package com.service;
	
	 
	import java.util.Stack;  
	/** 
	 *
	 **/  
	public class CalculatorImpl implements Calculator{  
		
//		public static void main(String[] args) {
//			String s ="6X5-5X15/4+3/3+4";
//			double result = new CalculatorImpl().toReversePolishNotation(s);
//			System.out.println(result);
//		}
		
		/*转换逆波兰式*/
		public double toReversePolishNotation(String s) throws NumberFormatException{
			
			Stack<Character> s1 = new Stack<Character>();//
			Stack<Double>    s2 = new Stack<Double>();
			int       lastIndex = -1;
			char           temp;
			String          num;
			
			for(int i=0; i<s.length(); i++){
				System.out.println("第"+i+"趟");
				temp = s.charAt(i);
				//判断是否为操作数，如果是，就截取操作数
				if(Character.isDigit(temp) || temp == '.' || temp == '-'){
					//对出现的前面的负号进行处理
					if( temp == '-'){
						lastIndex = readDouble(s, i+1);
						num = s.substring(i, lastIndex);
						System.out.println("截取字符串" + num);
						s2.push(Double.parseDouble(num));
						System.out.println("s2 入栈" + s2.peek());
						System.out.println("s1 入栈  --> +" );
						s1.push('+');
					}else{
						lastIndex = readDouble(s, i);
						num = s.substring(i, lastIndex);
						System.out.println("截取字符串" + num);
						s2.push(Double.parseDouble(num));
						System.out.println("s2 入栈" + s2.peek());
					}
					i = lastIndex -1;
					System.out.println("当前i" +i);
				}else{
					//乘除时，直接做运算
					if(temp == 'X' || temp== '/' ){
						System.out.println("s2出栈:-->" +s2.peek());
						double num1 = s2.pop();
						lastIndex   = readDouble(s, i+1);
						double num2 = Double.parseDouble(s.substring(i+1, lastIndex));
						System.out.println("操作数:" +num2);
						
						i = lastIndex -1;
						System.out.println("当前i"+i);
						double result = calculate(num1, temp, num2);
						System.out.println("num1" +temp+" num2 =" + result);
						System.out.println("result 入栈 s2" + result);
						s2.push(result);
					//当为加减时，让他直接入栈，等待操作
					}else if(temp == '+' || temp == '-'){
						System.out.println("s1 入栈" + temp);
						s1.push(temp);
					}
				}
				
			}
			//对剩下的加减运算，得出最终结果
			while(!s1.isEmpty()&&!s2.isEmpty() && s2.size()>=2){
				
				System.out.println("s2 出栈:" +s2.peek());
				double num2 = s2.pop();
				System.out.println("s2 出栈:" +s2.peek());
				double num1 = s2.pop();
				System.out.println("s1 出栈:" +s1.peek());
				double result = calculate(num1 , s1.pop(), num2);
				System.out.println("计算结果为: " +result);
				s2.push(result);
			}
			
			return s2.pop();
		}
		
//		/*读取科学计算器操作符*/
//		public int readTecOP(String s, int index){
//			char c;
//			for(int i = 0; i<s.length(); i++){
//				
//			}
//			
//		}
		/*读取操作数*/
		public int readDouble(String s, int index){
			
			char c;
			for(int i = index;i<s.length(); i++){
				c = s.charAt(i);
				if(c == 'X'|| c == '/' || c == '+' || c == '-' ){
					System.out.println("return i ="+i);
					return i;
				}else if(i == s.length()-1){
					System.out.println(s.length()+"last");
					return s.length();
				}
			}
			return -1;
		}
		
		/*取栈元素操作计算*/
		public double calculate(double pre, char op, double after){
			
			double result = 0;
			switch(op){
			case '+':
				result = pre+after;
				System.out.println(pre+"+"+after);
				break;
			case '-':
				if(after<0){
					result = after - pre;
				}else{
					result = pre-after;
				}
				System.out.println(pre+"-"+after);
				break;
			case 'X':
				result = pre*after;
				System.out.println(pre+"X"+after);
				break;
			case '/':
				result = pre/after;
				System.out.println(pre+"/"+after);
				break;
			default:
				break;
			}
			return result;
		}
		
	}