// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef EXTENSIONS_BROWSER_BLOB_READER_H_
#define EXTENSIONS_BROWSER_BLOB_READER_H_

#include <stdint.h>

#include <memory>
#include <string>

#include "base/callback.h"
#include "base/macros.h"
#include "mojo/public/cpp/bindings/binding.h"
#include "mojo/public/cpp/system/data_pipe_drainer.h"
#include "third_party/blink/public/mojom/blob/blob.mojom.h"
#include "url/gurl.h"

namespace content {
class BrowserContext;
}

// This class may only be used from the UI thread. It self-deletes when finished
// reading.
class BlobReader : public blink::mojom::BlobReaderClient,
                   public mojo::DataPipeDrainer::Client {
 public:
  // |blob_data| contains the portion of the Blob requested. |blob_total_size|
  // is the total size of the Blob, and may be larger than |blob_data->size()|.
  // |blob_total_size| is -1 if it cannot be determined.
  typedef base::OnceCallback<void(std::unique_ptr<std::string> blob_data,
                                  int64_t blob_total_size)>
      BlobReadCallback;

  BlobReader(content::BrowserContext* browser_context,
             const std::string& blob_uuid,
             BlobReadCallback callback);
  BlobReader(blink::mojom::BlobPtr blob, BlobReadCallback callback);
  ~BlobReader() override;

  void SetByteRange(int64_t offset, int64_t length);

  void Start();

 private:
  // blink::mojom::BlobReaderClient:
  void OnCalculatedSize(uint64_t total_size,
                        uint64_t expected_content_size) override;
  void OnComplete(int32_t status, uint64_t data_length) override {}

  // mojo::DataPipeDrainer:
  void OnDataAvailable(const void* data, size_t num_bytes) override;
  void OnDataComplete() override;

  void Failed();
  void Succeeded();

  BlobReadCallback callback_;
  blink::mojom::BlobPtr blob_;
  struct Range {
    uint64_t offset;
    uint64_t length;
  };
  base::Optional<Range> read_range_;

  mojo::Binding<blink::mojom::BlobReaderClient> binding_;
  std::unique_ptr<mojo::DataPipeDrainer> data_pipe_drainer_;

  base::Optional<uint64_t> blob_length_;
  std::unique_ptr<std::string> blob_data_;
  bool data_complete_ = false;

  DISALLOW_COPY_AND_ASSIGN(BlobReader);
};

#endif  // EXTENSIONS_BROWSER_BLOB_READER_H_