/*
 * Copyright (C) 2006 Apple Computer, 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 COMPUTER, INC. ``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 COMPUTER, INC. OR
 * 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 "Pasteboard.h"

#import "CachedResource.h"
#import "ClipboardMac.h"
#import "DOMRangeInternal.h"
#import "Document.h"
#import "DocumentFragment.h"
#import "DocumentLoader.h"
#import "Editor.h"
#import "EditorClient.h"
#import "Frame.h"
#import "FrameView.h"
#import "FrameLoaderClient.h"
#import "HitTestResult.h"
#import "HTMLAnchorElement.h"
#import "HTMLConverter.h"
#import "htmlediting.h"
#import "HTMLNames.h"
#import "Image.h"
#import "KURL.h"
#import "LegacyWebArchive.h"
#import "LoaderNSURLExtras.h"
#import "MIMETypeRegistry.h"
#import "Page.h"
#import "RenderImage.h"
#import "Text.h"
#import "WebCoreNSStringExtras.h"
#import "WebNSAttributedStringExtras.h"
#import "markup.h"
#import <wtf/StdLibExtras.h>
#import <wtf/RetainPtr.h>
#import <wtf/UnusedParam.h>
#import <wtf/text/StringBuilder.h>
#import <wtf/unicode/CharacterNames.h>

#if USE(PLATFORM_STRATEGIES)
#include "PasteboardStrategy.h"
#include "PlatformStrategies.h"
#endif

namespace WebCore {

// FIXME: It's not great to have these both here and in WebKit.
const char* WebArchivePboardType = "Apple Web Archive pasteboard type";
const char* WebSmartPastePboardType = "NeXT smart paste pasteboard type";
const char* WebURLNamePboardType = "public.url-name";
const char* WebURLPboardType = "public.url";
const char* WebURLsWithTitlesPboardType = "WebURLsWithTitlesPboardType";

static Vector<String> selectionPasteboardTypes(bool canSmartCopyOrDelete, bool selectionContainsAttachments)
{
    Vector<String> types;
    if (canSmartCopyOrDelete)
        types.append(WebSmartPastePboardType);
    types.append(WebArchivePboardType);
    if (selectionContainsAttachments)
        types.append(String(NSRTFDPboardType));
    types.append(String(NSRTFPboardType));
    types.append(String(NSStringPboardType));

    return types;
}

static const Vector<String> writableTypesForURL()
{
    Vector<String> types;
    
    types.append(WebURLsWithTitlesPboardType);
    types.append(String(NSURLPboardType));
    types.append(WebURLPboardType);
    types.append(WebURLNamePboardType);
    types.append(String(NSStringPboardType));        
    return types;
}

static inline Vector<String> createWritableTypesForImage()
{
    Vector<String> types;
    
    types.append(String(NSTIFFPboardType));
    types.append(writableTypesForURL());
    types.append(String(NSRTFDPboardType));
    return types;
}

static Vector<String> writableTypesForImage()
{
    Vector<String> types;
    types.append(createWritableTypesForImage());
    return types;
}

Pasteboard* Pasteboard::generalPasteboard() 
{
    static Pasteboard* pasteboard = new Pasteboard(NSGeneralPboard);
    return pasteboard;
}

Pasteboard::Pasteboard(const String& pasteboardName)
    : m_pasteboardName(pasteboardName)
{
    ASSERT(pasteboardName);
}

void Pasteboard::clear()
{
    platformStrategies()->pasteboardStrategy()->setTypes(Vector<String>(), m_pasteboardName);
}

String Pasteboard::getStringSelection(Frame* frame)
{
    String text = frame->editor()->selectedText();
    text.replace(noBreakSpace, ' ');
    return text;
}

PassRefPtr<SharedBuffer> Pasteboard::getDataSelection(Frame* frame, const String& pasteboardType)
{
    if (pasteboardType == WebArchivePboardType) {
        RefPtr<LegacyWebArchive> archive = LegacyWebArchive::createFromSelection(frame);
        RetainPtr<CFDataRef> data = archive ? archive->rawDataRepresentation() : 0;
        return SharedBuffer::wrapNSData((NSData *)data.get());
    }

