logpile/internal/exporter/reanimator_converter.go

package exporter

import (
	"fmt"
	"net/url"
	"regexp"
	"sort"
	"strings"
	"time"

	"git.mchus.pro/mchus/logpile/internal/models"
)

// ConvertToReanimator converts AnalysisResult to Reanimator export format
func ConvertToReanimator(result *models.AnalysisResult) (*ReanimatorExport, error) {
	if result == nil {
		return nil, fmt.Errorf("no data available for export")
	}

	if result.Hardware == nil {
		return nil, fmt.Errorf("no hardware data available for export")
	}

	if result.Hardware.BoardInfo.SerialNumber == "" {
		return nil, fmt.Errorf("board serial_number is required for Reanimator export")
	}

	// Determine target host (optional field)
	targetHost := inferTargetHost(result.TargetHost, result.Filename)

	collectedAt := formatRFC3339(result.CollectedAt)

	export := &ReanimatorExport{
		Filename:    result.Filename,
		SourceType:  normalizeSourceType(result.SourceType),
		Protocol:    normalizeProtocol(result.Protocol),
		TargetHost:  targetHost,
		CollectedAt: collectedAt,
		Hardware: ReanimatorHardware{
			Board:         convertBoard(result.Hardware.BoardInfo),
			Firmware:      dedupeFirmware(convertFirmware(result.Hardware.Firmware)),
			CPUs:          dedupeCPUs(convertCPUs(result.Hardware.CPUs, collectedAt)),
			Memory:        dedupeMemory(convertMemory(result.Hardware.Memory, collectedAt)),
			Storage:       dedupeStorage(convertStorage(result.Hardware.Storage, collectedAt)),
			PCIeDevices:   dedupePCIe(convertPCIeDevices(result.Hardware, collectedAt)),
			PowerSupplies: dedupePSUs(convertPowerSupplies(result.Hardware.PowerSupply, collectedAt)),
		},
	}

	return export, nil
}

// formatRFC3339 formats time in RFC3339 format, returns current time if zero
func formatRFC3339(t time.Time) string {
	if t.IsZero() {
		return time.Now().UTC().Format(time.RFC3339)
	}
	return t.UTC().Format(time.RFC3339)
}

// convertBoard converts BoardInfo to Reanimator format
func convertBoard(board models.BoardInfo) ReanimatorBoard {
	return ReanimatorBoard{
		Manufacturer: normalizeNullableString(board.Manufacturer),
		ProductName:  normalizeNullableString(board.ProductName),
		SerialNumber: board.SerialNumber,
		PartNumber:   board.PartNumber,
		UUID:         board.UUID,
	}
}

// convertFirmware converts firmware information to Reanimator format
func convertFirmware(firmware []models.FirmwareInfo) []ReanimatorFirmware {
	if len(firmware) == 0 {
		return nil
	}

	result := make([]ReanimatorFirmware, 0, len(firmware))
	for _, fw := range firmware {
		result = append(result, ReanimatorFirmware{
			DeviceName: fw.DeviceName,
			Version:    fw.Version,
		})
	}
	return result
}

// convertCPUs converts CPU information to Reanimator format
func convertCPUs(cpus []models.CPU, collectedAt string) []ReanimatorCPU {
	if len(cpus) == 0 {
		return nil
	}

	result := make([]ReanimatorCPU, 0, len(cpus))
	for _, cpu := range cpus {
		manufacturer := inferCPUManufacturer(cpu.Model)

		cpuStatus := normalizeStatus(cpu.Status, false)
		if strings.TrimSpace(cpu.Status) == "" {
			cpuStatus = "Unknown"
		}
		meta := buildStatusMeta(
			cpuStatus,
			cpu.StatusCheckedAt,
			cpu.StatusChangedAt,
			cpu.StatusAtCollect,
			cpu.StatusHistory,
			cpu.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorCPU{
			Socket:           cpu.Socket,
			Model:            cpu.Model,
			Cores:            cpu.Cores,
			Threads:          cpu.Threads,
			FrequencyMHz:     cpu.FrequencyMHz,
			MaxFrequencyMHz:  cpu.MaxFreqMHz,
			Manufacturer:     manufacturer,
			Status:           cpuStatus,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}
	return result
}

