Set up default currency accounts automatically (#72)

backend/product/providers/sendico/accounts.go

@@ -0,0 +1,87 @@
+package sendico
+
+import (
+	"context"
+	"net/http"
+
+	"git.sendico.io/tech/sxchnge/product/payments"
+	merrors "git.sendico.io/tech/sxchnge/shared/errors"
+)
+
+func (c *Client) validCustomerAccount(a accountDTO, subject string) bool {
+	return validRef(a.ID) && a.ScopeRef == c.config.OrganizationID && a.Owner == "" &&
+		a.Type == "ACCOUNT_TYPE_ASSET" && a.LedgerRole == "ACCOUNT_ROLE_OPERATING" &&
+		a.Status == "ACCOUNT_STATUS_ACTIVE" && !a.AllowNegative && a.Metadata["sxchnge_subject_ref"] == subject &&
+		(a.Metadata["external_subject_ref"] == "" || a.Metadata["external_subject_ref"] == subject)
+}
+
+// EnsureAccounts also repairs older customers, using provider-enforced
+// organization/subject/currency uniqueness for safe retries after lost responses.
+func (c *Client) EnsureAccounts(ctx context.Context, subject string) error {
+	if !validRef(subject) {
+		return payments.Unavailable
+	}
+	root := "/ledger_accounts/" + c.config.OrganizationID
+	var data accountListDTO
+	if err := c.paymentRequest(ctx, http.MethodGet, root, nil, &data); err != nil {
+		return err
+	}
+	existing := map[string]bool{}
+	reconcile := map[string]bool{}
+	for _, a := range data.Accounts {
+		if a.Metadata["sxchnge_subject_ref"] != subject && a.Metadata["external_subject_ref"] != subject {
+			continue
+		}
+		if !c.validCustomerAccount(a, subject) || existing[a.Currency] {
+			return payments.Unavailable
+		}
+		existing[a.Currency] = true
+		reconcile[a.Currency] = a.Metadata["external_subject_ref"] == subject
+	}
+	missing := []string{}
+	for _, code := range []string{"RUB", "USDT", "USDC"} {
+		if !existing[code] || reconcile[code] {
+			missing = append(missing, code)
+		}
+	}
+	if len(missing) == 0 {
+		return nil
+	}
+	// Older providers can accept the metadata but cannot prevent duplicates.
+	// Require the explicit capability before issuing the first create.
+	if !data.ExternalSubjectAccounts {
+		return payments.Unavailable
+	}
+	var catalog struct {
+		Rows []currencyDTO `json:"currencies"`
+	}
+	if err := c.paymentRequest(ctx, http.MethodGet, "/payments/fx/currencies/"+c.config.OrganizationID, nil, &catalog); err != nil {
+		return err
+	}
+	for _, code := range missing {
+		found := false
+		for _, currency := range catalog.Rows {
+			if currency.Code == code && currency.Scale != nil && *currency.Scale >= 0 && *currency.Scale <= 8 {
+				found = true
+			}
+		}
+		if !found {
+			return merrors.OpaqueWrap(payments.Unavailable, payments.Unsupported, "default currency missing from provider catalog")
+		}
+	}
+	// Replaying a bound create also resumes Sendico's durable wallet/route setup
+	// if a previous response failed after the ledger itself had been committed.
+	for _, code := range missing {
+		var response struct {
+			Account accountDTO `json:"account"`
+		}
+		request := createAccountDTO{Currency: code, Type: "asset", LedgerRole: "operating", Metadata: map[string]string{"external_subject_ref": subject, "sxchnge_subject_ref": subject}}
+		if err := c.paymentRequest(ctx, http.MethodPost, root, request, &response, http.StatusCreated); err != nil {
+			return err
+		}
+		if !c.validCustomerAccount(response.Account, subject) || response.Account.Currency != code || response.Account.Metadata["external_subject_ref"] != subject {
+			return payments.Unavailable
+		}
+	}
+	return nil
+}