//
//  MPOperatorChain.m
//  MathPad
//
//  Created by Kim Wittenburg on 11.10.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPOperatorChain.h"

@implementation MPOperatorChain

- (id)init
{
    self = [super init];
    if (self) {
    }
    return self;
}

- (instancetype)initWithTokenStream:(MPTokenStream *)tokenStream
{
    self = [self init];
    if (self) {
        [tokenStream beginIgnoringWhitespaceTokens];
        MPToken *currentToken = tokenStream.currentToken;
        
        if (currentToken.tokenType != MPOperatorListToken) {
            @throw [NSException exceptionWithName:NSInternalInconsistencyException reason:@"Expected Operators" userInfo:nil];
        }
        
        NSString *operatorString = currentToken.stringValue;
        operatorString = [[operatorString componentsSeparatedByString:@" "] componentsJoinedByString:@""];
        _negating = NO;
        _numberOfOperators = operatorString.length;
        for (NSUInteger index = 0; index < _numberOfOperators; index++) {
            if ([[operatorString substringWithRange:NSMakeRange(index, 1)] isEqualToString:@"-"]) {
                _negating = !_negating;
            }
        }
        
        [tokenStream currentTokenConsumed];
        [tokenStream endIgnoringOrAcceptingWhitespaceTokens];
    }
    return self;
}

- (BOOL)validate:(NSError *__autoreleasing *)error
{
    return YES;
}

- (NSDecimalNumber *)evaluate
{
    return self.negating ? [[NSDecimalNumber alloc] initWithInteger:-1] : [NSDecimalNumber one];
}

@end