//
//  PDFThumbnailViewController.m
//  PDFReader
//
//  Copyright © 2014-2022 PDF Technologies, Inc. All Rights Reserved.
//
//  The PDF Reader Sample applications are licensed with a modified BSD license.
//  Please see License for details. This notice may not be removed from this file.
//

#import "PDFThumbnailViewController.h"

@interface PDFThumbnailView : UIView

@property (nonatomic,assign) CGPDFPageRef pageRef;

@end

@implementation PDFThumbnailView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
        tiledLayer.levelsOfDetail = 4;
        tiledLayer.levelsOfDetailBias = 4;
        tiledLayer.tileSize = CGSizeMake(1024.0, 1024.0);
    }
    return self;
}

- (void)dealloc {
    CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
    tiledLayer.contents = nil;
    tiledLayer.delegate = nil;
    [tiledLayer removeFromSuperlayer];
    [super dealloc];
}

+ (Class)layerClass {
    return [CATiledLayer class];
}

+ (CFTimeInterval)fadeDuration {
    return 0.0;
}

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];
    
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 1.0);
    CGContextFillRect(context, CGContextGetClipBoundingBox(context));
    CGContextSaveGState(context);
    
    if (!self.pageRef) {
        return;
    }
    
    CGAffineTransform transform = CGPDFPageGetDrawingTransform(self.pageRef,
                                                               kCGPDFCropBox,
                                                               self.bounds,
                                                               0,
                                                               true);
    CGContextSaveGState(context);
    CGContextTranslateCTM(context, 0, rect.size.height);
    CGContextScaleCTM(context, 1, -1);
    CGContextConcatCTM(context, transform);
    CGContextSetInterpolationQuality(context, kCGInterpolationLow);
    CGContextSetRenderingIntent(context, kCGRenderingIntentDefault);
    CGContextSetShouldAntialias(context, NO);
    CGContextSetShouldSmoothFonts(context, NO);
    CGContextDrawPDFPage(context, self.pageRef);
    CGContextRestoreGState(context);
}

@end


@interface PDFThumbnailViewCell : UICollectionViewCell {
    PDFThumbnailView *_thumbnailView;
}

@property (nonatomic,retain) UILabel *textLabel;

- (void)setPageRef:(CGPDFPageRef)pageRef;

@end

@implementation PDFThumbnailViewCell

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _thumbnailView = [[PDFThumbnailView alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height-12)];
        _thumbnailView.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
        _thumbnailView.clipsToBounds = YES;
        _thumbnailView.layer.borderWidth = 1.0;
        _thumbnailView.layer.borderColor = [UIColor colorWithRed:214.0/255.0 green:214.0/255.0 blue:214.0/255.0 alpha:1.0].CGColor;
        [self.contentView addSubview:_thumbnailView];
        
        _textLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, frame.size.height-12, frame.size.width, 12)];
        _textLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleTopMargin;
        _textLabel.textAlignment = NSTextAlignmentCenter;
        _textLabel.font = [UIFont systemFontOfSize:10];
        _textLabel.textColor = [UIColor blackColor];
        [self.contentView addSubview:_textLabel];
    }
    return self;
}

- (void)dealloc {
    [_thumbnailView release];
    [_textLabel release];
    [super dealloc];
}

- (void)setPageRef:(CGPDFPageRef)pageRef {
    CGRect boxRect = CGRectZero;
    if (pageRef) {
        boxRect = CGPDFPageGetBoxRect(pageRef, kCGPDFCropBox);
        CGRect displayBounds = CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height-12);
        CGAffineTransform transform = CGPDFPageGetDrawingTransform(pageRef,
                                                                   kCGPDFCropBox,
                                                                   displayBounds,
                                                                   0,
                                                                   true);
        boxRect = CGRectApplyAffineTransform(boxRect, transform);
    }
    _thumbnailView.frame = boxRect;
    _thumbnailView.pageRef = pageRef;
    [_thumbnailView setNeedsDisplay];
}

