import { EventBus } from '../core/EventBus';
import { IEventBus, CalendarEvent, RenderContext } from '../types/CalendarTypes';
import { CoreEvents } from '../constants/CoreEvents';
import { calendarConfig } from '../core/CalendarConfig';
import { CalendarTypeFactory } from '../factories/CalendarTypeFactory';
import { EventManager } from '../managers/EventManager';
import { EventRendererStrategy } from './EventRenderer';

/**
 * EventRenderingService - Render events i DOM med positionering using Strategy Pattern
 * Håndterer event positioning og overlap detection
 */
export class EventRenderingService {
    private eventBus: IEventBus;
    private eventManager: EventManager;
    private strategy: EventRendererStrategy;

    constructor(eventBus: IEventBus, eventManager: EventManager) {
        this.eventBus = eventBus;
        this.eventManager = eventManager;
        
        // Cache strategy at initialization
        const calendarType = calendarConfig.getCalendarMode();
        this.strategy = CalendarTypeFactory.getEventRenderer(calendarType);
        
        this.setupEventListeners();
    }

    /**
     * Render events in a specific container for a given period
     */
    public renderEvents(context: RenderContext): void {
        
        // Clear existing events in the specific container first
        this.strategy.clearEvents(context.container);
        
        // Get events from EventManager for the period
        const events = this.eventManager.getEventsForPeriod(
            context.startDate,
            context.endDate
        );
        
        
        if (events.length === 0) {
            return;
        }
        
        // Use cached strategy to render events in the specific container
        this.strategy.renderEvents(events, context.container, calendarConfig);
        
        // Emit EVENTS_RENDERED event for filtering system
        this.eventBus.emit(CoreEvents.EVENTS_RENDERED, {
            events: events,
            container: context.container
        });
    }

    private setupEventListeners(): void {
        // Event-driven rendering: React to grid and container events
        this.eventBus.on(CoreEvents.GRID_RENDERED, (event: Event) => {
            this.handleGridRendered(event as CustomEvent);
        });

        // CONTAINER_READY_FOR_EVENTS removed - events are now pre-rendered synchronously
        // this.eventBus.on(EventTypes.CONTAINER_READY_FOR_EVENTS, (event: Event) => {
        //     this.handleContainerReady(event as CustomEvent);
        // });

        this.eventBus.on(CoreEvents.VIEW_CHANGED, (event: Event) => {
            this.handleViewChanged(event as CustomEvent);
        });
    }


    /**
     * Handle GRID_RENDERED event - render events in the current grid
     */
    private handleGridRendered(event: CustomEvent): void {
        const { container, startDate, endDate, currentDate } = event.detail;
        
        if (!container) {
            return;
        }

        let periodStart: Date;
        let periodEnd: Date;

        if (startDate && endDate) {
            // Direct date format - use as provided
            periodStart = startDate;
            periodEnd = endDate;
        } else if (currentDate) {
            return;
        } else {
            return;
        }
        
        this.renderEvents({
            container: container,
            startDate: periodStart,
            endDate: periodEnd
        });
    }

    /**
     * Handle CONTAINER_READY_FOR_EVENTS event - render events in pre-rendered container
     */
    private handleContainerReady(event: CustomEvent): void {
        const { container, startDate, endDate } = event.detail;
        
        if (!container || !startDate || !endDate) {
            return;
        }

        this.renderEvents({
            container: container,
            startDate: new Date(startDate),
            endDate: new Date(endDate)
        });
    }

    /**
     * Handle VIEW_CHANGED event - clear and re-render for new view
     */
    private handleViewChanged(event: CustomEvent): void {
        // Clear all existing events since view structure may have changed
        this.clearEvents();
        
        // New rendering will be triggered by subsequent GRID_RENDERED event
    }
    private clearEvents(container?: HTMLElement): void {
        this.strategy.clearEvents(container);
    }

    public refresh(container?: HTMLElement): void {
        // Clear events in specific container or globally
        this.clearEvents(container);
    }

    public destroy(): void {
        this.clearEvents();
    }
}