Discounts applied per line item price instead of sum

README.md

@@ -24,10 +24,12 @@ Unlike other tax regimes, Italy requires simplified invoices to include the cust
 You can find copies of the Italian FatturaPA schema in the [schemas folder](./schema).
 
 Key websites:
-- [FatturaPA & SDI service documentation page on  on Italy's tax authority's website](https://www.agenziaentrate.gov.it/portale/web/guest/fatturazione-elettronica-e-dati-fatture-transfrontaliere-new/)
+
+- [FatturaPA & SDI service documentation page on on Italy's tax authority's website](https://www.agenziaentrate.gov.it/portale/web/guest/fatturazione-elettronica-e-dati-fatture-transfrontaliere-new/)
 - [FatturaPA documentation page on FatturaPA's dedicated website](https://www.fatturapa.gov.it/en/norme-e-regole/documentazione-fattura-elettronica/formato-fatturapa/)
 
 Useful files:
+
 - [Ordinary Schema V1.2.1 Spec Table View (EN)](https://www.fatturapa.gov.it/export/documenti/fatturapa/v1.2.1/Table-view-B2B-Ordinary-invoice.pdf) - by far the most comprehensible spec doc. Since the difference between 1.2.2 and 1.2.1 is minimal, this is perfectly usable.
 - [Ordinary Schema V1.2.2 PDF (IT)](https://www.fatturapa.gov.it/export/documenti/Specifiche_tecniche_del_formato_FatturaPA_v1.3.1.pdf) - most up-to-date but difficult
 - [XSD V1.2.2](https://www.fatturapa.gov.it/export/documenti/fatturapa/v1.2.2/Schema_del_file_xml_FatturaPA_v1.2.2.xsd)
@@ -154,13 +156,3 @@ cat input.json > ./gobl.fatturapa output.xml
 ## Notes
 
 - In all cases Go structures have been written using the same naming from the XML style document. This means names are not repeated in tags and generally makes it a bit easier to map the XML output to the internal structures.
-
-## Integration Tests
-
-There are some integration and XML generation tests available in the `/test` path. to generate the FatturaPA XML documents from the GOBL sources, use the digital certificates that are available in the `/test/certificates` path:
-
-```
-mage -v TestConversion
-```
-
-Sample data sources are contained in the `/test/data` directory. JSON (for tests) documents are stored in the Git repository, but the XML must be generated using the above commands.

body.go

@@ -57,9 +57,9 @@ type datiBollo struct {
 // scontoMaggiorazione contains data about price adjustments like discounts and
 // charges.
 type scontoMaggiorazione struct {
-	Tipo        string
-	Percentuale string
-	Importo     string
+	Tipo        string `xml:"Tipo"`
+	Percentuale string `xml:"Percentuale,omitempty"`
+	Importo     string `xml:"Importo,omitempty"`
 }
 
 func newFatturaElettronicaBody(inv *bill.Invoice) (*fatturaElettronicaBody, error) {

helpers.go

@@ -4,12 +4,18 @@ import "github.com/invopop/gobl/num"
 
 func formatPercentage(p *num.Percentage) string {
 	if p == nil {
-		return num.MakePercentage(0, 4).StringWithoutSymbol()
+		return ""
 	}
-
 	return p.Rescale(4).StringWithoutSymbol()
 }
 
+func formatPercentageWithZero(p *num.Percentage) string {
+	if p == nil {
+		p = num.NewPercentage(0, 4)
+	}
+	return formatPercentage(p)
+}
+
 func formatAmount(a *num.Amount) string {
 	if a == nil {
 		return ""