    ExceptionCode ec;
    RefPtr<Range> range = frame->editor()->selectedRange();
    Node* commonAncestor = range->commonAncestorContainer(ec);
    ASSERT(commonAncestor);
    Node* enclosingAnchor = enclosingNodeWithTag(firstPositionInNode(commonAncestor), HTMLNames::aTag);
    if (enclosingAnchor && comparePositions(firstPositionInOrBeforeNode(range->startPosition().anchorNode()), range->startPosition()) >= 0)
        range->setStart(enclosingAnchor, 0, ec);
    
    NSAttributedString* attributedString = nil;
    RetainPtr<WebHTMLConverter> converter(AdoptNS, [[WebHTMLConverter alloc] initWithDOMRange:kit(range.get())]);
    if (converter)
        attributedString = [converter.get() attributedString];
    
    if (pasteboardType == String(NSRTFDPboardType)) {
        NSData *RTFDData = [attributedString RTFDFromRange:NSMakeRange(0, [attributedString length]) documentAttributes:nil];
        return SharedBuffer::wrapNSData((NSData *)RTFDData);
    }
    if (pasteboardType == String(NSRTFPboardType)) {
        if ([attributedString containsAttachments])
            attributedString = attributedStringByStrippingAttachmentCharacters(attributedString);
        NSData *RTFData = [attributedString RTFFromRange:NSMakeRange(0, [attributedString length]) documentAttributes:nil];
        return SharedBuffer::wrapNSData((NSData *)RTFData);
    }
    return 0;
}

void Pasteboard::writeSelectionForTypes(const Vector<String>& pasteboardTypes, bool canSmartCopyOrDelete, Frame* frame)
{
    NSAttributedString* attributedString = nil;
    RetainPtr<WebHTMLConverter> converter(AdoptNS, [[WebHTMLConverter alloc] initWithDOMRange:kit(frame->editor()->selectedRange().get())]);
    if (converter)
        attributedString = [converter.get() attributedString];
    
    const Vector<String> types = !pasteboardTypes.isEmpty() ? pasteboardTypes : selectionPasteboardTypes(canSmartCopyOrDelete, [attributedString containsAttachments]);
    platformStrategies()->pasteboardStrategy()->setTypes(types, m_pasteboardName);
    frame->editor()->client()->didSetSelectionTypesForPasteboard();
    
    // Put HTML on the pasteboard.
    if (types.contains(WebArchivePboardType))
        platformStrategies()->pasteboardStrategy()->setBufferForType(getDataSelection(frame, WebArchivePboardType), WebArchivePboardType, m_pasteboardName);
    
    // Put the attributed string on the pasteboard (RTF/RTFD format).
    if (types.contains(String(NSRTFDPboardType)))
        platformStrategies()->pasteboardStrategy()->setBufferForType(getDataSelection(frame, NSRTFDPboardType), NSRTFDPboardType, m_pasteboardName);

    if (types.contains(String(NSRTFPboardType)))
        platformStrategies()->pasteboardStrategy()->setBufferForType(getDataSelection(frame, NSRTFPboardType), NSRTFPboardType, m_pasteboardName);
    
    // Put plain string on the pasteboard.
    if (types.contains(String(NSStringPboardType)))
        platformStrategies()->pasteboardStrategy()->setStringForType(getStringSelection(frame), NSStringPboardType, m_pasteboardName);
    
    if (types.contains(WebSmartPastePboardType))
        platformStrategies()->pasteboardStrategy()->setBufferForType(0, WebSmartPastePboardType, m_pasteboardName);
}

void Pasteboard::writePlainText(const String& text)
{
    Vector<String> types;
    types.append(NSStringPboardType);
    platformStrategies()->pasteboardStrategy()->setTypes(types, m_pasteboardName);
    platformStrategies()->pasteboardStrategy()->setStringForType(text, NSStringPboardType, m_pasteboardName);
}
    
void Pasteboard::writeSelection(Range*, bool canSmartCopyOrDelete, Frame* frame)
{
    writeSelectionForTypes(Vector<String>(), canSmartCopyOrDelete, frame);
}

static void writeURLForTypes(const Vector<String>& types, const String& pasteboardName, const KURL& url, const String& titleStr, Frame* frame)
{
    platformStrategies()->pasteboardStrategy()->setTypes(types, pasteboardName);
    
