Enhance tender estimated value resolution and add unit tests

- Updated the `ResolvedEstimatedValueAndCurrency` method to aggregate procurement lot values when the tender-level estimated value is not set, improving accuracy in value retrieval.
- Introduced the `AggregateProcurementLotEstimatedValue` function to sum estimated values from procurement lots and return the first found currency.
- Modified the `ToResponseWithLanguage` method to utilize the new estimated value resolution logic.
- Added unit tests for the new functionality, ensuring correct behavior for various scenarios in the `entity_test.go` and `budget_test.go` files.

This update improves the handling of estimated values in tenders, enhancing the overall reliability of the tender management system.

ted/model.go

@@ -3,6 +3,7 @@ package ted
 import (
 	"encoding/xml"
 	"fmt"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -337,15 +338,11 @@ func (pin PriorInformationNotice) GetTenderDeadline() string {
 
 // GetBudget returns the estimated contract amount and currency.
 func (pin PriorInformationNotice) GetBudget() (amount string, currency string) {
-	if pin.firstLot() != nil &&
-		pin.firstLot().ProcurementProject != nil &&
-		pin.firstLot().ProcurementProject.RequestedTenderTotal != nil {
-		contractAmount := pin.firstLot().ProcurementProject.RequestedTenderTotal.EstimatedOverallContractAmount
-		return contractAmount.Text, contractAmount.CurrencyID
+	if amount, currency = budgetFromProcurementLots(pin.ProcurementProjectLot); amount != "" {
+		return amount, currency
 	}
 	if pin.ProcurementProject != nil && pin.ProcurementProject.RequestedTenderTotal != nil {
-		a := pin.ProcurementProject.RequestedTenderTotal.EstimatedOverallContractAmount
-		return a.Text, a.CurrencyID
+		return pin.ProcurementProject.RequestedTenderTotal.AmountAndCurrency()
 	}
 	return "", ""
 }
@@ -1551,12 +1548,34 @@ type ProcessJustification struct {
 type RequestedTenderTotal struct {
 	XMLName                        xml.Name     `xml:"RequestedTenderTotal"`
 	EstimatedOverallContractAmount CurrencyText `xml:"EstimatedOverallContractAmount"`
+	TotalAmount                    CurrencyText `xml:"TotalAmount,omitempty"`
+}
+
+// AmountAndCurrency returns the best-effort amount text and currency from RequestedTenderTotal.
+func (r *RequestedTenderTotal) AmountAndCurrency() (amount string, currency string) {
+	if r == nil {
+		return "", ""
+	}
+	if amount, currency = r.EstimatedOverallContractAmount.AmountAndCurrency(); amount != "" {
+		return amount, currency
+	}
+	return r.TotalAmount.AmountAndCurrency()
 }
 
 // CurrencyText represents text with currency attribute
 type CurrencyText struct {
 	CurrencyID string `xml:"currencyID,attr,omitempty"`
 	Text       string `xml:",chardata"`
+	Value      string `xml:"Value,omitempty"`
+}
+
+// AmountAndCurrency returns the amount text and currency id from a CurrencyText node.
+func (c CurrencyText) AmountAndCurrency() (amount string, currency string) {
+	amount = strings.TrimSpace(c.Text)
+	if amount == "" {
+		amount = strings.TrimSpace(c.Value)
+	}
+	return amount, strings.TrimSpace(c.CurrencyID)
 }
 
 // MainCommodityClassification contains main commodity classification
@@ -1972,21 +1991,43 @@ func (cn ContractNotice) GetTenderDeadline() string {
 }
 
 // GetBudget returns the estimated contract amount and currency.
-// Lot-level BT-27 is preferred; procedure-level BT-27 is used when lots omit RequestedTenderTotal.
+// Lot-level BT-27 values are summed when present; procedure-level BT-27 is used when lots omit RequestedTenderTotal.
 func (cn ContractNotice) GetBudget() (amount string, currency string) {
-	if cn.firstLot() != nil &&
-		cn.firstLot().ProcurementProject != nil &&
-		cn.firstLot().ProcurementProject.RequestedTenderTotal != nil {
-		contractAmount := cn.firstLot().ProcurementProject.RequestedTenderTotal.EstimatedOverallContractAmount
-		return contractAmount.Text, contractAmount.CurrencyID
+	if amount, currency = budgetFromProcurementLots(cn.ProcurementProjectLots); amount != "" {
+		return amount, currency
 	}
 	if cn.ProcurementProject != nil && cn.ProcurementProject.RequestedTenderTotal != nil {
-		a := cn.ProcurementProject.RequestedTenderTotal.EstimatedOverallContractAmount
-		return a.Text, a.CurrencyID
+		return cn.ProcurementProject.RequestedTenderTotal.AmountAndCurrency()
 	}
 	return "", ""
 }
 
+func budgetFromProcurementLots(lots []ProcurementProjectLot) (amount string, currency string) {
+	var total float64
+	for i := range lots {
+		pp := lots[i].ProcurementProject
+		if pp == nil || pp.RequestedTenderTotal == nil {
+			continue
+		}
+		lotAmount, lotCurrency := pp.RequestedTenderTotal.AmountAndCurrency()
+		if lotAmount == "" {
+			continue
+		}
+		value, ok := ParseEuropeanAmount(lotAmount)
+		if !ok || value <= 0 {
+			continue
+		}
+		total += value
+		if currency == "" {
+			currency = lotCurrency
+		}
+	}
+	if total <= 0 {
+		return "", ""
+	}
+	return strconv.FormatFloat(total, 'f', -1, 64), currency
+}
+
 // GetDuration returns the contract duration and unit
 func (cn ContractNotice) GetDuration() (duration string, unit string) {
 	if cn.firstLot() != nil &&
@@ -2223,7 +2264,7 @@ func (can ContractAwardNotice) GetMainClassificationDescription() string {
 func (can ContractAwardNotice) GetTotalAwardValue() (amount string, currency string) {
 	noticeResult := can.GetNoticeResult()
 	if noticeResult != nil && noticeResult.TotalAmount != nil {
-		return noticeResult.TotalAmount.Text, noticeResult.TotalAmount.CurrencyID
+		return noticeResult.TotalAmount.AmountAndCurrency()
 	}
 	return "", ""
 }