initiative/packages/domain/src/auto-number.ts

/**
 * Resolves a creature name against existing combatant names,
 * handling auto-numbering for duplicates.
 *
 * - No conflict: returns name as-is, no renames.
 * - First conflict (one existing match): renames existing to "Name 1",
 *   new becomes "Name 2".
 * - Subsequent conflicts: new gets next number suffix.
 */
export function resolveCreatureName(
	baseName: string,
	existingNames: readonly string[],
): {
	newName: string;
	renames: ReadonlyArray<{ from: string; to: string }>;
} {
	// Find exact matches and numbered matches (e.g., "Goblin 1", "Goblin 2")
	const exactMatches: number[] = [];
	let maxNumber = 0;

	for (let i = 0; i < existingNames.length; i++) {
		const name = existingNames[i];
		if (name === baseName) {
			exactMatches.push(i);
		} else {
			const match = new RegExp(
				String.raw`^${escapeRegExp(baseName)} (\d+)$`,
			).exec(name);
			// biome-ignore lint/nursery/noUnnecessaryConditions: RegExp.exec() returns null on no match — false positive
			if (match) {
				const num = Number.parseInt(match[1], 10);
				if (num > maxNumber) maxNumber = num;
			}
		}
	}

	// No conflict at all
	if (exactMatches.length === 0 && maxNumber === 0) {
		return { newName: baseName, renames: [] };
	}

	// First conflict: one exact match, no numbered ones yet
	if (exactMatches.length === 1 && maxNumber === 0) {
		return {
			newName: `${baseName} 2`,
			renames: [{ from: baseName, to: `${baseName} 1` }],
		};
	}

	// Subsequent conflicts: append next number
	const nextNumber = Math.max(maxNumber, exactMatches.length) + 1;
	return { newName: `${baseName} ${nextNumber}`, renames: [] };
}

function escapeRegExp(s: string): string {
	return s.replaceAll(/[.*+?^${}()|[\]\\]/g, String.raw`\$&`);
}