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 * modification, are permitted provided that the following conditions are
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 *
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#ifndef THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_SCRIPT_PROMISE_H_
#define THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_SCRIPT_PROMISE_H_

#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/bindings/core/v8/script_value.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/platform/heap/handle.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
#include "v8/include/v8.h"

namespace blink {

class DOMException;
class ExceptionState;
class NewScriptFunction;

// ScriptPromise is the class for representing Promise values in C++ world.
// ScriptPromise holds a Promise.
// So holding a ScriptPromise as a member variable in DOM object causes
// memory leaks since it has a reference from C++ to V8.
//
// There are cases where promises cannot work (e.g., where the thread is being
// terminated). In such cases operations will silently fail, so you should not
// use promises for critical use such as releasing a resource.
class CORE_EXPORT ScriptPromise final {
  DISALLOW_NEW();

 public:
  // Constructs an empty promise.
  ScriptPromise() = default;

  // Constructs a ScriptPromise from |promise|.
  // If |promise| is not a Promise object, throws a v8 TypeError.
  ScriptPromise(ScriptState*, v8::Local<v8::Value> promise);

  ScriptPromise(const ScriptPromise&);

  ~ScriptPromise() = default;

  ScriptPromise Then(v8::Local<v8::Function> on_fulfilled,
                     v8::Local<v8::Function> on_rejected = {});
  ScriptPromise Then(NewScriptFunction* on_fulfilled,
                     NewScriptFunction* on_rejected = nullptr);

  bool IsObject() const { return promise_.IsObject(); }

  bool IsNull() const { return promise_.IsNull(); }

  bool IsUndefinedOrNull() const {
    return promise_.IsUndefined() || promise_.IsNull();
  }

  ScriptValue AsScriptValue() const { return promise_; }

  v8::Local<v8::Value> V8Value() const { return promise_.V8Value(); }
  v8::Local<v8::Promise> V8Promise() const {
    // This is safe because `promise_` always stores a promise value as long
    // as it's non-empty.
    return V8Value().As<v8::Promise>();
  }

  v8::Isolate* GetIsolate() const { return script_state_->GetIsolate(); }

  bool IsEmpty() const { return promise_.IsEmpty(); }

  void Clear() { promise_.Clear(); }

  // Marks this promise as handled to avoid reporting unhandled rejections.
  void MarkAsHandled();

  bool operator==(const ScriptPromise& value) const {
    return promise_ == value.promise_;
  }

  bool operator!=(const ScriptPromise& value) const {
    return !operator==(value);
  }

  // Constructs and returns a ScriptPromise from |value|.
  // if |value| is not a Promise object, returns a Promise object
  // resolved with |value|.
  // Returns |value| itself if it is a Promise.
  static ScriptPromise Cast(ScriptState*, const ScriptValue& /*value*/);
  static ScriptPromise Cast(ScriptState*, v8::Local<v8::Value> /*value*/);

  // Constructs and returns a ScriptPromise resolved with undefined.
  static ScriptPromise CastUndefined(ScriptState*);

  static ScriptPromise Reject(ScriptState*, const ScriptValue&);
  static ScriptPromise Reject(ScriptState*, v8::Local<v8::Value>);
  // Rejects with a given exception. The ExceptionState gets cleared.
  static ScriptPromise Reject(ScriptState*, ExceptionState&);

  static ScriptPromise RejectWithDOMException(ScriptState*, DOMException*);

  static v8::Local<v8::Promise> RejectRaw(ScriptState*, v8::Local<v8::Value>);

  // Constructs and returns a ScriptPromise to be resolved when all |promises|
  // are resolved. If one of |promises| is rejected, the returned
  // ScriptPromise is rejected.
  static ScriptPromise All(ScriptState*,
                           const HeapVector<ScriptPromise>& promises);

  void Trace(Visitor* visitor) const {
    visitor->Trace(promise_);
    visitor->Trace(script_state_);
  }

  // This is a utility class intended to be used internally.
  // ScriptPromiseResolver is for general purpose.
  class CORE_EXPORT InternalResolver final {
    DISALLOW_NEW();

   public:
    explicit InternalResolver(ScriptState*);
    v8::Local<v8::Promise> V8Promise() const;
    ScriptPromise Promise() const;
    void Resolve(v8::Local<v8::Value>);
    void Reject(v8::Local<v8::Value>);
    void Clear() { resolver_.Clear(); }
    ScriptState* GetScriptState() const { return script_state_; }
    void Trace(Visitor* visitor) const {
      visitor->Trace(script_state_);
      visitor->Trace(resolver_);
    }

   private:
    Member<ScriptState> script_state_;
    ScriptValue resolver_;
  };

  bool IsAssociatedWith(ScriptState* script_state) const {
    return script_state == script_state_;
  }

 private:
  static void IncreaseInstanceCount();
  static void DecreaseInstanceCount();

  Member<ScriptState> script_state_;
  ScriptValue promise_;
};

}  // namespace blink

namespace WTF {

template <>
struct VectorTraits<blink::ScriptPromise>
    : VectorTraitsBase<blink::ScriptPromise> {
  STATIC_ONLY(VectorTraits);
  static constexpr bool kCanClearUnusedSlotsWithMemset = true;
};

}  // namespace WTF

#endif  // THIRD_PARTY_BLINK_RENDERER_BINDINGS_CORE_V8_SCRIPT_PROMISE_H_