// convertMemory converts memory modules to Reanimator format
func convertMemory(memory []models.MemoryDIMM, collectedAt string) []ReanimatorMemory {
	if len(memory) == 0 {
		return nil
	}

	result := make([]ReanimatorMemory, 0, len(memory))
	for _, mem := range memory {
		status := normalizeStatus(mem.Status, true)
		if strings.TrimSpace(mem.Status) == "" {
			if mem.Present {
				status = "OK"
			} else {
				status = "Empty"
			}
		}

		meta := buildStatusMeta(
			status,
			mem.StatusCheckedAt,
			mem.StatusChangedAt,
			mem.StatusAtCollect,
			mem.StatusHistory,
			mem.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorMemory{
			Slot:             mem.Slot,
			Location:         mem.Location,
			Present:          mem.Present,
			SizeMB:           mem.SizeMB,
			Type:             mem.Type,
			MaxSpeedMHz:      mem.MaxSpeedMHz,
			CurrentSpeedMHz:  mem.CurrentSpeedMHz,
			Manufacturer:     mem.Manufacturer,
			SerialNumber:     mem.SerialNumber,
			PartNumber:       mem.PartNumber,
			Status:           status,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}
	return result
}

// convertStorage converts storage devices to Reanimator format
func convertStorage(storage []models.Storage, collectedAt string) []ReanimatorStorage {
	if len(storage) == 0 {
		return nil
	}

	result := make([]ReanimatorStorage, 0, len(storage))
	for _, stor := range storage {
		// Skip storage without serial number
		if stor.SerialNumber == "" {
			continue
		}

		status := inferStorageStatus(stor)
		if strings.TrimSpace(stor.Status) != "" {
			status = normalizeStatus(stor.Status, false)
		}
		meta := buildStatusMeta(
			status,
			stor.StatusCheckedAt,
			stor.StatusChangedAt,
			stor.StatusAtCollect,
			stor.StatusHistory,
			stor.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorStorage{
			Slot:             stor.Slot,
			Type:             stor.Type,
			Model:            stor.Model,
			SizeGB:           stor.SizeGB,
			SerialNumber:     stor.SerialNumber,
			Manufacturer:     stor.Manufacturer,
			Firmware:         stor.Firmware,
			Interface:        stor.Interface,
			Present:          stor.Present,
			Status:           status,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}
	return result
}

// convertPCIeDevices converts PCIe devices, GPUs, and network adapters to Reanimator format
func convertPCIeDevices(hw *models.HardwareConfig, collectedAt string) []ReanimatorPCIe {
	result := make([]ReanimatorPCIe, 0)
	gpuSlots := make(map[string]struct{}, len(hw.GPUs))
	for _, gpu := range hw.GPUs {
		slot := strings.ToLower(strings.TrimSpace(gpu.Slot))
		if slot != "" {
			gpuSlots[slot] = struct{}{}
		}
	}

	// Convert regular PCIe devices
	for _, pcie := range hw.PCIeDevices {
		slot := strings.ToLower(strings.TrimSpace(pcie.Slot))
		if _, isDedicatedGPU := gpuSlots[slot]; isDedicatedGPU || isDisplayClass(pcie.DeviceClass) {
			// Skip GPU-like PCIe entries to avoid duplicates:
			// dedicated GPUs are exported from hw.GPUs with richer metadata.
			continue
		}

		serialNumber := normalizedSerial(pcie.SerialNumber)

