Refactors date handling to use DateService

Standardizes date manipulation across the application by leveraging the DateService.
This change improves consistency and reduces code duplication by removing redundant date calculations.

src/managers/GridManager.ts

@@ -156,7 +156,7 @@ export class GridManager {
         nextDate = this.dateService.addWeeks(this.currentDate, 1);
         break;
       case 'month':
-        nextDate = this.addMonths(this.currentDate, 1);
+        nextDate = this.dateService.addMonths(this.currentDate, 1);
         break;
       case 'day':
         nextDate = this.dateService.addDays(this.currentDate, 1);
@@ -187,7 +187,7 @@ export class GridManager {
         prevDate = this.dateService.addWeeks(this.currentDate, -1);
         break;
       case 'month':
-        prevDate = this.addMonths(this.currentDate, -1);
+        prevDate = this.dateService.addMonths(this.currentDate, -1);
         break;
       case 'day':
         prevDate = this.dateService.addDays(this.currentDate, -1);
@@ -299,33 +299,22 @@ export class GridManager {
     }
   }
 
-  /**
-   * Helper method to add months to a date
-   */
-  private addMonths(date: Date, months: number): Date {
-    const result = new Date(date);
-    result.setMonth(result.getMonth() + months);
-    return result;
-  }
-  
   /**
    * Helper method to get month start
    */
   private getMonthStart(date: Date): Date {
-    const result = new Date(date);
-    result.setDate(1);
-    result.setHours(0, 0, 0, 0);
-    return result;
+    const year = date.getFullYear();
+    const month = date.getMonth();
+    return this.dateService.startOfDay(new Date(year, month, 1));
   }
 
   /**
    * Helper method to get month end
    */
   private getMonthEnd(date: Date): Date {
-    const result = new Date(date);
-    result.setMonth(result.getMonth() + 1, 0);
-    result.setHours(23, 59, 59, 999);
-    return result;
+    const nextMonth = this.dateService.addMonths(date, 1);
+    const firstOfNextMonth = this.getMonthStart(nextMonth);
+    return this.dateService.endOfDay(this.dateService.addDays(firstOfNextMonth, -1));
   }
 
   /**
@@ -336,8 +325,10 @@ export class GridManager {
     const monthStart = this.getMonthStart(date);
     const monthEnd = this.getMonthEnd(date);
 
-    for (let d = new Date(monthStart); d <= monthEnd; d.setDate(d.getDate() + 1)) {
-      dates.push(new Date(d));
+    const totalDays = Math.ceil((monthEnd.getTime() - monthStart.getTime()) / (1000 * 60 * 60 * 24)) + 1;
+
+    for (let i = 0; i < totalDays; i++) {
+      dates.push(this.dateService.addDays(monthStart, i));
     }
 
     return dates;

src/managers/NavigationManager.ts

@@ -153,14 +153,14 @@ export class NavigationManager {
   }
 
   private navigateToPreviousWeek(): void {
-    this.targetWeek.setDate(this.targetWeek.getDate() - 7);
+    this.targetWeek = this.dateService.addWeeks(this.targetWeek, -1);
     const weekToShow = new Date(this.targetWeek);
     this.animationQueue++;
     this.animateTransition('prev', weekToShow);
   }
 
   private navigateToNextWeek(): void {
-    this.targetWeek.setDate(this.targetWeek.getDate() + 7);
+    this.targetWeek = this.dateService.addWeeks(this.targetWeek, 1);
     const weekToShow = new Date(this.targetWeek);
     this.animationQueue++;
     this.animateTransition('next', weekToShow);

src/renderers/EventRenderer.ts

@@ -11,7 +11,7 @@ import { DragOffset, StackLinkData } from '../types/DragDropTypes';
 import { ColumnBounds } from '../utils/ColumnDetectionUtils';
 import { DragColumnChangeEventPayload, DragMoveEventPayload, DragStartEventPayload } from '../types/EventTypes';
 import { DateService } from '../utils/DateService';
-import { format, setHours, setMinutes, setSeconds, addDays } from 'date-fns';
+import { format } from 'date-fns';
 
 /**
  * Interface for event rendering strategies
@@ -164,40 +164,25 @@ export class DateEventRenderer implements EventRendererStrategy {
    * Update data-start and data-end attributes with ISO timestamps
    */
   private updateDateTimeAttributes(element: HTMLElement, columnDate: Date, startMinutes: number, endMinutes: number): void {
-    const startDate = this.createDateWithMinutes(columnDate, startMinutes);
+    const startDate = this.dateService.createDateAtTime(columnDate, startMinutes);
 
-    let endDate = this.createDateWithMinutes(columnDate, endMinutes);
+    let endDate = this.dateService.createDateAtTime(columnDate, endMinutes);
 
