// Copyright (c) 2016 GitHub, Inc.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.

#ifndef ATOM_BROWSER_ATOM_BLOB_READER_H_
#define ATOM_BROWSER_ATOM_BLOB_READER_H_

#include <memory>
#include <string>

#include "base/callback.h"
#include "shell/common/promise_util.h"

namespace content {
class ChromeBlobStorageContext;
}

namespace net {
class IOBuffer;
}

namespace storage {
class BlobDataHandle;
class BlobReader;
}  // namespace storage

namespace v8 {
template <class T>
class Local;
class Value;
}  // namespace v8

namespace atom {

// A class to keep track of the blob context. All methods,
// except Ctor are expected to be called on IO thread.
class AtomBlobReader {
 public:
  explicit AtomBlobReader(content::ChromeBlobStorageContext* blob_context);
  ~AtomBlobReader();

  void StartReading(const std::string& uuid, atom::util::Promise promise);

 private:
  // A self-destroyed helper class to read the blob data.
  // Must be accessed on IO thread.
  class BlobReadHelper {
   public:
    using CompletionCallback = base::OnceCallback<void(char*, int)>;

    BlobReadHelper(std::unique_ptr<storage::BlobReader> blob_reader,
                   BlobReadHelper::CompletionCallback callback);
    ~BlobReadHelper();

    void Read();

   private:
    void DidCalculateSize(int result);
    void DidReadBlobData(const scoped_refptr<net::IOBuffer>& blob_data,
                         int bytes_read);

    std::unique_ptr<storage::BlobReader> blob_reader_;
    BlobReadHelper::CompletionCallback completion_callback_;

    DISALLOW_COPY_AND_ASSIGN(BlobReadHelper);
  };

  scoped_refptr<content::ChromeBlobStorageContext> blob_context_;

  DISALLOW_COPY_AND_ASSIGN(AtomBlobReader);
};

}  // namespace atom

#endif  // ATOM_BROWSER_ATOM_BLOB_READER_H_