		// Determine model (prefer PartNumber, fallback to DeviceClass)
		model := pcie.PartNumber
		if model == "" {
			model = pcie.DeviceClass
		}

		status := normalizeStatus(pcie.Status, false)
		meta := buildStatusMeta(
			status,
			pcie.StatusCheckedAt,
			pcie.StatusChangedAt,
			pcie.StatusAtCollect,
			pcie.StatusHistory,
			pcie.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorPCIe{
			Slot:             pcie.Slot,
			VendorID:         pcie.VendorID,
			DeviceID:         pcie.DeviceID,
			BDF:              pcie.BDF,
			DeviceClass:      pcie.DeviceClass,
			Manufacturer:     pcie.Manufacturer,
			Model:            model,
			LinkWidth:        pcie.LinkWidth,
			LinkSpeed:        pcie.LinkSpeed,
			MaxLinkWidth:     pcie.MaxLinkWidth,
			MaxLinkSpeed:     pcie.MaxLinkSpeed,
			SerialNumber:     serialNumber,
			Firmware:         "", // PCIeDevice doesn't have firmware in models
			Status:           status,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}

	// Convert GPUs as PCIe devices
	for _, gpu := range hw.GPUs {
		serialNumber := normalizedSerial(gpu.SerialNumber)

		// Determine device class
		deviceClass := "DisplayController"

		status := normalizeStatus(gpu.Status, false)
		meta := buildStatusMeta(
			status,
			gpu.StatusCheckedAt,
			gpu.StatusChangedAt,
			gpu.StatusAtCollect,
			gpu.StatusHistory,
			gpu.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorPCIe{
			Slot:             gpu.Slot,
			VendorID:         gpu.VendorID,
			DeviceID:         gpu.DeviceID,
			BDF:              gpu.BDF,
			DeviceClass:      deviceClass,
			Manufacturer:     gpu.Manufacturer,
			Model:            gpu.Model,
			LinkWidth:        gpu.CurrentLinkWidth,
			LinkSpeed:        gpu.CurrentLinkSpeed,
			MaxLinkWidth:     gpu.MaxLinkWidth,
			MaxLinkSpeed:     gpu.MaxLinkSpeed,
			SerialNumber:     serialNumber,
			Firmware:         gpu.Firmware,
			Status:           status,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}

	// Convert network adapters as PCIe devices
	for _, nic := range hw.NetworkAdapters {
		if !nic.Present {
			continue
		}

		serialNumber := normalizedSerial(nic.SerialNumber)

		status := normalizeStatus(nic.Status, false)
		meta := buildStatusMeta(
			status,
			nic.StatusCheckedAt,
			nic.StatusChangedAt,
			nic.StatusAtCollect,
			nic.StatusHistory,
			nic.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorPCIe{
			Slot:             nic.Slot,
			VendorID:         nic.VendorID,
			DeviceID:         nic.DeviceID,
			BDF:              "",
			DeviceClass:      "NetworkController",
			Manufacturer:     nic.Vendor,
			Model:            nic.Model,
			LinkWidth:        0,
			LinkSpeed:        "",
			MaxLinkWidth:     0,
			MaxLinkSpeed:     "",
			SerialNumber:     serialNumber,
			Firmware:         nic.Firmware,
			Status:           status,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}

	return result
}

func isDisplayClass(deviceClass string) bool {
	class := strings.ToLower(strings.TrimSpace(deviceClass))
	return strings.Contains(class, "display") ||
		strings.Contains(class, "vga") ||
		strings.Contains(class, "3d controller")
}

// convertPowerSupplies converts power supplies to Reanimator format
func convertPowerSupplies(psus []models.PSU, collectedAt string) []ReanimatorPSU {
	if len(psus) == 0 {
		return nil
	}

	result := make([]ReanimatorPSU, 0, len(psus))
	for _, psu := range psus {
		// Skip PSUs without serial number (if not present)
		if !psu.Present || psu.SerialNumber == "" {
			continue
		}

		status := normalizeStatus(psu.Status, false)
		meta := buildStatusMeta(
			status,
			psu.StatusCheckedAt,
			psu.StatusChangedAt,
			psu.StatusAtCollect,
			psu.StatusHistory,
			psu.ErrorDescription,
			collectedAt,
		)

