export module NumberEx {

	/**
	 * 检测数字是否越界，如果越界给出提示
	 * @param {*number} num 输入数
	 */
	function checkBoundary(num: number) {
		if (_boundaryCheckingState) {
			if (num > Number.MAX_SAFE_INTEGER || num < Number.MIN_SAFE_INTEGER) {
				console.warn(`${num} is beyond boundary when transfer to integer, the results may not be accurate`);
			}
		}
	}

	/**
	 * 精确乘法
	 */
	export function times(num1: number, num2: number, ...others: number[]): number {
		if (others.length > 0) {
			return times(times(num1, num2), others[0], ...others.slice(1));
		}
		const num1Changed = num1.Float2Fixed();
		const num2Changed = num2.Float2Fixed();
		const baseNum = num1.DigitLength() + num2.DigitLength();
		const leftValue = num1Changed * num2Changed;

		checkBoundary(leftValue);

		return leftValue / Math.pow(10, baseNum);
	}

	/**
	 * 精确加法
	 */
	export function plus(num1: number, num2: number, ...others: number[]): number {
		if (others.length > 0) {
			return plus(plus(num1, num2), others[0], ...others.slice(1));
		}
		const baseNum = Math.pow(10, Math.max(num1.DigitLength(), num2.DigitLength()));
		return (times(num1, baseNum) + times(num2, baseNum)) / baseNum;
	}

	/**
	 * 精确减法
	 */
	export function minus(num1: number, num2: number, ...others: number[]): number {
		if (others.length > 0) {
			return minus(minus(num1, num2), others[0], ...others.slice(1));
		}
		const baseNum = Math.pow(10, Math.max(num1.DigitLength(), num2.DigitLength()));
		return (times(num1, baseNum) - times(num2, baseNum)) / baseNum;
	}

	/**
	 * 精确除法
	 */
	export function divide(num1: number, num2: number, ...others: number[]): number {
		if (others.length > 0) {
			return divide(divide(num1, num2), others[0], ...others.slice(1));
		}
		const num1Changed = num1.Float2Fixed();
		const num2Changed = num2.Float2Fixed();
		checkBoundary(num1Changed);
		checkBoundary(num2Changed);
		return times((num1Changed / num2Changed), Math.pow(10, num2.DigitLength() - num1.DigitLength()));
	}

	/**
	 * 四舍五入
	 */
	export function round(num: number, ratio: number): number {
		const base = Math.pow(10, ratio);
		return divide(Math.round(times(num, base)), base);
	}

	let _boundaryCheckingState = false;
	/**
	 * 是否进行边界检查
	 * @param flag 标记开关，true 为开启，false 为关闭
	*/
	function enableBoundaryChecking(flag = true) {
		_boundaryCheckingState = flag;
	}
}