//
//  MPProduct.m
//  MathPad
//
//  Created by Kim Wittenburg on 09.10.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPProduct.h"
#import "MPValueGroup.h"

@implementation MPProduct {
    NSMutableArray *_factors;
    NSRange _range;
}

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

- (instancetype)initWithTokenStream:(MPTokenStream *)tokenStream
{
    self = [self init];
    if (self) {
        [tokenStream beginIgnoringWhitespaceTokens];
        
        MPTokenStreamRecordCurrentLocation(tokenStream);
        while (tokenStream.currentToken.tokenType != MPOperatorListToken && tokenStream.currentToken.tokenType != MPEOFToken) {
            [_factors addObject:[[MPFactor alloc] initWithTokenStream:tokenStream]];
        }
        _range = MPTokenStreamRecordedRange(tokenStream);
        [tokenStream endIgnoringOrAcceptingWhitespaceTokens];
    }
    return self;
}

- (NSRange)range
{
    return _range;
}

- (BOOL)validate:(MPParseError *__autoreleasing *)error
{
    if (_factors.count == 0) {
        if (error) {
            *error = MPParseError(_range, @"Expected Value");
        }
        return NO;
    }
    MPFactor *factor = _factors[0];
    if (factor.hasMultiplicationSymbol) {
        if (error) {
            *error = MPParseError(factor.multiplicationSymbolRange, @"Unexpected Symbol.");
        }
        return NO;
    }
    if (![factor.value validate:error]) {
        return NO;
    }
    for (NSUInteger index = 1; index < _factors.count; index++) {
        factor = _factors[index];
        if (![factor validate:error]) {
            return NO;
        }
    }
    return YES;
}

- (NSDecimalNumber *)evaluate
{
    NSDecimalNumber *value = [NSDecimalNumber one];
    for (MPFactor *factor in _factors) {
        NSDecimalNumber *currentValue = [factor evaluate];
        if ([currentValue isEqualToNumber:[NSDecimalNumber notANumber]]) {
            value = currentValue;
            break;
        }
        value = [value decimalNumberByMultiplyingBy:currentValue];
        if ([value compare:@(0)] == NSOrderedSame) {
            break;
        }
    }
    return value;
}

- (NSArray *)expressionElements
{
    NSMutableArray *elements = [[NSMutableArray alloc] init];
    for (MPFactor *factor in _factors) {
        [elements addObjectsFromArray:factor.expressionElements];
    }
    return elements;
}

- (NSArray *)factors
{
    return _factors;
}

- (void)appendFactor:(MPFactor *)factor
{
    [_factors addObject:factor];
}

- (void)insertFactor:(MPFactor *)factor
             atIndex:(NSUInteger)index
{
    [_factors insertObject:factor
                   atIndex:index];
}

- (void)removeFactor:(MPFactor *)factor
{
    [_factors removeObject:factor];
}

- (void)removeFactorAtIndex:(NSUInteger)index
{
    [_factors removeObjectAtIndex:index];
}

- (MPFactor *)factorAtIndex:(NSUInteger)index
{
    return [_factors objectAtIndex:index];
}

@end