Provides tcfapi interface to iframe window using amp-consent data

ampIframeTcfapiProxy.js

// amp-iframe tcfapi proxy
// The cne video player inside the iframe on amp does not have access to consent data.
// This script is creating a __tcfapi proxy that scripts needing it can call to obtain TCData.
// TCData is sourced from a postMessage with type=send-consent-data to sentinel=amp
// Should only execute on AMP pages where gdpr is enabled

var consentMetadata;
var consentString;
var gdprApplies;
var queue = [];
try {
  // only add the proxy if a __tcfapiLocator frame is present
  var tcfapiLocatorDetected = false;
  try {
    if (window.top.frames['__tcfapiLocator']) {
      tcfapiLocatorDetected = true;
    }
  } catch (error) {
    tcfapiLocatorDetected = false;
  }
  if (tcfapiLocatorDetected) {

  // create a __tcfapi proxy that can be called by required scripts within the iframe
  window.__tcfapi = function (cmd, version, callback, parameter) {
    console.log(cmd);
    console.log(version);
    console.log(callback);
    console.log(parameter);

    if (!cmd) {
      return queue;
    } else if (cmd === 'ping') {
      if (callback === 'function') {
        if (consentString) {
          callback({
            gdprApplies: gdprApplies,
            cmpLoaded: true,
            cmpStatus: 'loaded'
          });
        } else {
          callback({
            gdprApplies: gdprApplies,
            cmpLoaded: false,
            cmpStatus: 'stub'
          });
        }
      }
    // https://github.com/InteractiveAdvertisingBureau/GDPR-Transparency-and-Consent-Framework/blob/master/TCFv2/IAB%20Tech%20Lab%20-%20CMP%20API%20v2.md#gettcdata
    } else if (cmd === 'getTCData') {
      // https://github.com/InteractiveAdvertisingBureau/GDPR-Transparency-and-Consent-Framework/blob/master/TCFv2/IAB%20Tech%20Lab%20-%20CMP%20API%20v2.md#tcdata
      if (typeof callback === 'function') {
        var tcData = Object.assign({
          tcString: consentString
        }, consentMetadata);
        callback({
          tcData: tcData,
          success: true
        });
      }
    } else if (cmd === 'addEventListener') {
      var listener = {cmd:cmd, version:version, callback:callback, parameter:parameter, id: Math.random() + ''}
      queue.push(listener);
      if (consentString && typeof listener.callback === 'function') {
        var tcData = Object.assign({
          tcString: consentString,
          eventStatus:'tcloaded',
          listenderId:listener.id,
          cmpStatus: 'loaded'
        }, consentMetadata);
        console.log(tcData);
        console.log(consentString);
        listener.callback(tcData, true);
      }
    } else if (cmd === 'removeEventListener') {
      if (parameter) {
        for (var i=0; i < queue.length; i++) {
          if (listener.id && listener.id === parameter) {
            queue.splice(i, 1);
            if (callback === 'function') {
              callback(true); // success = true
            }
          }
        }
      }
    }
  }

  var processQueue = function () {
    if (consentString) {
      for (var i=0; i < queue.length; i++) {
        var listener = queue[i];
        if (listener.callback && typeof listener.callback === 'function') {
          console.log('processQueue ' + listener.id);
          var tcData = Object.assign({
            tcString: consentString,
            eventStatus:'tcloaded',
            cmpStatus: 'loaded',
            listenderId:listener.id
          }, consentMetadata);
          listener.callback(tcData, true);
        }
      }
    }
  }

  var isAmpMessage = function isAmpMessage(event, type) {
    return (event.source == window.parent && event.origin != window.location.origin && event.data && event.data.sentinel == 'amp' && event.data.type == type);
  }

  var postMessageHandler = function postMessageHandler(event) {
    // response from amp-consent get-consent-data
    if (isAmpMessage(event, 'consent-data')) {
      // save consent data so it can be returned with 'getTCData'
      gdprApplies = true;
      consentMetadata = event.data.consentMetadata;
      consentString = event.data.consentString;
      console.log(consentMetadata);
      console.log(consentString);
      processQueue();
    } else {
      // could be any other postMessage on the window here
      var msgIsString = typeof event.data === 'string';
      var json = {};

      if (msgIsString) {
        try {
          /**
          * Try to parse the data from the event.  This is important
          * to have in a try/catch because often messages may come
          * through that are not JSON
          */
          json = JSON.parse(event.data);
        } catch (ignore) { }
      } else {
        json = event.data;
      }

      var payload = (typeof json === 'object') ? json.__tcfapiCall : null;

      if (payload) {
        // this should be a message with __tcfapiCall asking for a response from __tcfapi
        window.__tcfapi(payload.command, payload.version, function (retValue, success) {
          var returnMsg = {
            __tcfapiReturn: {
              returnValue: retValue,
              success: success,
              callId: payload.callId,
            },
          };

          if (event && event.source && event.source.postMessage) {
            event.source.postMessage((msgIsString) ? JSON.stringify(returnMsg) : returnMsg, '*');
          }
        }, payload.parameter);
      }
    }
  }
  window.addEventListener('message', postMessageHandler, false);
  // https://github.com/ampproject/amphtml/blob/main/extensions/amp-iframe/0.1/amp-iframe.md#iframe--consent-data
  window.parent.postMessage({
    sentinel: 'amp',
    type: 'send-consent-data'
  }, '*');
  }
} catch (error) {
  console.log(error)
}