/*
 *  Copyright (c) 2014-present, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 *
 */

#import "ASRatioLayoutSpec.h"

#import <algorithm>
#import <vector>

#import "ASAssert.h"
#import "ASBaseDefines.h"

#import "ASInternalHelpers.h"

@implementation ASRatioLayoutSpec
{
  CGFloat _ratio;
  id<ASLayoutable> _child;
}

+ (instancetype)newWithRatio:(CGFloat)ratio child:(id<ASLayoutable>)child
{
  ASDisplayNodeAssert(ratio > 0, @"Ratio should be strictly positive, but received %f", ratio);
  if (child == nil) {
    return nil;
  }

  ASRatioLayoutSpec *spec = [super new];
  if (spec) {
    spec->_ratio = ratio;
    spec->_child = child;
  }
  return spec;
}

+ (instancetype)new
{
    ASDISPLAYNODE_NOT_DESIGNATED_INITIALIZER();
}

- (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
{
  std::vector<CGSize> sizeOptions;
  if (!isinf(constrainedSize.max.width)) {
    sizeOptions.push_back(ASSizeRangeClamp(constrainedSize, {
      constrainedSize.max.width,
      ASFloorPixelValue(_ratio * constrainedSize.max.width)
    }));
  }
  if (!isinf(constrainedSize.max.height)) {
    sizeOptions.push_back(ASSizeRangeClamp(constrainedSize, {
      ASFloorPixelValue(constrainedSize.max.height / _ratio),
      constrainedSize.max.height
    }));
  }

  // Choose the size closest to the desired ratio.
  const auto &bestSize = std::max_element(sizeOptions.begin(), sizeOptions.end(), [&](const CGSize &a, const CGSize &b){
    return fabs((a.height / a.width) - _ratio) > fabs((b.height / b.width) - _ratio);
  });

  // If there is no max size in *either* dimension, we can't apply the ratio, so just pass our size range through.
  const ASSizeRange childRange = (bestSize == sizeOptions.end()) ? constrainedSize : ASSizeRangeMake(*bestSize, *bestSize);
  ASLayout *childLayout = [_child calculateLayoutThatFits:childRange];
  childLayout.position = CGPointZero;
  return [ASLayout newWithLayoutableObject:self size:childLayout.size children:@[childLayout]];
}

@end