/**
 * 将整数部分按每 4 位分组，适用于中文金额展示。
 * 例如：999999.99 -> 99,9999.99。
 */
export function formatWanInteger(value: number | string): string {
	const text = String(value).trim();
	const negative = text.startsWith("-");
	const integerText = (negative || text.startsWith("+")) ? text.slice(1) : text;
	const normalizedText = integerText.replace(/^0+(?=\d)/, "") || "0";
	const groupedText = normalizedText.replace(/\B(?=(\d{4})+(?!\d))/g, ",");
	return `${negative ? "-" : ""}${groupedText}`;
}

/** 将整数分转换为带两位小数的金额展示文本。 */
export function formatCentsAmount(cents?: number | null): string {
	if (cents === undefined || cents === null || !Number.isFinite(cents)) {
		return "未设置";
	}

	const negative = cents < 0;
	const absolute = Math.abs(Math.trunc(cents));
	const yuan = Math.floor(absolute / 100);
	const fen = String(absolute % 100).padStart(2, "0");
	return `${negative ? "-" : ""}${formatWanInteger(yuan)}.${fen}`;
}

/** 将元金额转换为按每 4 位分组的展示文本，最多保留两位小数。 */
export function formatYuanAmount(value?: number | null): string {
	if (value === undefined || value === null || !Number.isFinite(value)) {
		return "0";
	}

	const [integerText, fractionText = ""] = value.toFixed(2).split(".");
	const normalizedFractionText = fractionText.replace(/0+$/, "");
	return `${formatWanInteger(integerText)}${normalizedFractionText ? `.${normalizedFractionText}` : ""}`;
}