/*
 * 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.
 */

#ifndef WrapperTypeInfo_h
#define WrapperTypeInfo_h

#include "gin/public/wrapper_info.h"
#include "platform/heap/Handle.h"
#include "wtf/Assertions.h"
#include <v8.h>

namespace blink {

class ActiveDOMObject;
class EventTarget;
class Node;
class ScriptWrappableBase;

static const int v8DOMWrapperTypeIndex = static_cast<int>(gin::kWrapperInfoIndex);
static const int v8DOMWrapperObjectIndex = static_cast<int>(gin::kEncodedValueIndex);
static const int v8DefaultWrapperInternalFieldCount = static_cast<int>(gin::kNumberOfInternalFields);
static const int v8PrototypeTypeIndex = 0;
static const int v8PrototypeInternalFieldcount = 1;

static const uint16_t v8DOMNodeClassId = 1;
static const uint16_t v8DOMObjectClassId = 2;

typedef v8::Handle<v8::FunctionTemplate> (*DomTemplateFunction)(v8::Isolate*);
typedef void (*DerefObjectFunction)(ScriptWrappableBase* internalPointer);
typedef ActiveDOMObject* (*ToActiveDOMObjectFunction)(v8::Handle<v8::Object>);
typedef EventTarget* (*ToEventTargetFunction)(v8::Handle<v8::Object>);
typedef void (*ResolveWrapperReachabilityFunction)(ScriptWrappableBase* internalPointer, const v8::Persistent<v8::Object>&, v8::Isolate*);
typedef void (*InstallPerContextEnabledPrototypePropertiesFunction)(v8::Handle<v8::Object>, v8::Isolate*);

enum WrapperTypePrototype {
    WrapperTypeObjectPrototype,
    WrapperTypeExceptionPrototype
};

enum GCType {
    GarbageCollectedObject,
    WillBeGarbageCollectedObject,
    RefCountedObject,
};

inline void setObjectGroup(ScriptWrappableBase* internalPointer, const v8::Persistent<v8::Object>& wrapper, v8::Isolate* isolate)
{
    isolate->SetObjectGroupId(wrapper, v8::UniqueId(reinterpret_cast<intptr_t>(internalPointer)));
}

// This struct provides a way to store a bunch of information that is helpful when unwrapping
// v8 objects. Each v8 bindings class has exactly one static WrapperTypeInfo member, so
// comparing pointers is a safe way to determine if types match.
struct WrapperTypeInfo {

    static const WrapperTypeInfo* unwrap(v8::Handle<v8::Value> typeInfoWrapper)
    {
        return reinterpret_cast<const WrapperTypeInfo*>(v8::External::Cast(*typeInfoWrapper)->Value());
    }


    bool equals(const WrapperTypeInfo* that) const
    {
        return this == that;
    }

    bool isSubclass(const WrapperTypeInfo* that) const
    {
        for (const WrapperTypeInfo* current = this; current; current = current->parentClass) {
            if (current == that)
                return true;
        }

        return false;
    }

    v8::Handle<v8::FunctionTemplate> domTemplate(v8::Isolate* isolate) const
    {
        return domTemplateFunction(isolate);
    }

    void installPerContextEnabledMethods(v8::Handle<v8::Object> prototypeTemplate, v8::Isolate* isolate) const
    {
        if (installPerContextEnabledMethodsFunction)
            installPerContextEnabledMethodsFunction(prototypeTemplate, isolate);
    }

    ActiveDOMObject* toActiveDOMObject(v8::Handle<v8::Object> object) const
    {
        if (!toActiveDOMObjectFunction)
            return 0;
        return toActiveDOMObjectFunction(object);
    }

    EventTarget* toEventTarget(v8::Handle<v8::Object> object) const
    {
        if (!toEventTargetFunction)
            return 0;
        return toEventTargetFunction(object);
    }

    void visitDOMWrapper(ScriptWrappableBase* internalPointer, const v8::Persistent<v8::Object>& wrapper, v8::Isolate* isolate) const
    {
        if (!visitDOMWrapperFunction)
            setObjectGroup(internalPointer, wrapper, isolate);
        else
            visitDOMWrapperFunction(internalPointer, wrapper, isolate);
    }

