feat(config): ✨ Add PopulateFromDSN method to parse connection DSN

pkg/config/dbmanager.go

@@ -2,6 +2,9 @@ package config
 
 import (
 	"fmt"
+	"net/url"
+	"strconv"
+	"strings"
 	"time"
 )
 
@@ -91,6 +94,160 @@ func (c *DBManagerConfig) ToManagerConfig() interface{} {
 	return c
 }
 
+// PopulateFromDSN parses a DSN and populates the connection fields
+func (cc *DBConnectionConfig) PopulateFromDSN() error {
+	if cc.DSN == "" {
+		return nil // Nothing to populate
+	}
+
+	switch cc.Type {
+	case "postgres":
+		return cc.populatePostgresDSN()
+	case "mongodb":
+		return cc.populateMongoDSN()
+	case "mssql":
+		return cc.populateMSSQLDSN()
+	case "sqlite":
+		return cc.populateSQLiteDSN()
+	default:
+		return fmt.Errorf("cannot parse DSN for unsupported database type: %s", cc.Type)
+	}
+}
+
+// populatePostgresDSN parses PostgreSQL DSN format
+// Example: host=localhost port=5432 user=postgres password=secret dbname=mydb sslmode=disable
+func (cc *DBConnectionConfig) populatePostgresDSN() error {
+	parts := strings.Fields(cc.DSN)
+	for _, part := range parts {
+		kv := strings.SplitN(part, "=", 2)
+		if len(kv) != 2 {
+			continue
+		}
+		key, value := kv[0], kv[1]
+
+		switch key {
+		case "host":
+			cc.Host = value
+		case "port":
+			port, err := strconv.Atoi(value)
+			if err != nil {
+				return fmt.Errorf("invalid port in DSN: %w", err)
+			}
+			cc.Port = port
+		case "user":
+			cc.User = value
+		case "password":
+			cc.Password = value
+		case "dbname":
+			cc.Database = value
+		case "sslmode":
+			cc.SSLMode = value
+		case "search_path":
+			cc.Schema = value
+		}
+	}
+	return nil
+}
+
+// populateMongoDSN parses MongoDB DSN format
+// Example: mongodb://user:password@host:port/database?authSource=admin&replicaSet=rs0
+func (cc *DBConnectionConfig) populateMongoDSN() error {
+	u, err := url.Parse(cc.DSN)
+	if err != nil {
+		return fmt.Errorf("invalid MongoDB DSN: %w", err)
+	}
+
+	// Extract user and password
+	if u.User != nil {
+		cc.User = u.User.Username()
+		if password, ok := u.User.Password(); ok {
+			cc.Password = password
+		}
+	}
+
+	// Extract host and port
+	if u.Host != "" {
+		host := u.Host
+		if strings.Contains(host, ":") {
+			hostPort := strings.SplitN(host, ":", 2)
+			cc.Host = hostPort[0]
+			if port, err := strconv.Atoi(hostPort[1]); err == nil {
+				cc.Port = port
+			}
+		} else {
+			cc.Host = host
+		}
+	}
+
+	// Extract database
+	if u.Path != "" {
+		cc.Database = strings.TrimPrefix(u.Path, "/")
+	}
+
+	// Extract query parameters
+	params := u.Query()
+	if authSource := params.Get("authSource"); authSource != "" {
+		cc.AuthSource = authSource
+	}
+	if replicaSet := params.Get("replicaSet"); replicaSet != "" {
+		cc.ReplicaSet = replicaSet
+	}
+	if readPref := params.Get("readPreference"); readPref != "" {
+		cc.ReadPreference = readPref
+	}
+
+	return nil
+}
+
+// populateMSSQLDSN parses MSSQL DSN format
+// Example: sqlserver://username:password@host:port?database=dbname&schema=dbo
+func (cc *DBConnectionConfig) populateMSSQLDSN() error {
+	u, err := url.Parse(cc.DSN)
+	if err != nil {
+		return fmt.Errorf("invalid MSSQL DSN: %w", err)
+	}
+
+	// Extract user and password
+	if u.User != nil {
+		cc.User = u.User.Username()
+		if password, ok := u.User.Password(); ok {
+			cc.Password = password
+		}
+	}
+
+	// Extract host and port
+	if u.Host != "" {
+		host := u.Host
+		if strings.Contains(host, ":") {
+			hostPort := strings.SplitN(host, ":", 2)
+			cc.Host = hostPort[0]
+			if port, err := strconv.Atoi(hostPort[1]); err == nil {
+				cc.Port = port
+			}
+		} else {
+			cc.Host = host
+		}
+	}
+
+	// Extract query parameters
+	params := u.Query()
+	if database := params.Get("database"); database != "" {
+		cc.Database = database
+	}
+	if schema := params.Get("schema"); schema != "" {
+		cc.Schema = schema
+	}
+
+	return nil
+}
+
+// populateSQLiteDSN parses SQLite DSN format
+// Example: /path/to/database.db or :memory:
+func (cc *DBConnectionConfig) populateSQLiteDSN() error {
+	cc.FilePath = cc.DSN
+	return nil
+}
+
 // Validate validates the DBManager configuration
 func (c *DBManagerConfig) Validate() error {
 	if len(c.Connections) == 0 {

pkg/config/manager.go

@@ -97,6 +97,29 @@ func (m *Manager) GetConfig() (*Config, error) {
 	return &cfg, nil
 }
 
