// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_ML_ML_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_ML_ML_H_

#include "services/webnn/public/mojom/webnn_context_provider.mojom-blink.h"
#include "third_party/blink/renderer/bindings/core/v8/script_promise.h"
#include "third_party/blink/renderer/core/execution_context/execution_context.h"
#include "third_party/blink/renderer/core/execution_context/execution_context_lifecycle_observer.h"
#include "third_party/blink/renderer/modules/ml/ml_context.h"
#include "third_party/blink/renderer/modules/modules_export.h"
#include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_hash_set.h"
#include "third_party/blink/renderer/platform/heap/member.h"
#include "third_party/blink/renderer/platform/heap/visitor.h"
#include "third_party/blink/renderer/platform/mojo/heap_mojo_remote.h"

namespace blink {

class MLContextOptions;
class ScriptState;

// This class represents the "Machine Learning" object "navigator.ml" used by
// the WebNN API. See https://www.w3.org/TR/webnn/#api-ml.
class MODULES_EXPORT ML final : public ScriptWrappable,
                                public ExecutionContextClient {
  DEFINE_WRAPPERTYPEINFO();

 public:
  explicit ML(ExecutionContext* execution_context);

  ML(const ML&) = delete;
  ML& operator=(const ML&) = delete;

  void Trace(blink::Visitor*) const override;

  // IDL interface:
  ScriptPromise<MLContext> createContext(ScriptState* state,
                                         MLContextOptions* option,
                                         ExceptionState& exception_state);
 private:
  // Reset the remote of `WebNNContextProvider` if the remote is cut off from
  // its receiver.
  void OnWebNNServiceConnectionError();

  // There is only one WebNN service running out of renderer process to access
  // the hardware accelerated OS machine learning API. Every `navigator.ml`
  // object has one `WebNNContextProvider` message pipe to create `WebNNContext`
  // mojo interface.
  void EnsureWebNNServiceConnection();

  // Creates an in-renderer WebNN context provider for CPU inference that
  // bypasses the GPU process entirely. The provider is created in the renderer
  // process and bound to a local Mojo self-pipe.
  void EnsureInProcessServiceConnection();

  // Reset the remote of the in-renderer `WebNNContextProvider` if the
  // remote is cut off from its receiver.
  void OnInProcessServiceConnectionError();

  // Creates a WebNN context using the in-renderer backend. Called as a
  // fallback when the GPU-process backend signals via
  // `Error::Code::kFallbackToInProcess`.
  void CreateInProcessContext(ScriptPromiseResolver<MLContext>* resolver,
                              MLContextOptions* options,
                              webnn::ScopedTrace scoped_trace);

  // In-renderer context provider for CPU device, bypassing the GPU process.
  // Uses a cross-variant Mojo pipe: the blink-variant remote is connected to
  // a non-blink receiver hosting WebNNContextProviderInRenderer. The wire
  // format is identical across variants.
  HeapMojoRemote<webnn::mojom::blink::WebNNContextProvider>
      in_process_context_provider_;

  // Resolvers for requests currently in-flight on the in-renderer path.
  // Kept separate from `pending_resolvers_` so that a GPU-process disconnect
  // does not incorrectly reject in-renderer requests (and vice-versa).
  HeapHashSet<Member<ScriptPromiseResolver<MLContext>>>
      in_process_pending_resolvers_;

  // WebNN support multiple types of neural network inference hardware
  // acceleration such as CPU, GPU and ML specialized accelerator, the context
  // of webnn in service is used to map different device and represent a state
  // of graph execution processes.
  HeapMojoRemote<webnn::mojom::blink::WebNNContextProvider>
      webnn_context_provider_;

  // Resolvers for requests currently in-flight on the GPU-process
  // WebNN backend. Rejected when that Mojo pipe disconnects.
  HeapHashSet<Member<ScriptPromiseResolver<MLContext>>> pending_resolvers_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_ML_ML_H_