// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_BASE_TEST_COMPLETION_CALLBACK_H_
#define NET_BASE_TEST_COMPLETION_CALLBACK_H_

#include <stdint.h>

#include <memory>
#include <optional>
#include <utility>

#include "base/compiler_specific.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "net/base/completion_once_callback.h"
#include "net/base/net_errors.h"

//-----------------------------------------------------------------------------
// completion callback helper

// A helper class for completion callbacks, designed to make it easy to run
// tests involving asynchronous operations.  Just call WaitForResult to wait
// for the asynchronous operation to complete.  Uses a RunLoop to spin the
// current MessageLoop while waiting.  The callback must be invoked on the same
// thread WaitForResult is called on.
//
// NOTE: Since this runs a message loop to wait for the completion callback,
// there could be other side-effects resulting from WaitForResult.  For this
// reason, this class is probably not ideal for a general application.
//
namespace base {
class RunLoop;
}

namespace net {

class IOBuffer;

namespace internal {

class TestCompletionCallbackBaseInternal {
 public:
  TestCompletionCallbackBaseInternal(
      const TestCompletionCallbackBaseInternal&) = delete;
  TestCompletionCallbackBaseInternal& operator=(
      const TestCompletionCallbackBaseInternal&) = delete;
  bool have_result() const { return have_result_; }

 protected:
  TestCompletionCallbackBaseInternal();
  virtual ~TestCompletionCallbackBaseInternal();

  void DidSetResult();
  void WaitForResult();

 private:
  // RunLoop.  Only non-NULL during the call to WaitForResult, so the class is
  // reusable.
  std::unique_ptr<base::RunLoop> run_loop_;
  bool have_result_ = false;
};

template <typename R>
struct NetErrorIsPendingHelper {
  bool operator()(R status) const { return status == ERR_IO_PENDING; }
};

template <typename R, typename IsPendingHelper = NetErrorIsPendingHelper<R>>
class TestCompletionCallbackTemplate
    : public TestCompletionCallbackBaseInternal {
 public:
  TestCompletionCallbackTemplate(const TestCompletionCallbackTemplate&) =
      delete;
  TestCompletionCallbackTemplate& operator=(
      const TestCompletionCallbackTemplate&) = delete;
  ~TestCompletionCallbackTemplate() override = default;

  R WaitForResult() {
    TestCompletionCallbackBaseInternal::WaitForResult();
    return std::move(result_);
  }

  R GetResult(R result) {
    IsPendingHelper check_pending;
    if (!check_pending(result))
      return std::move(result);
    return WaitForResult();
  }

 protected:
  TestCompletionCallbackTemplate() : result_(R()) {}

  // Override this method to gain control as the callback is running.
  virtual void SetResult(R result) {
    result_ = std::move(result);
    DidSetResult();
  }

 private:
  R result_;
};

}  // namespace internal

class TestClosure : public internal::TestCompletionCallbackBaseInternal {
 public:
  using internal::TestCompletionCallbackBaseInternal::WaitForResult;

  TestClosure() = default;
  TestClosure(const TestClosure&) = delete;
  TestClosure& operator=(const TestClosure&) = delete;
  ~TestClosure() override;

  base::OnceClosure closure() {
    return base::BindOnce(&TestClosure::DidSetResult, base::Unretained(this));
  }
};

// Base class overridden by custom implementations of TestCompletionCallback.
typedef internal::TestCompletionCallbackTemplate<int>
    TestCompletionCallbackBase;

typedef internal::TestCompletionCallbackTemplate<int64_t>
    TestInt64CompletionCallbackBase;

class TestCompletionCallback : public TestCompletionCallbackBase {
 public:
  TestCompletionCallback() = default;
  TestCompletionCallback(const TestCompletionCallback&) = delete;
  TestCompletionCallback& operator=(const TestCompletionCallback&) = delete;
  ~TestCompletionCallback() override;

  CompletionOnceCallback callback() {
    return base::BindOnce(&TestCompletionCallback::SetResult,
                          base::Unretained(this));
  }
};

class TestInt64CompletionCallback : public TestInt64CompletionCallbackBase {
 public:
  TestInt64CompletionCallback() = default;
  TestInt64CompletionCallback(const TestInt64CompletionCallback&) = delete;
  TestInt64CompletionCallback& operator=(const TestInt64CompletionCallback&) =
      delete;
  ~TestInt64CompletionCallback() override;

  Int64CompletionOnceCallback callback() {
    return base::BindOnce(&TestInt64CompletionCallback::SetResult,
                          base::Unretained(this));
  }
};

// Makes sure that the buffer is not referenced when the callback runs.
class ReleaseBufferCompletionCallback: public TestCompletionCallback {
 public:
  explicit ReleaseBufferCompletionCallback(IOBuffer* buffer);
  ReleaseBufferCompletionCallback(const ReleaseBufferCompletionCallback&) =
      delete;
  ReleaseBufferCompletionCallback& operator=(
      const ReleaseBufferCompletionCallback&) = delete;
  ~ReleaseBufferCompletionCallback() override;

 private:
  void SetResult(int result) override;

  raw_ptr<IOBuffer> buffer_;
};

}  // namespace net

#endif  // NET_BASE_TEST_COMPLETION_CALLBACK_H_