- (void)setSelected:(BOOL)selected {
    [super setSelected:selected];
    if (selected) {
        _thumbnailView.layer.borderWidth = 1.0;
        _thumbnailView.layer.borderColor = [UIColor colorWithRed:0.0 green:124.0/255.0 blue:1.0 alpha:1.0].CGColor;
        self.textLabel.textColor = [UIColor colorWithRed:0.0 green:124.0/255.0 blue:1.0 alpha:1.0];
    } else {
        _thumbnailView.layer.borderWidth = 1.0;
        _thumbnailView.layer.borderColor = [UIColor colorWithRed:214.0/255.0 green:214.0/255.0 blue:214.0/255.0 alpha:1.0].CGColor;
        self.textLabel.textColor = [UIColor blackColor];
    }
}

@end


@interface PDFThumbnailViewController () <UICollectionViewDelegate,UICollectionViewDataSource> {
    CGPDFDocumentRef _documentRef;
}

@property (nonatomic,retain) UICollectionView *collectionView;

@end

@implementation PDFThumbnailViewController

#pragma mark - Init Methods

- (void)dealloc {
    if (_documentRef) {
        CGPDFDocumentRelease(_documentRef);
    }
    _collectionView.delegate = nil;
    _collectionView.dataSource = nil;
    [_collectionView release];
    [super dealloc];
}

#pragma mark - UIViewController Methods

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // Do any additional setup after loading the view.
    UICollectionViewFlowLayout *layout = [[[UICollectionViewFlowLayout alloc] init] autorelease];
    layout.itemSize = CGSizeMake(70, 95);
    layout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5);
    layout.minimumInteritemSpacing = 5;
    layout.minimumLineSpacing = 5;
    
    self.collectionView = [[[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout] autorelease];
    [self.collectionView registerClass:[PDFThumbnailViewCell class] forCellWithReuseIdentifier:@"cell"];
    self.collectionView.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
    self.collectionView.delegate = self;
    self.collectionView.dataSource = self;
    self.collectionView.backgroundColor = [UIColor clearColor];
    self.collectionView.alwaysBounceVertical = YES;
    if (@available(iOS 11.0, *)) {
        self.collectionView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentAlways;
    }
    [self.view addSubview:self.collectionView];
    
    NSURL *documentURL = [self.pdfViewController.pdfView.document documentURL];
    if (documentURL) {
        _documentRef = CGPDFDocumentCreateWithURL((CFURLRef)documentURL);
        if ([self.pdfViewController.pdfView.document password]) {
            CGPDFDocumentUnlockWithPassword(_documentRef, [[self.pdfViewController.pdfView.document password] UTF8String]);
        }
    } else {
        _documentRef = NULL;
    }
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    
    [self.collectionView reloadData];
    NSInteger pageIndex = [self.pdfViewController.pdfView currentPageIndex];
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:pageIndex inSection:0];
    [self.collectionView selectItemAtIndexPath:indexPath
                                      animated:NO
                                scrollPosition:UICollectionViewScrollPositionCenteredVertically];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    
    NSInteger pageIndex = [self.pdfViewController.pdfView currentPageIndex];
    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:pageIndex inSection:0];
    [self.collectionView scrollToItemAtIndexPath:indexPath
                                atScrollPosition:UICollectionViewScrollPositionCenteredVertically
                                        animated:YES];
}

#pragma mark - UICollectionViewDataSource

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return CGPDFDocumentGetNumberOfPages(_documentRef);
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    PDFThumbnailViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
    CGPDFPageRef pageRef = CGPDFDocumentGetPage(_documentRef, indexPath.item+1);
    [cell setPageRef:pageRef];
    cell.textLabel.text = [NSString stringWithFormat:@"%@",@(indexPath.item+1)];
    return cell;
}

#pragma mark - UICollectionViewDelegate

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
    [self dismissViewControllerAnimated:YES completion:^{
        [self.pdfViewController.pdfView goToPageIndex:indexPath.item animated:NO];
    }];
}

@end