import { IColumnDataSource, IColumnInfo } from '../types/ColumnDataSource';
import { DateService } from '../utils/DateService';
import { Configuration } from '../configurations/CalendarConfig';
import { CalendarView } from '../types/CalendarTypes';

/**
 * DateColumnDataSource - Provides date-based columns
 *
 * Calculates which dates to display based on:
 * - Current date
 * - Current view (day/week/month)
 * - Workweek settings
 */
export class DateColumnDataSource implements IColumnDataSource {
  private dateService: DateService;
  private config: Configuration;
  private currentDate: Date;
  private currentView: CalendarView;

  constructor(
    dateService: DateService,
    config: Configuration,
    currentDate: Date,
    currentView: CalendarView
  ) {
    this.dateService = dateService;
    this.config = config;
    this.currentDate = currentDate;
    this.currentView = currentView;
  }

  /**
   * Get columns (dates) to display
   */
  public getColumns(): IColumnInfo[] {
    let dates: Date[];

    switch (this.currentView) {
      case 'week':
        dates = this.getWeekDates();
        break;
      case 'month':
        dates = this.getMonthDates();
        break;
      case 'day':
        dates = [this.currentDate];
        break;
      default:
        dates = this.getWeekDates();
    }

    // Convert Date[] to IColumnInfo[]
    return dates.map(date => ({
      identifier: this.dateService.formatISODate(date),
      data: date
    }));
  }

  /**
   * Get type of datasource
   */
  public getType(): 'date' | 'resource' {
    return 'date';
  }

  /**
   * Update current date
   */
  public setCurrentDate(date: Date): void {
    this.currentDate = date;
  }

  /**
   * Update current view
   */
  public setCurrentView(view: CalendarView): void {
    this.currentView = view;
  }

  /**
   * Get dates for week view based on workweek settings
   */
  private getWeekDates(): Date[] {
    const weekStart = this.getISOWeekStart(this.currentDate);
    const workWeekSettings = this.config.getWorkWeekSettings();
    return this.dateService.getWorkWeekDates(weekStart, workWeekSettings.workDays);
  }

  /**
   * Get all dates in current month
   */
  private getMonthDates(): Date[] {
    const dates: Date[] = [];
    const monthStart = this.getMonthStart(this.currentDate);
    const monthEnd = this.getMonthEnd(this.currentDate);

    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;
  }

  /**
   * Get ISO week start (Monday)
   */
  private getISOWeekStart(date: Date): Date {
    const weekBounds = this.dateService.getWeekBounds(date);
    return this.dateService.startOfDay(weekBounds.start);
  }

  /**
   * Get month start
   */
  private getMonthStart(date: Date): Date {
    const year = date.getFullYear();
    const month = date.getMonth();
    return this.dateService.startOfDay(new Date(year, month, 1));
  }

  /**
   * Get month end
   */
  private getMonthEnd(date: Date): Date {
    const nextMonth = this.dateService.addMonths(date, 1);
    const firstOfNextMonth = this.getMonthStart(nextMonth);
    return this.dateService.endOfDay(this.dateService.addDays(firstOfNextMonth, -1));
  }
}