impCentral API Example Code: Working with Access Tokens

accesstokens.js

// CONSTANTS
// Replace the 'USERNAME' and 'PASSWORD' values with your own
const USERNAME = '...'
const PASSWORD = '...'
const API_URL = 'api.electricimp.com'
const API_VER = '/v5/'
const FILE_NAME = '.impCentralData'

// GLOBALS
var https = require('https');
var fs = require('fs');
var products = [];
var accessToken = null;
var expiryDate = null;
var refreshToken = null;

// FUNCTIONS
function setLoginOptions() {
  // Returns an HTTPS request options object primed to get your access token
  return {
    hostname: API_URL,
    path: API_VER + 'auth',
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    }
  };
}

function setTokenUpdateOptions(token) {
  // Returns an HTTPS request options object primed to refresh your access token
  return {
    hostname: API_URL,
    path: API_VER + 'auth/token',
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    }
  };
}

function setOptions(verb, path, token) {
  // Returns an HTTPS request options object primed for API usage
  return {
    hostname: API_URL,
    path: API_VER + path,
    method: verb,
    headers: {
      'Content-Type': 'application/vnd.api+json',
      'Authorization': 'Bearer ' + token
    }
  };
}

function showError(resp) {
  console.log(`STATUS: ${resp.statusCode}`);
  console.log(`HEADERS: ${JSON.stringify(resp.headers)}`);
}

function login(cb = null) {
  // Login to the server - ie. get the initial access token
  let req = https.request(setLoginOptions(), (resp) => {
    // Construct the returned response body
    let body = '';
    resp.setEncoding('utf8');
    resp.on('data', (chunk) => { body += chunk; });

    // Code that's called when the body is retrieved
    resp.on('end', () => {
      if (body.length > 0) {
        try {
          // Is the returned data valid JSON?
          const data = JSON.parse(body);

          if (resp.statusCode === 200) {
            // We have the new access token and other credentials
            accessToken = data.access_token;
            expiryDate = data.expires_at;
            refreshToken = data.refresh_token;

            // Save the credentials locally
            writeData();

            // Call the passed in function
            if (cb) checkAccessToken(cb);
           } else {
            // API Error
            console.log('API ERROR: ' + data.code + ' (' + data.message + ')');
          }
        } catch (err) {
          // JSON error
          console.error(err.message);
        }
      } else {
        // HTTP Error
        showError(resp);
      }
    });
  });

  // Error callback
  req.on('error', (err) => { console.error(`REQUEST ERROR: ${err.message}`); });

  // Begin by setting credentials as request body
  req.write(JSON.stringify({
    'id': USERNAME,
    'password': PASSWORD
  }));

  // Send the request
  req.end();
}

function checkAccessToken(cb = null) {
  if (accessToken === null) {
    // Don't have the token, so load it
    console.log('We don\'t have an access token - trying local file');

    fs.readFile(FILE_NAME, {'encoding': 'utf8', 'flag': 'a+'}, (err, data) => {
      if (err) return console.error(err);
      if (data !== null && data.length > 0) {
        try {
          let fdata = JSON.parse(data);
          if ('at' in fdata) {
            accessToken = fdata.at;
            refreshToken = fdata.rt;
            expiryDate = fdata.ed;

            console.log('Read in access token');
            checkAccessToken(cb);
          } else {
            console.log('No locally stored access token - getting a new one');
            login(cb);
          }
        } catch (e) {
          console.error(e);
        }
      } else {
        console.log('No locally stored access token - getting a new one');
        login(cb);
      }
    });
  } else {
    console.log('We have an access token - checking it');
    let expiry = new Date(expiryDate);
    let now = new Date();

    if (expiry < now) {
      // Access token expired
      console.log('Access Token Expired - updating...');

      let req = https.request(setTokenUpdateOptions(), (resp) => {
        // Construct the returned response body
        let body = '';
        resp.setEncoding('utf8');
        resp.on('data', (chunk) => { body += chunk; });
        // Code that's called when the body is retrieved
        resp.on('end', () => {
          if (body.length > 0) {
            try {
              // Is the returned data valid JSON?
              const data = JSON.parse(body);

              if (resp.statusCode < 400) {
                // Success - retain the new token and expiry info
                accessToken = data.access_token;
                expiryDate = data.expires_at;

                // Store the data locally
                writeData();

                // Call the passed in function
                if (cb) cb();
              } else {
                // API Error
                console.error('API ERROR: ' + data.code + ' (' + data.message + ')');
              }
            } catch (err) {
              // JSON error
              console.error(err.message);
            }
          } else {
            // HTTP Error
            showError(resp);
          }
        });
      });

      // Error callback
      req.on('error', (err) => { console.error(`REQUEST ERROR: ${err.message}`); });

      req.write(JSON.stringify({
        'token': refreshToken
      }));

      // Send the request
      req.end();
    } else {
      // Access token is good - use it
      console.log("Access Token OK - ready to access impCentral");
      if (cb) cb();
    }
  }
}

function writeData() {
  // Write the access token data
  let data = {};
  data.at = accessToken;
  data.rt = refreshToken;
  data.ed = expiryDate;

  fs.writeFile(FILE_NAME, JSON.stringify(data), (err) => {
    if (err) return console.error(err);
    console.log("Access Token acquired, written to local storage");
  });
}

// RUNTIME
checkAccessToken(() => {
  // Create a request to get the account's products
  let req = https.request(setOptions('GET', 'products', accessToken), (resp) => {
    let body = '';
    resp.setEncoding('utf8');
    resp.on('data', (chunk) => { body += chunk; });
    resp.on('end', () => {
      if (body.length > 0) {
        try {
          let data = JSON.parse(body);
          data = data.data;
          if (resp.statusCode === 200) {
            // 'data' is an array of product objects
            for (let item of data) {
              let product = {};
              product.id = item.id;
              product.name = item.attributes.name;
              product.devicegroups = [];
              products.push(product);
            }

            console.log(`You have ${products.length} product(s) in your account:`);
            let tabs = 0;
            for (let product of products) {
              if (product.name.length > tabs) {
                tabs = product.name.length;
              }
            }

            let pcount = 0;
            for (let product of products) {
              let sp = "               ".substring(0, tabs - product.name.length + 1);
              console.log(` ${pcount + 1}. ${product.name}${sp}(ID: ${product.id})`);
              pcount += 1;
            }
          } else {
            // API Error
            console.log('API ERROR: ' + data.code + ' (' + data.message + ')');
          }
        } catch (err) {
          // JSON Error
          console.error(err.message);
        }
      } else {
        // HTTP Error
        showError(resp);
      }
    });
  });

  // Error callback
  req.on('error', (err) => { console.error(`REQUEST ERROR: ${err.message}`); });

  // Send the request
  req.end();
});