//
//  WRCoreTextLayoutFrame.h
//  WeRead
//
//  Reverse-engineered from binary analysis
//  Single page layout frame for WeRead's reading engine
//

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <CoreText/CoreText.h>

@class WRBookCoverView;
@class WRDiscover;

NS_ASSUME_NONNULL_BEGIN

#pragma mark - Layout Line

/**
 * Represents a single line of laid-out text.
 * Wrapper around CTLine with additional metadata.
 */
@interface WRCoreTextLayoutLine : NSObject

/** The CTLine this wraps */
@property (nonatomic, assign, readonly) CTLineRef ctLine;

/** Origin point of this line in the frame */
@property (nonatomic, assign) CGPoint origin;

/** The range of characters in this line */
@property (nonatomic, assign) NSRange stringRange;

/** Ascent of the line */
@property (nonatomic, assign, readonly) CGFloat ascent;

/** Desent of the line */
@property (nonatomic, assign, readonly) CGFloat descent;

/** Leading of the line */
@property (nonatomic, assign, readonly) CGFloat leading;

/** Total height of the line (ascent + descent + leading) */
@property (nonatomic, assign, readonly) CGFloat height;

/** Width of the line */
@property (nonatomic, assign, readonly) CGFloat width;

/** Whether this line is the last line in a paragraph */
@property (nonatomic, assign) BOOL isLastLineInParagraph;

@end

#pragma mark - WRCoreTextLayoutFrame

/**
 * WRCoreTextLayoutFrame - Manages a single page of text layout.
 *
 * This class wraps CTFrame and provides high-level access to the
 * layout of a single page. It handles:
 * - Text rendering to CGContext
 * - Image placement within text
 * - avoidPageBreakInside CSS property
 * - Render height calculation
 * - Line-by-line access for hit testing and selection
 *
 * Architecture:
 * - Contains CTFrame internally
 * - Manages array of WRCoreTextLayoutLine objects
 * - Supports direct drawing to CGContext
 * - Handles image attachments inline
 * - Integrates with RACSubject for reactive updates
 */
@interface WRCoreTextLayoutFrame : NSObject

#pragma mark - Core Layout Data

/** The attributed string that was laid out */
@property (nonatomic, strong, nullable) NSAttributedString *attributedString;

/** The range of the attributed string represented by this frame */
@property (nonatomic, assign) NSRange stringRange;

/** Array of WRCoreTextLayoutLine objects for this frame */
@property (nonatomic, strong, readonly) NSArray<WRCoreTextLayoutLine *> *layoutLines;

/** The bounding rectangle for this frame */
@property (nonatomic, assign) CGRect frame;

/** The CTFrame reference (accessor for internal use) */
@property (nonatomic, assign, readonly) CTFrameRef ctFrame;

#pragma mark - Layout Properties

/** Whether to avoid page breaks inside certain elements */
@property (nonatomic, assign) BOOL avoidPageBreakInside;

/** The rendered content height (may differ from frame height) */
@property (nonatomic, assign, readonly) CGFloat renderedContentHeight;

/** Padding around the content area */
@property (nonatomic, assign) UIEdgeInsets contentInsets;

/** Number of columns in this frame */
@property (nonatomic, assign) NSUInteger numberOfColumns;

/** Gap between columns */
@property (nonatomic, assign) CGFloat columnGap;

#pragma mark - Content Arrays

/** Array of attachment objects (images, etc.) */
@property (nonatomic, strong, nullable) NSArray *attachments;

/** Array of strikethrough ranges */
@property (nonatomic, strong, nullable) NSArray *strikethroughRanges;

/** Array of underline ranges */
@property (nonatomic, strong, nullable) NSArray *underlineRanges;

/** Array of highlight ranges */
@property (nonatomic, strong, nullable) NSArray *highlightRanges;

/** Set of selected line indices */
@property (nonatomic, strong, nullable) NSMutableSet *selectedLineIndices;

/** Current selection string */
@property (nonatomic, copy, nullable) NSString *selectionString;

/** Array of link ranges for tap handling */
@property (nonatomic, strong, nullable) NSArray *linkRanges;

/** Search result string */
@property (nonatomic, copy, nullable) NSString *searchResultString;

/** Array of search result ranges */
@property (nonatomic, strong, nullable) NSArray *searchResultRanges;

#pragma mark - Reactive Components

/** Subject for layout change notifications */
@property (nonatomic, strong, nullable) RACSubject *layoutChangeSubject;

#pragma mark - UI Elements

/** Long press gesture recognizer for text selection */
@property (nonatomic, strong, nullable) UILongPressGestureRecognizer *longPressRecognizer;

/** Book cover view (for cover pages) */
@property (nonatomic, strong, nullable) WRBookCoverView *bookCoverView;

/** Layer for custom drawing */
@property (nonatomic, strong, nullable) CALayer *customDrawingLayer;

/** Discover view (for social features) */
@property (nonatomic, strong, nullable) WRDiscover *discoverView;

/** Additional layout data */
@property (nonatomic, strong, nullable) NSArray *additionalLayoutData;

