<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <script src="/tests/SimpleTest/SimpleTest.js"></script>
    <link rel="stylesheet" href="/tests/SimpleTest/test.css" />
  </head>
  <body>
    <script>
      ok(
        SpecialPowers.getBoolPref("dom.webgpu.enabled"),
        "Pref should be enabled."
      );

      async function testBody() {
        const adapter = await navigator.gpu.requestAdapter();
        const device = await adapter.requestDevice();

        const bufferRead = device.createBuffer({
          size: 4,
          usage: GPUBufferUsage.MAP_READ | GPUBufferUsage.COPY_DST,
        });
        const bufferWrite = device.createBuffer({
          size: 4,
          usage: GPUBufferUsage.COPY_SRC,
          mappedAtCreation: true,
        });
        new Float32Array(bufferWrite.getMappedRange()).set([1.0]);
        bufferWrite.unmap();

        const encoder = device.createCommandEncoder();
        encoder.copyBufferToBuffer(bufferWrite, 0, bufferRead, 0, 4);
        device.queue.submit([encoder.finish()]);

        await bufferRead.mapAsync(GPUMapMode.READ);

        try {
          bufferRead.getMappedRange(0, 5);
          ok(false, "mapped with size outside buffer should throw");
        } catch (e) {
          ok(
            true,
            "mapped with size outside buffer should throw OperationError"
          );
        }

        try {
          bufferRead.getMappedRange(4, 1);
          ok(false, "mapped with offset outside buffer should throw");
        } catch (e) {
          ok(
            true,
            "mapped with offset outside buffer should throw OperationError"
          );
        }

        const data = bufferRead.getMappedRange();
        is(data.byteLength, 4, "array should be 4 bytes long");

        const value = new Float32Array(data)[0];
        ok(value == 1.0, "value == 1.0");

        bufferRead.unmap();
        is(data.byteLength, 0, "array should be detached after explicit unmap");
      }

      SimpleTest.waitForExplicitFinish();
      testBody()
        .catch(e => ok(false, "Unhandled exception " + e))
        .finally(() => SimpleTest.finish());
    </script>
  </body>
</html>