     // Handle cross-midnight events
     if (endMinutes >= 1440) {
       const extraDays = Math.floor(endMinutes / 1440);
-      endDate = addDays(endDate, extraDays);
+      endDate = this.dateService.addDays(endDate, extraDays);
     }
 
     element.dataset.start = startDate.toISOString();
     element.dataset.end = endDate.toISOString();
   }
 
-  /**
-   * Create a date with specific minutes since midnight
-   */
-  private createDateWithMinutes(baseDate: Date, totalMinutes: number): Date {
-    const hours = Math.floor(totalMinutes / 60);
-    const minutes = totalMinutes % 60;
-    
-    return setSeconds(setMinutes(setHours(baseDate, hours), minutes), 0);
-  }
-
   /**
    * Format minutes since midnight to time string
    */
   private formatTimeFromMinutes(totalMinutes: number): string {
-    const hours = Math.floor(totalMinutes / 60);
-    const minutes = totalMinutes % 60;
-    const date = new Date();
-    date.setHours(hours, minutes, 0, 0);
-    
-    return format(date, 'HH:mm');
+    return this.dateService.minutesToTime(totalMinutes);
   }
 
   /**

src/strategies/MonthViewStrategy.ts

@@ -98,8 +98,10 @@ export class MonthViewStrategy implements ViewStrategy {
   }
   
   private getMonthDates(monthDate: Date): Date[] {
-    // Get first day of month
-    const firstOfMonth = new Date(monthDate.getFullYear(), monthDate.getMonth(), 1);
+    // Get first day of month using DateService
+    const year = monthDate.getFullYear();
+    const month = monthDate.getMonth();
+    const firstOfMonth = this.dateService.startOfDay(new Date(year, month, 1));
 
     // Get Monday of the week containing first day
     const weekBounds = this.dateService.getWeekBounds(firstOfMonth);
@@ -120,11 +122,17 @@ export class MonthViewStrategy implements ViewStrategy {
   }
   
   getNextPeriod(currentDate: Date): Date {
-    return new Date(currentDate.getFullYear(), currentDate.getMonth() + 1, 1);
+    const nextMonth = this.dateService.addMonths(currentDate, 1);
+    const year = nextMonth.getFullYear();
+    const month = nextMonth.getMonth();
+    return this.dateService.startOfDay(new Date(year, month, 1));
   }
 
   getPreviousPeriod(currentDate: Date): Date {
-    return new Date(currentDate.getFullYear(), currentDate.getMonth() - 1, 1);
+    const prevMonth = this.dateService.addMonths(currentDate, -1);
+    const year = prevMonth.getFullYear();
+    const month = prevMonth.getMonth();
+    return this.dateService.startOfDay(new Date(year, month, 1));
   }
   
   getPeriodLabel(date: Date): string {
@@ -140,7 +148,9 @@ export class MonthViewStrategy implements ViewStrategy {
   
   getPeriodRange(baseDate: Date): { startDate: Date; endDate: Date } {
     // Month view shows events for the entire month grid (including partial weeks)
-    const firstOfMonth = new Date(baseDate.getFullYear(), baseDate.getMonth(), 1);
+    const year = baseDate.getFullYear();
+    const month = baseDate.getMonth();
+    const firstOfMonth = this.dateService.startOfDay(new Date(year, month, 1));
 
     // Get Monday of the week containing first day
     const weekBounds = this.dateService.getWeekBounds(firstOfMonth);

src/utils/DateService.ts

@@ -20,6 +20,7 @@ import {
   startOfWeek,
   endOfWeek,
   addWeeks,
+  addMonths,
   isSameDay,
   getISOWeek
 } from 'date-fns';
@@ -258,6 +259,16 @@ export class DateService {
     return addWeeks(date, weeks);
   }
 
+  /**
+   * Add months to a date
+   * @param date - Base date
+   * @param months - Number of months to add (can be negative)
+   * @returns New date
+   */
+  public addMonths(date: Date, months: number): Date {
+    return addMonths(date, months);
+  }
+  
   /**
    * Get ISO week number (1-53)
    * @param date - Date to get week number for

src/utils/PositionUtils.ts

@@ -226,12 +226,7 @@ export class PositionUtils {
      */
     public static timeStringToIso(timeString: string, date: Date = new Date()): string {
         const totalMinutes = PositionUtils.dateService.timeToMinutes(timeString);
-        const hours = Math.floor(totalMinutes / 60);
-        const minutes = totalMinutes % 60;
-        
-        const newDate = new Date(date);
-        newDate.setHours(hours, minutes, 0, 0);
-        
+        const newDate = PositionUtils.dateService.createDateAtTime(date, totalMinutes);
         return newDate.toISOString();
     }