//
//  DTCoreTextGlyphRun.m
//  WeRead
//
//  Reverse-engineered from binary analysis
//  Based on DTCoreText open-source library, customized by WeRead
//
//  This file contains pseudo-code reconstruction of the DTCoreTextGlyphRun
//  class based on ivar analysis, method signatures, and the open-source DTCoreText library.
//

#import "DTCoreTextGlyphRun.h"
#import "DTCoreTextLayoutLine.h"
#import <CoreText/CoreText.h>

#pragma mark - DTTextAttachment Stub

/**
 * Stub for DTTextAttachment class.
 * Represents an embedded object (image, view, etc.) in the text.
 */
@interface DTTextAttachment : NSObject

@property (nonatomic, strong) UIImage *image;
@property (nonatomic, assign) CGSize displaySize;
@property (nonatomic, assign) CGRect frame;
@property (nonatomic, copy) NSString *contentType;

@end

@implementation DTTextAttachment
@end

#pragma mark - Private Interface

@interface DTCoreTextGlyphRun () {
    // Cached glyph data
    CGGlyph *_glyphs;
    CGPoint *_positions;
    CGFloat *_advances;
    CFIndex _glyphCount;

    // Whether glyph data has been extracted
    BOOL _glyphsExtracted;

    // Cached metrics
    CGFloat _cachedAscent;
    CGFloat _cachedDescent;
    CGFloat _cachedLeading;
    CGFloat _cachedWidth;
    BOOL _metricsCached;

    // Internal lock
    NSLock *_lock;
}

@end

#pragma mark - DTCoreTextGlyphRun Implementation

@implementation DTCoreTextGlyphRun

#pragma mark - Lifecycle

- (instancetype)initWithCTRun:(CTRunRef)ctRun
                        frame:(CGRect)frame
                        range:(NSRange)range
                   attributes:(NSDictionary *)attributes
                        index:(NSUInteger)index {
    self = [super init];
    if (self) {
        _lock = [[NSLock alloc] init];

        // Store the CTRun with a retain
        if (ctRun) {
            _ctRun = (CTRunRef)CFRetain(ctRun);
        }

        _frame = frame;
        _stringRange = range;
        _attributes = [attributes copy];
        _runIndex = index;

        // Initialize state
        _glyphsExtracted = NO;
        _metricsCached = NO;
        _glyphs = NULL;
        _positions = NULL;
        _advances = NULL;
        _glyphCount = 0;

        // Extract common attributes
        [self extractAttributes];
    }
    return self;
}

- (void)dealloc {
    if (_ctRun) {
        CFRelease(_ctRun);
        _ctRun = NULL;
    }

    // Free allocated glyph data
    if (_glyphs) {
        free(_glyphs);
        _glyphs = NULL;
    }
    if (_positions) {
        free(_positions);
        _positions = NULL;
    }
    if (_advances) {
        free(_advances);
        _advances = NULL;
    }
}

#pragma mark - Attribute Extraction

/**
 * Extracts common attributes from the attributes dictionary.
 */
- (void)extractAttributes {
    if (!_attributes) {
        return;
    }

    // Extract font
    CTFontRef ctFont = (__bridge CTFontRef)_attributes[(__bridge NSString *)kCTFontAttributeName];
    if (ctFont) {
        _font = [UIFont fontWithDescriptor:[UIFontDescriptor fontDescriptorWithCTFont:ctFont]
                                      size:CTFontGetSize(ctFont)];
    }

    // Extract text color
    CGColorRef textColor = (__bridge CGColorRef)_attributes[(__bridge NSString *)kCTForegroundColorAttributeName];
    if (textColor) {
        _textColor = [UIColor colorWithCGColor:textColor];
    }

    // Extract background color
    CGColorRef bgColor = (__bridge CGColorRef)_attributes[@"DTBackgroundColor"];
    if (bgColor) {
        _backgroundColor = [UIColor colorWithCGColor:bgColor];
    }

    // Extract strikethrough
    NSNumber *strikethrough = _attributes[(__bridge NSString *)kCTSuperscriptAttributeName];
    if (strikethrough) {
        _hasStrikethrough = [strikethrough boolValue];
    }

    // Extract underline
    NSNumber *underlineStyle = _attributes[(__bridge NSString *)kCTUnderlineColorAttributeName];
    if (underlineStyle) {
        _hasUnderline = YES;
        _underlineStyle = [underlineStyle integerValue];
    }

    // Check for attachment
    _attachment = _attributes[@"DTTextAttachment"];
    if (_attachment) {
        _isAttachment = YES;
    }

