Initial commit

src/diceRoller/utils/parseDiceUserInput.ts

@@ -0,0 +1,69 @@
+import { Dice } from "../types";
+
+const ALLOWED_DICE_SIDES = new Set(Object.values(Dice));
+
+export function parseDiceUserInput(input: string): DiceParseResult {
+	if (typeof input !== "string" || !input.trim()) {
+		throw new Error("Input must be a non-empty string.");
+	}
+
+	let clean = input.toLowerCase().trim();
+	clean = clean.replace(/\b(roll|dice|die)\b/g, "");
+	clean = clean.replace(/\s+/g, "");
+
+	if (/^\d+$/.test(clean)) {
+		const sides = Number.parseInt(clean, 10);
+		if (!ALLOWED_DICE_SIDES.has(sides)) {
+			throw new Error(
+				`Allowed dice sides are ${[...ALLOWED_DICE_SIDES].join(", ")}. Received: ${sides}`,
+			);
+		}
+		return { dices: [sides], mod: 0 };
+	}
+
+	const tokenRegex = /(\d*d\d+|[+\-]\d+)/g;
+	const tokens = clean.match(tokenRegex);
+
+	if (!tokens) {
+		throw new Error(
+			"Unable to parse any dice or modifiers. Examples: '3d6+5', 'd20-2', '2d8+1d6+4'.",
+		);
+	}
+
+	const dices: number[] = [];
+	let mod = 0;
+
+	for (const token of tokens) {
+		if (token.includes("d")) {
+			const [countPart, sidesPart] = token.split("d");
+
+			let diceCount = countPart ? Number.parseInt(countPart, 10) : 1;
+			if (Number.isNaN(diceCount) || diceCount < 1) {
+				diceCount = 1;
+			}
+
+			const sides = Number.parseInt(sidesPart, 10);
+			if (Number.isNaN(sides) || sides <= 0) {
+				throw new Error(`Invalid number of sides: "${sidesPart}"`);
+			}
+
+			if (!ALLOWED_DICE_SIDES.has(sides)) {
+				throw new Error(
+					`Allowed dice sides are ${[...ALLOWED_DICE_SIDES].join(", ")}. Received: ${sides}`,
+				);
+			}
+
+			for (let i = 0; i < diceCount; i++) {
+				dices.push(sides);
+			}
+		} else {
+			const parsedMod = Number.parseInt(token, 10);
+			if (Number.isNaN(parsedMod)) {
+				throw new Error(`Invalid modifier: "${token}"`);
+			}
+			mod += parsedMod;
+		}
+	}
+
+	return { dices, mod };
+}