package strategy

import (
	"backea/internal/backup/config"
	"backea/internal/backup/strategy/kopia"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"
)

// Factory handles backup strategy creation
type Factory struct {
	Config     *config.Configuration
	ConfigPath string
}

// NewFactory initializes and returns a Factory
func NewFactory(configPath string) (*Factory, error) {
	cfg, err := config.LoadConfig(configPath)
	if err != nil {
		return nil, fmt.Errorf("failed to load config: %w", err)
	}
	return &Factory{Config: cfg, ConfigPath: configPath}, nil
}

// CreateBackupStrategyForService returns a backup strategy based on config
func (f *Factory) CreateBackupStrategyForService(groupName, serviceIndex string) (Strategy, error) {
	serviceConfig, err := f.getServiceConfig(groupName, serviceIndex)
	if err != nil {
		return nil, err
	}
	sourcePath, err := f.getServicePath(groupName)
	if err != nil {
		return nil, err
	}

	switch serviceConfig.BackupStrategy.Type {
	case "kopia":
		return f.createKopiaStrategy(serviceConfig, sourcePath)
	default:
		return nil, fmt.Errorf("unknown strategy type: %s", serviceConfig.BackupStrategy.Type)
	}
}

// createKopiaStrategy initializes a Kopia strategy
func (f *Factory) createKopiaStrategy(serviceConfig *config.BackupConfig, sourcePath string) (Strategy, error) {
	provider, err := f.createKopiaProvider(serviceConfig.BackupStrategy)
	if err != nil {
		return nil, fmt.Errorf("failed to create kopia provider: %w", err)
	}

	retention := kopia.Retention(serviceConfig.BackupStrategy.Retention)
	configPath := generateTempConfigPath(provider.GetProviderType())

	return kopia.NewStrategy(retention, provider, configPath, sourcePath), nil
}

// createKopiaProvider returns a Kopia storage provider
func (f *Factory) createKopiaProvider(strategyConfig config.StrategyConfig) (kopia.Provider, error) {
	switch strategyConfig.Provider {
	case "local":
		return kopia.NewLocalProvider(getDefaultPath(strategyConfig.Destination.Path)), nil
	case "b2", "backblaze":
		return kopia.NewB2Provider(), nil
	// case "sftp":
	// 	return createSFTPProvider(strategyConfig.Destination)
	default:
		return nil, fmt.Errorf("unknown kopia provider type: %s", strategyConfig.Provider)
	}
}

// createSFTPProvider handles SFTP provider creation
func createSFTPProvider(dest DestinationConfig) (kopia.Provider, error) {
	host, username := parseSFTPHost(dest.Host)
	if host == "" {
		return nil, fmt.Errorf("SFTP host not specified")
	}
	return kopia.NewSFTPProvider(host, getDefaultPath(dest.Path), username, getSSHKeyPath(dest.SSHKey)), nil
}

// parseSFTPHost extracts the username and host from "user@host"
func parseSFTPHost(host string) (string, string) {
	if atIndex := strings.Index(host, "@"); atIndex > 0 {
		return host[atIndex+1:], host[:atIndex]
	}
	return host, getEnvUser()
}

// getDefaultPath returns the given path or a default
func getDefaultPath(path string) string {
	if path != "" {
		return path
	}
	home, _ := os.UserHomeDir()
	return filepath.Join(home, ".backea", "repos")
}

// getEnvUser returns the system username
func getEnvUser() string {
	if user := os.Getenv("USER"); user != "" {
		return user
	}
	return "root"
}

// getSSHKeyPath returns the SSH key path
func getSSHKeyPath(key string) string {
	if key != "" {
		return key
	}
	home, _ := os.UserHomeDir()
	return filepath.Join(home, ".ssh", "id_rsa")
}

// getServicePath returns a service's path
func (f *Factory) getServicePath(groupName string) (string, error) {
	if serviceGroup, exists := f.Config.Services[groupName]; exists {
		return serviceGroup.Source.Path, nil
	}
	return "", fmt.Errorf("service group not found: %s", groupName)
}

// getServiceConfig returns a service's config
func (f *Factory) getServiceConfig(groupName, serviceIndex string) (*config.BackupConfig, error) {
	if serviceGroup, exists := f.Config.Services[groupName]; exists {
		if backupConfig, exists := serviceGroup.BackupConfigs[serviceIndex]; exists {
			return &backupConfig, nil
		}
	}
	return nil, fmt.Errorf("backup config not found: %s.%s", groupName, serviceIndex)
}

// ReloadConfig reloads configuration
func (f *Factory) ReloadConfig() error {
	cfg, err := config.LoadConfig(f.ConfigPath)
	if err != nil {
		return fmt.Errorf("could not reload config: %w", err)
	}
	f.Config = cfg
	return nil
}

// generateTempConfigPath creates a temp Kopia config path
func generateTempConfigPath(providerType string) string {
	tmpConfigDir := filepath.Join(os.TempDir(), "kopia_configs")
	_ = os.MkdirAll(tmpConfigDir, 0755) // Ensure directory exists
	return filepath.Join(tmpConfigDir, fmt.Sprintf("kopia_%s_%d.config", providerType, time.Now().UnixNano()))
}