knowfoolery/backend/shared/valueobjects/player_name.go

package valueobjects

import (
	"regexp"
	"strings"

	"knowfoolery/backend/shared/errors"
	"knowfoolery/backend/shared/types"
)

// PlayerName represents a validated player name value object
type PlayerName struct {
	value string
}

// NewPlayerName creates a new PlayerName after validation
func NewPlayerName(name string) (*PlayerName, error) {
	if err := validatePlayerName(name); err != nil {
		return nil, err
	}

	normalized := normalizePlayerName(name)
	return &PlayerName{value: normalized}, nil
}

// Value returns the underlying string value
func (p *PlayerName) Value() string {
	return p.value
}

// String returns the string representation
func (p *PlayerName) String() string {
	return p.value
}

// Equals checks if two PlayerName values are equal
func (p *PlayerName) Equals(other *PlayerName) bool {
	if other == nil {
		return false
	}
	return p.value == other.value
}

// IsEmpty checks if the player name is empty
func (p *PlayerName) IsEmpty() bool {
	return p.value == ""
}

// Length returns the length of the player name
func (p *PlayerName) Length() int {
	return len(p.value)
}

// validatePlayerName validates a player name according to business rules
func validatePlayerName(name string) error {
	// Check if empty
	if strings.TrimSpace(name) == "" {
		return errors.ErrInvalidPlayerName(name, "name cannot be empty")
	}

	// Check length constraints
	trimmed := strings.TrimSpace(name)
	if len(trimmed) < types.MinPlayerNameLength {
		return errors.ErrInvalidPlayerName(name,
			"name must be at least 2 characters long")
	}

	if len(trimmed) > types.MaxPlayerNameLength {
		return errors.ErrInvalidPlayerName(name,
			"name cannot exceed 50 characters")
	}

	// Check for valid characters (alphanumeric + spaces)
	validChars := regexp.MustCompile(`^[a-zA-Z0-9\s]+$`)
	if !validChars.MatchString(trimmed) {
		return errors.ErrInvalidPlayerName(name,
			"name can only contain letters, numbers, and spaces")
	}

	// Check for excessive consecutive spaces
	multipleSpaces := regexp.MustCompile(`\s{2,}`)
	if multipleSpaces.MatchString(trimmed) {
		return errors.ErrInvalidPlayerName(name,
			"name cannot contain multiple consecutive spaces")
	}

	// Check that name doesn't start or end with space (after trimming this shouldn't happen, but being explicit)
	if strings.HasPrefix(trimmed, " ") || strings.HasSuffix(trimmed, " ") {
		return errors.ErrInvalidPlayerName(name,
			"name cannot start or end with spaces")
	}

	// Check for reserved/inappropriate names (can be extended)
	if isReservedName(trimmed) {
		return errors.ErrInvalidPlayerName(name,
			"name is reserved and cannot be used")
	}

	return nil
}

// normalizePlayerName normalizes a player name (trim spaces, handle capitalization, etc.)
func normalizePlayerName(name string) string {
	// Trim leading and trailing spaces
	normalized := strings.TrimSpace(name)

	// Replace multiple spaces with single space
	multipleSpaces := regexp.MustCompile(`\s+`)
	normalized = multipleSpaces.ReplaceAllString(normalized, " ")

	// For consistency, we could apply title case, but let's preserve user's capitalization choice
	// normalized = strings.Title(strings.ToLower(normalized))

	return normalized
}

// isReservedName checks if a name is in the reserved names list
func isReservedName(name string) bool {
	// Convert to lowercase for case-insensitive comparison
	lowerName := strings.ToLower(name)

	reservedNames := []string{
		"admin",
		"administrator",
		"moderator",
		"system",
		"null",
		"undefined",
		"anonymous",
		"guest",
		"user",
		"player",
		"test",
		"bot",
		"api",
		"root",
		"support",
		// Add more reserved names as needed
	}

	for _, reserved := range reservedNames {
		if lowerName == reserved {
			return true
		}
	}

	return false
}

// PlayerNameFromString creates a PlayerName from a string without validation
// This is used when loading from persistence where validation already occurred
func PlayerNameFromString(value string) *PlayerName {
	return &PlayerName{value: value}
}

// MustCreatePlayerName creates a PlayerName and panics if validation fails
// Only use when you're certain the name is valid (e.g., in tests)
func MustCreatePlayerName(name string) *PlayerName {
	playerName, err := NewPlayerName(name)
	if err != nil {
		panic(err)
	}
	return playerName
}