import { GetTokenOptions, TokenCredential } from '@azure/core-auth'
import { AuthConfiguration, MsalTokenProvider } from './'

/**
 * Token credential implementation that uses MSAL (Microsoft Authentication Library) to acquire access tokens.
 * Implements the Azure Core Auth TokenCredential interface for authentication scenarios.
 */
export class MsalTokenCredential implements TokenCredential {
  /**
   * Creates a new instance of MsalTokenCredential.
   * @param authConfig The authentication configuration to use for token acquisition.
   */
  constructor (private authConfig: AuthConfiguration) {}

  /**
   * Retrieves an access token for the specified scopes using MSAL authentication.
   * @param scopes Array of scopes for which to request an access token. The first scope is used to determine the resource.
   * @param options Optional parameters for token retrieval (currently unused).
   * @returns Promise that resolves to an access token with expiration timestamp.
   */
  public async getToken (scopes: string[], options?: GetTokenOptions) {
    const scope = scopes[0].substring(0, scopes[0].lastIndexOf('/'))
    const token = await new MsalTokenProvider().getAccessToken(this.authConfig, scope)
    return {
      token,
      expiresOnTimestamp: Date.now() + 10000
    }
  }
}