// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef ASH_SYSTEM_TIME_CALENDAR_VIEW_CONTROLLER_H_
#define ASH_SYSTEM_TIME_CALENDAR_VIEW_CONTROLLER_H_

#include <list>
#include <map>
#include <memory>
#include <optional>
#include <set>

#include "ash/ash_export.h"
#include "ash/system/time/calendar_model.h"
#include "base/memory/raw_ptr.h"
#include "base/observer_list.h"
#include "base/time/time.h"
#include "google_apis/calendar/calendar_api_response_types.h"
#include "google_apis/common/api_error_codes.h"
#include "ui/events/event.h"

namespace ash {

class CalendarDateCellView;

// Controller of the `CalendarView`.
class ASH_EXPORT CalendarViewController {
 public:
  CalendarViewController();
  CalendarViewController(const CalendarViewController& other) = delete;
  CalendarViewController& operator=(const CalendarViewController& other) =
      delete;
  virtual ~CalendarViewController();

  class Observer : public base::CheckedObserver {
   public:
    // Gets called when `currently_shown_date_ ` changes.
    virtual void OnMonthChanged() {}

    // Invoked when a date cell is clicked to open the event list.
    virtual void OpenEventList() {}

    // Invoked when the close button is clicked to close the event list.
    virtual void CloseEventList() {}

    // Invoked when the selected date is updated in the
    // `CalendarViewController`.
    virtual void OnSelectedDateUpdated() {}

    // Invoked when the calendar UI has completed rendering (including business
    // logic like scrolling to the current month).
    virtual void OnCalendarLoaded() {}
  };

  void AddObserver(Observer* observer);
  void RemoveObserver(Observer* observer);

  // Updates the `currently_shown_date_`.
  void UpdateMonth(const base::Time current_month_first_date);

  // A callback passed into the`CalendarDateCellView`, which is called when the
  // cell is clicked to show the event list view.
  void ShowEventListView(CalendarDateCellView* selected_calendar_date_cell_view,
                         base::Time selected_date,
                         int row_index);

  // A callback passed into the`CalendarEventListView`, which is called when the
  // close button is clicked to close the event list view.
  void CloseEventListView();

  // Gets called when the `CalendarEventListView` is opened.
  void OnEventListOpened();

  // Gets called when the `CalendarEventListView` is closed.
  void OnEventListClosed();

  // Gets called when the `CalendarView` has completed loading its UI.
  void CalendarLoaded();

  // Records the event list item being pressed on and the type of event.
  // Captures whether it was from the `CalendarEventListView` or implicitly the
  // `CalendarUpNextView` (the only other place the `CalendarEventListItemView`
  // is used currently).
  void RecordEventListItemActivated(const ui::Event& event);

  // Records a metric for the "Join" meeting button being pressed.
  // Captures whether it was from the `CalendarEventListView` or implicitly the
  // `CalendarUpNextView` (the only other place the `CalendarEventListItemView`
  // is used currently).
  void RecordJoinMeetingButtonPressed(const ui::Event& event);

  // Called when a calendar event is about to launch. Used to record metrics.
  void OnCalendarEventWillLaunch();

  // Called when the CalendarDateCellView representing today gets a fetch.
  void OnTodaysEventFetchComplete();

  // Called when the on screen month has finished loading and has any events to
  // display to the user. Logs a metric once per CalendarView lifetime.
  void EventsDisplayedToUser();

  // If the selected date in the current month. This is used to inform the
  // `CalendarView` if the month should be updated when a date is selected.
  bool IsSelectedDateInCurrentMonth();

  // Gets the first day of the `currently_shown_date_`'s month, in UTC time.
  // Time difference is applied.
  base::Time GetOnScreenMonthFirstDayUTC();

  // Gets the first day of the nth-previous month based on the
  // `currently_shown_date_`'s month, in UTC time. Time difference is applied.
  base::Time GetPreviousMonthFirstDayUTC(unsigned int num_months);

  // Gets the first day of the nth-next month based on the
  // `currently_shown_date_`'s month, in UTC time. Time difference is applied.
  base::Time GetNextMonthFirstDayUTC(unsigned int num_months);

  // Gets the month name of the `currently_shown_date_`'s month.
  std::u16string GetOnScreenMonthName() const;

  // Gets the month name of the next `num_months` month based on the
  // `currently_shown_date_`'s month.
  std::u16string GetNextMonthName(int num_months = 1);

  // Gets the month name of the previous month based `currently_shown_date_`'s
  // month.
  std::u16string GetPreviousMonthName();

  // Getters of the today's row position, top and bottom.
  int GetTodayRowTopHeight() const;
  int GetTodayRowBottomHeight() const;

  // The calendar events of the selected date.
  SingleDayEventList SelectedDateEvents();

  // Selected date events split into two lists, one of multi day events only,
  // the other excluding multi day events i.e. same day events. These are
  // displayed to the user in two separate list views.
  std::tuple<SingleDayEventList, SingleDayEventList>
  SelectedDateEventsSplitByMultiDayAndSameDay();