    // Extract writing direction
    NSArray *writingDirection = _attributes[(__bridge NSString *)kCTWritingDirectionAttributeName];
    if ([writingDirection count] > 0) {
        _writingDirection = [writingDirection[0] integerValue];
    }
}

#pragma mark - Glyph Extraction

/**
 * Extracts glyph data from the CTRun.
 *
 * This method extracts:
 * - Glyph values (CGGlyph)
 * - Glyph positions (CGPoint)
 * - Glyph advances (CGFloat)
 */
- (void)extractGlyphs {
    if (_glyphsExtracted || !_ctRun) {
        return;
    }

    [_lock lock];

    // Get the number of glyphs
    _glyphCount = CTRunGetGlyphCount(_ctRun);

    if (_glyphCount == 0) {
        _glyphsExtracted = YES;
        [_lock unlock];
        return;
    }

    // Allocate memory for glyph data
    _glyphs = (CGGlyph *)malloc(sizeof(CGGlyph) * _glyphCount);
    _positions = (CGPoint *)malloc(sizeof(CGPoint) * _glyphCount);
    _advances = (CGFloat *)malloc(sizeof(CGFloat) * _glyphCount);

    // Extract glyph values
    CTRunGetGlyphs(_ctRun, CFRangeMake(0, 0), _glyphs);

    // Extract glyph positions
    CTRunGetPositions(_ctRun, CFRangeMake(0, 0), _positions);

    // Extract glyph advances
    CTRunGetAdvances(_ctRun, CFRangeMake(0, 0), (CGSize *)_advances);

    _glyphsExtracted = YES;

    [_lock unlock];
}

#pragma mark - Glyph Access

- (CGGlyph)glyphAtIndex:(NSUInteger)index {
    [self extractGlyphs];

    if (index >= _glyphCount || !_glyphs) {
        return 0;
    }

    return _glyphs[index];
}

- (CGPoint)positionForGlyphAtIndex:(NSUInteger)index {
    [self extractGlyphs];

    if (index >= _glyphCount || !_positions) {
        return CGPointZero;
    }

    return _positions[index];
}

- (CGFloat)advanceForGlyphAtIndex:(NSUInteger)index {
    [self extractGlyphs];

    if (index >= _glyphCount || !_advances) {
        return 0;
    }

    return _advances[index];
}

- (CGRect)rectForGlyphAtIndex:(NSUInteger)index {
    [self extractGlyphs];

    if (index >= _glyphCount) {
        return CGRectNull;
    }

    CGPoint position = _positions[index];
    CGFloat advance = _advances[index];

    // Calculate the rect for this glyph
    // The position is relative to the run's origin
    return CGRectMake(
        _frame.origin.x + position.x,
        _frame.origin.y,
        advance,
        _frame.size.height
    );
}

#pragma mark - Path Operations

/**
 * Creates a CGPath containing all glyphs in this run.
 *
 * This method creates a path by transforming each glyph's outline
 * to its position within the run. This is used for:
 * - Custom drawing with effects
 * - Hit testing with complex shapes
 * - Creating outlines for selection
 *
 * Algorithm:
 * 1. Extract all glyph data
 * 2. For each glyph:
 *    a. Get the glyph's path from the font
 *    b. Transform to the glyph's position
 *    c. Add to the combined path
 * 3. Return the combined path
 *
 * @return A CGPath containing all glyph outlines
 */
- (CGPathRef)newPathWithGlyphs {
    [self extractGlyphs];

    if (!_ctRun || _glyphCount == 0) {
        return NULL;
    }

    // Create a mutable path for the combined glyphs
    CGMutablePathRef combinedPath = CGPathCreateMutable();

    // Get the font from attributes
    CTFontRef font = (__bridge CTFontRef)_attributes[(__bridge NSString *)kCTFontAttributeName];
    if (!font) {
        return combinedPath;
    }

    // Process each glyph
    for (CFIndex i = 0; i < _glyphCount; i++) {
        CGGlyph glyph = _glyphs[i];
        CGPoint position = _positions[i];

        // Get the path for this glyph from the font
        CGPathRef glyphPath = CTFontCreatePathForGlyph(font, glyph, NULL);

        if (glyphPath) {
            // Create a transform to position the glyph
            // The position is relative to the run's origin
            CGAffineTransform transform = CGAffineTransformMakeTranslation(
                _frame.origin.x + position.x,
                _frame.origin.y + position.y
            );

            // Add the transformed glyph path to the combined path
            CGPathAddPath(combinedPath, &transform, glyphPath);

