var countDecimals = function(num) {
	var len = 0;
	try {
		num = Number(num);
		var str = num.toString().toUpperCase();
		if (str.split('E').length === 2) { // scientific notation
			var isDecimal = false;
			if (str.split('.').length === 2) {
				str = str.split('.')[1];
				if (parseInt(str.split('E')[0]) !== 0) {
					isDecimal = true;
				}
			}
			let x = str.split('E');
			if (isDecimal) {
				len = x[0].length;
			}
			len -= parseInt(x[1]);
		} else if (str.split('.').length === 2) { // decimal
			if (parseInt(str.split('.')[1]) !== 0) {
				len = str.split('.')[1].length;
			}
		}
	} catch (e) {
		throw e;
	} finally {
		if (isNaN(len) || len < 0) {
			len = 0;
		}
		return len;
	}
};

var convertToInt = function(num) {
	num = Number(num);
	var newNum = num;
	var times = countDecimals(num);
	var temp_num = num.toString().toUpperCase();
	if (temp_num.split('E').length === 2) {
		newNum = Math.round(num * Math.pow(10, times));
	} else {
		newNum = Number(temp_num.replace(".", ""));
	}
	return newNum;
};

var getCorrectResult = function(type, num1, num2, result) {
	var temp_result = 0;
	switch (type) {
		case "add":
			temp_result = num1 + num2;
			break;
		case "sub":
			temp_result = num1 - num2;
			break;
		case "div":
			temp_result = num1 / num2;
			break;
		case "mul":
			temp_result = num1 * num2;
			break;
	}
	if (Math.abs(result - temp_result) > 1) {
		return temp_result;
	}
	return result;
};
export default {
	// 加法
	accAdd(num1, num2) {
		num1 = Number(num1);
		num2 = Number(num2);
		var dec1, dec2, times;
		try {
			dec1 = countDecimals(num1) + 1;
		} catch (e) {
			dec1 = 0;
		}
		try {
			dec2 = countDecimals(num2) + 1;
		} catch (e) {
			dec2 = 0;
		}
		times = Math.pow(10, Math.max(dec1, dec2));
		// var result = (num1 * times + num2 * times) / times;
		var result = (this.accMul(num1, times) + this.accMul(num2, times)) / times;
		return getCorrectResult("add", num1, num2, result);
		// return result;
	},
	// 减法
	accSub(num1, num2) {
		num1 = Number(num1);
		num2 = Number(num2);
		var dec1, dec2, times;
		try {
			dec1 = countDecimals(num1) + 1;
		} catch (e) {
			dec1 = 0;
		}
		try {
			dec2 = countDecimals(num2) + 1;
		} catch (e) {
			dec2 = 0;
		}
		times = Math.pow(10, Math.max(dec1, dec2));
		// var result = Number(((num1 * times - num2 * times) / times);
		var result = Number((this.accMul(num1, times) - this.accMul(num2, times)) / times);
		return getCorrectResult("sub", num1, num2, result);
		// return result;
	},
	// 除法
	accDiv(num1, num2) {
		num1 = Number(num1);
		num2 = Number(num2);
		var t1 = 0,
			t2 = 0,
			dec1, dec2;
		try {
			t1 = countDecimals(num1);
		} catch (e) {}
		try {
			t2 = countDecimals(num2);
		} catch (e) {}
		dec1 = convertToInt(num1);
		dec2 = convertToInt(num2);
		var result = this.accMul((dec1 / dec2), Math.pow(10, t2 - t1));
		return getCorrectResult("div", num1, num2, result);
		// return result;
	},
	// 乘法
	accMul(num1, num2) {
		num1 = Number(num1);
		num2 = Number(num2);
		var times = 0,
			s1 = num1.toString(),
			s2 = num2.toString();
		try {
			times += countDecimals(s1);
		} catch (e) {}
		try {
			times += countDecimals(s2);
		} catch (e) {}
		var result = convertToInt(s1) * convertToInt(s2) / Math.pow(10, times);
		return getCorrectResult("mul", num1, num2, result);
		// return result;
	}
}
