/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "platform/mhtml/MHTMLParser.h"

#include "platform/MIMETypeRegistry.h"
#include "platform/mhtml/MHTMLArchive.h"
#include "platform/network/ParsedContentType.h"
#include "platform/text/QuotedPrintable.h"
#include "wtf/HashMap.h"
#include "wtf/RefCounted.h"
#include "wtf/text/Base64.h"
#include "wtf/text/StringBuilder.h"
#include "wtf/text/StringConcatenate.h"
#include "wtf/text/StringHash.h"
#include "wtf/text/WTFString.h"

namespace WebCore {

// This class is a limited MIME parser used to parse the MIME headers of MHTML files.
class MIMEHeader : public RefCounted<MIMEHeader> {
public:
    enum Encoding {
        QuotedPrintable,
        Base64,
        EightBit,
        SevenBit,
        Binary,
        Unknown
    };

    static PassRefPtr<MIMEHeader> parseHeader(SharedBufferChunkReader* crLFLineReader);

    bool isMultipart() const { return m_contentType.startsWith("multipart/"); }

    String contentType() const { return m_contentType; }
    String charset() const { return m_charset; }
    Encoding contentTransferEncoding() const { return m_contentTransferEncoding; }
    String contentLocation() const { return m_contentLocation; }

    // Multi-part type and boundaries are only valid for multipart MIME headers.
    String multiPartType() const { return m_multipartType; }
    String endOfPartBoundary() const { return m_endOfPartBoundary; }
    String endOfDocumentBoundary() const { return m_endOfDocumentBoundary; }

private:
    MIMEHeader();

    static Encoding parseContentTransferEncoding(const String&);

    String m_contentType;
    String m_charset;
    Encoding m_contentTransferEncoding;
    String m_contentLocation;
    String m_multipartType;
    String m_endOfPartBoundary;
    String m_endOfDocumentBoundary;
};

typedef HashMap<String, String> KeyValueMap;

static KeyValueMap retrieveKeyValuePairs(WebCore::SharedBufferChunkReader* buffer)
{
    KeyValueMap keyValuePairs;
    String line;
    String key;
    StringBuilder value;
    while (!(line = buffer->nextChunkAsUTF8StringWithLatin1Fallback()).isNull()) {
        if (line.isEmpty())
            break; // Empty line means end of key/value section.
        if (line[0] == '\t') {
            ASSERT(!key.isEmpty());
            value.append(line.substring(1));
            continue;
        }
        // New key/value, store the previous one if any.
        if (!key.isEmpty()) {
            if (keyValuePairs.find(key) != keyValuePairs.end())
                WTF_LOG_ERROR("Key duplicate found in MIME header. Key is '%s', previous value replaced.", key.ascii().data());
            keyValuePairs.add(key, value.toString().stripWhiteSpace());
            key = String();
            value.clear();
        }
        size_t semiColonIndex = line.find(':');
        if (semiColonIndex == kNotFound) {
            // This is not a key value pair, ignore.
            continue;
        }
        key = line.substring(0, semiColonIndex).lower().stripWhiteSpace();
        value.append(line.substring(semiColonIndex + 1));
    }
    // Store the last property if there is one.
    if (!key.isEmpty())
        keyValuePairs.set(key, value.toString().stripWhiteSpace());
    return keyValuePairs;
}

PassRefPtr<MIMEHeader> MIMEHeader::parseHeader(SharedBufferChunkReader* buffer)
{
    RefPtr<MIMEHeader> mimeHeader = adoptRef(new MIMEHeader);
    KeyValueMap keyValuePairs = retrieveKeyValuePairs(buffer);
    KeyValueMap::iterator mimeParametersIterator = keyValuePairs.find("content-type");
    if (mimeParametersIterator != keyValuePairs.end()) {
        ParsedContentType parsedContentType(mimeParametersIterator->value);
        mimeHeader->m_contentType = parsedContentType.mimeType();
        if (!mimeHeader->isMultipart()) {
            mimeHeader->m_charset = parsedContentType.charset().stripWhiteSpace();
        } else {
            mimeHeader->m_multipartType = parsedContentType.parameterValueForName("type");
            mimeHeader->m_endOfPartBoundary = parsedContentType.parameterValueForName("boundary");
            if (mimeHeader->m_endOfPartBoundary.isNull()) {
                WTF_LOG_ERROR("No boundary found in multipart MIME header.");
                return nullptr;
            }
            mimeHeader->m_endOfPartBoundary.insert("--", 0);
            mimeHeader->m_endOfDocumentBoundary = mimeHeader->m_endOfPartBoundary;
            mimeHeader->m_endOfDocumentBoundary.append("--");
        }
    }

