#import "ViewController.h"
typedef enum{
    kStausNum,
    kStausOperation
}kStaus;

typedef enum{
    kOperationTypeAdd = 1,
    kOperationTypeMinus,
    kOperationTypeMultiply,
    kOperationTypeDevide,
    kOperationTypeEqual,
    kOperationTypeNone
}kOperationType;

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *result_label;
@property (nonatomic,assign) long long firstParam; //记录第一个参数
@property (nonatomic,assign) kOperationType lastOperation;//保存上一次的操作数
@property (nonatomic,assign) BOOL status;//记录当前的状态

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //赋初值
    self.firstParam = 0;
    self.lastOperation = kOperationTypeNone;
    self.status = kStausNum;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (IBAction)numButtonDidClicked:(UIButton *)sender {
    //获取点击的按钮上的数字
    int num = [sender.titleLabel.text intValue];
    //判断继续拼接还是单独显示
    long long showNum;
    if (self.status == kStausNum) {
        //获取之前显示的结果
    long long orgNum = [self.result_label.text longLongValue];
    
    //计算最终显示结果
    showNum = orgNum * 10 + num;
    }else{
        showNum = num;
        self.status = kStausNum;
    }
        
    //显示结果
    self.result_label.text = [NSString stringWithFormat:@"%lld",showNum];
    
    }

//操作键+-*÷
- (IBAction)operationButtonDidClicked:(UIButton *)sender {
    if (self.status != kStausOperation) {
        self.status = kStausOperation;
    }
    self.status = kStausOperation;
    //有两种情况
    //1.第一次操作，只需保存只一次操作
    //2.前面有操作需要计算，并保存这一次的操作
    //3.判断是不是第一次操作
    if (self.lastOperation != kOperationTypeNone) {
        //2.前面有操作需要计算，保存这次操作
        [self calculate];
    }else{
        //第一个参数输入完毕 保存
        self.firstParam = [self.result_label.text longLongValue];
    }
    //保存这一次操作
    if (sender.tag == kOperationTypeEqual) {
        self.lastOperation = kOperationTypeNone;
    }else{
        self.lastOperation = (kOperationType)sender.tag;//自定义tag的值
    }
    
}

//计算结果
-(void)calculate{
    int secondParam = [self.result_label.text intValue];
    long long result;
    
    switch (self.lastOperation) {
        case kOperationTypeAdd:
            result = self.firstParam + secondParam;
            break;
        case kOperationTypeMinus:
            result = self.firstParam - secondParam;
            break;
        case kOperationTypeMultiply:
            result = self.firstParam * secondParam;
            break;
        case kOperationTypeDevide:
            result = self.firstParam / secondParam;
            break;
        default:
            break;
    }
    //显示最终结果
    self.result_label.text = [NSString stringWithFormat:@"%lld",result];
    
    //当前的结果就是下一次的第一个参数的值
    self.firstParam = result;
    
    //更改操作符
    self.lastOperation = kOperationTypeNone;
}

- (IBAction)resetButtonDidClicked:(UIButton *)sender {
    self.result_label.text = @"0";
    self.lastOperation = kOperationTypeNone;
    self.status = kStausNum;
}

@end