<!DOCTYPE html>
<html>
  <head>
    <title>Test Simple AudioWorklet I/O</title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <script src="/webaudio/resources/audit.js"></script>
    <script src="/webaudio/resources/audit-util.js"></script>
  </head>

  <body>
    <script>
      // Arbitrary sample rate
      const sampleRate = 48000;

      // The offset to be applied by the worklet to its inputs.
      const offset = 1;

      // Location of the worklet's code
      const filePath = 'processors/add-offset.js';

      let audit = Audit.createTaskRunner();

      // Context to be used for the tests.
      let context;

      audit.define('Initialize worklet', (task, should) => {
        // Two channels for testing.  Channel 0 is the output of the
        // AudioWorklet.  Channel 1 is the oscillator so we can compare
        // the outputs.
        context = new OfflineAudioContext(
            {numberOfChannels: 2, length: sampleRate, sampleRate: sampleRate});

        // Load up the code for the worklet.
        should(
            context.audioWorklet.addModule(filePath),
            'Creation of AudioWorklet')
            .beResolved()
            .then(() => task.done());
      });

      audit.define(
          {label: 'test', description: 'Simple AudioWorklet I/O'},
          (task, should) => {
            let merger = new ChannelMergerNode(
                context, {numberOfChannels: context.destination.channelCount});
            merger.connect(context.destination);

            let src = new OscillatorNode(context);

            let worklet = new AudioWorkletNode(
                context, 'add-offset-processor',
                {processorOptions: {offset: offset}});

            src.connect(worklet).connect(merger, 0, 0);
            src.connect(merger, 0, 1);

            // Start and stop the source.  The stop time is fairly arbitrary,
            // but use a render quantum boundary for simplicity.
            const stopFrame = RENDER_QUANTUM_FRAMES;
            src.start(0);
            src.stop(stopFrame / context.sampleRate);

            context.startRendering()
                .then(buffer => {
                  let ch0 = buffer.getChannelData(0);
                  let ch1 = buffer.getChannelData(1);

                  let shifted = ch1.slice(0, stopFrame).map(x => x + offset);

                  // The initial part of the output should be the oscillator
                  // shifted by |offset|.
                  should(
                      ch0.slice(0, stopFrame),
                      `AudioWorklet output[0:${stopFrame - 1}]`)
                      .beCloseToArray(shifted, {absoluteThreshold: 0});

                  // Output should be constant after the source has stopped.
                  should(
                      ch0.slice(stopFrame),
                      `AudioWorklet output[${stopFrame}:]`)
                      .beConstantValueOf(offset);
                })
                .then(() => task.done());
          });

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