    mimeParametersIterator = keyValuePairs.find("content-transfer-encoding");
    if (mimeParametersIterator != keyValuePairs.end())
        mimeHeader->m_contentTransferEncoding = parseContentTransferEncoding(mimeParametersIterator->value);

    mimeParametersIterator = keyValuePairs.find("content-location");
    if (mimeParametersIterator != keyValuePairs.end())
        mimeHeader->m_contentLocation = mimeParametersIterator->value;

    return mimeHeader.release();
}

MIMEHeader::Encoding MIMEHeader::parseContentTransferEncoding(const String& text)
{
    String encoding = text.stripWhiteSpace().lower();
    if (encoding == "base64")
        return Base64;
    if (encoding == "quoted-printable")
        return QuotedPrintable;
    if (encoding == "8bit")
        return EightBit;
    if (encoding == "7bit")
        return SevenBit;
    if (encoding == "binary")
        return Binary;
    WTF_LOG_ERROR("Unknown encoding '%s' found in MIME header.", text.ascii().data());
    return Unknown;
}

MIMEHeader::MIMEHeader()
    : m_contentTransferEncoding(Unknown)
{
}

static bool skipLinesUntilBoundaryFound(SharedBufferChunkReader& lineReader, const String& boundary)
{
    String line;
    while (!(line = lineReader.nextChunkAsUTF8StringWithLatin1Fallback()).isNull()) {
        if (line == boundary)
            return true;
    }
    return false;
}

MHTMLParser::MHTMLParser(SharedBuffer* data)
    : m_lineReader(data, "\r\n")
{
}

PassRefPtr<MHTMLArchive> MHTMLParser::parseArchive()
{
    RefPtr<MIMEHeader> header = MIMEHeader::parseHeader(&m_lineReader);
    return parseArchiveWithHeader(header.get());
}

PassRefPtr<MHTMLArchive> MHTMLParser::parseArchiveWithHeader(MIMEHeader* header)
{
    if (!header) {
        WTF_LOG_ERROR("Failed to parse MHTML part: no header.");
        return nullptr;
    }

    RefPtr<MHTMLArchive> archive = MHTMLArchive::create();
    if (!header->isMultipart()) {
        // With IE a page with no resource is not multi-part.
        bool endOfArchiveReached = false;
        RefPtr<ArchiveResource> resource = parseNextPart(*header, String(), String(), endOfArchiveReached);
        if (!resource)
            return nullptr;
        archive->setMainResource(resource);
        return archive;
    }

    // Skip the message content (it's a generic browser specific message).
    skipLinesUntilBoundaryFound(m_lineReader, header->endOfPartBoundary());

    bool endOfArchive = false;
    while (!endOfArchive) {
        RefPtr<MIMEHeader> resourceHeader = MIMEHeader::parseHeader(&m_lineReader);
        if (!resourceHeader) {
            WTF_LOG_ERROR("Failed to parse MHTML, invalid MIME header.");
            return nullptr;
        }
        if (resourceHeader->contentType() == "multipart/alternative") {
            // Ignore IE nesting which makes little sense (IE seems to nest only some of the frames).
            RefPtr<MHTMLArchive> subframeArchive = parseArchiveWithHeader(resourceHeader.get());
            if (!subframeArchive) {
                WTF_LOG_ERROR("Failed to parse MHTML subframe.");
                return nullptr;
            }
            bool endOfPartReached = skipLinesUntilBoundaryFound(m_lineReader, header->endOfPartBoundary());
            ASSERT_UNUSED(endOfPartReached, endOfPartReached);
            // The top-frame is the first frame found, regardless of the nesting level.
            if (subframeArchive->mainResource())
                addResourceToArchive(subframeArchive->mainResource(), archive.get());
            archive->addSubframeArchive(subframeArchive);
            continue;
        }

        RefPtr<ArchiveResource> resource = parseNextPart(*resourceHeader, header->endOfPartBoundary(), header->endOfDocumentBoundary(), endOfArchive);
        if (!resource) {
            WTF_LOG_ERROR("Failed to parse MHTML part.");
            return nullptr;
        }
        addResourceToArchive(resource.get(), archive.get());
    }

    return archive.release();
}

void MHTMLParser::addResourceToArchive(ArchiveResource* resource, MHTMLArchive* archive)
{
    const AtomicString& mimeType = resource->mimeType();
    if (!MIMETypeRegistry::isSupportedNonImageMIMEType(mimeType) || MIMETypeRegistry::isSupportedJavaScriptMIMEType(mimeType) || mimeType == "text/css") {
        m_resources.append(resource);
        return;
    }

    // The first document suitable resource is the main frame.
    if (!archive->mainResource()) {
        archive->setMainResource(resource);
        m_frames.append(archive);
        return;
    }

