/*

 * Copyright (C) 2010 Google 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:

 *

 *     * 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.

 *     * Neither the name of Google Inc. nor the names of its

 * 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,

 * 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.

 */

#include "config.h"

#include "SerializedScriptValue.h"

#include "Blob.h"

#include "ByteArray.h"

#include "CanvasPixelArray.h"

#include "ExceptionCode.h"

#include "File.h"

#include "FileList.h"

#include "ImageData.h"

#include "SharedBuffer.h"

#include "V8Binding.h"

#include "V8Blob.h"

#include "V8File.h"

#include "V8FileList.h"

#include "V8ImageData.h"

#include "V8Proxy.h"

#include <wtf/Assertions.h>

#include <wtf/RefCounted.h>

#include <wtf/Vector.h>

// FIXME:

// - catch V8 exceptions

// - consider crashing in debug mode on deserialization errors

namespace WebCore {

namespace {

typedef UChar BufferValueType;

// Serialization format is a sequence of (tag, optional data)

// pairs. Tag always takes exactly one byte.

enum SerializationTag {

    InvalidTag = '!',

    PaddingTag = '\0',

    UndefinedTag = '_',

    NullTag = '0',

    TrueTag = 'T',

    FalseTag = 'F',

    StringTag = 'S',

    Int32Tag = 'I',

    Uint32Tag = 'U',

    DateTag = 'D',

    NumberTag = 'N',

    BlobTag = 'b',

    FileTag = 'f',

    FileListTag = 'l',

    ImageDataTag = '#',

    ArrayTag = '[',

    ObjectTag = '{',

    SparseArrayTag = '@',

};

static bool shouldCheckForCycles(int depth)

{

    ASSERT(depth >= 0);

    // Since we are not required to spot the cycle as soon as it

    // happens we can check for cycles only when the current depth

    // is a power of two.

    return !(depth & (depth - 1));

}

static const int maxDepth = 20000;

// VarInt encoding constants.

static const int varIntShift = 7;

static const int varIntMask = (1 << varIntShift) - 1;

// ZigZag encoding helps VarInt encoding stay small for negative

// numbers with small absolute values.

class ZigZag {

public:

    static uint32_t encode(uint32_t value)

    {

        if (value & (1U << 31))

            value = ((~value) << 1) + 1;

        else

            value <<= 1;

        return value;

    }

    static uint32_t decode(uint32_t value)

    {

        if (value & 1)

            value = ~(value >> 1);

        else

            value >>= 1;

        return value;

    }

private:

    ZigZag();

};

// Writer is responsible for serializing primitive types and storing

// information used to reconstruct composite types.

class Writer : Noncopyable {

public:

    Writer()

        : m_position(0)

    {

    }

    // Write functions for primitive types.

    void writeUndefined() { append(UndefinedTag); }

    void writeNull() { append(NullTag); }

    void writeTrue() { append(TrueTag); }

    void writeFalse() { append(FalseTag); }

    void writeString(const char* data, int length)

    {

        ASSERT(length >= 0);

        append(StringTag);

        doWriteString(data, length);

    }

    void writeWebCoreString(const String& string)

    {

        // Uses UTF8 encoding so we can read it back as either V8 or

        // WebCore string.

        append(StringTag);

        doWriteWebCoreString(string);

    }

    void writeInt32(int32_t value)

    {

        append(Int32Tag);

        doWriteUint32(ZigZag::encode(static_cast<uint32_t>(value)));

    }

    void writeUint32(uint32_t value)

    {

        append(Uint32Tag);

        doWriteUint32(value);

    }

    void writeDate(double numberValue)

    {

        append(DateTag);

        doWriteNumber(numberValue);

    }

    void writeNumber(double number)

    {

        append(NumberTag);

        doWriteNumber(number);

    }

    void writeBlob(const String& path)

    {

        append(BlobTag);

        doWriteWebCoreString(path);

    }

    void writeFile(const String& path)

    {

        append(FileTag);

        doWriteWebCoreString(path);

    }

    void writeFileList(const FileList& fileList)

    {

        append(FileListTag);

        uint32_t length = fileList.length();

        doWriteUint32(length);

        for (unsigned i = 0; i < length; ++i)

            doWriteWebCoreString(fileList.item(i)->path());

    }

    void writeImageData(uint32_t width, uint32_t height, const uint8_t* pixelData, uint32_t pixelDataLength)