items.go

@@ -17,14 +17,14 @@ type datiBeniServizi struct {
 
 // dettaglioLinee contains line data such as description, quantity, price, etc.
 type dettaglioLinee struct {
-	NumeroLinea         string
-	Descrizione         string
-	Quantita            string
-	PrezzoUnitario      string
-	ScontoMaggiorazione []*scontoMaggiorazione `xml:",omitempty"`
-	PrezzoTotale        string
-	AliquotaIVA         string
-	Natura              string `xml:",omitempty"`
+	NumeroLinea         string                 `xml:"NumeroLinea"`
+	Descrizione         string                 `xml:"Descrizione"`
+	Quantita            string                 `xml:"Quantita"`
+	PrezzoUnitario      string                 `xml:"PrezzoUnitario"`
+	ScontoMaggiorazione []*scontoMaggiorazione `xml:"ScontoMaggiorazione,omitempty"`
+	PrezzoTotale        string                 `xml:"PrezzoTotale"`
+	AliquotaIVA         string                 `xml:"AliquotaIVA"`
+	Natura              string                 `xml:"Natura,omitempty"`
 }
 
 // datiRiepilogo contains tax summary data such as tax rate, tax amount, etc.
@@ -58,7 +58,7 @@ func generateLineDetails(inv *bill.Invoice) []*dettaglioLinee {
 		if line.Taxes != nil && len(line.Taxes) > 0 {
 			vatTax := line.Taxes.Get(tax.CategoryVAT)
 			if vatTax != nil {
-				d.AliquotaIVA = formatPercentage(vatTax.Percent)
+				d.AliquotaIVA = formatPercentageWithZero(vatTax.Percent)
 				d.Natura = vatTax.Ext[it.ExtKeySDINature].String()
 			}
 		}
@@ -82,7 +82,7 @@ func generateTaxSummary(inv *bill.Invoice) []*datiRiepilogo {
 
 	for _, rateTotal := range vatRateTotals {
 		dr = append(dr, &datiRiepilogo{
-			AliquotaIVA:          formatPercentage(rateTotal.Percent),
+			AliquotaIVA:          formatPercentageWithZero(rateTotal.Percent),
 			Natura:               rateTotal.Ext[it.ExtKeySDINature].String(),
 			ImponibileImporto:    formatAmount(&rateTotal.Base),
 			Imposta:              formatAmount(&rateTotal.Amount),
@@ -94,25 +94,30 @@ func generateTaxSummary(inv *bill.Invoice) []*datiRiepilogo {
 }
 
 func extractLinePriceAdjustments(line *bill.Line) []*scontoMaggiorazione {
-	var scontiMaggiorazioni []*scontoMaggiorazione
+	list := make([]*scontoMaggiorazione, 0)
 
 	for _, discount := range line.Discounts {
-		scontiMaggiorazioni = append(scontiMaggiorazioni, &scontoMaggiorazione{
+		// Unlike most formats, FatturaPA applies the discount to the unit price
+		// instead of the line sum.
+		// Quick ref: https://fex-app.com/FatturaElettronica/FatturaElettronicaBody/DatiBeniServizi/DettaglioLinee/PrezzoTotale
+		a := discount.Amount.Divide(line.Quantity)
+		list = append(list, &scontoMaggiorazione{
 			Tipo:        scontoMaggiorazioneTypeDiscount,
 			Percentuale: formatPercentage(discount.Percent),
-			Importo:     formatAmount(&discount.Amount),
+			Importo:     formatAmount(&a),
 		})
 	}
 
 	for _, charge := range line.Charges {
-		scontiMaggiorazioni = append(scontiMaggiorazioni, &scontoMaggiorazione{
+		a := charge.Amount.Divide(line.Quantity)
+		list = append(list, &scontoMaggiorazione{
 			Tipo:        scontoMaggiorazioneTypeCharge,
 			Percentuale: formatPercentage(charge.Percent),
-			Importo:     formatAmount(&charge.Amount),
+			Importo:     formatAmount(&a),
 		})
 	}
 