		result = append(result, ReanimatorPSU{
			Slot:             psu.Slot,
			Present:          psu.Present,
			Model:            psu.Model,
			Vendor:           psu.Vendor,
			WattageW:         psu.WattageW,
			SerialNumber:     psu.SerialNumber,
			PartNumber:       psu.PartNumber,
			Firmware:         psu.Firmware,
			Status:           status,
			InputType:        psu.InputType,
			InputPowerW:      psu.InputPowerW,
			OutputPowerW:     psu.OutputPowerW,
			InputVoltage:     psu.InputVoltage,
			StatusCheckedAt:  meta.StatusCheckedAt,
			StatusChangedAt:  meta.StatusChangedAt,
			StatusAtCollect:  meta.StatusAtCollection,
			StatusHistory:    meta.StatusHistory,
			ErrorDescription: meta.ErrorDescription,
		})
	}
	return result
}

type convertedStatusMeta struct {
	StatusCheckedAt    string
	StatusChangedAt    string
	StatusAtCollection *ReanimatorStatusAtCollection
	StatusHistory      []ReanimatorStatusHistoryEntry
	ErrorDescription   string
}

func buildStatusMeta(
	currentStatus string,
	checkedAt time.Time,
	changedAt time.Time,
	statusAtCollection *models.StatusAtCollection,
	history []models.StatusHistoryEntry,
	errorDescription string,
	collectedAt string,
) convertedStatusMeta {
	meta := convertedStatusMeta{
		StatusCheckedAt:  formatOptionalRFC3339(checkedAt),
		StatusChangedAt:  formatOptionalRFC3339(changedAt),
		ErrorDescription: strings.TrimSpace(errorDescription),
	}

	convertedHistory := make([]ReanimatorStatusHistoryEntry, 0, len(history))
	for _, h := range history {
		changed := formatOptionalRFC3339(h.ChangedAt)
		if changed == "" {
			continue
		}
		convertedHistory = append(convertedHistory, ReanimatorStatusHistoryEntry{
			Status:    normalizeStatus(h.Status, true),
			ChangedAt: changed,
			Details:   strings.TrimSpace(h.Details),
		})
	}
	sort.Slice(convertedHistory, func(i, j int) bool {
		return convertedHistory[i].ChangedAt < convertedHistory[j].ChangedAt
	})
	if len(convertedHistory) > 0 {
		meta.StatusHistory = convertedHistory
		if meta.StatusChangedAt == "" {
			meta.StatusChangedAt = convertedHistory[len(convertedHistory)-1].ChangedAt
		}
	}

	if statusAtCollection != nil {
		at := formatOptionalRFC3339(statusAtCollection.At)
		if at != "" && strings.TrimSpace(statusAtCollection.Status) != "" {
			meta.StatusAtCollection = &ReanimatorStatusAtCollection{
				Status: normalizeStatus(statusAtCollection.Status, true),
				At:     at,
			}
		}
	}
	if meta.StatusAtCollection == nil && strings.TrimSpace(currentStatus) != "" && collectedAt != "" {
		meta.StatusAtCollection = &ReanimatorStatusAtCollection{
			Status: currentStatus,
			At:     collectedAt,
		}
	}

	if meta.StatusCheckedAt == "" && len(meta.StatusHistory) > 0 {
		meta.StatusCheckedAt = meta.StatusHistory[len(meta.StatusHistory)-1].ChangedAt
	}
	if meta.StatusCheckedAt == "" && strings.TrimSpace(currentStatus) != "" && collectedAt != "" {
		meta.StatusCheckedAt = collectedAt
	}

	return meta
}

func formatOptionalRFC3339(t time.Time) string {
	if t.IsZero() {
		return ""
	}
	return t.UTC().Format(time.RFC3339)
}

func dedupeFirmware(items []ReanimatorFirmware) []ReanimatorFirmware {
	if len(items) < 2 {
		return items
	}
	seen := make(map[string]struct{}, len(items))
	result := make([]ReanimatorFirmware, 0, len(items))
	for _, item := range items {
		key := strings.ToLower(strings.TrimSpace(item.DeviceName))
		if key == "" {
			key = strings.ToLower(strings.TrimSpace(item.Version))
		}
		if _, ok := seen[key]; ok {
			continue
		}
		seen[key] = struct{}{}
		result = append(result, item)
	}
	return result
}

