WhatsApp Business API (Meta)

WHATSAPP_API_KEY=EAAxxxxxxxx          # Meta Graph API access token
WHATSAPP_API_BASE_URL=https://graph.facebook.com/v19.0
WHATSAPP_FROM=123456789012345         # Platform's verified WhatsApp Business phone number ID

interface WhatsAppBusinessConfig {
  apiKey:        string;  // Meta Graph API access token (permanent token from System User)
  baseUrl:       string;  // "https://graph.facebook.com/v19.0"
  phoneNumberId: string;  // Phone Number ID from Meta Business Manager (not the phone number itself)
}

import axios from 'axios';
 
class WhatsAppBusinessProvider implements WhatsAppProvider {
  readonly name = 'whatsapp_business_api';
 
  constructor(
    private apiKey:        string,
    private baseUrl:       string,
    private phoneNumberId: string,
  ) {}
 
  async sendTemplate(message: WhatsAppMessage): Promise<WhatsAppSendResult> {
    const url = `${this.baseUrl}/${this.phoneNumberId}/messages`;
 
    const body = {
      messaging_product: 'whatsapp',
      to:                message.to,   // E.164: "+919876543210"
      type:              'template',
      template: {
        name:     message.template.name,
        language: { code: message.template.languageCode ?? 'en' },
        components: message.template.components?.map(comp => ({
          type:       comp.type,       // 'body' | 'header' | 'button'
          parameters: comp.parameters.map(p => ({
            type: 'text',
            text: message.variables[p.key],
          })),
        })),
      },
    };
 
    const response = await axios.post(url, body, {
      headers: {
        Authorization:  `Bearer ${this.apiKey}`,
        'Content-Type': 'application/json',
      },
    });
 
    return {
      messageId: response.data.messages[0].id,
      provider:  'whatsapp_business_api',
      status:    response.data.messages[0].message_status,
    };
  }
 
  async verify(): Promise<void> {
    // Fetch phone number info to verify credentials and phone number ID
    const url = `${this.baseUrl}/${this.phoneNumberId}`;
    const response = await axios.get(url, {
      headers: { Authorization: `Bearer ${this.apiKey}` },
    });
    if (!response.data.id) {
      throw new Error('WhatsApp Business API verification failed — phone number not found');
    }
  }
}

interface WhatsAppTemplateDefinition {
  name:         string;           // e.g. "hitl_review_request"
  languageCode?: string;          // e.g. "en" (default), "hi", "ta"
  components?:  WhatsAppComponent[];
}
 
interface WhatsAppComponent {
  type:       'body' | 'header' | 'button';
  parameters: { key: string }[];  // keys into message.variables
}