Authentication: Get Access Token (JavaScript)

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// This script responds with a bearer token and is called from each of the other scripts in this project. 
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// Variables are in .env and need to be updated for your Sigma hosted environment and API keys
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// 1: Load environment variables from a specific .env file for configuration
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require('dotenv').config({ path: 'sigma-api-recipes/.env' });
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// 2: Import Axios for making HTTP requests
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const axios = require('axios');
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// 4: Load use-case specific variables from environment variables
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const authURL = process.env.authURL; // The URL for your Sigma Instance
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const clientId = process.env.CLIENT_ID; // Your client ID
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const secret = process.env.SECRET; // Your API secret
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// Asynchronous function to obtain a bearer token using the credentials grant type
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async function getBearerToken() {
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  try {
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    // Prepare the data for the request using URLSearchParams to encode it as application/x-www-form-urlencoded
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    const requestData = new URLSearchParams({
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      grant_type: 'client_credentials', // Indicates the grant type for OAuth 2.0
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      client_id: clientId, // Your client ID
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      client_secret: secret, // Your client secret
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    });
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    // Log the constructed URL before sending the request
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      console.log(`URL sent to Sigma: ${authURL}`);
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    // Make a POST request to the authentication URL with the encoded data and headers
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    const response = await axios.post(authURL, requestData, {
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      headers: {
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        'Content-Type': 'application/x-www-form-urlencoded', // Ensure the server treats the sent data as URL-encoded form data
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      },
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    });
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    // Log the success message and the obtained bearer token
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    console.log('Bearer token obtained successfully:', response.data.access_token);
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    return response.data.access_token; // Return the obtained token for use in subsequent API requests
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  } catch (error) {
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    // Log any errors that occur during the token acquisition process
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    console.error('Error obtaining Bearer token:', error.response ? error.response.data : error.message);
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    return null; // Return null to indicate that the token acquisition failed
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  }
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}
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// Check if this script is being run directly and not imported as a module in another script. This is so we can run standalone and verify we get a token response.
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if (require.main === module) {
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    // Call getBearerToken and handle the promise it returns
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    getBearerToken().then(token => {
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        // Log the acquired token for verification
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        console.log('Token acquired:', token);
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    }).catch(error => {
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        // Log any errors that occur when trying to acquire the token
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        console.error('Failed to acquire token:', error);
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    });
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}
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// Export the getBearerToken function to make it available for import in other use-case scripts
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module.exports = getBearerToken;