    {

        append(ImageDataTag);

        doWriteUint32(width);

        doWriteUint32(height);

        doWriteUint32(pixelDataLength);

        append(pixelData, pixelDataLength);

    }

    void writeArray(uint32_t length)

    {

        append(ArrayTag);

        doWriteUint32(length);

    }

    void writeObject(uint32_t numProperties)

    {

        append(ObjectTag);

        doWriteUint32(numProperties);

    }

    void writeSparseArray(uint32_t numProperties, uint32_t length)

    {

        append(SparseArrayTag);

        doWriteUint32(numProperties);

        doWriteUint32(length);

    }

    Vector<BufferValueType>& data()

    {

        fillHole();

        return m_buffer;

    }

private:

    void doWriteString(const char* data, int length)

    {

        doWriteUint32(static_cast<uint32_t>(length));

        append(reinterpret_cast<const uint8_t*>(data), length);

    }

    void doWriteWebCoreString(const String& string)

    {

        RefPtr<SharedBuffer> buffer = utf8Buffer(string);

        doWriteString(buffer->data(), buffer->size());

    }

    void doWriteUint32(uint32_t value)

    {

        while (true) {

            uint8_t b = (value & varIntMask);

            value >>= varIntShift;

            if (!value) {

                append(b);

                break;

            }

            append(b | (1 << varIntShift));

        }

    }

    void doWriteNumber(double number)

    {

        append(reinterpret_cast<uint8_t*>(&number), sizeof(number));

    }

    void append(SerializationTag tag)

    {

        append(static_cast<uint8_t>(tag));

    }

    void append(uint8_t b)

    {

        ensureSpace(1);

        *byteAt(m_position++) = b;

    }

    void append(const uint8_t* data, int length)

    {

        ensureSpace(length);

        memcpy(byteAt(m_position), data, length);

        m_position += length;

    }

    void ensureSpace(int extra)

    {

        COMPILE_ASSERT(sizeof(BufferValueType) == 2, BufferValueTypeIsTwoBytes);

        m_buffer.grow((m_position + extra + 1) / 2); // "+ 1" to round up.

    }

    void fillHole()

    {

        COMPILE_ASSERT(sizeof(BufferValueType) == 2, BufferValueTypeIsTwoBytes);

        // If the writer is at odd position in the buffer, then one of

        // the bytes in the last UChar is not initialized.

        if (m_position % 2)

            *byteAt(m_position) = static_cast<uint8_t>(PaddingTag);

    }

    uint8_t* byteAt(int position) { return reinterpret_cast<uint8_t*>(m_buffer.data()) + position; }

    Vector<BufferValueType> m_buffer;

    unsigned m_position;

};

class Serializer {

    class StateBase;

public:

    explicit Serializer(Writer& writer)

        : m_writer(writer)

        , m_depth(0)

        , m_hasError(false)

    {

    }

    bool serialize(v8::Handle<v8::Value> value)

    {

        v8::HandleScope scope;

        StateBase* state = doSerialize(value, 0);

        while (state)

            state = state->advance(*this);

        return !m_hasError;

    }

    // Functions used by serialization states.

    StateBase* doSerialize(v8::Handle<v8::Value> value, StateBase* next);

    StateBase* writeArray(uint32_t length, StateBase* state)

    {

        m_writer.writeArray(length);

        return pop(state);

    }

    StateBase* writeObject(uint32_t numProperties, StateBase* state)

    {

        m_writer.writeObject(numProperties);

        return pop(state);

    }

    StateBase* writeSparseArray(uint32_t numProperties, uint32_t length, StateBase* state)

    {

        m_writer.writeSparseArray(numProperties, length);

        return pop(state);

    }

private:

    class StateBase : public Noncopyable {

    public:

        virtual ~StateBase() { }

        // Link to the next state to form a stack.

