add tickets api

internal/services/ticket_service/service.go

@@ -0,0 +1,88 @@
+package ticket_service
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"net/url"
+	"strings"
+
+	"evening_detective_server/internal/repos/tickets_repo"
+)
+
+const maxTicketsPerRequest = 100
+
+var (
+	ErrInvalidTicketCount = errors.New("количество билетов должно быть от 1 до 100")
+	ErrInvalidBaseURL     = errors.New("необходимо настроить APP_BASE_URL — публичный адрес приложения")
+)
+
+type Ticket struct {
+	ID  int
+	URL string
+}
+
+type Service struct {
+	repo       *tickets_repo.Repo
+	appBaseURL string
+}
+
+func New(repo *tickets_repo.Repo, appBaseURL string) *Service {
+	return &Service{repo: repo, appBaseURL: appBaseURL}
+}
+
+func (s *Service) Issue(ctx context.Context, gameID, count int) ([]*Ticket, error) {
+	if count < 1 || count > maxTicketsPerRequest {
+		return nil, ErrInvalidTicketCount
+	}
+
+	base, err := parseBaseURL(s.appBaseURL)
+	if err != nil {
+		return nil, err
+	}
+
+	hashes := make([][]byte, count)
+	tokens := make([]string, count)
+	for i := range count {
+		token, err := newToken()
+		if err != nil {
+			return nil, err
+		}
+		hash := sha256.Sum256([]byte(token))
+		tokens[i] = token
+		hashes[i] = hash[:]
+	}
+
+	ids, err := s.repo.CreateBatch(ctx, gameID, hashes)
+	if err != nil {
+		return nil, err
+	}
+
+	tickets := make([]*Ticket, count)
+	for i, id := range ids {
+		link := *base
+		link.Path = strings.TrimRight(base.Path, "/") + "/tickets/" + tokens[i]
+		link.RawPath = ""
+		tickets[i] = &Ticket{ID: id, URL: link.String()}
+	}
+	return tickets, nil
+}
+
+func newToken() (string, error) {
+	data := make([]byte, 32)
+	if _, err := rand.Read(data); err != nil {
+		return "", fmt.Errorf("generate ticket token: %w", err)
+	}
+	return base64.RawURLEncoding.EncodeToString(data), nil
+}
+
+func parseBaseURL(value string) (*url.URL, error) {
+	base, err := url.Parse(strings.TrimSpace(value))
+	if err != nil || base.Host == "" || (base.Scheme != "http" && base.Scheme != "https") || base.User != nil || base.RawQuery != "" || base.Fragment != "" {
+		return nil, ErrInvalidBaseURL
+	}
+	return base, nil
+}