  // Returns upcoming events for the "Up next" view.
  SingleDayEventList UpcomingEvents();

  // The calendar events number of the `date`.
  int GetEventNumber(base::Time date);

  // Getters and setters: the row index when the event list view is showing,
  // today's row number, today's row height and expanded area height.
  int GetExpandedRowIndex() const;

  // Get the current date, which can be today or the first day of the current
  // month if current month is not today's month.
  base::Time currently_shown_date() { return currently_shown_date_; }

  // The currently selected date to show the event list.
  std::optional<base::Time> selected_date() { return selected_date_; }

  // The midnight of the currently selected date adjusted to the local timezone.
  base::Time selected_date_midnight() { return selected_date_midnight_; }

  // The midnight of the selected date in UTC time.
  base::Time selected_date_midnight_utc() {
    return selected_date_midnight_utc_;
  }

  // The row index of the currently selected date. This is used for auto
  // scrolling to this row when the event list is expanded.
  int selected_date_row_index() { return selected_date_row_index_; }

  void set_expanded_row_index(int row_index) {
    expanded_row_index_ = row_index;
  }

  int today_row() const { return today_row_; }
  void set_today_row(int row) { today_row_ = row; }

  int row_height() const { return row_height_; }
  void set_row_height(int height) { row_height_ = height; }

  CalendarDateCellView* selected_date_cell_view() {
    return selected_date_cell_view_;
  }
  void set_selected_date_cell_view(
      CalendarDateCellView* todays_date_cell_view) {
    selected_date_cell_view_ = todays_date_cell_view;
  }

  CalendarDateCellView* todays_date_cell_view() {
    return todays_date_cell_view_;
  }
  void set_todays_date_cell_view(CalendarDateCellView* todays_date_cell_view) {
    todays_date_cell_view_ = todays_date_cell_view;
  }

  bool is_date_cell_clickable() const { return is_date_cell_clickable_; }
  void set_is_date_cell_clickable(bool is_clickable) {
    is_date_cell_clickable_ = is_clickable;
  }

  bool is_event_list_showing() const { return is_event_list_showing_; }

  // Returns whether the events for `start_of_month` have been successfully
  // fetched. The `FetchingStatus` should be either `kSuccess` or `kRefetching`.
  bool IsSuccessfullyFetched(base::Time start_of_month);

 private:
  // For unit tests.
  friend class CalendarMonthViewTest;
  friend class CalendarViewAnimationTest;
  friend class CalendarViewEventListViewFetchTest;
  friend class CalendarViewEventListViewTest;
  friend class CalendarViewTest;
  friend class CalendarViewEventListItemViewTest;

  // Adds the time difference and returns the adjusted time.
  base::Time ApplyTimeDifference(base::Time date);

  // The currently shown date, which can be today or the first day of the
  // current month if current month is not today's month.
  base::Time currently_shown_date_;

  // The time the CalendarViewController was created, which coincides with the
  // time the view was created.
  base::TimeTicks calendar_open_time_;

  // The time the user spends in a month before navigating to another one.
  base::TimeTicks month_dwell_time_;

  // The today's date cell row number (which is index +1) in its
  // `CalendarMonthView`.
  int today_row_ = 0;

  // Each row's height. Every row should have the same height, so this height is
  // only updated once with today's row.
  int row_height_ = 0;

  // If the event list is expanded.
  bool is_event_list_showing_ = false;

  // Whether the user journey time has been recorded. It is recorded when an
  // event is launched, or when this (which is owned by the view) is destroyed.
  bool user_journey_time_recorded_ = false;

  // Whether the metric for recording time to show the user the first fetch of
  // events has been recorded.
  bool todays_date_cell_fetch_recorded_ = false;

  // Record if any events are displayed (via the dots in the current month) on
  // screen to the user.
  bool events_shown_to_user_recorded_ = false;

  // Whether date cells are clickable. When the event list animation is running,
  // date cells should become unclickable until the animation completes.
  bool is_date_cell_clickable_ = true;

  // The currently selected date.
  std::optional<base::Time> selected_date_;

  // The currently selected CalendarDateCellView
  raw_ptr<CalendarDateCellView> selected_date_cell_view_ = nullptr;

  // The CalendarDateCellView which represents today.
  raw_ptr<CalendarDateCellView> todays_date_cell_view_ = nullptr;

  // The midnight of the currently selected date adjusted to the local timezone.
  base::Time selected_date_midnight_;

  // The midnight of the selected date in UTC time.
  base::Time selected_date_midnight_utc_;

  // The row index of the currently selected date.
  int selected_date_row_index_ = 0;

  // The current row index when the event list view is shown.
  int expanded_row_index_ = 0;

  // Maximum distance, in months, from the on-screen month first displayed in
  // the calendar when it was opened. This is logged as a metric when the
  // calendar is closed.
  size_t max_distance_browsed_ = 0;

  // The first date shown, used to record max distance browsed metrics.
  const base::Time first_shown_date_;

  base::ObserverList<Observer> observers_;

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

}  // namespace ash

#endif  // ASH_SYSTEM_TIME_CALENDAR_VIEW_CONTROLLER_H_