        StateBase* nextState() { return m_next; }

        // Composite object we're processing in this state.

        v8::Handle<v8::Value> composite() { return m_composite; }

        // Serializes (a part of) the current composite and returns

        // the next state to process or null when this is the final

        // state.

        virtual StateBase* advance(Serializer&) = 0;

    protected:

        StateBase(v8::Handle<v8::Value> composite, StateBase* next)

            : m_composite(composite)

            , m_next(next)

        {

        }

    private:

        v8::Handle<v8::Value> m_composite;

        StateBase* m_next;

    };

    // Dummy state that is used to signal serialization errors.

    class ErrorState : public StateBase {

    public:

        ErrorState()

            : StateBase(v8::Handle<v8::Value>(), 0)

        {

        }

        virtual StateBase* advance(Serializer&)

        {

            delete this;

            return 0;

        }

    };

    template <typename T>

    class State : public StateBase {

    public:

        v8::Handle<T> composite() { return v8::Handle<T>::Cast(StateBase::composite()); }

    protected:

        State(v8::Handle<T> composite, StateBase* next)

            : StateBase(composite, next)

        {

        }

    };

#if 0

    // Currently unused, see comment in newArrayState.

    class ArrayState : public State<v8::Array> {

    public:

        ArrayState(v8::Handle<v8::Array> array, StateBase* next)

            : State<v8::Array>(array, next)

            , m_index(-1)

        {

        }

        virtual StateBase* advance(Serializer& serializer)

        {

            ++m_index;

            for (; m_index < composite()->Length(); ++m_index) {

                if (StateBase* newState = serializer.doSerialize(composite()->Get(m_index), this))

                    return newState;

            }

            return serializer.writeArray(composite()->Length(), this);

        }

    private:

        unsigned m_index;

    };

#endif

    class AbstractObjectState : public State<v8::Object> {

    public:

        AbstractObjectState(v8::Handle<v8::Object> object, StateBase* next)

            : State<v8::Object>(object, next)

            , m_propertyNames(object->GetPropertyNames())

            , m_index(-1)

            , m_numSerializedProperties(0)

            , m_nameDone(false)

        {

        }

        virtual StateBase* advance(Serializer& serializer)

        {

            ++m_index;

            for (; m_index < m_propertyNames->Length(); ++m_index) {

                if (m_propertyName.IsEmpty()) {

                    v8::Local<v8::Value> propertyName = m_propertyNames->Get(m_index);

                    if ((propertyName->IsString() && composite()->HasRealNamedProperty(propertyName.As<v8::String>()))

                        || (propertyName->IsUint32() && composite()->HasRealIndexedProperty(propertyName->Uint32Value()))) {

                        m_propertyName = propertyName;

                    } else

                        continue;

                }

                ASSERT(!m_propertyName.IsEmpty());

                if (!m_nameDone) {

                    m_nameDone = true;

                    if (StateBase* newState = serializer.doSerialize(m_propertyName, this))

                        return newState;

                }

                v8::Local<v8::Value> value = composite()->Get(m_propertyName);

                m_nameDone = false;

                m_propertyName.Clear();

                ++m_numSerializedProperties;

                if (StateBase* newState = serializer.doSerialize(value, this))

                    return newState;

            }

            return objectDone(m_numSerializedProperties, serializer);

        }

    protected:

        virtual StateBase* objectDone(unsigned numProperties, Serializer&) = 0;

    private:

        v8::Local<v8::Array> m_propertyNames;

        v8::Local<v8::Value> m_propertyName;

        unsigned m_index;

        unsigned m_numSerializedProperties;

        bool m_nameDone;

    };

    class ObjectState : public AbstractObjectState {

    public:

        ObjectState(v8::Handle<v8::Object> object, StateBase* next)

            : AbstractObjectState(object, next)

        {

        }

    protected:

        virtual StateBase* objectDone(unsigned numProperties, Serializer& serializer)

        {

            return serializer.writeObject(numProperties, this);

        }

    };

    class SparseArrayState : public AbstractObjectState {

    public:

        SparseArrayState(v8::Handle<v8::Array> array, StateBase* next)

            : AbstractObjectState(array, next)

        {

        }

    protected:

        virtual StateBase* objectDone(unsigned numProperties, Serializer& serializer)

        {

            return serializer.writeSparseArray(numProperties, composite().As<v8::Array>()->Length(), this);

        }

    };

    StateBase* push(StateBase* state)

    {

        ASSERT(state);

        ++m_depth;

        return checkComposite(state) ? state : handleError(state);

    }

    StateBase* pop(StateBase* state)

    {

        ASSERT(state);

        --m_depth;

        StateBase* next = state->nextState();

        delete state;

        return next;

    }

    StateBase* handleError(StateBase* state)

    {

        m_hasError = true;

        while (state) {