package service

import (
	"fmt"
	"io"
	"os"
	"sort"
	"strconv"
	"strings"

	"spore-registry/internal/models"
	"spore-registry/internal/repository"
	"spore-registry/internal/storage"
)

// FirmwareService handles business logic for firmware operations
type FirmwareService struct {
	repo    *repository.FirmwareRepository
	storage *storage.FileStorage
}

// NewFirmwareService creates a new firmware service
func NewFirmwareService(repo *repository.FirmwareRepository, storage *storage.FileStorage) *FirmwareService {
	return &FirmwareService{
		repo:    repo,
		storage: storage,
	}
}

// UploadFirmware uploads firmware binary and metadata
func (s *FirmwareService) UploadFirmware(metadata models.FirmwareMetadata, data io.Reader) (*models.UploadResponse, error) {
	// Validate required fields
	if metadata.Name == "" || metadata.Version == "" {
		return nil, fmt.Errorf("name and version are required")
	}

	// Store firmware binary
	filePath, size, err := s.storage.StoreFirmwareBinary(metadata.Name, metadata.Version, data)
	if err != nil {
		return nil, fmt.Errorf("failed to store firmware binary: %w", err)
	}

	// Store metadata in database
	if err := s.repo.StoreFirmwareMetadata(metadata, size); err != nil {
		// Try to clean up the file if database operation fails
		os.Remove(filePath)
		return nil, fmt.Errorf("failed to store firmware metadata: %w", err)
	}

	return &models.UploadResponse{
		Success: true,
		Name:    metadata.Name,
		Version: metadata.Version,
		Size:    size,
	}, nil
}

// ListFirmware retrieves firmware records with optional filtering
func (s *FirmwareService) ListFirmware(name, version string) ([]models.GroupedFirmware, error) {
	records, err := s.repo.GetFirmwareRecords(name, version)
	if err != nil {
		return nil, fmt.Errorf("failed to retrieve firmware records: %w", err)
	}

	grouped := s.groupFirmwareByName(records)
	return grouped, nil
}

// UpdateFirmwareMetadata updates firmware metadata
func (s *FirmwareService) UpdateFirmwareMetadata(name, version string, metadata models.FirmwareMetadata) (*models.UploadResponse, error) {
	// Validate that the name and version match the URL
	if metadata.Name != name || metadata.Version != version {
		return nil, fmt.Errorf("name and version in URL must match metadata")
	}

	// Check if firmware exists
	records, err := s.repo.GetFirmwareRecords(name, version)
	if err != nil {
		return nil, fmt.Errorf("failed to check if firmware exists: %w", err)
	}

	if len(records) == 0 {
		return nil, fmt.Errorf("firmware not found")
	}

	// Get existing firmware size (keep the same size since we're not updating the binary)
	existingRecord := records[0]
	size := existingRecord.Size

	// Update metadata in database
	if err := s.repo.StoreFirmwareMetadata(metadata, size); err != nil {
		return nil, fmt.Errorf("failed to update firmware metadata: %w", err)
	}

	return &models.UploadResponse{
		Success: true,
		Name:    metadata.Name,
		Version: metadata.Version,
		Size:    size,
		Message: "Metadata updated successfully",
	}, nil
}

// GetFirmwarePath returns the file path for downloading firmware
func (s *FirmwareService) GetFirmwarePath(name, version string) (string, error) {
	if !s.storage.FirmwareExists(name, version) {
		return "", fmt.Errorf("firmware not found")
	}

	return s.storage.GetFirmwareBinaryPath(name, version), nil
}

// DeleteFirmware deletes firmware binary and metadata
func (s *FirmwareService) DeleteFirmware(name, version string) error {
	// Validate required fields
	if name == "" || version == "" {
		return fmt.Errorf("name and version are required")
	}

	// Check if firmware exists
	if !s.storage.FirmwareExists(name, version) {
		return fmt.Errorf("firmware not found")
	}

	// Delete from database first
	if err := s.repo.DeleteFirmwareMetadata(name, version); err != nil {
		return fmt.Errorf("failed to delete firmware metadata: %w", err)
	}

	// Delete firmware binary
	if err := s.storage.DeleteFirmwareBinary(name, version); err != nil {
		return fmt.Errorf("failed to delete firmware binary: %w", err)
	}

	return nil
}

// groupFirmwareByName groups firmware records by name
func (s *FirmwareService) groupFirmwareByName(records []models.FirmwareRecord) []models.GroupedFirmware {
	nameMap := make(map[string][]models.FirmwareRecord)

	// Group records by name
	for _, record := range records {
		nameMap[record.Name] = append(nameMap[record.Name], record)
	}

	// Convert to slice
	var grouped []models.GroupedFirmware
	for name, firmware := range nameMap {
		// Sort firmware versions by version number (highest first)
		sort.Slice(firmware, func(i, j int) bool {
			return compareVersions(firmware[i].Version, firmware[j].Version) > 0
		})

		grouped = append(grouped, models.GroupedFirmware{
			Name:     name,
			Firmware: firmware,
		})
	}

	// Sort firmware groups by name (A to Z)
	sort.Slice(grouped, func(i, j int) bool {
		return grouped[i].Name < grouped[j].Name
	})

	return grouped
}

// compareVersions compares two semantic version strings
// Returns: -1 if v1 < v2, 0 if v1 == v2, 1 if v1 > v2
func compareVersions(v1, v2 string) int {
	// Remove 'v' prefix if present
	v1 = strings.TrimPrefix(v1, "v")
	v2 = strings.TrimPrefix(v2, "v")

	parts1 := strings.Split(v1, ".")
	parts2 := strings.Split(v2, ".")

	// Pad shorter version with zeros
	maxLen := len(parts1)
	if len(parts2) > maxLen {
		maxLen = len(parts2)
	}

	for len(parts1) < maxLen {
		parts1 = append(parts1, "0")
	}
	for len(parts2) < maxLen {
		parts2 = append(parts2, "0")
	}

	// Compare each part
	for i := 0; i < maxLen; i++ {
		num1, err1 := strconv.Atoi(parts1[i])
		num2, err2 := strconv.Atoi(parts2[i])

		// If parsing fails, do string comparison
		if err1 != nil || err2 != nil {
			if parts1[i] < parts2[i] {
				return -1
			} else if parts1[i] > parts2[i] {
				return 1
			}
			continue
		}

		if num1 < num2 {
			return -1
		} else if num1 > num2 {
			return 1
		}
	}

	return 0
}