import type {
  SeverityLevel,
  NotificationAction,
  NotificationPayload,
  SendResult,
} from './types';
import type { NotifyClient } from './client';

/**
 * Builder for creating notifications with a fluent API.
 */
export class EventBuilder {
  private readonly client: NotifyClient;
  private readonly eventType: string;
  private title: string = '';
  private message?: string;
  private severity: SeverityLevel = 'info';
  private metadata: Record<string, unknown> = {};
  private actions: NotificationAction[] = [];
  private userId?: string;
  private groupKey?: string;
  private deduplicationKey?: string;
  private expiresAt?: Date;

  constructor(client: NotifyClient, eventType: string) {
    this.client = client;
    this.eventType = eventType;
  }

  /**
   * Set the notification title.
   */
  withTitle(title: string): this {
    this.title = title;
    return this;
  }

  /**
   * Set the notification message.
   */
  withMessage(message: string): this {
    this.message = message;
    return this;
  }

  /**
   * Set the severity level.
   */
  withSeverity(severity: SeverityLevel): this {
    this.severity = severity;
    return this;
  }

  /**
   * Set metadata for the notification.
   */
  withMetadata(metadata: Record<string, unknown>): this {
    this.metadata = { ...this.metadata, ...metadata };
    return this;
  }

  /**
   * Add an action button to the notification.
   */
  withAction(action: NotificationAction): this {
    this.actions.push(action);
    return this;
  }

  /**
   * Set the target user ID.
   */
  forUser(userId: string): this {
    this.userId = userId;
    return this;
  }

  /**
   * Set the group key for grouping related notifications.
   */
  withGroupKey(groupKey: string): this {
    this.groupKey = groupKey;
    return this;
  }

  /**
   * Set the deduplication key to prevent duplicate notifications.
   */
  withDeduplicationKey(key: string): this {
    this.deduplicationKey = key;
    return this;
  }

  /**
   * Set the expiration time for the notification.
   */
  expiresIn(ms: number): this {
    this.expiresAt = new Date(Date.now() + ms);
    return this;
  }

  /**
   * Set the expiration date for the notification.
   */
  expiresOn(date: Date): this {
    this.expiresAt = date;
    return this;
  }

  /**
   * Build the notification payload.
   */
  build(): NotificationPayload {
    if (!this.title) {
      throw new Error('Notification title is required');
    }

    return {
      eventType: this.eventType,
      title: this.title,
      message: this.message,
      severity: this.severity,
      metadata: Object.keys(this.metadata).length > 0 ? this.metadata : undefined,
      actions: this.actions.length > 0 ? this.actions : undefined,
      userId: this.userId,
      groupKey: this.groupKey,
      deduplicationKey: this.deduplicationKey,
      expiresAt: this.expiresAt?.toISOString(),
    };
  }

  /**
   * Send the notification.
   */
  async send(): Promise<SendResult> {
    const payload = this.build();
    return this.client.sendPayload(payload);
  }
}