Connect Constant Contact: Event Marketing & Broadcast Email

export class ConstantContactClient {
  private apiKey: string;
  private secret?: string;
  private refreshToken?: string;
  private fromEmail?: string;

  constructor(credentials?: ProviderCredentials) {
    this.apiKey = credentials?.constantContactApiKey || credentials?.apiKey || process.env.CONSTANT_CONTACT_API_KEY || '';
    this.secret = credentials?.constantContactSecret || process.env.CONSTANT_CONTACT_SECRET;
    this.refreshToken = credentials?.constantContactRefreshToken || process.env.CONSTANT_CONTACT_REFRESH_TOKEN;
    this.fromEmail = (credentials?.fromEmail || process.env.CONSTANT_CONTACT_FROM_EMAIL || '').trim().toLowerCase();
  }

  private async getAccessToken(): Promise<string | null> {
    if (!this.refreshToken || !this.apiKey || !this.secret) {
      return this.apiKey || null;
    }

    try {
      const authHeader = Buffer.from(`${this.apiKey}:${this.secret}`).toString('base64');
      const res = await fetch('https://authz.constantcontact.com/oauth2/default/v1/token', {
        method: 'POST',
        headers: {
          Authorization: `Basic ${authHeader}`,
          'Content-Type': 'application/x-www-form-urlencoded',
        },
        body: new URLSearchParams({
          grant_type: 'refresh_token',
          refresh_token: this.refreshToken,
        }).toString(),
      });

      if (!res.ok) return this.apiKey || null;
      const data: any = await res.json().catch(() => ({}));
      return data?.access_token || this.apiKey || null;
    } catch {
      return this.apiKey || null;
    }
  }
}