    ASSERT(!url.isEmpty());
    
    NSURL *cocoaURL = url;
    NSString *userVisibleString = frame->editor()->client()->userVisibleString(cocoaURL);
    
    NSString *title = (NSString*)titleStr;
    if ([title length] == 0) {
        title = [[cocoaURL path] lastPathComponent];
        if ([title length] == 0)
            title = userVisibleString;
    }
    if (types.contains(WebURLsWithTitlesPboardType)) {
        Vector<String> paths;
        paths.append([cocoaURL absoluteString]);
        paths.append(titleStr.stripWhiteSpace());
        platformStrategies()->pasteboardStrategy()->setPathnamesForType(paths, WebURLsWithTitlesPboardType, pasteboardName);
    }
    if (types.contains(String(NSURLPboardType)))
        platformStrategies()->pasteboardStrategy()->setStringForType([cocoaURL absoluteString], NSURLPboardType, pasteboardName);
    if (types.contains(WebURLPboardType))
        platformStrategies()->pasteboardStrategy()->setStringForType(userVisibleString, WebURLPboardType, pasteboardName);
    if (types.contains(WebURLNamePboardType))
        platformStrategies()->pasteboardStrategy()->setStringForType(title, WebURLNamePboardType, pasteboardName);
    if (types.contains(String(NSStringPboardType)))
        platformStrategies()->pasteboardStrategy()->setStringForType(userVisibleString, NSStringPboardType, pasteboardName);
}
    
void Pasteboard::writeURL(const KURL& url, const String& titleStr, Frame* frame)
{
    writeURLForTypes(writableTypesForURL(), m_pasteboardName, url, titleStr, frame);
}

static NSFileWrapper* fileWrapperForImage(CachedResource* resource, NSURL *url)
{
    SharedBuffer* coreData = resource->data();
    NSData *data = [[[NSData alloc] initWithBytes:coreData->data() length:coreData->size()] autorelease];
    NSFileWrapper *wrapper = [[[NSFileWrapper alloc] initRegularFileWithContents:data] autorelease];
    String coreMIMEType = resource->response().mimeType();
    NSString *MIMEType = nil;
    if (!coreMIMEType.isNull())
        MIMEType = coreMIMEType;
    [wrapper setPreferredFilename:suggestedFilenameWithMIMEType(url, MIMEType)];
    return wrapper;
}

static void writeFileWrapperAsRTFDAttachment(NSFileWrapper* wrapper, const String& pasteboardName)
{
    NSTextAttachment *attachment = [[NSTextAttachment alloc] initWithFileWrapper:wrapper];
    
    NSAttributedString *string = [NSAttributedString attributedStringWithAttachment:attachment];
    [attachment release];
    
    NSData *RTFDData = [string RTFDFromRange:NSMakeRange(0, [string length]) documentAttributes:nil];
    platformStrategies()->pasteboardStrategy()->setBufferForType(SharedBuffer::wrapNSData((NSData *)RTFDData).get(), NSRTFDPboardType, pasteboardName);
}

void Pasteboard::writeImage(Node* node, const KURL& url, const String& title)
{
    ASSERT(node);

    if (!(node->renderer() && node->renderer()->isImage()))
        return;

    NSURL *cocoaURL = url;
    ASSERT(cocoaURL);

    RenderImage* renderer = toRenderImage(node->renderer());
    CachedImage* cachedImage = renderer->cachedImage();
    if (!cachedImage || cachedImage->errorOccurred())
        return;

    writeURLForTypes(writableTypesForImage(), m_pasteboardName, cocoaURL, nsStringNilIfEmpty(title), node->document()->frame());
    
    Image* image = cachedImage->imageForRenderer(renderer);
    ASSERT(image);
    
    platformStrategies()->pasteboardStrategy()->setBufferForType(SharedBuffer::wrapNSData((NSData *)[image->getNSImage() TIFFRepresentation]), NSTIFFPboardType, m_pasteboardName);

