@protocol ESVFlexManageType <NSObject>

/// Flex direction.
@property (nonatomic, assign) ESVDirection flexDirection;

/// Distribution mode along axis.
@property (nonatomic, assign) ESVJustify justifyContent;

/// Distribution mode cross axis.
@property (nonatomic, assign) ESVAlign alignItems;

/// Minium space between items.
@property (nonatomic, assign) CGFloat spaceBetween;

@end

@protocol ESVItemManageType <NSObject>

/// All items arranged in flex layout.
@property (nonatomic, readonly) NSArray<__kindof NSObject<ESVStackItemType> *> *arrangedItems;

/// Add item at the end of arranged subviews.
/// @param item Item to add
- (void)addArrangedItem:(NSObject<ESVStackItemType> *)item;

/// Delete item from arranged subview.
/// @param item Item to delete.
- (void)deleteArrangedItem:(NSObject<ESVStackItemType> *)item;

/// Insert item into arranged subviews.
/// @param item Item to insert.
/// @param index Index to insert.
- (void)insertArrangedItem:(NSObject<ESVStackItemType> *)item atIndex:(NSUInteger)index;

@property (nonatomic, readonly) NSArray<__kindof UIView *> *managedViews;

@property (nonatomic, weak) NSObject<ESVStackItemType> * superItem;
 
@end

@protocol ESVRefreshManageType <NSObject>

@property (readonly) BOOL dirty;

/// Mark this item as dirty, it layout soon after.
- (void)markAsDirty;

/// Try to all layout subviews if self or arranged items are dirty.
- (void)render;

/// This should not be called mannually.
- (void)applyItemFrame;

/// The preffered size of this view, which can properly hold all its arranged items.
@property (readonly) CGSize preferedSize;

@end

@protocol ESVConfigManageType <ESVItemManageType>

/// Settle config of item. -setNeedLayout will be called automatically after change config.
/// @param item The item you want to change config of.
/// @param configAction Change config in this block, will be called synchronized. There is no retain circle problem.
- (void)manageConfigOfItem:(NSObject<ESVStackItemType> *)item configAction:(void(^)(ESVStackItemConfig * _Nullable config))configAction;

/// Settle config of item. -setNeedLayout will be called automatically after change config.
/// @param index The index you want to change config of.
/// @param configAction Change config in this block, will be called synchronized. There is no retain circle problem.
- (void)manageConfigOfIndex:(NSUInteger)index configAction:(void(^)(ESVStackItemConfig * _Nullable config))configAction;

/// Get config of item. You must call -setNeedLayout by yourself to layout again.
/// @param item The item.
- (nullable ESVStackItemConfig *)configOfItem:(NSObject<ESVStackItemType> *)item;

/// Get config of index. You must call -setNeedLayout by yourself to layout again.
/// @param index The index of config.
- (nullable ESVStackItemConfig *)configOfIndex:(NSUInteger)index;

@end

@interface ESVStackItemConfig : NSObject

#pragma mark - Cache

/// Frame cache of view. DO NOT change this property value unless you are pretty sure what you are doing.
@property (nonatomic, assign) CGRect cacheTransformedFrame;

@property (nonatomic, assign) CGRect cacheFrame;

#pragma mark - Associate

/// The view this config is associated to.
@property (nonatomic, readonly) NSObject<ESVStackItemType> * item;

#pragma mark - Config

/// Is this view layouted according to alignSelf in this config. Default is false.
@property (nonatomic, assign) BOOL alignSelfOn;

/// Describe how to layout this view in flex layout. Only work when alignSelfOn is true.
@property (nonatomic, assign) ESVAlign alignSelf;

/// Orignal frame of the view. This is the reference size of the view during layout. Default is view's size when added into arranged views array.
@property (nonatomic, assign) CGSize originSize;

/// Minium margin inset of view in four direction. Default is {0, 0, 0, 0,}.
@property (nonatomic, assign) UIEdgeInsets margin;

/// Indicates whether this view will auto stretch when super view is not filled along axis. Default is false.
@property (nonatomic, assign) BOOL growth;

/// Indicates whether this view will auto shrink when super view is too narrow along axis. Default is false.
@property (nonatomic, assign) BOOL shrink;

- (instancetype)initWithItem:(NSObject<ESVStackItemType> *)item;

@end