    RefPtr<MHTMLArchive> subframe = MHTMLArchive::create();
    subframe->setMainResource(resource);
    m_frames.append(subframe);
}

PassRefPtr<ArchiveResource> MHTMLParser::parseNextPart(const MIMEHeader& mimeHeader, const String& endOfPartBoundary, const String& endOfDocumentBoundary, bool& endOfArchiveReached)
{
    ASSERT(endOfPartBoundary.isEmpty() == endOfDocumentBoundary.isEmpty());

    // If no content transfer encoding is specified, default to binary encoding.
    MIMEHeader::Encoding contentTransferEncoding = mimeHeader.contentTransferEncoding();
    if (contentTransferEncoding == MIMEHeader::Unknown)
        contentTransferEncoding = MIMEHeader::Binary;

    RefPtr<SharedBuffer> content = SharedBuffer::create();
    const bool checkBoundary = !endOfPartBoundary.isEmpty();
    bool endOfPartReached = false;
    if (contentTransferEncoding == MIMEHeader::Binary) {
        if (!checkBoundary) {
            WTF_LOG_ERROR("Binary contents requires end of part");
            return nullptr;
        }
        m_lineReader.setSeparator(endOfPartBoundary.utf8().data());
        Vector<char> part;
        if (!m_lineReader.nextChunk(part)) {
            WTF_LOG_ERROR("Binary contents requires end of part");
            return nullptr;
        }
        content->append(part);
        m_lineReader.setSeparator("\r\n");
        Vector<char> nextChars;
        if (m_lineReader.peek(nextChars, 2) != 2) {
            WTF_LOG_ERROR("Invalid seperator.");
            return nullptr;
        }
        endOfPartReached = true;
        ASSERT(nextChars.size() == 2);
        endOfArchiveReached = (nextChars[0] == '-' && nextChars[1] == '-');
        if (!endOfArchiveReached) {
            String line = m_lineReader.nextChunkAsUTF8StringWithLatin1Fallback();
            if (!line.isEmpty()) {
                WTF_LOG_ERROR("No CRLF at end of binary section.");
                return nullptr;
            }
        }
    } else {
        String line;
        while (!(line = m_lineReader.nextChunkAsUTF8StringWithLatin1Fallback()).isNull()) {
            endOfArchiveReached = (line == endOfDocumentBoundary);
            if (checkBoundary && (line == endOfPartBoundary || endOfArchiveReached)) {
                endOfPartReached = true;
                break;
            }
            // Note that we use line.utf8() and not line.ascii() as ascii turns special characters (such as tab, line-feed...) into '?'.
            content->append(line.utf8().data(), line.length());
            if (contentTransferEncoding == MIMEHeader::QuotedPrintable) {
                // The line reader removes the \r\n, but we need them for the content in this case as the QuotedPrintable decoder expects CR-LF terminated lines.
                content->append("\r\n", 2);
            }
        }
    }
    if (!endOfPartReached && checkBoundary) {
        WTF_LOG_ERROR("No bounday found for MHTML part.");
        return nullptr;
    }

    Vector<char> data;
    switch (contentTransferEncoding) {
    case MIMEHeader::Base64:
        if (!base64Decode(content->data(), content->size(), data)) {
            WTF_LOG_ERROR("Invalid base64 content for MHTML part.");
            return nullptr;
        }
        break;
    case MIMEHeader::QuotedPrintable:
        quotedPrintableDecode(content->data(), content->size(), data);
        break;
    case MIMEHeader::EightBit:
    case MIMEHeader::SevenBit:
    case MIMEHeader::Binary:
        data.append(content->data(), content->size());
        break;
    default:
        WTF_LOG_ERROR("Invalid encoding for MHTML part.");
        return nullptr;
    }
    RefPtr<SharedBuffer> contentBuffer = SharedBuffer::adoptVector(data);
    // FIXME: the URL in the MIME header could be relative, we should resolve it if it is.
    // The specs mentions 5 ways to resolve a URL: http://tools.ietf.org/html/rfc2557#section-5
    // IE and Firefox (UNMht) seem to generate only absolute URLs.
    KURL location = KURL(KURL(), mimeHeader.contentLocation());
    return ArchiveResource::create(contentBuffer, location, AtomicString(mimeHeader.contentType()), AtomicString(mimeHeader.charset()), String());
}

size_t MHTMLParser::frameCount() const
{
    return m_frames.size();
}

MHTMLArchive* MHTMLParser::frameAt(size_t index) const
{
    return m_frames[index].get();
}

size_t MHTMLParser::subResourceCount() const
{
    return m_resources.size();
}

ArchiveResource* MHTMLParser::subResourceAt(size_t index) const
{
    return m_resources[index].get();
}

}