Display single-letter commodity before quantity

src/db.ts

@@ -169,14 +169,75 @@ export function serialiseAmount(quantity: number, commodity: string): string {
 	return quantityString + ' ' + commodity;
 }
 
+function parseFloatStrict(quantity: string): number {
+	// Parses quantity as a float, throwing error on invalid input
+	if (!/^[0-9]+(\.[0-9]+)?$/.test(quantity)) {
+		throw new DeserialiseAmountError('Invalid quantity: ' + quantity);
+	}
+	return parseFloat(quantity);
+}
+
+export function validateCommodity(commodity: string) {
+	// Validate that the commodity is correctly formed
+	const commodityParts = commodity.split(' ');
+	if (commodityParts.length > 2) {
+		throw new DeserialiseAmountError('Invalid commodity (more spaces than expected): ' + commodity);
+	}
+	if (commodityParts.length === 2) {
+		// Validate that the second part is a cost basis
+		if (commodityParts[1].startsWith('{{') && commodityParts[1].endsWith('}}')) {
+			const costBase = commodityParts[1].substring(2, commodityParts[1].length - 2);
+			parseFloatStrict(costBase);
+		} else if (commodityParts[1].startsWith('{') && commodityParts[1].endsWith('}')) {
+			const costBase = commodityParts[1].substring(1, commodityParts[1].length - 1);
+			parseFloatStrict(costBase);
+		} else {
+			throw new DeserialiseAmountError('Invalid cost base: ' + commodityParts[1]);
+		}
+	}
+}
+
 export function deserialiseAmount(amount: string): { quantity: number, commodity: string } {
 	const factor = Math.pow(10, db.metadata.dps);
 	
+	if (amount.length === 0) {
+		throw new DeserialiseAmountError('Amount cannot be blank');
+	}
+	
+	if (amount.charAt(0) < '0' || amount.charAt(0) > '9') {
+		// Check for single letter commodity
+		if (amount.length === 1) {
+			throw new DeserialiseAmountError('Quantity cannot be blank (expected quantity after commodity symbol ' + amount + ')');
+		}
+		if (amount.charAt(1) < '0' || amount.charAt(1) > '9') {
+			throw new DeserialiseAmountError('Invalid quantity: ' + amount + ' (expected quantity after single-letter commodity symbol ' + amount.charAt(0) + ')');
+		}
+		
+		let quantity, commodity;
+		
+		if (amount.indexOf(' ') < 0) {
+			// No cost base
+			quantity = Math.round(parseFloatStrict(amount.substring(1)) * factor);
+			commodity = amount.charAt(0);
+		} else {
+			// Cost base specified
+			quantity = Math.round(parseFloatStrict(amount.substring(1, amount.indexOf(' '))) * factor);
+			commodity = amount.charAt(0) + amount.substring(amount.indexOf(' '));
+		}
+		
+		if (!Number.isSafeInteger(quantity)) { throw new DeserialiseAmountError('Quantity not representable by safe integer: ' + amount); }
+		validateCommodity(commodity);
+		
+		return {
+			'quantity': quantity,
+			'commodity': commodity
+		};
+	}
+	
 	if (amount.indexOf(' ') < 0) {
 		// Default commodity
-		const quantity = Math.round(parseFloat(amount) * factor)
+		const quantity = Math.round(parseFloatStrict(amount) * factor);
 		
-		if (Number.isNaN(quantity)) { throw new DeserialiseAmountError('Invalid quantity: ' + amount); }
 		if (!Number.isSafeInteger(quantity)) { throw new DeserialiseAmountError('Quantity not representable by safe integer: ' + amount); }
 		
 		return {
@@ -185,15 +246,14 @@ export function deserialiseAmount(amount: string): { quantity: number, commodity
 		};
 	}
 	
-	// FIXME: Parse single letter commodities
-	
+	// Must be multi-letter commodity
 	const quantityStr = amount.substring(0, amount.indexOf(' '));
-	const quantity = Math.round(parseFloat(quantityStr) * factor)
+	const quantity = Math.round(parseFloatStrict(quantityStr) * factor)
 	
-	if (Number.isNaN(quantity)) { throw new DeserialiseAmountError('Invalid quantity: ' + amount); }
 	if (!Number.isSafeInteger(quantity)) { throw new DeserialiseAmountError('Quantity not representable by safe integer: ' + amount); }
 	
 	const commodity = amount.substring(amount.indexOf(' ') + 1);
+	validateCommodity(commodity);
 	
 	return {
 		'quantity': quantity,

src/display.ts

@@ -1,6 +1,6 @@
 /*
 	DrCr: Web-based double-entry bookkeeping framework
-	Copyright (C) 2022–2025  Lee Yingtong Li (RunasSudo)
+	Copyright (C) 2022-2025  Lee Yingtong Li (RunasSudo)
 	
 	This program is free software: you can redistribute it and/or modify
 	it under the terms of the GNU Affero General Public License as published by
@@ -16,7 +16,7 @@
 	along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
-import { db } from './db.ts';
+import { db, validateCommodity } from './db.ts';
 
 export function pp(quantity: number): string {
 	// Pretty print the quantity
@@ -33,8 +33,16 @@ export function pp(quantity: number): string {
 
 export function ppWithCommodity(quantity: number, commodity: string): string {
 	// Pretty print the amount including commodity
-	if (commodity.length === 1) {
-		return commodity + pp(quantity);
+	validateCommodity(commodity);
+	
+	const commodityParts = commodity.split(' ');
+	
+	if (commodityParts[0].length === 1) {
+		if (commodityParts.length === 1) {
+			return commodityParts[0] + pp(quantity);
+		} else {
+			return commodityParts[0] + pp(quantity) + ' ' + commodityParts[1];
+		}
 	} else {
 		return pp(quantity) + ' ' + commodity;
 	}