calendar_view_demo/lib/calendar_controller/controller.dart

import 'package:calendar_view/utils/calendar_util.dart';
import 'package:calendar_view/utils/event_type.dart';
import 'package:get/get.dart';

class CalendarController extends GetxController {
  CalendarController();

  /// 数据项：当前年份，当前月份，当前日期
  int currentYear = 2022; // 当前年份
  int currentMonth = 12; // 当前月份
  int selectedDayIndex = 0; // 当前选择的日期的下标，从0开始，范围是0-34 有时是 0-41
  int maxDaysLength = 35; // 最大的日期数组长度，有时是42
  List<DayStructure> daysList = []; // 当前维护的日期列表
  ///TODO: 维护一个日程列表

  /// TODO[Gavin]: i18n
  String get currentYearMonth => '$currentYear年$currentMonth月';
  bool get isToday => daysList[selectedDayIndex].isToday;
  int get calendarLines => maxDaysLength ~/ 7;
  // _initData() {
  //   update(["calendar"]);
  // }
  FEventHandler<void> onDaysListChange = FEventHandler<void>();

  void onTap() {}

  @override
  void onInit() {
    super.onInit();

    /// 获取当前时间判断年月
    final DateTime now = DateTime.now();
    currentYear = now.year;
    currentMonth = now.month;
    daysList = _countDaysList(currentYear, currentMonth);
    selectToday();

    /// 虚拟的日程数据
    final List<DateTime> mockSchedule = [
      DateTime(2022, 12, 1),
      DateTime(2022, 12, 4),
      DateTime(2022, 12, 5),
      DateTime(2022, 12, 6),
      DateTime(2022, 12, 7),
      DateTime(2022, 12, 12),
      DateTime(2022, 12, 13),
      DateTime(2022, 12, 14),
      DateTime(2022, 12, 15),
      DateTime(2022, 12, 16),
      DateTime(2022, 12, 17),
      DateTime(2022, 12, 18),
      DateTime(2022, 12, 19),
      DateTime(2022, 12, 20),
      DateTime(2022, 12, 27),
      DateTime(2022, 12, 28),
      DateTime(2022, 12, 29),
      DateTime(2022, 12, 30),
      DateTime(2022, 12, 31),
    ];
    _setSchedule(mockSchedule);
    print("CalendarController 全局临时控制器初始化");
  }

  @override
  void onReady() {
    super.onReady();
    // _initData();
  }

  // @override
  // void onClose() {
  //   super.onClose();
  // }
  /// 传入起始年月，返回35个日期结构体
  List<DayStructure> _countDaysList(int year, int month) {
    maxDaysLength = _isNeedExtraRow(year, month) ? 42 : 35;
    final daysList = <DayStructure>[];
    final firstDay = DateTime(year, month, 1);
    final firstDayWeek = firstDay.weekday;
    final lastDay = DateTime(year, month + 1, 0);
    final lastDayOfMonth = lastDay.day;
    final lastDayOfLastMonth = DateTime(year, month, 0).day;
    final today = DateTime.now();

    /// 转换后的 firstDayWeek
    final firstDayWeekIndex = (firstDayWeek) % 7;
    int nextMonthDay = 1;

    // 上个月的日期
    for (var i = 0; i < firstDayWeekIndex; i++) {
      daysList.add(
        DayStructure(
          index: i,
          date: DateTime(
              year, month - 1, lastDayOfLastMonth - firstDayWeekIndex + i + 1),
          isCurrentMonth: false,
        ),
      );
    }

    // 当月的日期
    for (var i = 0;
        (i < lastDayOfMonth) && daysList.length < maxDaysLength;
        i++) {
      daysList.add(
        DayStructure(
          index: i + firstDayWeek,
          date: DateTime(year, month, i + 1),
          isToday:
              today.year == year && today.month == month && today.day == i + 1,
        ),
      );
    }

    while (daysList.length < maxDaysLength) {
      daysList.add(DayStructure(
        index: daysList.length,
        date: DateTime(month == 12 ? year + 1 : year,
            month == 12 ? 1 : month + 1, nextMonthDay),
        isCurrentMonth: false,
      ));
      nextMonthDay++;
    }
    return daysList;
  }

  /// 计算是否需要显示六行日期，一般为5行，但是有时候会有6行
  bool _isNeedExtraRow(int year, int month) {
    final firstDay = DateTime(year, month, 1);
    final firstDayWeek = firstDay.weekday;
    final lastDay = DateTime(year, month + 1, 0);
    final lastDayOfMonth = lastDay.day;

    /// 转换后的firstDayWeek，%7是因为DateTime的weekday是从周日开始的，而我们的日历是从周一开始的
    final firstDayWeekIndex = (firstDayWeek) % 7;
    return firstDayWeekIndex + lastDayOfMonth > 35;
  }

  /// 通过下标选中日期，下标从0开始，允许的范围是0-34，有时是 0-42
  void handleSelectedDayByIndex(int index) {
    assert(index >= 0 && index < maxDaysLength,
        'index must be in 0-$maxDaysLength');
    assert(daysList.length == maxDaysLength,
        'daysList length must be maxDaysLength');
    for (var element in daysList) {
      if (element.index == index) {
        element.isSelected = true;
      } else {
        element.isSelected = false;
      }
    }
    selectedDayIndex = index;
    onDaysListChange.emit(this, null);
  }

  /// 选中当月第一天
  void _selectFirstDay() {
    for (var element in daysList) {
      if (element.isCurrentMonth) {
        handleSelectedDayByIndex(element.index);
        break;
      }
    }
  }

  /// 选中今天
  void selectToday() {
    /// 如果当前不是当月，则切换到当月
    final DateTime now = DateTime.now();
    if (currentYear != now.year || currentMonth != now.month) {
      currentYear = now.year;
      currentMonth = now.month;
      daysList = _countDaysList(currentYear, currentMonth);
    }
    for (var element in daysList) {
      if (element.isToday) {
        handleSelectedDayByIndex(element.index);
        break;
      }
    }
  }

  /// 给日期设置日程的值
  void _setSchedule(List<DateTime> scheduleList) {
    /// 如果scheduleList中存在daysList中的日期，则设置hasSchedule为true
    for (var element in scheduleList) {
      for (var day in daysList) {
        if (element.year == day.date.year &&
            element.month == day.date.month &&
            element.day == day.date.day) {
          day.hasSchedule = true;
        }
      }
    }
  }

  /// 上个月
  void handleLastMonth() {
    if (currentMonth == 1) {
      currentMonth = 12;
      currentYear--;
    } else {
      currentMonth--;
    }
    daysList = _countDaysList(currentYear, currentMonth);
    _selectFirstDay();

    onDaysListChange.emit(this, null);
  }

  /// 下个月
  void handleNextMonth() {
    if (currentMonth == 12) {
      currentMonth = 1;
      currentYear++;
    } else {
      currentMonth++;
    }
    daysList = _countDaysList(currentYear, currentMonth);
    _selectFirstDay();

    onDaysListChange.emit(this, null);
  }
}