func dedupeCPUs(items []ReanimatorCPU) []ReanimatorCPU {
	if len(items) < 2 {
		return items
	}
	seen := make(map[int]struct{}, len(items))
	result := make([]ReanimatorCPU, 0, len(items))
	for _, item := range items {
		if _, ok := seen[item.Socket]; ok {
			continue
		}
		seen[item.Socket] = struct{}{}
		result = append(result, item)
	}
	return result
}

func dedupeMemory(items []ReanimatorMemory) []ReanimatorMemory {
	if len(items) < 2 {
		return items
	}
	seen := make(map[string]struct{}, len(items))
	result := make([]ReanimatorMemory, 0, len(items))
	for _, item := range items {
		key := strings.ToLower(strings.TrimSpace(item.Slot))
		if key == "" {
			key = strings.ToLower(strings.TrimSpace(item.Location))
		}
		if _, ok := seen[key]; ok {
			continue
		}
		seen[key] = struct{}{}
		result = append(result, item)
	}
	return result
}

func dedupeStorage(items []ReanimatorStorage) []ReanimatorStorage {
	if len(items) < 2 {
		return items
	}
	seen := make(map[string]struct{}, len(items))
	result := make([]ReanimatorStorage, 0, len(items))
	for _, item := range items {
		key := strings.ToLower(strings.TrimSpace(item.SerialNumber))
		if key == "" {
			key = "slot:" + strings.ToLower(strings.TrimSpace(item.Slot))
		}
		if _, ok := seen[key]; ok {
			continue
		}
		seen[key] = struct{}{}
		result = append(result, item)
	}
	return result
}

func dedupePSUs(items []ReanimatorPSU) []ReanimatorPSU {
	if len(items) < 2 {
		return items
	}
	seen := make(map[string]struct{}, len(items))
	result := make([]ReanimatorPSU, 0, len(items))
	for _, item := range items {
		key := strings.ToLower(strings.TrimSpace(item.SerialNumber))
		if key == "" {
			key = "slot:" + strings.ToLower(strings.TrimSpace(item.Slot))
		}
		if _, ok := seen[key]; ok {
			continue
		}
		seen[key] = struct{}{}
		result = append(result, item)
	}
	return result
}

func dedupePCIe(items []ReanimatorPCIe) []ReanimatorPCIe {
	if len(items) < 2 {
		return items
	}
	type scored struct {
		item  ReanimatorPCIe
		score int
		idx   int
	}
	byKey := make(map[string]scored, len(items))
	order := make([]string, 0, len(items))
	for i, item := range items {
		key := pcieDedupKey(item)
		curr := scored{item: item, score: pcieQualityScore(item), idx: i}
		existing, ok := byKey[key]
		if !ok {
			byKey[key] = curr
			order = append(order, key)
			continue
		}
		if curr.score > existing.score {
			byKey[key] = curr
		}
	}
	result := make([]ReanimatorPCIe, 0, len(byKey))
	for _, key := range order {
		result = append(result, byKey[key].item)
	}
	return result
}

func pcieDedupKey(item ReanimatorPCIe) string {
	slot := strings.ToLower(strings.TrimSpace(item.Slot))
	serial := strings.ToLower(strings.TrimSpace(item.SerialNumber))
	bdf := strings.ToLower(strings.TrimSpace(item.BDF))
	if slot != "" {
		return "slot:" + slot
	}
	if serial != "" {
		return "sn:" + serial
	}
	if bdf != "" {
		return "bdf:" + bdf
	}
	return strings.ToLower(strings.TrimSpace(item.DeviceClass)) + "|" + strings.ToLower(strings.TrimSpace(item.Model))
}