    String MIMEType = cachedImage->response().mimeType();
    ASSERT(MIMETypeRegistry::isSupportedImageResourceMIMEType(MIMEType));

    writeFileWrapperAsRTFDAttachment(fileWrapperForImage(cachedImage, cocoaURL), m_pasteboardName);
}

void Pasteboard::writeClipboard(Clipboard* clipboard)
{
    platformStrategies()->pasteboardStrategy()->copy(static_cast<ClipboardMac*>(clipboard)->pasteboardName(), m_pasteboardName);
}

bool Pasteboard::canSmartReplace()
{
    Vector<String> types;
    platformStrategies()->pasteboardStrategy()->getTypes(types, m_pasteboardName);
    return types.contains(WebSmartPastePboardType);
}

String Pasteboard::plainText(Frame* frame)
{
    Vector<String> types;
    platformStrategies()->pasteboardStrategy()->getTypes(types, m_pasteboardName);
    
    if (types.contains(String(NSStringPboardType)))
        return [(NSString *)platformStrategies()->pasteboardStrategy()->stringForType(NSStringPboardType, m_pasteboardName) precomposedStringWithCanonicalMapping];
    
    NSAttributedString *attributedString = nil;
    NSString *string;

    if (types.contains(String(NSRTFDPboardType))) {
        RefPtr<SharedBuffer> data = platformStrategies()->pasteboardStrategy()->bufferForType(NSRTFDPboardType, m_pasteboardName);
        attributedString = [[NSAttributedString alloc] initWithRTFD:[data->createNSData() autorelease] documentAttributes:NULL];
    }
    if (attributedString == nil && types.contains(String(NSRTFPboardType))) {
        RefPtr<SharedBuffer> data = platformStrategies()->pasteboardStrategy()->bufferForType(NSRTFPboardType, m_pasteboardName);
        attributedString = [[NSAttributedString alloc] initWithRTF:[data->createNSData() autorelease] documentAttributes:NULL];
    }
    if (attributedString != nil) {
        string = [[attributedString string] precomposedStringWithCanonicalMapping];
        [attributedString release];
        return string;
    }
    
    if (types.contains(String(NSFilenamesPboardType))) {
        Vector<String> pathnames;
        platformStrategies()->pasteboardStrategy()->getPathnamesForType(pathnames, NSFilenamesPboardType, m_pasteboardName);
        StringBuilder builder;
        for (size_t i = 0; i < pathnames.size(); i++)
            builder.append(i ? "\n" + pathnames[i] : pathnames[i]);
        string = builder.toString();
        return [string precomposedStringWithCanonicalMapping];
    }
    
    string = platformStrategies()->pasteboardStrategy()->stringForType(NSURLPboardType, m_pasteboardName);
    if ([string length]) {
        // FIXME: using the editorClient to call into webkit, for now, since 
        // calling _web_userVisibleString from WebCore involves migrating a sizable web of 
        // helper code that should either be done in a separate patch or figured out in another way.
        string = frame->editor()->client()->userVisibleString([NSURL URLWithString:string]);
        if ([string length] > 0)
            return [string precomposedStringWithCanonicalMapping];
    }

    
    return String(); 
}
    
static PassRefPtr<DocumentFragment> documentFragmentWithImageResource(Frame* frame, PassRefPtr<ArchiveResource> resource)
{
    if (!resource)
        return 0;
    
    if (DocumentLoader* loader = frame->loader()->documentLoader())
        loader->addArchiveResource(resource.get());

    RefPtr<Element> imageElement = frame->document()->createElement(HTMLNames::imgTag, false);
    if (!imageElement)
        return 0;

    NSURL *URL = resource->url();
    imageElement->setAttribute(HTMLNames::srcAttr, [URL isFileURL] ? [URL absoluteString] : resource->url());
    RefPtr<DocumentFragment> fragment = frame->document()->createDocumentFragment();
    if (fragment) {
        ExceptionCode ec;
        fragment->appendChild(imageElement, ec);
        return fragment.release();       
    }
    return 0;
}

static PassRefPtr<DocumentFragment> documentFragmentWithRTF(Frame* frame, NSString *pasteboardType,const String& pastebordName)
{
    if (!frame || !frame->document() || !frame->document()->isHTMLDocument())
        return 0;

