import { Component, OnChanges, Input, Output, EventEmitter, ChangeDetectorRef, OnInit, OnDestroy, LOCALE_ID, Inject, TemplateRef } from '@angular/core';
import { CalendarEvent, WeekDay, MonthView, MonthViewDay, CalendarEventTimesChangedEvent, getWeekViewHeader, getMonthView } from '../../../utils/calendar-utils/CalendarUtils';
import { Subject } from 'rxjs/Subject';
import { Subscription } from 'rxjs/Subscription';
import * as dateFns from 'date-fns';

/**
 * Shows all events on a given month. Example usage:
 *
 * ```
 * <novo-calendar-month-view
 *  [viewDate]="viewDate"
 *  [events]="events">
 * </novo-calendar-month-view>
 * ```
 */
@Component({
    selector: 'novo-calendar-month',
    template: `
    <div class="calendar-month-view">
       <novo-calendar-month-header
         [(viewDate)]="viewDate"
         [days]="columnHeaders"
         [locale]="locale"
         [customTemplate]="headerTemplate"
         (viewDateChange)="refreshAll()">
       </novo-calendar-month-header>
      <div class="calendar-days">
        <div *ngFor="let rowIndex of view.rowOffsets">
          <div class="calendar-cell-row">
            <novo-calendar-month-day
              *ngFor="let day of view.days | slice : rowIndex : rowIndex + (view.totalDaysVisibleInWeek)"
              [day]="day"
              [locale]="locale"
              [customTemplate]="cellTemplate"
              (click)="dayClicked.emit({day: day})"
              (eventClicked)="eventClicked.emit({ day: day, event: $event.event})">
            </novo-calendar-month-day>
          </div>
        </div>
      </div>
    </div>
  `
})
export class NovoCalendarMonthViewElement implements OnChanges, OnInit, OnDestroy {

    /**
     * The current view date
     */
    @Input() viewDate: Date;

    /**
     * An array of events to display on view
     */
    @Input() events: CalendarEvent[] = [];

    /**
     * An array of day indexes (0 = sunday, 1 = monday etc) that will be hidden on the view
     */
    @Input() excludeDays: number[] = [];

    /**
     * A function that will be called before each cell is rendered. The first argument will contain the calendar cell.
     * If you add the `cssClass` property to the cell it will add that class to the cell in the template
     */
    @Input() dayModifier: Function;

    /**
     * An observable that when emitted on will re-render the current view
     */
    @Input() refresh: Subject<any>;

    /**
     * The locale used to format dates
     */
    @Input() locale: string = 'en-US';

    /**
     * The placement of the event tooltip
     */
    @Input() tooltipPosition: string = 'top';

    /**
     * The start number of the week
     */
    @Input() weekStartsOn: number;

    /**
     * A custom template to use to replace the header
     */
    @Input() headerTemplate: TemplateRef<any>;

    /**
     * A custom template to use to replace the day cell
     */
    @Input() cellTemplate: TemplateRef<any>;

    /**
     * Called when the day cell is clicked
     */
    @Output() dayClicked: EventEmitter<{ day: MonthViewDay }> = new EventEmitter<{ day: MonthViewDay }>();

    /**
     * Called when the event title is clicked
     */
    @Output() eventClicked: EventEmitter<{ event: CalendarEvent }> = new EventEmitter<{ event: CalendarEvent }>();

    /**
     * Called when an event is dragged and dropped
     */
    @Output() eventTimesChanged: EventEmitter<CalendarEventTimesChangedEvent> = new EventEmitter<CalendarEventTimesChangedEvent>();

    @Output() viewDateChange: EventEmitter<Date> = new EventEmitter<Date>();

    /**
     * @hidden
     */
    columnHeaders: WeekDay[];

    /**
     * @hidden
     */
    view: MonthView;

    /**
     * @hidden
     */
    refreshSubscription: Subscription;

    /**
     * @hidden
     */
    constructor(private cdr: ChangeDetectorRef, @Inject(LOCALE_ID) locale: string) {
        this.locale = locale;
    }

    /**
     * @hidden
     */
    ngOnInit(): void {
        if (this.refresh) {
            this.refreshSubscription = this.refresh.subscribe(() => {
                this.refreshAll();
                this.cdr.markForCheck();
            });
        }
    }

    /**
     * @hidden
     */
    ngOnChanges(changes: any): void {
        if (changes.viewDate || changes.excludeDays) {
            this.refreshHeader();
        }
        if (changes.viewDate || changes.events || changes.excludeDays) {
            this.refreshBody();
        }
    }

    /**
     * @hidden
     */
    ngOnDestroy(): void {
        if (this.refreshSubscription) {
            this.refreshSubscription.unsubscribe();
        }
    }

    /**
     * @hidden
     */
    eventDropped(day: MonthViewDay, event: CalendarEvent): void {
        const year: number = dateFns.getYear(day.date);
        const month: number = dateFns.getMonth(day.date);
        const date: number = dateFns.getDate(day.date);
        const newStart: Date = dateFns.setYear(dateFns.setMonth(dateFns.setDate(event.start, date), month), year);
        let newEnd: Date;
        if (event.end) {
            const secondsDiff: number = dateFns.differenceInSeconds(newStart, event.start);
            newEnd = dateFns.addSeconds(event.end, secondsDiff);
        }
        this.eventTimesChanged.emit({ event, newStart, newEnd });
    }

    private refreshHeader(): void {
        this.columnHeaders = getWeekViewHeader({
            viewDate: this.viewDate,
            weekStartsOn: this.weekStartsOn,
            excluded: this.excludeDays
        });
    }

    private refreshBody(): void {
        this.view = getMonthView({
            events: this.events,
            viewDate: this.viewDate,
            weekStartsOn: this.weekStartsOn,
            excluded: this.excludeDays
        });
        if (this.dayModifier) {
            this.view.days.forEach(day => this.dayModifier(day));
        }
    }

    public refreshAll(): void {
        this.refreshHeader();
        this.refreshBody();
        this.viewDateChange.emit(this.viewDate);
    }
}