2>&1; then
        missing_modules+=("loop")
    fi
    
    if [ ${#missing_modules[@]} -ne 0 ]; then
        log_warning "Missing kernel modules: ${missing_modules[*]}" "bootupd-alternative"
        log_info "Load modules with: sudo modprobe ${missing_modules[*]}" "bootupd-alternative"
        log_info "Or install with: sudo apt install linux-modules-extra-$(uname -r)" "bootupd-alternative"
    else
        log_success "All required kernel modules available" "bootupd-alternative"
    fi
}

# Check for bootloader integration script
check_bootloader_integration() {
    local bootloader_script="/usr/local/bin/bootloader-integration.sh"
    
    if [[ -f "$bootloader_script" ]] && [[ -x "$bootloader_script" ]]; then
        log_debug "Bootloader integration script found: $bootloader_script" "bootupd-alternative"
        return 0
    else
        log_warning "Bootloader integration script not found or not executable: $bootloader_script" "bootupd-alternative"
        log_info "Advanced bootloader features will not be available" "bootupd-alternative"
        return 1
    fi
}

# Check for composefs integration script
check_composefs_integration() {
    local composefs_script="/usr/local/bin/composefs-alternative.sh"
    
    if [[ -f "$composefs_script" ]] && [[ -x "$composefs_script" ]]; then
        log_debug "ComposeFS integration script found: $composefs_script" "bootupd-alternative"
        return 0
    else
        log_warning "ComposeFS integration script not found or not executable: $composefs_script" "bootupd-alternative"
        log_info "ComposeFS-based boot images will not be available" "bootupd-alternative"
        return 1
    fi
}

# Validate boot device
validate_boot_device() {
    local device="$1"
    
    # Check if device exists
    if [[ ! -b "$device" ]]; then
        log_error "Boot device does not exist: $device" "bootupd-alternative"
        return 1
    fi
    
    # Check if device is readable
    if [[ ! -r "$device" ]]; then
        log_error "Boot device is not readable: $device" "bootupd-alternative"
        return 1
    fi
    
    # Check if device has boot partition
    local has_boot_partition=false
    while IFS= read -r line; do
        if [[ "$line" =~ boot ]] || [[ "$line" =~ efi ]]; then
            has_boot_partition=true
            break
        fi
    done < <(lsblk -o MOUNTPOINT "$device" 2>/dev/null)
    
    if [[ "$has_boot_partition" == "false" ]]; then
        log_warning "No boot partition detected on device: $device" "bootupd-alternative"
        log_info "This may be expected for some configurations" "bootupd-alternative"
    fi
    
    return 0
}

# Check available disk space
check_disk_space() {
    local required_space_mb="$1"
    local target_dir="${2:-$BOOTUPD_DIR}"
    
    local available_space_mb
    available_space_mb=$(get_available_space "$target_dir")
    
    if [[ $available_space_mb -lt $required_space_mb ]]; then
        log_error "Insufficient disk space: ${available_space_mb}MB available, need ${required_space_mb}MB" "bootupd-alternative"
        return 1
    fi
    
    log_debug "Disk space check passed: ${available_space_mb}MB available" "bootupd-alternative"
    return 0
}

# Check if system is bootable
check_system_bootability() {
    log_info "Checking system bootability..." "bootupd-alternative"
    
    local bootloader
    bootloader=$(detect_bootloader)
    
    case "$bootloader" in
        "uefi")
            # Check for UEFI firmware
            if [[ ! -d "/sys/firmware/efi" ]]; then
                log_error "UEFI firmware not detected" "bootupd-alternative"
                return 1
            fi
            
            # Check for EFI partition
            if ! mountpoint -q /boot/efi 2>/dev/null; then
                log_warning "EFI partition not mounted at /boot/efi" "bootupd-alternative"
            fi
            ;;
        "grub")
            # Check for GRUB configuration
            if [[ ! -f "/boot/grub/grub.cfg" ]] && [[ ! -f "/boot/grub2/grub.cfg" ]]; then
                log_warning "GRUB configuration not found" "bootupd-alternative"
            fi
            ;;
        "lilo")
            # Check for LILO configuration
            if [[ ! -f "/etc/lilo.conf" ]]; then
                log_warning "LILO configuration not found" "bootupd-alternative"
            fi
            ;;
        "syslinux")
            # Check for syslinux configuration
            if [[ ! -f "/boot/syslinux/syslinux.cfg" ]]; then
                log_warning "syslinux configuration not found" "bootupd-alternative"
            fi
            ;;
        "unknown")
            log_warning "Unknown bootloader type" "bootupd-alternative"
            ;;
    esac
    
    log_info "System bootability check completed" "bootupd-alternative"
    return 0
}

# Check for required filesystems
check_filesystems() {
    log_info "Checking required filesystems..." "bootupd-alternative"
    
    # Check for /boot
    if [[ ! -d "/boot" ]]; then
        log_error "/boot directory not found" "bootupd-alternative"
        return 1
    fi
    
    # Check for /boot/efi (UEFI systems)
    if [[ -d "/sys/firmware/efi" ]] && [[ ! -d "/boot/efi" ]]; then
        log_warning "EFI directory not found at /boot/efi" "bootupd-alternative"
    fi
    
    # Check for /etc/fstab
    if [[ ! -f "/etc/fstab" ]]; then
        log_warning "/etc/fstab not found" "bootupd-alternative"
    fi
    
    log_success "Filesystem check completed" "bootupd-alternative"
    return 0
}