-	return scontiMaggiorazioni
+	return list
 }
 
 func findRiferimentoNormativo(rateTotal *tax.RateTotal) string {

items_test.go

@@ -28,7 +28,7 @@ func TestDettaglioLinee(t *testing.T) {
 
 		assert.Equal(t, "SC", sm.Tipo)
 		assert.Equal(t, "10.00", sm.Percentuale)
-		assert.Equal(t, "180.00", sm.Importo)
+		assert.Equal(t, "9.00", sm.Importo)
 
 		dl = doc.FatturaElettronicaBody[0].DatiBeniServizi.DettaglioLinee[1]
 

test/data/invoice-hotel.json

@@ -4,7 +4,7 @@
 		"uuid": "679a2f25-7483-11ec-9722-7ea2cb436ff6",
 		"dig": {
 			"alg": "sha256",
-			"val": "aa6690ff798fe637147f95713634f33e34f8c03b1b5bba1b12150a8665c3fb2a"
+			"val": "4b6ec1bb24bdd707520a89e632279966d887f0a3339dc737c30f69f7664c5345"
 		}
 	},
 	"doc": {
@@ -85,20 +85,26 @@
 			},
 			{
 				"i": 2,
-				"quantity": "1",
+				"quantity": "2",
 				"item": {
 					"name": "Camera Matrimoniale",
 					"price": "125.00"
 				},
-				"sum": "125.00",
+				"sum": "250.00",
+				"discounts": [
+					{
+						"amount": "10.00",
+						"reason": "Sconto"
+					}
+				],
 				"taxes": [
 					{
 						"cat": "VAT",
 						"rate": "intermediate",
 						"percent": "10.0%"
 					}
 				],
-				"total": "125.00"
+				"total": "240.00"
 			}
 		],
 		"payment": {
@@ -112,9 +118,9 @@
 			]
 		},
 		"totals": {
-			"sum": "126.00",
-			"tax_included": "11.36",
-			"total": "114.64",
+			"sum": "241.00",
+			"tax_included": "21.82",
+			"total": "219.18",
 			"taxes": {
 				"categories": [
 					{
@@ -130,21 +136,21 @@
 							},
 							{
 								"key": "intermediate",
-								"base": "113.64",
+								"base": "218.18",
 								"percent": "10.0%",
-								"amount": "11.36"
+								"amount": "21.82"
 							}
 						],
-						"amount": "11.36"
+						"amount": "21.82"
 					}
 				],
-				"sum": "11.36"
+				"sum": "21.82"
 			},
-			"tax": "11.36",
-			"total_with_tax": "126.00",
-			"payable": "126.00",
+			"tax": "21.82",
+			"total_with_tax": "241.00",
+			"payable": "241.00",
 			"advance": "29.00",
-			"due": "97.00"
+			"due": "212.00"
 		}
 	}
 }

