//
//  MPLayout.m
//  MathPad
//
//  Created by Kim Wittenburg on 11.08.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPLayout.h"

@interface MPLayout ()

// Querying and Storing Caches
- (BOOL)hasCacheForElementAtIndex:(NSUInteger)index;
- (void)ensureCacheSizeForIndex:(NSUInteger)index;

@end

@implementation MPLayout {
    NSMutableArray *_cache;
    NSSize _cachedSize;
}

#pragma mark Creation Methods
- (id)init
{
    self = [super init];
    if (self) {
        _cache = [[NSMutableArray alloc] init];
        _cachedSize = NSZeroSize;
    }
    return self;
}

- (id)initWithPath:(NSIndexPath *)path
            parent:(MPLayout *)parent
{
    self = [self init];
    if (self) {
        _parent = parent;
    }
    return self;
}

#pragma Text System Objects
- (MPExpressionStorage *)expressionStorage
{
    return self.parent.expressionStorage;
}

#pragma mark Cache Tree
// Querying and Storing Caches
- (BOOL)hasCacheForElementAtIndex:(NSUInteger)index
{
    if (index >= _cache.count) {
        return NO;
    }
    return _cache[index] != MPNull;
}

- (id)cachableObjectForIndex:(NSUInteger)index
                   generator:(id (^)())generator
{
    if ([self hasCacheForElementAtIndex:index]) {
        return _cache[index];
    }
    id object = generator();
    [self ensureCacheSizeForIndex:index];
    _cache[index] = object;
    return object;
}

- (void)ensureCacheSizeForIndex:(NSUInteger)index
{
    while (index >= _cache.count) {
        [_cache addObject:MPNull];
    }
}

// Clearing Caches
- (void)clearCacheInRange:(NSRange)range
        replacementLength:(NSUInteger)replacementLength
{
    NSMutableArray *placeholders = [[NSMutableArray alloc] initWithCapacity:replacementLength];
    while (placeholders.count < replacementLength) {
        [placeholders addObject:MPNull];
    }
    [_cache replaceObjectsInRange:range
             withObjectsFromArray:placeholders];
    [self invalidate];
}

- (void)invalidate
{
    _cachedSize = NSZeroSize;
    [self.parent invalidate];
}

#pragma mark Calculation and Drawing Methods
- (NSSize)size
{
    if (NSEqualSizes(_cachedSize, NSZeroSize)) {
        _cachedSize = [self generateSize];
    }
    return _cachedSize;
}

- (void)drawAtPoint:(NSPoint)point
{
    
}

@end

@implementation MPLayout (MPSubclassImplement)

- (MPLayout *)childLayoutAtIndex:(NSUInteger)index
{
    return nil;
}

- (NSSize)sizeForChildAtIndex:(NSUInteger)index
{
    return NSZeroSize;
}

- (NSSize)generateSize
{
    return NSZeroSize;
}

@end