import type { PackageConfigStatus } from "@/types/Package";
import type { FundOperationType, FundRecordStatus } from "@/types/SalesOrder";
import { formatCentsAmount } from "@/utils/money";

/** 生成套餐业务幂等请求号。每次新操作必须重新生成。 */
export function createPackageRequestNo(): string {
	return window.crypto.randomUUID();
}

/** 将分转换为金额展示文本，不用浮点数做金额格式化。 */
export function formatPackageAmount(cents?: number | null): string {
	return formatCentsAmount(cents);
}

/** 将分转换为金额输入框文本。 */
export function formatPackageAmountInput(cents?: number | null): string {
	if (cents === undefined || cents === null) {
		return "";
	}
	const negative = cents < 0;
	const absolute = Math.abs(Math.trunc(cents));
	return `${negative ? "-" : ""}${Math.floor(absolute / 100)}.${String(absolute % 100).padStart(2, "0")}`;
}

/** 将用户输入的元金额精确转换为后端要求的分。 */
export function parsePackageAmount(value: string): number | undefined {
	const text = value.trim();
	if (!/^\d+(?:\.\d{1,2})?$/.test(text)) {
		return undefined;
	}
	const [yuanText, fenText = ""] = text.split(".");
	const cents = BigInt(yuanText) * 100n + BigInt(fenText.padEnd(2, "0") || "0");
	const result = Number(cents);
	return Number.isSafeInteger(result) ? result : undefined;
}

/** 规范化最多三位小数的非负定点数量。 */
export function normalizePackageQuantity(value: number | string): string | undefined {
	const text = String(value).trim();
	if (!/^\d+(?:\.\d{1,3})?$/.test(text)) {
		return undefined;
	}
	const [integerText, fractionText = ""] = text.split(".");
	const integer = integerText.replace(/^0+(?=\d)/, "") || "0";
	const fraction = fractionText.replace(/0+$/, "");
	return fraction ? `${integer}.${fraction}` : integer;
}

/** 使用 BigInt 比较定点数量，避免 JavaScript 二进制浮点误差。 */
export function comparePackageQuantity(left: number | string, right: number | string): number {
	const leftParts = toQuantityParts(left);
	const rightParts = toQuantityParts(right);
	if (!leftParts || !rightParts) {
		return 0;
	}
	const scale = Math.max(leftParts.scale, rightParts.scale);
	const leftValue = leftParts.value * 10n ** BigInt(scale - leftParts.scale);
	const rightValue = rightParts.value * 10n ** BigInt(scale - rightParts.scale);
	return leftValue < rightValue ? -1 : rightValue < leftValue ? 1 : 0;
}

/** 将当前单位数量精确换算为最多三位小数的基础单位数量。 */
export function toPackageBaseQuantity(quantity: number | string, baseQuantityPerUnit: number | string): string | undefined {
	const quantityParts = toDecimalParts(quantity, 3);
	const unitParts = toDecimalParts(baseQuantityPerUnit, 6);
	if (!quantityParts || !unitParts) {
		return undefined;
	}
	return formatDecimal(quantityParts.value * unitParts.value, quantityParts.scale + unitParts.scale, 3);
}

/** 将数量从一个单位精确换算到另一个单位，结果最多保留三位小数。 */
export function convertPackageQuantity(quantity: number | string, fromBaseQuantityPerUnit: number | string, toBaseQuantityPerUnit: number | string): string | undefined {
	const quantityParts = toDecimalParts(quantity, 3);
	const fromParts = toDecimalParts(fromBaseQuantityPerUnit, 6);
	const toParts = toDecimalParts(toBaseQuantityPerUnit, 6);
	if (!quantityParts || !fromParts || !toParts || toParts.value === 0n) {
		return undefined;
	}
	const numerator = quantityParts.value * fromParts.value * 10n ** BigInt(toParts.scale + 3);
	const denominator = 10n ** BigInt(quantityParts.scale + fromParts.scale) * toParts.value;
	if (numerator % denominator !== 0n) {
		return undefined;
	}
	return formatDecimal(numerator / denominator, 3, 3);
}

/** 精确相加两个最多三位小数的数量。 */
export function addPackageQuantity(left: number | string, right: number | string): string | undefined {
	const leftParts = toQuantityParts(left);
	const rightParts = toQuantityParts(right);
	if (!leftParts || !rightParts) {
		return undefined;
	}
	const scale = Math.max(leftParts.scale, rightParts.scale);
	const value = leftParts.value * 10n ** BigInt(scale - leftParts.scale) + rightParts.value * 10n ** BigInt(scale - rightParts.scale);
	return formatDecimal(value, scale, 3);
}

export function getPackageQuantityText(value?: number | string | null): string {
	if (value === undefined || value === null || value === "") {
		return "0";
	}
	return normalizePackageQuantity(value) || "0";
}

export function getPackageConfigStatusText(status?: PackageConfigStatus): string {
	return ({ DRAFT: "草稿", ACTIVE: "启用", INACTIVE: "停用" } as Record<string, string>)[status || ""] || "未知";
}

export function getFundOperationText(type?: FundOperationType): string {
	return ({ RECEIVE: "线下收款", REFUND: "退款", CONFIRM_NO_REFUND: "确认无需退款", REVOKE: "资金冲正" } as Record<string, string>)[type || ""] || "未知";
}

export function getFundStatusText(status?: FundRecordStatus): string {
	return ({ PENDING: "待核销", VERIFIED: "已核销", REJECTED: "已拒绝", CANCELLED: "已撤销" } as Record<string, string>)[status || ""] || "未知";
}

function toQuantityParts(value: number | string): { value: bigint; scale: number } | undefined {
	return toDecimalParts(value, 3);
}

function toDecimalParts(value: number | string, maxScale: number): { value: bigint; scale: number } | undefined {
	const text = String(value).trim();
	if (!new RegExp(`^\\d+(?:\\.\\d{1,${maxScale}})?$`).test(text)) {
		return undefined;
	}
	const [integerText, fractionText = ""] = text.split(".");
	return {
		value: BigInt(`${integerText}${fractionText}`),
		scale: fractionText.length
	};
}

function formatDecimal(value: bigint, scale: number, maxScale: number): string | undefined {
	while (maxScale < scale && value % 10n === 0n) {
		value /= 10n;
		scale--;
	}
	if (maxScale < scale) {
		return undefined;
	}
	const text = value.toString().padStart(scale + 1, "0");
	return normalizePackageQuantity(scale ? `${text.slice(0, -scale)}.${text.slice(-scale)}` : text);
}