test/data/out/invoice-hotel.xml

@@ -62,7 +62,7 @@
 				<Divisa>EUR</Divisa>
 				<Data>2023-05-21</Data>
 				<Numero>SAMPLE-002</Numero>
-				<ImportoTotaleDocumento>126.00</ImportoTotaleDocumento>
+				<ImportoTotaleDocumento>241.00</ImportoTotaleDocumento>
 			</DatiGeneraliDocumento>
 		</DatiGenerali>
 		<DatiBeniServizi>
@@ -78,9 +78,13 @@
 			<DettaglioLinee>
 				<NumeroLinea>2</NumeroLinea>
 				<Descrizione>Camera Matrimoniale</Descrizione>
-				<Quantita>1.00</Quantita>
+				<Quantita>2.00</Quantita>
 				<PrezzoUnitario>113.6364</PrezzoUnitario>
-				<PrezzoTotale>113.6364</PrezzoTotale>
+				<ScontoMaggiorazione>
+					<Tipo>SC</Tipo>
+					<Importo>4.5455</Importo>
+				</ScontoMaggiorazione>
+				<PrezzoTotale>218.1819</PrezzoTotale>
 				<AliquotaIVA>10.00</AliquotaIVA>
 			</DettaglioLinee>
 			<DatiRiepilogo>
@@ -92,8 +96,8 @@
 			</DatiRiepilogo>
 			<DatiRiepilogo>
 				<AliquotaIVA>10.00</AliquotaIVA>
-				<ImponibileImporto>113.64</ImponibileImporto>
-				<Imposta>11.36</Imposta>
+				<ImponibileImporto>218.18</ImponibileImporto>
+				<Imposta>21.82</Imposta>
 			</DatiRiepilogo>
 		</DatiBeniServizi>
 	</FatturaElettronicaBody>
@@ -106,7 +110,7 @@
 					<ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"></ds:Transform>
 				</ds:Transforms>
 				<ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha512"></ds:DigestMethod>
-				<ds:DigestValue>jYM7kYt27X2bFcXWHZD/pG60gB8fJoJB7rk1U8aOL+9iPydC3Y4Cp3NhBnN/LBpsV9z6cyOkXwGxFJ9BkmVxTQ==</ds:DigestValue>
+				<ds:DigestValue>4KAycPCYtM1f6vffnVi5gWc6nFXhyM2gMCRF61WzyF8/jWna05ffdB89Fz1bMn8ijwrJrJDA7iM3sFWBmMgY6g==</ds:DigestValue>
 			</ds:Reference>
 			<ds:Reference URI="#Certificate-679a2f25-7483-11ec-9722-7ea2cb436ff6">
 				<ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha512"></ds:DigestMethod>
@@ -117,7 +121,7 @@
 				<ds:DigestValue>7Tj/Vr2iDe5KuUvZfrT8ntgjkAtz6zIeztpC/liVkbigGbZLGFHcMpSsVtsRc+WIqqwsB7AwFVjqjSIKIDI3uw==</ds:DigestValue>
 			</ds:Reference>
 		</ds:SignedInfo>
-		<ds:SignatureValue Id="Signature-679a2f25-7483-11ec-9722-7ea2cb436ff6-SignatureValue">SEsDrtqY+j1efLLDlmmOdpVRA1LqFp2a1uigdfpUmeHB+YpGEQrmrImXqoxcw4sLyKYFDg81PptRg1lkAmA0+JaRw0RdX2FofnuUe72yzZiHvUcMTg9WjiEUrkrMJ2i6DDKpFC3ewCb6UqA6NQmhBUSKwq8MQ9AhQdgfC5M/yA9diAgT8Z9ntMckryFKH5U27LNXD/06kVvulyOxsA4cRRPevk4jxu55v/Oeu5C6MMy5ALgKLuJqIto6G67U1tYgco4Mpg4QIZ/5siajMrMrv0ohu8sLnD2FWQTuI8ngaveULpmPg9TSQeBShuMB+i84hSWZbLwt9H9svISRQNnY0w==</ds:SignatureValue>
+		<ds:SignatureValue Id="Signature-679a2f25-7483-11ec-9722-7ea2cb436ff6-SignatureValue">RewHnpuyoODyss60TEGSUPnYl9F4hpP7zPJkSenU8Sf2m1I53DD7shn+ioYVssu4pDtKvGE/EPaggktb9F14ov7kc+oPVAoX9vtho+yQelUtHFxFVRq1qgHcath9q1H2Iekm14HiK6Xm7ZUqQlxJn4LDtVU35eVfIeRGGu2j1vxdKdXNxQMZSd4wO2/7Xk5FuKNoHPYchkQUI+udWpW2SasxxXHvT1QFfLsBjHbIH735GhDw2f+rR/0GHolxFM/SSrCJzuCcBeGUAY9bDMCCQUWFMFf/UZnaWNPJnpfrQWbo2ja90JLfClofRY5nYkwB2HPhpKppu/b/gg3GYIMxFw==</ds:SignatureValue>
 		<ds:KeyInfo Id="Certificate-679a2f25-7483-11ec-9722-7ea2cb436ff6">
 			<ds:X509Data>
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