Add player profiles and community settings

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/internal/domain/model.go

@@ -4,9 +4,11 @@ import (
 	"errors"
 	"fmt"
 	"math/rand"
+	"regexp"
 	"slices"
 	"strings"
 	"time"
+	"unicode/utf8"
 )
 
 var (
@@ -63,6 +65,7 @@ type Player struct {
 	ID                 string    `json:"id"`
 	AccountID          string    `json:"accountId"`
 	DisplayName        string    `json:"displayName"`
+	BattleTag          string    `json:"battleTag"`
 	Ratings            Ratings   `json:"ratings"`
 	PreferredRoles     []Role    `json:"preferredRoles"`
 	PreferredPlayerIDs []string  `json:"preferredPlayerIds"`
@@ -71,6 +74,21 @@ type Player struct {
 	UpdatedAt          time.Time `json:"updatedAt"`
 }
 
+var battleTagPattern = regexp.MustCompile(`^[^#\s]{2,20}#[0-9]{3,12}$`)
+
+func (p *Player) ValidateIdentity() error {
+	p.DisplayName = strings.TrimSpace(p.DisplayName)
+	length := utf8.RuneCountInString(p.DisplayName)
+	if length < 2 || length > 32 {
+		return fmt.Errorf("%w: display name must contain 2 to 32 characters", ErrInvalid)
+	}
+	p.BattleTag = strings.TrimSpace(p.BattleTag)
+	if p.BattleTag != "" && !battleTagPattern.MatchString(p.BattleTag) {
+		return fmt.Errorf("%w: BattleTag must have the form Name#digits", ErrInvalid)
+	}
+	return nil
+}
+
 func (p Player) ValidatePreferences() error {
 	if len(p.PreferredPlayerIDs) > 3 {
 		return fmt.Errorf("%w: at most three preferred teammates are allowed", ErrInvalid)