//
//  CalculatorBrain.h
//  Calculator
//
//  Created by   on 7/28/12.
//  Copyright (c) 2012   All rights reserved.
//

#import <Foundation/Foundation.h>

@interface CalculatorBrain : NSObject

@property (strong,nonatomic) NSMutableArray* operandStack;

-(void)setOperandStack:(NSMutableArray *)operandStack;
-(void) pushOperand:(double) operand;
-(double)popOperand;
-(double) performOperation:(NSString*) operation;


@end








//
//  CalculatorBrain.m
//  Calculator
//
//  Created by  on 7/28/12.
//  Copyright (c) 2012 . All rights reserved.
//

#import "CalculatorBrain.h"

@implementation CalculatorBrain

@synthesize operandStack = _operandStack;

-(NSMutableArray*) operandStack{
    if(self.operandStack == NULL){
        _operandStack = [[NSMutableArray alloc] init];
    }
    return _operandStack;
}

-(void)setOperandStack:(NSMutableArray *)operandStack{
    _operandStack = operandStack;
}

-(void) pushOperand:(double) operand{
    [_operandStack addObject:[NSNumber numberWithDouble:operand]];
    int count = [_operandStack count];
    NSLog(@"Number pushed is %g", [[_operandStack objectAtIndex:count - 1] doubleValue]);
}

-(double)popOperand{
    int count = [_operandStack count];
    NSNumber* value = [_operandStack objectAtIndex:count - 1];
    double val = 0;
    if(value){
        val = [value doubleValue];
        [_operandStack removeLastObject];
    }
    NSLog(@"popped %g",val);
    return val;
}

-(double) performOperation:(NSString*) operation{
    double result = 0;
    if([@"+" isEqualToString:operation]){
        result = [self popOperand] + [self popOperand];
    }else if([@"*" isEqualToString:operation]){
        result = [self popOperand] * [self popOperand];
    }
    [self pushOperand:result];
    return result;
}

@end








//
//  ViewController.h
//  Calculator
//
//  Created by   on 7/28/12.
//  Copyright (c) 2012   All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

@property (weak, nonatomic) IBOutlet UILabel *display;

@end











//
//  ViewController.m
//  Calculator
//
//  Created by   on 7/28/12.
//  Copyright (c) 2012 AJ Gauravdeep. All rights reserved.
//

#import "ViewController.h"
#import "CalculatorBrain.h"

@interface ViewController ()

@property (nonatomic) Boolean amIInMiddleOfNumber;
@property (strong, nonatomic) CalculatorBrain* brain;

@end

@implementation ViewController

@synthesize brain = _brain;
@synthesize display = _display;
@synthesize amIInMiddleOfNumber = _amIInMiddleOfNumber;

-(CalculatorBrain *)Brain{
    if(self.Brain == NULL){
        _brain = [[CalculatorBrain alloc] init];
    }
    return _brain;
}

- (IBAction)numberPressed:(UIButton*)sender {
    NSString* digit = [sender currentTitle];
    if(_amIInMiddleOfNumber)
        _display.text = [_display.text stringByAppendingString:digit];
    else{
        _display.text = digit;
        _amIInMiddleOfNumber =YES;
    }
}

- (IBAction)enterPressed {
    double mynumber= [self.display.text doubleValue];
    NSLog(@"enter pressed....Number is %g", mynumber);
    [_brain pushOperand:mynumber];
    int count = [_brain.operandStack count];
    NSLog(@"enter pressed... pusehed operand is %g", [[_brain.operandStack objectAtIndex:count - 1] doubleValue]);
    _amIInMiddleOfNumber = NO;
}

- (IBAction)operationPressed:(UIButton *)sender {
    NSLog(@"Operation pressed is '%@'", sender.currentTitle);
    if(_amIInMiddleOfNumber)
        [self enterPressed];
    double result = [_brain performOperation:sender.currentTitle];
    self.display.text = [NSString stringWithFormat:@"%g",result];
}


@end