func pcieQualityScore(item ReanimatorPCIe) int {
	score := 0
	if strings.TrimSpace(item.SerialNumber) != "" {
		score += 4
	}
	if strings.TrimSpace(item.Model) != "" && !isGenericPCIeModel(item.Model) {
		score += 3
	}
	status := strings.ToLower(strings.TrimSpace(item.Status))
	if status == "ok" || status == "warning" || status == "critical" {
		score += 2
	}
	if strings.TrimSpace(item.BDF) != "" {
		score++
	}
	if strings.EqualFold(strings.TrimSpace(item.DeviceClass), "DisplayController") {
		score++
	}
	return score
}

func isGenericPCIeModel(model string) bool {
	switch strings.ToLower(strings.TrimSpace(model)) {
	case "", "unknown", "vga", "3d controller", "display controller":
		return true
	default:
		return false
	}
}

// inferCPUManufacturer determines CPU manufacturer from model string
func inferCPUManufacturer(model string) string {
	upper := strings.ToUpper(model)

	// Intel patterns
	if strings.Contains(upper, "INTEL") ||
		strings.Contains(upper, "XEON") ||
		strings.Contains(upper, "CORE I") {
		return "Intel"
	}

	// AMD patterns
	if strings.Contains(upper, "AMD") ||
		strings.Contains(upper, "EPYC") ||
		strings.Contains(upper, "RYZEN") ||
		strings.Contains(upper, "THREADRIPPER") {
		return "AMD"
	}

	// ARM patterns
	if strings.Contains(upper, "ARM") ||
		strings.Contains(upper, "CORTEX") {
		return "ARM"
	}

	// Ampere patterns
	if strings.Contains(upper, "AMPERE") ||
		strings.Contains(upper, "ALTRA") {
		return "Ampere"
	}

	return ""
}

func normalizedSerial(serial string) string {
	s := strings.TrimSpace(serial)
	if s == "" {
		return ""
	}
	switch strings.ToUpper(s) {
	case "N/A", "NA", "NONE", "NULL", "UNKNOWN", "-":
		return ""
	default:
		return s
	}
}

// inferStorageStatus determines storage device status
func inferStorageStatus(stor models.Storage) string {
	if !stor.Present {
		return "Unknown"
	}
	return "Unknown"
}

func normalizeSourceType(sourceType string) string {
	normalized := strings.ToLower(strings.TrimSpace(sourceType))
	switch normalized {
	case "api", "logfile", "manual":
		return normalized
	default:
		return ""
	}
}

func normalizeProtocol(protocol string) string {
	normalized := strings.ToLower(strings.TrimSpace(protocol))
	switch normalized {
	case "redfish", "ipmi", "snmp", "ssh":
		return normalized
	default:
		return ""
	}
}

func normalizeNullableString(v string) string {
	trimmed := strings.TrimSpace(v)
	if strings.EqualFold(trimmed, "NULL") {
		return ""
	}
	return trimmed
}

func normalizeStatus(status string, allowEmpty bool) string {
	switch strings.ToLower(strings.TrimSpace(status)) {
	case "ok":
		return "OK"
	case "pass":
		return "OK"
	case "warning":
		return "Warning"
	case "critical":
		return "Critical"
	case "fail":
		return "Critical"
	case "unknown":
		return "Unknown"
	case "empty":
		if allowEmpty {
			return "Empty"
		}
		return "Unknown"
	default:
		if allowEmpty {
			return "Unknown"
		}
		return "Unknown"
	}
}

var (
	ipv4Regex = regexp.MustCompile(`(?:^|[^0-9])((?:\d{1,3}\.){3}\d{1,3})(?:[^0-9]|$)`)
)

func inferTargetHost(targetHost, filename string) string {
	if trimmed := strings.TrimSpace(targetHost); trimmed != "" {
		return trimmed
	}

	candidate := strings.TrimSpace(filename)
	if candidate == "" {
		return ""
	}

	if parsed, err := url.Parse(candidate); err == nil && parsed.Hostname() != "" {
		return parsed.Hostname()
	}

	if submatches := ipv4Regex.FindStringSubmatch(candidate); len(submatches) > 1 {
		return submatches[1]
	}

	return ""
}