function WGLUPreserveGLState(gl, bindings, callback) {
  if (!bindings) {
    callback(gl);
    return;
  }

  var boundValues = [];

  var activeTexture = null;
  for (var i = 0; i < bindings.length; ++i) {
    var binding = bindings[i];
    switch (binding) {
      case gl.TEXTURE_BINDING_2D:
      case gl.TEXTURE_BINDING_CUBE_MAP:
        var textureUnit = bindings[++i];
        if (textureUnit < gl.TEXTURE0 || textureUnit > gl.TEXTURE31) {
          console.error("TEXTURE_BINDING_2D or TEXTURE_BINDING_CUBE_MAP must be followed by a valid texture unit");
          boundValues.push(null, null);
          break;
        }
        if (!activeTexture) {
          activeTexture = gl.getParameter(gl.ACTIVE_TEXTURE);
        }
        gl.activeTexture(textureUnit);
        boundValues.push(gl.getParameter(binding), null);
        break;
      case gl.ACTIVE_TEXTURE:
        activeTexture = gl.getParameter(gl.ACTIVE_TEXTURE);
        boundValues.push(null);
        break;
      default:
        boundValues.push(gl.getParameter(binding));
        break;
    }
  }

  callback(gl);

  for (var i = 0; i < bindings.length; ++i) {
    var binding = bindings[i];
    var boundValue = boundValues[i];
    switch (binding) {
      case gl.ACTIVE_TEXTURE:
        break; // Ignore this binding, since we special-case it to happen last.
      case gl.ARRAY_BUFFER_BINDING:
        gl.bindBuffer(gl.ARRAY_BUFFER, boundValue);
        break;
      case gl.COLOR_CLEAR_VALUE:
        gl.clearColor(boundValue[0], boundValue[1], boundValue[2], boundValue[3]);
        break;
      case gl.COLOR_WRITEMASK:
        gl.colorMask(boundValue[0], boundValue[1], boundValue[2], boundValue[3]);
        break;
      case gl.CURRENT_PROGRAM:
        gl.useProgram(boundValue);
        break;
      case gl.ELEMENT_ARRAY_BUFFER_BINDING:
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, boundValue);
        break;
      case gl.FRAMEBUFFER_BINDING:
        gl.bindFramebuffer(gl.FRAMEBUFFER, boundValue);
        break;
      case gl.RENDERBUFFER_BINDING:
        gl.bindRenderbuffer(gl.RENDERBUFFER, boundValue);
        break;
      case gl.TEXTURE_BINDING_2D:
        var textureUnit = bindings[++i];
        if (textureUnit < gl.TEXTURE0 || textureUnit > gl.TEXTURE31)
          break;
        gl.activeTexture(textureUnit);
        gl.bindTexture(gl.TEXTURE_2D, boundValue);
        break;
      case gl.TEXTURE_BINDING_CUBE_MAP:
        var textureUnit = bindings[++i];
        if (textureUnit < gl.TEXTURE0 || textureUnit > gl.TEXTURE31)
          break;
        gl.activeTexture(textureUnit);
        gl.bindTexture(gl.TEXTURE_CUBE_MAP, boundValue);
        break;
      case gl.VIEWPORT:
        gl.viewport(boundValue[0], boundValue[1], boundValue[2], boundValue[3]);
        break;
      case gl.BLEND:
      case gl.CULL_FACE:
      case gl.DEPTH_TEST:
      case gl.SCISSOR_TEST:
      case gl.STENCIL_TEST:
        if (boundValue) {
          gl.enable(binding);
        } else {
          gl.disable(binding);
        }
        break;
      default:
        console.log("No GL restore behavior for 0x" + binding.toString(16));
        break;
    }

    if (activeTexture) {
      gl.activeTexture(activeTexture);
    }
  }
}

module.exports = WGLUPreserveGLState;