/** Frame identifier */
@property (nonatomic, copy, nullable) NSString *frameId;

/** Content identifier */
@property (nonatomic, copy, nullable) NSString *contentId;

/** Mutable dictionary for custom attributes */
@property (nonatomic, strong, nullable) NSMutableDictionary *customAttributes;

/** Mutable array for tracking visible elements */
@property (nonatomic, strong, nullable) NSMutableArray *visibleElements;

/** Mutable array for tracking accessibility elements */
@property (nonatomic, strong, nullable) NSMutableArray *accessibilityElements;

/** Mutable dictionary for caching computed values */
@property (nonatomic, strong, nullable) NSMutableDictionary *computedValueCache;

#pragma mark - Initialization

/**
 * Initialize with a CTFrame and string range.
 *
 * @param ctFrame The CoreText frame
 * @param range The string range
 * @return Initialized layout frame
 */
- (instancetype)initWithCTFrame:(CTFrameRef)ctFrame
                          range:(NSRange)range;

/**
 * Set the CTFrame and range (used by WRCoreTextLayouter).
 */
- (void)setCTFrame:(CTFrameRef)ctFrame range:(NSRange)range;

#pragma mark - Line Access

/**
 * Returns the array of layout lines.
 * This triggers line extraction from the CTFrame if not already done.
 *
 * @return Array of WRCoreTextLayoutLine objects
 */
- (NSArray<WRCoreTextLayoutLine *> *)lines;

/**
 * Returns the number of lines in this frame.
 */
- (NSUInteger)lineCount;

/**
 * Returns the layout line at the specified index.
 */
- (nullable WRCoreTextLayoutLine *)lineAtIndex:(NSUInteger)index;

#pragma mark - Height Calculation

/**
 * Returns the rendered content height.
 *
 * This calculates the actual height of the rendered content,
 * which may be less than the frame height if there's unused space.
 *
 * @return The height of the rendered content in points
 */
- (CGFloat)getRenderHeight;

/**
 * Returns the height of the last line's descent.
 * Used for precise baseline alignment.
 */
- (CGFloat)lastLineDescent;

#pragma mark - Drawing

/**
 * Draw the layout frame content into a CGContext.
 *
 * This is the primary rendering method. It draws:
 * 1. Text content using CTFrameDraw
 * 2. Image attachments at their calculated positions
 * 3. Decorative elements (strikethrough, underline, etc.)
 *
 * @param context The CGContext to draw into
 * @param image Optional image to draw (for cover pages)
 * @param size The size of the drawing area
 * @param rect The rectangle to draw within
 * @param position The position offset for the content
 */
- (void)drawInContext:(CGContextRef)context
                image:(nullable UIImage *)image
                 size:(CGSize)size
               inRect:(CGRect)rect
             position:(CGPoint)position;

/**
 * Draw only the text content (no images).
 */
- (void)drawTextInContext:(CGContextRef)context
                    inRect:(CGRect)rect;

/**
 * Draw image attachments.
 */
- (void)drawAttachmentsInContext:(CGContextRef)context
                          inRect:(CGRect)rect;

#pragma mark - Page Break Avoidance

/**
 * Removes the last lines if needed to avoid page breaks inside certain elements.
 *
 * This implements the CSS 'avoid-page-break-inside' property. When an element
 * (like a table, code block, or list) cannot fit entirely on the current page,
 * this method removes lines from the end until the element can fit.
 *
 * @return YES if lines were removed, NO otherwise
 */
- (BOOL)avoidPageBreakInsideByRemovingLastLinesIfNeeded;

/**
 * Check if a range of text has the avoid-page-break-inside property.
 */
- (BOOL)shouldAvoidPageBreakInRange:(NSRange)range;

#pragma mark - Hit Testing

/**
 * Returns the character index at a given point.
 *
 * @param point The point to test (in the frame's coordinate system)
 * @return The character index, or NSNotFound if no character at that point
 */
- (NSUInteger)characterIndexAtPoint:(CGPoint)point;

/**
 * Returns the line index at a given point.
 *
 * @param point The point to test
 * @return The line index, or NSNotFound
 */
- (NSUInteger)lineIndexAtPoint:(CGPoint)point;

/**
 * Returns the rect for a character at the given index.
 */
- (CGRect)rectForCharacterAtIndex:(NSUInteger)index;

#pragma mark - Selection

/**
 * Returns the selected text string.
 */
- (nullable NSString *)selectedText;

/**
 * Returns the ranges of selected text.
 */
- (NSArray<NSValue *> *)selectedRanges;

/**
 * Selects text in the given range.
 */
- (void)selectTextInRange:(NSRange)range;

/**
 * Clears the current selection.
 */
- (void)clearSelection;

#pragma mark - Search

/**
 * Highlights search results within this frame.
 *
 * @param searchString The string to highlight
 * @return The number of matches found
 */
- (NSUInteger)highlightSearchResults:(NSString *)searchString;

/**
 * Clears all search result highlights.
 */
- (void)clearSearchHighlights;

@end

NS_ASSUME_NONNULL_END