feat: backend service

backend/internal/user/limit.go

@@ -0,0 +1,77 @@
+package user
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+// ActiveLimit is the read-side projection of a row in `limit_active`
+// joined with the audit columns from the underlying `limit_records`
+// row. It mirrors the OpenAPI `ActiveLimit` schema.
+type ActiveLimit struct {
+	LimitCode string
+	Value int32
+	ReasonCode string
+	Actor ActorRef
+	AppliedAt time.Time
+	ExpiresAt *time.Time
+}
+
+// ApplyLimitInput carries the admin-supplied parameters of
+// `POST /api/v1/admin/users/{user_id}/limits`.
+type ApplyLimitInput struct {
+	UserID uuid.UUID
+	LimitCode string
+	Value int32
+	ReasonCode string
+	Actor ActorRef
+	ExpiresAt *time.Time
+}
+
+// ApplyLimit persists a fresh `limit_records` row and upserts
+// `limit_active` in one transaction. The implementation keeps `limit_code` as an
+// open string; The implementation may add a CHECK constraint once the closed
+// set is locked in.
+func (s *Service) ApplyLimit(ctx context.Context, input ApplyLimitInput) (Account, error) {
+	if input.UserID == uuid.Nil {
+		return Account{}, ErrAccountNotFound
+	}
+	if strings.TrimSpace(input.LimitCode) == "" {
+		return Account{}, fmt.Errorf("%w: limit_code must be non-empty", ErrInvalidInput)
+	}
+	if err := input.Actor.Validate(); err != nil {
+		return Account{}, err
+	}
+	if strings.TrimSpace(input.ReasonCode) == "" {
+		return Account{}, fmt.Errorf("%w: reason_code must be non-empty", ErrInvalidInput)
+	}
+
+	now := s.deps.Now().UTC()
+	expiresAt := input.ExpiresAt
+	if expiresAt != nil {
+		t := expiresAt.UTC()
+		expiresAt = &t
+	}
+
+	if err := s.deps.Store.ApplyLimitTx(ctx, limitInsert{
+		UserID: input.UserID,
+		LimitCode: input.LimitCode,
+		Value: input.Value,
+		ReasonCode: input.ReasonCode,
+		ActorType: input.Actor.Type,
+		ActorID: input.Actor.ID,
+		AppliedAt: now,
+		ExpiresAt: expiresAt,
+	}); err != nil {
+		if errors.Is(err, ErrAccountNotFound) {
+			return Account{}, err
+		}
+		return Account{}, fmt.Errorf("user apply limit: %w", err)
+	}
+	return s.GetAccount(ctx, input.UserID)
+}