    NSAttributedString *string = nil;
    if (pasteboardType == NSRTFDPboardType) {
        RefPtr<SharedBuffer> data = platformStrategies()->pasteboardStrategy()->bufferForType(NSRTFDPboardType, pastebordName);
        string = [[NSAttributedString alloc] initWithRTFD:[data->createNSData() autorelease] documentAttributes:NULL];
    }
    if (string == nil) {
        RefPtr<SharedBuffer> data = platformStrategies()->pasteboardStrategy()->bufferForType(NSRTFPboardType, pastebordName);
        string = [[NSAttributedString alloc] initWithRTF:[data->createNSData() autorelease] documentAttributes:NULL];
    }
    if (string == nil)
        return nil;

    bool wasDeferringCallbacks = frame->page()->defersLoading();
    if (!wasDeferringCallbacks)
        frame->page()->setDefersLoading(true);

    Vector<RefPtr<ArchiveResource> > resources;
    RefPtr<DocumentFragment> fragment = frame->editor()->client()->documentFragmentFromAttributedString(string, resources);

    size_t size = resources.size();
    if (size) {
        DocumentLoader* loader = frame->loader()->documentLoader();
        for (size_t i = 0; i < size; ++i)
            loader->addArchiveResource(resources[i]);    
    }

    if (!wasDeferringCallbacks)
        frame->page()->setDefersLoading(false);

    [string release];
    return fragment.release();
}

#define WebDataProtocolScheme @"webkit-fake-url"

static NSURL* uniqueURLWithRelativePart(NSString *relativePart)
{
    CFUUIDRef UUIDRef = CFUUIDCreate(kCFAllocatorDefault);
    NSString *UUIDString = (NSString *)CFUUIDCreateString(kCFAllocatorDefault, UUIDRef);
    CFRelease(UUIDRef);
    NSURL *URL = [NSURL URLWithString:[NSString stringWithFormat:@"%@://%@/%@", WebDataProtocolScheme, UUIDString, relativePart]];
    CFRelease(UUIDString);

    return URL;
}

PassRefPtr<DocumentFragment> Pasteboard::documentFragment(Frame* frame, PassRefPtr<Range> context, bool allowPlainText, bool& chosePlainText)
{
    Vector<String> types;
    platformStrategies()->pasteboardStrategy()->getTypes(types, m_pasteboardName);
    RefPtr<DocumentFragment> fragment;
    chosePlainText = false;

    if (types.contains(WebArchivePboardType)) {
        RefPtr<LegacyWebArchive> coreArchive = LegacyWebArchive::create(KURL(), platformStrategies()->pasteboardStrategy()->bufferForType(WebArchivePboardType, m_pasteboardName).get());
        if (coreArchive) {
            RefPtr<ArchiveResource> mainResource = coreArchive->mainResource();
            if (mainResource) {
                NSString *MIMEType = mainResource->mimeType();
                if (!frame || !frame->document())
                    return 0;
                if (frame->loader()->client()->canShowMIMETypeAsHTML(MIMEType)) {
                    NSString *markupString = [[NSString alloc] initWithData:[mainResource->data()->createNSData() autorelease] encoding:NSUTF8StringEncoding];
                    // FIXME: seems poor form to do this as a side effect of getting a document fragment
                    if (DocumentLoader* loader = frame->loader()->documentLoader())
                        loader->addAllArchiveResources(coreArchive.get());
                    
                    fragment = createFragmentFromMarkup(frame->document(), markupString, mainResource->url(), DisallowScriptingContent);
                    [markupString release];
                } else if (MIMETypeRegistry::isSupportedImageMIMEType(MIMEType))
                   fragment = documentFragmentWithImageResource(frame, mainResource);                    
            }
        }
        if (fragment)
            return fragment.release();
    } 

    if (types.contains(String(NSFilenamesPboardType))) {
        Vector<String> paths;
        platformStrategies()->pasteboardStrategy()->getPathnamesForType(paths, NSFilenamesPboardType, m_pasteboardName);
        Vector< RefPtr<Node> > refNodesVector;
        Vector<Node*> nodesVector;

