// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_PRELOADING_SEARCH_PRELOAD_SEARCH_PRELOAD_PIPELINE_MANAGER_H_
#define CHROME_BROWSER_PRELOADING_SEARCH_PRELOAD_SEARCH_PRELOAD_PIPELINE_MANAGER_H_

#include "base/callback_list.h"
#include "base/containers/flat_map.h"
#include "base/memory/weak_ptr.h"
#include "chrome/browser/preloading/prerender/search_preload_progress_service.h"
#include "chrome/browser/preloading/search_preload/search_preload_pipeline.h"
#include "content/public/browser/web_contents_observer.h"
#include "content/public/browser/web_contents_user_data.h"
#include "url/gurl.h"

class AutocompleteResult;
class Profile;
class SearchPreloadService;
class TemplateURLService;
struct AutocompleteMatch;

namespace content {
class WebContents;
}

namespace omnibox::mojom {
enum class NavigationPredictor;
}

// Roles:
//
// - Manages preload pipelines per WebContents.
// - Starts preloads in response to Omnibox events.
class SearchPreloadPipelineManager
    : public content::WebContentsUserData<SearchPreloadPipelineManager>,
      public content::WebContentsObserver {
 public:
  ~SearchPreloadPipelineManager() override;

  // Not movable nor copyable.
  SearchPreloadPipelineManager(const SearchPreloadPipelineManager&&) = delete;
  SearchPreloadPipelineManager& operator=(
      const SearchPreloadPipelineManager&&) = delete;
  SearchPreloadPipelineManager(const SearchPreloadPipelineManager&) = delete;
  SearchPreloadPipelineManager& operator=(const SearchPreloadPipelineManager&) =
      delete;

  base::WeakPtr<SearchPreloadPipelineManager> GetWeakPtr() {
    return weak_factory_.GetWeakPtr();
  }

  // Implements `content::WebContentsObserver`
  void DidFinishNavigation(
      content::NavigationHandle* navigation_handle) override;

  // Clears all preloads.
  void ClearPreloads();

  // Called when autocomplete is updated.
  void OnAutocompleteResultChanged(
      Profile& profile,
      base::WeakPtr<SearchPreloadService> search_preload_service,
      const AutocompleteResult& result,
      const std::optional<net::HttpNoVarySearchData>& no_vary_search_hint);

  // Called when a user is likely to navigate to the match.
  //
  // Returns true iff a new prefetch is triggered by this call. Note that it
  // returns false if a prefetch for the same canonical URL has already
  // triggered.
  bool OnNavigationLikely(
      Profile& profile,
      base::WeakPtr<SearchPreloadService> search_preload_service,
      const AutocompleteMatch& match,
      omnibox::mojom::NavigationPredictor navigation_predictor,
      const std::optional<net::HttpNoVarySearchData>& no_vary_search_hint);

  // Invalidates a pipeline with `canonical_url`.
  //
  // Returns true iff invalidated successfully.
  bool InvalidatePipelineForTesting(GURL canonical_url);

  void OnSearchPrewarmFinished();

 private:
  friend content::WebContentsUserData<SearchPreloadPipelineManager>;
  WEB_CONTENTS_USER_DATA_KEY_DECL();
  explicit SearchPreloadPipelineManager(content::WebContents* contents);

  void EraseNotAlivePipelines();

  // Returns `(singal_result_prefetch, signal_result_prerender)`.
  std::tuple<std::optional<SearchPreloadSignalResult>,
             std::optional<SearchPreloadSignalResult>>
  OnAutocompleteResultChangedProcessOne(
      Profile& profile,
      base::WeakPtr<SearchPreloadService> search_preload_service,
      TemplateURLService& template_url_service,
      const AutocompleteMatch& match,
      const std::optional<net::HttpNoVarySearchData>& no_vary_search_hint);

  // Helper to record histograms.
  void RecordPreloadHistograms(
      std::tuple<std::optional<SearchPreloadSignalResult>,
                 std::optional<SearchPreloadSignalResult>> signal_results);

  // Keeps the information of search prefetch/prerender requests, which can be
  // used to trigger the preloads.
  //
  // It's a pure data structure and intended to be used in only
  // `SearchPreloadPipelineManager`.
  struct TriggerPreloadsData {
    TriggerPreloadsData(
        base::WeakPtr<SearchPreloadService> search_preload_service,
        GURL canonical_url,
        GURL prefetch_url,
        std::optional<GURL> prerender_url,
        std::optional<net::HttpNoVarySearchData> no_vary_search_hint,
        int confidence);
    // Movable but not copyable.
    TriggerPreloadsData(TriggerPreloadsData&& other);
    TriggerPreloadsData& operator=(TriggerPreloadsData&& other);
    TriggerPreloadsData(const TriggerPreloadsData& other) = delete;
    TriggerPreloadsData& operator=(const TriggerPreloadsData& other) = delete;
    ~TriggerPreloadsData();

    base::WeakPtr<SearchPreloadService> search_preload_service;
    GURL canonical_url;
    GURL prefetch_url;
    std::optional<GURL> prerender_url;
    std::optional<net::HttpNoVarySearchData> no_vary_search_hint;
    int confidence;
  };

  // Only the latest trigger data is stored, as only the latest input is the
  // most likely to navigate.
  std::optional<TriggerPreloadsData> deferred_trigger_data_;

  // Prewarm page loading status tracker to throttle the concurrent requests to
  // search.
  base::WeakPtr<SearchPreloadProgressService> prewarm_progress_service_;

  base::CallbackListSubscription prewarm_finished_subscription_;

  // Trigger prefetch and prerender for a specific URL, which can be deferred.
  std::tuple<std::optional<SearchPreloadSignalResult>,
             std::optional<SearchPreloadSignalResult>>
  TriggerPreloads(TriggerPreloadsData data);

  // Manages pipeline per canonical URL.
  base::flat_map<GURL, std::unique_ptr<SearchPreloadPipeline>> pipelines_;

  base::WeakPtrFactory<SearchPreloadPipelineManager> weak_factory_{this};
};

#endif  // CHROME_BROWSER_PRELOADING_SEARCH_PRELOAD_SEARCH_PRELOAD_PIPELINE_MANAGER_H_