/*
 * Copyright (C) 2014 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#import "config.h"
#import "WKPDFView.h"

#if PLATFORM(IOS)

#import <CoreGraphics/CGPDFDocumentPrivate.h>
#import <CorePDF/UIPDFDocument.h>
#import <CorePDF/UIPDFPageView.h>
#import <WebCore/FloatRect.h>
#import <wtf/RetainPtr.h>
#import <wtf/Vector.h>

using namespace WebCore;

const CGFloat pdfPageMargin = 8;
const CGFloat pdfMinimumZoomScale = 1;
const CGFloat pdfMaximumZoomScale = 5;

const float overdrawHeightMultiplier = 1.5;

typedef struct {
    CGRect frame;
    RetainPtr<UIPDFPageView> view;
    RetainPtr<UIPDFPage> page;
} PDFPageInfo;

@implementation WKPDFView {
    RetainPtr<UIPDFDocument> _pdfDocument;
    RetainPtr<NSString> _suggestedFilename;

    Vector<PDFPageInfo> _pages;
    CGRect _documentFrame;

    CGSize _minimumSize;
    UIScrollView *_scrollView;
}

- (instancetype)initWithFrame:(CGRect)frame
{
    if (!(self = [super initWithFrame:frame]))
        return nil;

    self.backgroundColor = [UIColor grayColor];

    return self;
}

- (NSData *)documentData
{    
    return [(NSData *)CGDataProviderCopyData(CGPDFDocumentGetDataProvider([_pdfDocument CGDocument])) autorelease];
}

- (NSString *)suggestedFilename
{
    return _suggestedFilename.get();
}

- (void)web_setContentProviderData:(NSData *)data suggestedFilename:(NSString *)filename
{
    _suggestedFilename = adoptNS([filename copy]);

    for (auto& page : _pages)
        [page.view removeFromSuperview];

    _pages.clear();

    RetainPtr<CGDataProvider> dataProvider = adoptCF(CGDataProviderCreateWithCFData((CFDataRef)data));
    RetainPtr<CGPDFDocumentRef> cgPDFDocument = adoptCF(CGPDFDocumentCreateWithProvider(dataProvider.get()));
    _pdfDocument = adoptNS([[UIPDFDocument alloc] initWithCGPDFDocument:cgPDFDocument.get()]);

    [self _computePageAndDocumentFrames];
    [self _revalidateViews];
}

- (void)web_setMinimumSize:(CGSize)size
{
    _minimumSize = size;

    [self _computePageAndDocumentFrames];
    [self _revalidateViews];
}

- (void)web_setScrollView:(UIScrollView *)scrollView
{
    _scrollView = scrollView;

    [_scrollView setMinimumZoomScale:pdfMinimumZoomScale];
    [_scrollView setMaximumZoomScale:pdfMaximumZoomScale];
    [_scrollView setContentSize:_documentFrame.size];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if (scrollView.isZoomBouncing)
        return;

    [self _revalidateViews];
}

- (void)_revalidateViews
{
    CGRect targetRect = [_scrollView convertRect:_scrollView.bounds toView:self];

    // We apply overdraw after applying scale in order to avoid excessive
    // memory use caused by scaling the overdraw.
    targetRect = CGRectInset(targetRect, 0, -targetRect.size.height * overdrawHeightMultiplier);

    for (auto& pageInfo : _pages) {
        if (!CGRectIntersectsRect(pageInfo.frame, targetRect)) {
            [pageInfo.view removeFromSuperview];
            pageInfo.view = nullptr;
            continue;
        }

        if (pageInfo.view)
            continue;

        pageInfo.view = adoptNS([[UIPDFPageView alloc] initWithPage:pageInfo.page.get() tiledContent:YES]);
        [pageInfo.view setUseBackingLayer:YES];
        [self addSubview:pageInfo.view.get()];

        [pageInfo.view setFrame:pageInfo.frame];
        [pageInfo.view contentLayer].contentsScale = self.window.screen.scale;
    }
}

- (void)_computePageAndDocumentFrames
{
    NSUInteger pageCount = [_pdfDocument numberOfPages];

    for (auto& pageInfo : _pages)
        [pageInfo.view removeFromSuperview];

    _pages.clear();
    _pages.reserveCapacity(pageCount);

    CGRect pageFrame = CGRectMake(0, 0, _minimumSize.width, _minimumSize.height);
    for (NSUInteger pageNumber = 0; pageNumber < pageCount; ++pageNumber) {
        UIPDFPage *page = [_pdfDocument pageAtIndex:pageNumber];
        if (!page)
            continue;

        CGSize pageSize = [page size];
        pageFrame.size.height = pageSize.height / pageSize.width * pageFrame.size.width;
        CGRect pageFrameWithMarginApplied = CGRectInset(pageFrame, pdfPageMargin, pdfPageMargin);

        PDFPageInfo pageInfo;
        pageInfo.page = page;
        pageInfo.frame = pageFrameWithMarginApplied;
        _pages.append(pageInfo);
        pageFrame.origin.y += pageFrame.size.height - pdfPageMargin;
    }

    _documentFrame = [self frame];
    _documentFrame.size.width = _minimumSize.width;
    _documentFrame.size.height = std::max(pageFrame.origin.y + pdfPageMargin, _minimumSize.height);

    [self setFrame:_documentFrame];
    [_scrollView setContentSize:_documentFrame.size];
}

@end

#endif /* PLATFORM(IOS) */