//
//  MPParsedOperator.m
//  MathPad
//
//  Created by Kim Wittenburg on 13.09.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPParsedOperator.h"

@interface MPParsedOperator ()
@property (nonatomic) NSRange range;
@property (nonatomic) NSUInteger numberOfOperators;
@property (nonatomic, strong) NSDecimalNumber *multiplicator;
@end

@implementation MPParsedOperator

- (instancetype)initWithRange:(NSRange)range
                     inString:(NSString *)string
{
    self = [super init];
    if (self) {
        _range = range;
        if (range.location == NSNotFound) {
            _multiplicator = [NSDecimalNumber one];
            _numberOfOperators = 0;
        } else {
            NSString *stringValue = [string substringWithRange:range];
            NSString *operators = [[stringValue componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:@""];
            NSInteger multiplicator = 1;
            for (NSUInteger characterIndex = 0; characterIndex < operators.length; characterIndex++) {
                if ([[operators substringWithRange:NSMakeRange(characterIndex, 1)] isEqualToString:@"-"]) {
                    multiplicator *= -1;
                }
            }
            _multiplicator = [[NSDecimalNumber alloc] initWithInteger:multiplicator];
            _numberOfOperators = operators.length;
        }
    }
    return self;
}

- (BOOL)exists
{
    return self.range.location != NSNotFound;
}

- (NSDecimalNumber *)evaluateWithError:(MPParseError *__autoreleasing *)error
{
    return self.multiplicator;
}

@end