<!doctype html>
<html>
  <head>
    <title>Test k-rate AudioParam of AudioWorkletNode</title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <script src="/webaudio/resources/audit-util.js"></script>
    <script src="/webaudio/resources/audit.js"></script>
  </head>

  <body>
    <script>
      const audit = Audit.createTaskRunner();

      // Use the worklet gain node to test k-rate parameters.
      const filePath =
          '../the-audioworklet-interface/processors/gain-processor.js';

      // Context for testing
      let context;

      audit.define('Create Test Worklet', (task, should) => {

        // Arbitrary sample rate and duration.
        const sampleRate = 8000;

        // Only new a few render quanta to verify things are working.
        const testDuration = 4 * 128 / sampleRate;

        context = new OfflineAudioContext({
          numberOfChannels: 3,
          sampleRate: sampleRate,
          length: testDuration * sampleRate
        });

        should(
            context.audioWorklet.addModule(filePath),
            'Construction of AudioWorklet')
            .beResolved()
            .then(() => task.done());
      });

      audit.define('AudioWorklet k-rate AudioParam', (task, should) => {
        let src = new ConstantSourceNode(context);

        let kRateNode = new AudioWorkletNode(context, 'gain');

        src.connect(kRateNode).connect(context.destination);

        let kRateParam = kRateNode.parameters.get('gain');
        kRateParam.automationRate = 'k-rate';

        // Automate the gain
        kRateParam.setValueAtTime(0, 0);
        kRateParam.linearRampToValueAtTime(
            10, context.length / context.sampleRate);

        src.start();

        context.startRendering()
            .then(audioBuffer => {
              let output = audioBuffer.getChannelData(0);

              // Verify that the output from the worklet is step-wise
              // constant.
              for (let k = 0; k < output.length; k += 128) {
                should(
                    output.slice(k, k + 128),
                    ` k-rate output [${k}: ${k + 127}]`)
                    .beConstantValueOf(output[k]);
              }
            })
            .then(() => task.done());
      });

      audit.run();
    </script>
  </body>
</html>
