//
//  WRPageViewController.h
//  WeRead (微信读书)
//
//  Reverse-engineered header reconstruction.
//  Based on UIPageViewController. Supports UIPageCurl (simulation) and
//  Scroll (slide) page turning styles. Includes fault detection and
//  patching mechanisms for known UIPageViewController bugs.
//

#import <UIKit/UIKit.h>

@class WRPageView;
@class WRChapterData;

NS_ASSUME_NONNULL_BEGIN

// ============================================================================
#pragma mark - Page Flipping Style
// ============================================================================

/// The visual style used when transitioning between pages.
typedef NS_ENUM(NSInteger, WRPageFlippingStyle) {
    WRPageFlippingStyleCurl   = 0,  // UIPageCurl simulation (paper fold)
    WRPageFlippingStyleSlide  = 1,  // UIScrollView-based horizontal slide
    WRPageFlippingStyleFade   = 2,  // Crossfade transition
    WRPageFlippingStyleNone   = 3,  // Instant switch, no animation
};

// ============================================================================
#pragma mark - WRPageViewControllerDelegate
// ============================================================================

@protocol WRPageViewControllerDelegate <NSObject>
@optional

/// Called when the page view controller transitions to a new page.
- (void)pageViewController:(WRPageViewController *)pageViewController
        didFinishAnimating:(BOOL)finished
   previousViewControllers:(NSArray<UIViewController *> *)previousViewControllers
       transitionCompleted:(BOOL)completed;

/// Called before a page transition begins.
- (void)pageViewController:(WRPageViewController *)pageViewController
      willTransitionToViewControllers:(NSArray<UIViewController *> *)pendingViewControllers;

/// Called to determine the spine location for interface orientation changes.
- (UIPageViewControllerSpineLocation)pageViewController:(WRPageViewController *)pageViewController
                   spineLocationForInterfaceOrientation:(UIInterfaceOrientation)orientation;

/// Called when the current page index changes.
- (void)pageViewController:(WRPageViewController *)pageViewController
         didChangePageIndex:(NSUInteger)pageIndex;

@end

// ============================================================================
#pragma mark - WRPageViewControllerDataSource
// ============================================================================

@protocol WRPageViewControllerDataSource <NSObject>

/// Returns the view controller before the given one (for right-to-left paging).
- (nullable UIViewController *)pageViewController:(WRPageViewController *)pageViewController
               viewControllerBeforeViewController:(UIViewController *)viewController;

/// Returns the view controller after the given one (for left-to-right paging).
- (nullable UIViewController *)pageViewController:(WRPageViewController *)pageViewController
                viewControllerAfterViewController:(UIViewController *)viewController;

@end

// ============================================================================
#pragma mark - WRPageViewController
// ============================================================================

@interface WRPageViewController : UIViewController

// ---- Delegates ----
@property (nonatomic, weak, nullable) id<WRPageViewControllerDelegate> pageDelegate;
@property (nonatomic, weak, nullable) id<WRPageViewControllerDataSource> pageDataSource;

// ---- Configuration ----
/// The current page flipping style.
@property (nonatomic, assign) WRPageFlippingStyle pageFlippingStyle;

/// Whether the user can interact to change pages.
@property (nonatomic, assign) BOOL pagingEnabled;

/// The underlying UIPageViewController used for page curl and scroll styles.
@property (nonatomic, strong, readonly) UIPageViewController *uiPageViewController;

// ---- State ----
/// The currently visible page index (0-based within the current chapter).
@property (nonatomic, assign, readonly) NSUInteger currentPageIndex;

/// Whether a page transition is currently in progress.
@property (nonatomic, assign, readonly) BOOL isTransitioning;

// ============================================================================
#pragma mark - Initialization
// ============================================================================

/// Designated initializer.
/// @param delegate     The page delegate.
/// @param pageType     The UIPageViewControllerTransitionStyle (curl or scroll).
/// @param flippingStyle The WRPageFlippingStyle to use.
- (instancetype)initWithDelegate:(id<WRPageViewControllerDelegate>)delegate
                    withPageType:(UIPageViewControllerTransitionStyle)pageType
                pageFlippingStyle:(WRPageFlippingStyle)flippingStyle;

// ============================================================================
#pragma mark - Page Navigation
// ============================================================================

/// Sets the current page index, optionally animated.
- (void)setCurrentPageIndex:(NSUInteger)pageIndex animated:(BOOL)animated;

/// Advances to the next page. Returns YES if successful, NO if at the end.
- (BOOL)goToNextPageAnimated:(BOOL)animated;

/// Goes back to the previous page. Returns YES if successful, NO if at the beginning.
- (BOOL)goToPreviousPageAnimated:(BOOL)animated;

/// Replaces the currently displayed view controllers.
- (void)setViewControllers:(NSArray<UIViewController *> *)viewControllers
                 direction:(UIPageViewControllerNavigationDirection)direction
                  animated:(BOOL)animated
                completion:(void (^ __nullable)(BOOL finished))completion;

// ============================================================================
#pragma mark - Fault Detection & Patching
// ============================================================================

///
/// Detects a navigation direction crash in UIPageViewController's
/// queuingScrollView:didScrollWithAnimation: callback.
///
/// This addresses a known Apple bug where the internal
/// UIPageViewControllerQueuingScrollView can enter an inconsistent state
/// and crash with an invalid navigation direction.
///
/// @param pageVC           The UIPageViewController to check.
/// @param queuingScrollView The internal queuing scroll view (if accessible).
/// @param methodDidScroll   Whether this is called from the didScroll callback.
/// @param force             Force the detection even if already patched.
/// @param logDetail         Whether to log detailed diagnostic info.
/// @param logCrashReason    Whether to log the crash reason string.
/// @return YES if a fault was detected (and hopefully patched).
///
+ (BOOL)detectNavigationDirectionCrashWithPageViewController:(UIPageViewController *)pageVC
                                         queuingScrollView:(UIScrollView *)queuingScrollView
                              inMethodDidScrollWithAnimation:(BOOL)methodDidScroll
                                                      force:(BOOL)force
                                                  logDetail:(BOOL)logDetail
                                             logCrashReason:(BOOL)logCrashReason;

///
/// Patches the navigation direction fault by swizzling or resetting
/// the internal state of UIPageViewController.
+ (void)patchNavigationDirectionFault;

///
/// Patches the "no view controller managing page view" fault.
/// This occurs when UIPageViewController loses track of its child VCs.
+ (void)patchNoViewControllerManagingPageViewFault;

///
/// Patches the UIPageCurl animation fault that can cause visual glitches
/// or crashes during rapid page flipping.
+ (void)patchUIPageCurlFault;

@end

NS_ASSUME_NONNULL_END