        for (size_t i = 0; i < paths.size(); i++) {
            // Non-image file types; _web_userVisibleString is appropriate here because this will
            // be pasted as visible text.
            NSString *url = frame->editor()->client()->userVisibleString([NSURL fileURLWithPath:paths[i]]);
            RefPtr<Node> textNode = frame->document()->createTextNode(url);
            refNodesVector.append(textNode.get());
            nodesVector.append(textNode.get());
        }
        fragment = createFragmentFromNodes(frame->document(), nodesVector);
        if (fragment && fragment->firstChild())
            return fragment.release();
    }

    if (types.contains(String(NSHTMLPboardType))) {
        NSString *HTMLString = platformStrategies()->pasteboardStrategy()->stringForType(NSHTMLPboardType, m_pasteboardName);
        // This is a hack to make Microsoft's HTML pasteboard data work. See 3778785.
        if ([HTMLString hasPrefix:@"Version:"]) {
            NSRange range = [HTMLString rangeOfString:@"<html" options:NSCaseInsensitiveSearch];
            if (range.location != NSNotFound) {
                HTMLString = [HTMLString substringFromIndex:range.location];
            }
        }
        if ([HTMLString length] != 0 &&
            (fragment = createFragmentFromMarkup(frame->document(), HTMLString, "", DisallowScriptingContent)))
            return fragment.release();
    }

    if (types.contains(String(NSRTFDPboardType)) &&
        (fragment = documentFragmentWithRTF(frame, NSRTFDPboardType, m_pasteboardName)))
       return fragment.release();

    if (types.contains(String(NSRTFPboardType)) &&
        (fragment = documentFragmentWithRTF(frame, NSRTFPboardType, m_pasteboardName)))
        return fragment.release();

    if (types.contains(String(NSTIFFPboardType)) &&
        (fragment = documentFragmentWithImageResource(frame, ArchiveResource::create(platformStrategies()->pasteboardStrategy()->bufferForType(NSTIFFPboardType, m_pasteboardName), uniqueURLWithRelativePart(@"image.tiff"), "image/tiff", "", ""))))
        return fragment.release();

    if (types.contains(String(NSPDFPboardType)) &&
        (fragment = documentFragmentWithImageResource(frame, ArchiveResource::create(platformStrategies()->pasteboardStrategy()->bufferForType(NSPDFPboardType, m_pasteboardName).get(), uniqueURLWithRelativePart(@"application.pdf"), "application/pdf", "", ""))))
        return fragment.release();

    if (types.contains(String(kUTTypePNG)) &&
        (fragment = documentFragmentWithImageResource(frame, ArchiveResource::create(platformStrategies()->pasteboardStrategy()->bufferForType(String(kUTTypePNG), m_pasteboardName), uniqueURLWithRelativePart(@"image.png"), "image/png", "", ""))))
        return fragment.release();

    if (types.contains(String(NSURLPboardType))) {
        NSURL *URL = platformStrategies()->pasteboardStrategy()->url(m_pasteboardName);
        Document* document = frame->document();
        ASSERT(document);
        if (!document)
            return 0;
        RefPtr<Element> anchor = document->createElement(HTMLNames::aTag, false);
        NSString *URLString = [URL absoluteString]; // Original data is ASCII-only, so there is no need to precompose.
        if ([URLString length] == 0)
            return nil;
        NSString *URLTitleString = [platformStrategies()->pasteboardStrategy()->stringForType(WebURLNamePboardType, m_pasteboardName) precomposedStringWithCanonicalMapping];
        ExceptionCode ec;
        anchor->setAttribute(HTMLNames::hrefAttr, URLString);
        anchor->appendChild(document->createTextNode(URLTitleString), ec);
        fragment = document->createDocumentFragment();
        if (fragment) {
            fragment->appendChild(anchor, ec);
            return fragment.release();
        }
    }

    if (allowPlainText && types.contains(String(NSStringPboardType))) {
        chosePlainText = true;
        fragment = createFragmentFromText(context.get(), [platformStrategies()->pasteboardStrategy()->stringForType(NSStringPboardType, m_pasteboardName) precomposedStringWithCanonicalMapping]);
        return fragment.release();
    }

    return 0;
}

}