    // This field must be the first member of the struct WrapperTypeInfo. This is also checked by a COMPILE_ASSERT() below.
    const gin::GinEmbedder ginEmbedder;

    const DomTemplateFunction domTemplateFunction;
    const DerefObjectFunction derefObjectFunction;
    const ToActiveDOMObjectFunction toActiveDOMObjectFunction;
    const ToEventTargetFunction toEventTargetFunction;
    const ResolveWrapperReachabilityFunction visitDOMWrapperFunction;
    const InstallPerContextEnabledPrototypePropertiesFunction installPerContextEnabledMethodsFunction;
    const WrapperTypeInfo* parentClass;
    const WrapperTypePrototype wrapperTypePrototype;
    const GCType gcType;
};


COMPILE_ASSERT(offsetof(struct WrapperTypeInfo, ginEmbedder) == offsetof(struct gin::WrapperInfo, embedder), wrapper_type_info_compatible_to_gin);

template<typename T, int offset>
inline T* getInternalField(const v8::Persistent<v8::Object>& persistent)
{
    // This would be unsafe, but InternalFieldCount and GetAlignedPointerFromInternalField are guaranteed not to allocate
    const v8::Handle<v8::Object>& object = reinterpret_cast<const v8::Handle<v8::Object>&>(persistent);
    ASSERT(offset < object->InternalFieldCount());
    return static_cast<T*>(object->GetAlignedPointerFromInternalField(offset));
}

template<typename T, int offset>
inline T* getInternalField(v8::Handle<v8::Object> wrapper)
{
    ASSERT(offset < wrapper->InternalFieldCount());
    return static_cast<T*>(wrapper->GetAlignedPointerFromInternalField(offset));
}

inline ScriptWrappableBase* toInternalPointer(v8::Handle<v8::Object> wrapper)
{
    return getInternalField<ScriptWrappableBase, v8DOMWrapperObjectIndex>(wrapper);
}

inline const WrapperTypeInfo* toWrapperTypeInfo(const v8::Persistent<v8::Object>& wrapper)
{
    return getInternalField<WrapperTypeInfo, v8DOMWrapperTypeIndex>(wrapper);
}

inline const WrapperTypeInfo* toWrapperTypeInfo(v8::Handle<v8::Object> wrapper)
{
    return getInternalField<WrapperTypeInfo, v8DOMWrapperTypeIndex>(wrapper);
}

inline const PersistentNode* toPersistentHandle(const v8::Handle<v8::Object>& wrapper)
{
    // Persistent handle is stored in the last internal field.
    return static_cast<PersistentNode*>(wrapper->GetAlignedPointerFromInternalField(wrapper->InternalFieldCount() - 1));
}

inline void releaseObject(v8::Handle<v8::Object> wrapper)
{
    const WrapperTypeInfo* typeInfo = toWrapperTypeInfo(wrapper);
    if (typeInfo->gcType == GarbageCollectedObject) {
        const PersistentNode* handle = toPersistentHandle(wrapper);
        // This will be null iff a wrapper for a hidden wrapper object,
        // see V8DOMWrapper::setNativeInfoForHiddenWrapper().
        delete handle;
    } else if (typeInfo->gcType == WillBeGarbageCollectedObject) {
#if ENABLE(OILPAN)
        const PersistentNode* handle = toPersistentHandle(wrapper);
        // This will be null iff a wrapper for a hidden wrapper object,
        // see V8DOMWrapper::setNativeInfoForHiddenWrapper().
        delete handle;
#else
        ASSERT(typeInfo->derefObjectFunction);
        typeInfo->derefObjectFunction(toInternalPointer(wrapper));
#endif
    } else {
        ASSERT(typeInfo->derefObjectFunction);
        typeInfo->derefObjectFunction(toInternalPointer(wrapper));
    }
}

struct WrapperConfiguration {

    enum Lifetime {
        Dependent, Independent
    };

    void configureWrapper(v8::PersistentBase<v8::Object>* wrapper) const
    {
        wrapper->SetWrapperClassId(classId);
        if (lifetime == Independent)
            wrapper->MarkIndependent();
    }

    const uint16_t classId;
    const Lifetime lifetime;
};

inline WrapperConfiguration buildWrapperConfiguration(void*, WrapperConfiguration::Lifetime lifetime)
{
    WrapperConfiguration configuration = {v8DOMObjectClassId, lifetime};
    return configuration;
}

inline WrapperConfiguration buildWrapperConfiguration(Node*, WrapperConfiguration::Lifetime lifetime)
{
    WrapperConfiguration configuration = {v8DOMNodeClassId, lifetime};
    return configuration;
}

} // namespace blink

#endif // WrapperTypeInfo_h
