// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Common functionality for unittest and browsertest harnesses.

#ifndef COMPONENTS_PERFORMANCE_MANAGER_TEST_SUPPORT_TEST_HARNESS_HELPER_H_
#define COMPONENTS_PERFORMANCE_MANAGER_TEST_SUPPORT_TEST_HARNESS_HELPER_H_

#include <memory>

#include "base/functional/callback.h"
#include "components/performance_manager/embedder/graph_features.h"
#include "components/performance_manager/graph/graph_impl.h"

namespace content {
class BrowserContext;
class WebContents;
}  // namespace content

namespace performance_manager {

class PerformanceManagerImpl;
class PerformanceManagerRegistry;

// A test harness helper. Manages the PM in a test environment.
//
// Note that in some test environments we have automatic WebContents creation
// hooks, and in others the test code must manually call "OnWebContentsCreated".
//
// Rough directions for use:
//
// In browser tests:
// - components_browsertests:
//   The PerformanceManagerBrowserTestHarness fixture brings its own
//   OnWebContentsCreated hooks.
// - browser_tests:
//   The PerformanceManagerBrowserTestHarness and
//   ChromeRenderViewHostTestHarness have their own OnWebContentsCreated hooks.
//   If using ChromeRenderViewHostTestHarness you need to embed an instance of
//   this helper in order to initialize the PM.
//
// In unit tests:
// - components_unittests:
//   The PerformanceManagerTestHarness brings its own OnWebContentsCreated
//   hooks providing you use its CreateTestWebContents helper.
// - unit_tests:
//   The ChromeRenderViewHostTestHarness brings its own OnWebContentsCreated
//   hooks, but you need to embed an instance of this helper in order to
//   initialize the PM.
//
// This helper initializes the performance manager in the call to SetUp(), and
// tears it down in TearDown().
class PerformanceManagerTestHarnessHelper {
 public:
  using GraphImplCallback = base::OnceCallback<void(GraphImpl*)>;

  PerformanceManagerTestHarnessHelper();
  PerformanceManagerTestHarnessHelper(
      const PerformanceManagerTestHarnessHelper&) = delete;
  PerformanceManagerTestHarnessHelper& operator=(
      const PerformanceManagerTestHarnessHelper&) = delete;
  virtual ~PerformanceManagerTestHarnessHelper();

  // Sets up the PM and registry, etc. This will return once the PM is fully
  // initialized, and after any GraphImplCallback has been invoked.
  virtual void SetUp();

  // Tears down the PM and registry, etc. Blocks on the main thread until they
  // are torn down.
  virtual void TearDown();

  // Attaches tab helpers to the provided |contents|. This should only need to
  // be called explicitly in components_unittests. In unit_tests, browser_tests
  // and components_browsertests we have the necessary hooks into WebContents
  // creation to automatically add our observers; it suffices to ensure that the
  // PM is initialized (ie, initialize an instance of this helper).
  void OnWebContentsCreated(content::WebContents* contents);

  // Creates worker helpers for the provided `browser_context`. The helpers must
  // be deleted with OnBrowserContextRemoved() before calling TearDown().
  void OnBrowserContextAdded(content::BrowserContext* browser_context);

  // Deletes the worker helpers for the provided `browser_context`. The helpers
  // must have been created with OnBrowserContextAdded() before calling this.
  void OnBrowserContextRemoved(content::BrowserContext* browser_context);

  // Allows configuring which Graph features are initialized during "SetUp".
  // This defaults to initializing no features.
  GraphFeatures& GetGraphFeatures();

  // Allows configuring a Graph callback that will be invoked when the Graph
  // is initialized in "SetUp".
  void SetGraphImplCallback(GraphImplCallback graph_impl_callback) {
    graph_impl_callback_ = std::move(graph_impl_callback);
  }

 private:
  GraphFeatures graph_features_;
  GraphImplCallback graph_impl_callback_;
  std::unique_ptr<PerformanceManagerImpl> perf_man_;
  std::unique_ptr<PerformanceManagerRegistry> registry_;
};

}  // namespace performance_manager

#endif  // COMPONENTS_PERFORMANCE_MANAGER_TEST_SUPPORT_TEST_HARNESS_HELPER_H_