            // Release the individual glyph path
            CGPathRelease(glyphPath);
        }
    }

    return combinedPath;
}

/**
 * Creates a CGPath for a specific glyph.
 */
- (CGPathRef)newPathForGlyphAtIndex:(NSUInteger)index {
    [self extractGlyphs];

    if (!_ctRun || index >= _glyphCount) {
        return NULL;
    }

    // Get the font from attributes
    CTFontRef font = (__bridge CTFontRef)_attributes[(__bridge NSString *)kCTFontAttributeName];
    if (!font) {
        return NULL;
    }

    CGGlyph glyph = _glyphs[index];
    CGPoint position = _positions[index];

    // Get the path for this glyph
    CGPathRef glyphPath = CTFontCreatePathForGlyph(font, glyph, NULL);

    if (!glyphPath) {
        return NULL;
    }

    // Create a transform to position the glyph
    CGAffineTransform transform = CGAffineTransformMakeTranslation(
        _frame.origin.x + position.x,
        _frame.origin.y + position.y
    );

    // Create a new path with the transform applied
    CGMutablePathRef transformedPath = CGPathCreateMutable();
    CGPathAddPath(transformedPath, &transform, glyphPath);

    // Release the original glyph path
    CGPathRelease(glyphPath);

    return transformedPath;
}

/**
 * Creates a bounding path for all glyphs.
 */
- (CGPathRef)newBoundingPath {
    [self extractGlyphs];

    if (_glyphCount == 0) {
        return NULL;
    }

    // Create a simple rectangular path that bounds all glyphs
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, _frame);

    return path;
}

#pragma mark - Image Operations

/**
 * Returns the image for the glyph at the specified index.
 *
 * This is used for custom rendering where glyphs are replaced with images.
 */
- (UIImage *)imageForGlyphAtIndex:(NSUInteger)index {
    if (!_glyphImages || index >= [_glyphImages count]) {
        return nil;
    }

    return _glyphImages[index];
}

/**
 * Returns the bounding rect for the glyph image.
 */
- (CGRect)imageRectForGlyphAtIndex:(NSUInteger)index {
    [self extractGlyphs];

    if (index >= _glyphCount) {
        return CGRectNull;
    }

    CGPoint position = _positions[index];
    CGFloat advance = _advances[index];

    // The image rect is centered on the glyph position
    return CGRectMake(
        _frame.origin.x + position.x,
        _frame.origin.y,
        advance,
        _frame.size.height
    );
}

#pragma mark - Hit Testing

/**
 * Returns the glyph index at the given point.
 *
 * This method checks if the point falls within any glyph's bounding rect.
 *
 * @param point The point to test
 * @return The glyph index, or NSNotFound
 */
- (NSUInteger)glyphIndexAtPoint:(CGPoint)point {
    [self extractGlyphs];

    for (NSUInteger i = 0; i < _glyphCount; i++) {
        CGRect glyphRect = [self rectForGlyphAtIndex:i];

        if (CGRectContainsPoint(glyphRect, point)) {
            return i;
        }
    }

    return NSNotFound;
}

/**
 * Returns the string index at the given point.
 */
- (NSUInteger)stringIndexAtPoint:(CGPoint)point {
    NSUInteger glyphIndex = [self glyphIndexAtPoint:point];

    if (glyphIndex == NSNotFound) {
        return NSNotFound;
    }

    // Convert glyph index to string index
    // This assumes a 1:1 mapping between glyphs and characters
    // For complex scripts, this may need more sophisticated mapping
    return _stringRange.location + glyphIndex;
}

/**
 * Returns the rect for a given string index.
 */
- (CGRect)rectForStringIndex:(NSUInteger)index {
    if (index < _stringRange.location ||
        index >= _stringRange.location + _stringRange.length) {
        return CGRectNull;
    }

    // Convert string index to glyph index
    NSUInteger glyphIndex = index - _stringRange.location;

    return [self rectForGlyphAtIndex:glyphIndex];
}

#pragma mark - Drawing

/**
 * Draws this run into a CGContext.
 *
 * This method draws the glyphs using CTLineDraw or by manually
 * drawing each glyph at its position.
 *
 * @param context The CGContext to draw into
 */
- (void)drawInContext:(CGContextRef)context {
    if (!context || !_ctRun) {
        return;
    }

    // Save graphics state
    CGContextSaveGState(context);

    // Draw the run using CoreText
    CTRunDraw(_ctRun, context, CFRangeMake(0, 0));

    // Restore graphics state
    CGContextRestoreGState(context);
}

/**
 * Draws this run with a specific color.
 */
- (void)drawInContext:(CGContextRef)context withColor:(UIColor *)color {
    if (!context || !_ctRun || !color) {
        return;
    }

    // Save graphics state
    CGContextSaveGState(context);

    // Set the text color
    CGContextSetFillColorWithColor(context, color.CGColor);