+// SetConfig sets the complete configuration
+func (m *Manager) SetConfig(cfg *Config) error {
+	configMap := make(map[string]interface{})
+
+	// Marshal the config to a map structure that viper can use
+	if err := m.v.Unmarshal(&configMap); err != nil {
+		return fmt.Errorf("failed to prepare config map: %w", err)
+	}
+
+	// Use viper's merge to apply the config
+	m.v.Set("server", cfg.Server)
+	m.v.Set("tracing", cfg.Tracing)
+	m.v.Set("cache", cfg.Cache)
+	m.v.Set("logger", cfg.Logger)
+	m.v.Set("error_tracking", cfg.ErrorTracking)
+	m.v.Set("middleware", cfg.Middleware)
+	m.v.Set("cors", cfg.CORS)
+	m.v.Set("event_broker", cfg.EventBroker)
+	m.v.Set("dbmanager", cfg.DBManager)
+
+	return nil
+}
+
 // Get returns a configuration value by key
 func (m *Manager) Get(key string) interface{} {
 	return m.v.Get(key)
@@ -122,6 +145,14 @@ func (m *Manager) Set(key string, value interface{}) {
 	m.v.Set(key, value)
 }
 
+// SaveConfig writes the current configuration to the specified path
+func (m *Manager) SaveConfig(path string) error {
+	if err := m.v.WriteConfigAs(path); err != nil {
+		return fmt.Errorf("failed to save config to %s: %w", path, err)
+	}
+	return nil
+}
+
 // setDefaults sets default configuration values
 func setDefaults(v *viper.Viper) {
 	// Server defaults
@@ -166,6 +197,34 @@ func setDefaults(v *viper.Viper) {
 	// Database defaults
 	v.SetDefault("database.url", "")
 
+	// Database Manager defaults
+	v.SetDefault("dbmanager.default_connection", "default")
+	v.SetDefault("dbmanager.max_open_conns", 25)
+	v.SetDefault("dbmanager.max_idle_conns", 5)
+	v.SetDefault("dbmanager.conn_max_lifetime", "30m")
+	v.SetDefault("dbmanager.conn_max_idle_time", "5m")
+	v.SetDefault("dbmanager.retry_attempts", 3)
+	v.SetDefault("dbmanager.retry_delay", "1s")
+	v.SetDefault("dbmanager.retry_max_delay", "10s")
+	v.SetDefault("dbmanager.health_check_interval", "30s")
+	v.SetDefault("dbmanager.enable_auto_reconnect", true)
+
+	// Default PostgreSQL connection
+	v.SetDefault("dbmanager.connections.default.name", "default")
+	v.SetDefault("dbmanager.connections.default.type", "postgres")
+	v.SetDefault("dbmanager.connections.default.host", "localhost")
+	v.SetDefault("dbmanager.connections.default.port", 5432)
+	v.SetDefault("dbmanager.connections.default.user", "postgres")
+	v.SetDefault("dbmanager.connections.default.password", "")
+	v.SetDefault("dbmanager.connections.default.database", "resolvespec")
+	v.SetDefault("dbmanager.connections.default.sslmode", "disable")
+	v.SetDefault("dbmanager.connections.default.connect_timeout", "10s")
+	v.SetDefault("dbmanager.connections.default.query_timeout", "30s")
+	v.SetDefault("dbmanager.connections.default.enable_tracing", false)
+	v.SetDefault("dbmanager.connections.default.enable_metrics", false)
+	v.SetDefault("dbmanager.connections.default.enable_logging", false)
+	v.SetDefault("dbmanager.connections.default.default_orm", "bun")
+
 	// Event Broker defaults
 	v.SetDefault("event_broker.enabled", false)
 	v.SetDefault("event_broker.provider", "memory")

pkg/dbmanager/manager.go

@@ -50,6 +50,59 @@ type connectionManager struct {
 	wg           sync.WaitGroup
 }
 
+var (
+	// singleton instance of the manager
+	instance Manager
+	// instanceMu protects the singleton instance
+	instanceMu sync.RWMutex
+)
+
+// SetupManager initializes the singleton database manager with the provided configuration.
+// This function must be called before GetInstance().
+// Returns an error if the manager is already initialized or if configuration is invalid.
+func SetupManager(cfg ManagerConfig) error {
+	instanceMu.Lock()
+	defer instanceMu.Unlock()
+
+	if instance != nil {
+		return fmt.Errorf("manager already initialized")
+	}
+
+	mgr, err := NewManager(cfg)
+	if err != nil {
+		return fmt.Errorf("failed to create manager: %w", err)
+	}
+
+	instance = mgr
+	return nil
+}
+
+// GetInstance returns the singleton instance of the database manager.
+// Returns an error if SetupManager has not been called yet.
+func GetInstance() (Manager, error) {
+	instanceMu.RLock()
+	defer instanceMu.RUnlock()
+
+	if instance == nil {
+		return nil, fmt.Errorf("manager not initialized: call SetupManager first")
+	}
+
+	return instance, nil
+}
+
+// ResetInstance resets the singleton instance (primarily for testing purposes).
+// WARNING: This should only be used in tests. Calling this in production code
+// while the manager is in use can lead to undefined behavior.
+func ResetInstance() {
+	instanceMu.Lock()
+	defer instanceMu.Unlock()
+
+	if instance != nil {
+		_ = instance.Close()
+	}
+	instance = nil
+}
+
 // NewManager creates a new database connection manager
 func NewManager(cfg ManagerConfig) (Manager, error) {
 	// Apply defaults and validate configuration