/**
 * Domain Entity: PageView
 * 
 * Represents a single page view event for analytics tracking.
 * Captures visitor interactions with leagues, drivers, teams, races.
 */

export type EntityType = 'league' | 'driver' | 'team' | 'race' | 'sponsor';
export type VisitorType = 'anonymous' | 'driver' | 'sponsor';

export interface PageViewProps {
  id: string;
  entityType: EntityType;
  entityId: string;
  visitorId?: string;
  visitorType: VisitorType;
  sessionId: string;
  referrer?: string;
  userAgent?: string;
  country?: string;
  timestamp: Date;
  durationMs?: number;
}

export class PageView {
  readonly id: string;
  readonly entityType: EntityType;
  readonly entityId: string;
  readonly visitorId?: string;
  readonly visitorType: VisitorType;
  readonly sessionId: string;
  readonly referrer?: string;
  readonly userAgent?: string;
  readonly country?: string;
  readonly timestamp: Date;
  readonly durationMs?: number;

  private constructor(props: PageViewProps) {
    this.id = props.id;
    this.entityType = props.entityType;
    this.entityId = props.entityId;
    this.visitorId = props.visitorId;
    this.visitorType = props.visitorType;
    this.sessionId = props.sessionId;
    this.referrer = props.referrer;
    this.userAgent = props.userAgent;
    this.country = props.country;
    this.timestamp = props.timestamp;
    this.durationMs = props.durationMs;
  }

  static create(props: Omit<PageViewProps, 'timestamp'> & { timestamp?: Date }): PageView {
    this.validate(props);

    return new PageView({
      ...props,
      timestamp: props.timestamp ?? new Date(),
    });
  }

  private static validate(props: Omit<PageViewProps, 'timestamp'>): void {
    if (!props.id || props.id.trim().length === 0) {
      throw new Error('PageView ID is required');
    }

    if (!props.entityType) {
      throw new Error('PageView entityType is required');
    }

    if (!props.entityId || props.entityId.trim().length === 0) {
      throw new Error('PageView entityId is required');
    }

    if (!props.sessionId || props.sessionId.trim().length === 0) {
      throw new Error('PageView sessionId is required');
    }
  }

  /**
   * Update duration when visitor leaves page
   */
  withDuration(durationMs: number): PageView {
    if (durationMs < 0) {
      throw new Error('Duration must be non-negative');
    }

    return new PageView({
      ...this,
      durationMs,
    });
  }

  /**
   * Check if this is a meaningful view (not a bounce)
   */
  isMeaningfulView(): boolean {
    return this.durationMs !== undefined && this.durationMs >= 5000; // 5+ seconds
  }

  /**
   * Check if view came from external source
   */
  isExternalReferral(): boolean {
    if (!this.referrer) return false;
    return !this.referrer.includes('gridpilot');
  }
}