package geospatial

// Config holds all geospatial calculation configuration
type Config struct {
	// Earth model parameters
	EarthRadiusKm     float64 `json:"earth_radius_km"`     // Default: 6371.0 km
	EarthRadiusMeters float64 `json:"earth_radius_meters"` // Default: 6371000.0 m

	// Distance calculation preferences
	DefaultDistanceMethod string `json:"default_distance_method"` // "haversine" or "vincenty"
	UseEllipsoidalModel   bool   `json:"use_ellipsoidal_model"`   // Use WGS84 ellipsoid for Vincenty

	// Coordinate system defaults
	DefaultCoordinateSystem CoordinateSystem `json:"default_coordinate_system"` // Default: WGS84

	// Validation parameters
	MaxLatitude  float64 `json:"max_latitude"`  // Default: 90.0
	MinLatitude  float64 `json:"min_latitude"`  // Default: -90.0
	MaxLongitude float64 `json:"max_longitude"` // Default: 180.0
	MinLongitude float64 `json:"min_longitude"` // Default: -180.0

	// Route calculation parameters
	AverageSpeedKmh float64 `json:"average_speed_kmh"` // Default: 50 km/h for urban areas

	// Clustering defaults
	DefaultClusteringAlgorithm ClusteringAlgorithm `json:"default_clustering_algorithm"`
	DefaultClusteringRadiusKm  float64             `json:"default_clustering_radius_km"`
	DefaultMinPointsPerCluster int                 `json:"default_min_points_per_cluster"`

	// PostGIS integration
	PostGISEnabled bool `json:"postgis_enabled"`
	PostGISSRID    int  `json:"postgis_srid"` // Default: 4326 (WGS84)

	// Performance tuning
	MaxDistanceMatrixSize int `json:"max_distance_matrix_size"` // Prevent excessive memory usage
}

// DefaultConfig returns the default configuration
func DefaultConfig() *Config {
	return &Config{
		EarthRadiusKm:              6371.0,
		EarthRadiusMeters:          6371000.0,
		DefaultDistanceMethod:      "haversine",
		UseEllipsoidalModel:        false, // Use spherical model by default for speed
		DefaultCoordinateSystem:    WGS84,
		MaxLatitude:                90.0,
		MinLatitude:                -90.0,
		MaxLongitude:               180.0,
		MinLongitude:               -180.0,
		AverageSpeedKmh:            50.0, // Urban average speed
		DefaultClusteringAlgorithm: AlgorithmDBSCAN,
		DefaultClusteringRadiusKm:  5.0, // 5km default radius
		DefaultMinPointsPerCluster: 3,
		PostGISEnabled:             false, // Enable when PostGIS is available
		PostGISSRID:                4326,
		MaxDistanceMatrixSize:      1000, // Prevent matrices larger than 1000x1000
	}
}

// Validate validates the configuration
func (c *Config) Validate() error {
	if c.EarthRadiusKm <= 0 {
		return ErrInvalidEarthRadius
	}
	if c.MaxLatitude <= c.MinLatitude {
		return ErrInvalidLatitudeRange
	}
	if c.MaxLongitude <= c.MinLongitude {
		return ErrInvalidLongitudeRange
	}
	if c.DefaultDistanceMethod != "haversine" && c.DefaultDistanceMethod != "vincenty" {
		return ErrInvalidDistanceMethod
	}
	return nil
}