    // Draw the run
    CTRunDraw(_ctRun, context, CFRangeMake(0, 0));

    // Restore graphics state
    CGContextRestoreGState(context);
}

/**
 * Draws the attachment (if any) into the context.
 */
- (void)drawAttachmentInContext:(CGContextRef)context {
    if (!context || !_attachment || !_attachment.image) {
        return;
    }

    // Save graphics state
    CGContextSaveGState(context);

    // Draw the attachment image at the run's frame
    CGContextDrawImage(context, _frame, _attachment.image.CGImage);

    // Restore graphics state
    CGContextRestoreGState(context);
}

#pragma mark - Run Comparison

/**
 * Compares this run to another run for ordering.
 */
- (NSComparisonResult)compareToRun:(DTCoreTextGlyphRun *)otherRun {
    // Compare by string range location
    if (_stringRange.location < otherRun.stringRange.location) {
        return NSOrderedAscending;
    } else if (_stringRange.location > otherRun.stringRange.location) {
        return NSOrderedDescending;
    }

    // If same location, compare by run index
    if (_runIndex < otherRun.runIndex) {
        return NSOrderedAscending;
    } else if (_runIndex > otherRun.runIndex) {
        return NSOrderedDescending;
    }

    return NSOrderedSame;
}

/**
 * Returns whether this run contains the given string index.
 */
- (BOOL)containsStringIndex:(NSUInteger)index {
    return index >= _stringRange.location &&
           index < _stringRange.location + _stringRange.length;
}

/**
 * Returns whether this run intersects with the given range.
 */
- (BOOL)intersectsRange:(NSRange)range {
    NSRange intersection = NSIntersectionRange(_stringRange, range);
    return intersection.length > 0;
}

#pragma mark - Metrics

- (void)calculateMetrics {
    if (_metricsCached || !_ctRun) {
        return;
    }

    [_lock lock];

    // Get typographic bounds from CTRun
    _cachedWidth = CTRunGetTypographicBounds(_ctRun, CFRangeMake(0, 0),
                                              &_cachedAscent, &_cachedDescent, &_cachedLeading);

    _metricsCached = YES;

    [_lock unlock];
}

- (CGFloat)getTypographicBoundsAscent:(CGFloat *)ascent
                              descent:(CGFloat *)descent
                              leading:(CGFloat *)leading {
    [self calculateMetrics];

    if (ascent) *ascent = _cachedAscent;
    if (descent) *descent = _cachedDescent;
    if (leading) *leading = _cachedLeading;

    return _cachedWidth;
}

- (CGRect)bounds {
    [self calculateMetrics];

    return CGRectMake(0, -_cachedDescent, _cachedWidth, _cachedAscent + _cachedDescent);
}

- (CGFloat)width {
    [self calculateMetrics];
    return _cachedWidth;
}

- (CGFloat)height {
    [self calculateMetrics];
    return _cachedAscent + _cachedDescent;
}

- (NSUInteger)numberOfGlyphs {
    [self extractGlyphs];
    return _glyphCount;
}

- (NSArray<NSNumber *> *)glyphs {
    [self extractGlyphs];

    NSMutableArray *glyphArray = [NSMutableArray arrayWithCapacity:_glyphCount];
    for (CFIndex i = 0; i < _glyphCount; i++) {
        [glyphArray addObject:@(_glyphs[i])];
    }

    return [glyphArray copy];
}

- (NSArray<NSValue *> *)glyphPositions {
    [self extractGlyphs];

    NSMutableArray *positionArray = [NSMutableArray arrayWithCapacity:_glyphCount];
    for (CFIndex i = 0; i < _glyphCount; i++) {
        [positionArray addObject:[NSValue valueWithCGPoint:_positions[i]]];
    }

    return [positionArray copy];
}

- (NSArray<NSNumber *> *)glyphAdvances {
    [self extractGlyphs];

    NSMutableArray *advanceArray = [NSMutableArray arrayWithCapacity:_glyphCount];
    for (CFIndex i = 0; i < _glyphCount; i++) {
        [advanceArray addObject:@(_advances[i])];
    }

    return [advanceArray copy];
}

- (BOOL)isRTL {
    return _writingDirection == kCTWritingDirectionRightToLeft;
}

- (BOOL)isWhitespace {
    if (!_ctRun || _glyphCount == 0) {
        return NO;
    }

    // Check if all characters in the range are whitespace
    // This would need access to the full attributed string
    // For now, return NO as a conservative default
    return NO;
}

- (BOOL)isNewline {
    if (!_ctRun || _glyphCount == 0) {
        return NO;
    }

    // Check if the run contains only newline characters
    // This would need access to the full attributed string
    return NO;
}

@end