// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "flutter/content_handler/vulkan_rasterizer.h"

#include <fcntl.h>
#include <fdio/watcher.h>
#include <unistd.h>
#include <zircon/device/vfs.h>

#include <chrono>
#include <thread>
#include <utility>

#include "flutter/common/threads.h"
#include "flutter/glue/trace_event.h"
#include "lib/fxl/files/unique_fd.h"

namespace flutter_runner {

constexpr char kDisplayDriverClass[] = "/dev/class/display";

static zx_status_t DriverWatcher(int dirfd,
                                 int event,
                                 const char* fn,
                                 void* cookie) {
  if (event == WATCH_EVENT_ADD_FILE && !strcmp(fn, "000")) {
    return ZX_ERR_STOP;
  }
  return ZX_OK;
}

bool WaitForFirstDisplayDriver() {
  fxl::UniqueFD fd(open(kDisplayDriverClass, O_DIRECTORY | O_RDONLY));
  if (fd.get() < 0) {
    FXL_DLOG(ERROR) << "Failed to open " << kDisplayDriverClass;
    return false;
  }

  zx_status_t status = fdio_watch_directory(
      fd.get(), DriverWatcher, zx_deadline_after(ZX_SEC(1)), nullptr);
  return status == ZX_ERR_STOP;
}

VulkanRasterizer::VulkanRasterizer() : compositor_context_(nullptr) {
  valid_ = WaitForFirstDisplayDriver();
}

VulkanRasterizer::~VulkanRasterizer() = default;

bool VulkanRasterizer::IsValid() const {
  return valid_;
}

void VulkanRasterizer::SetScene(
    fidl::InterfaceHandle<scenic::SceneManager> scene_manager,
    zx::eventpair import_token,
    fxl::Closure metrics_changed_callback) {
  ASSERT_IS_GPU_THREAD;
  FXL_DCHECK(valid_ && !session_connection_);
  session_connection_ = std::make_unique<SessionConnection>(
      scenic::SceneManagerPtr::Create(std::move(scene_manager)),
      std::move(import_token));
  session_connection_->set_metrics_changed_callback(
      std::move(metrics_changed_callback));
}

void VulkanRasterizer::Draw(std::unique_ptr<flow::LayerTree> layer_tree,
                            fxl::Closure callback) {
  ASSERT_IS_GPU_THREAD;
  FXL_DCHECK(callback != nullptr);

  if (layer_tree == nullptr) {
    FXL_LOG(ERROR) << "Layer tree was not valid.";
    callback();
    return;
  }

  if (!session_connection_) {
    FXL_LOG(ERROR) << "Session was not valid.";
    callback();
    return;
  }

  if (!session_connection_->has_metrics()) {
    // Still awaiting metrics.  Will redraw when we get them.
    callback();
    return;
  }

  compositor_context_.engine_time().SetLapTime(layer_tree->construction_time());

  flow::CompositorContext::ScopedFrame frame = compositor_context_.AcquireFrame(
      nullptr, nullptr, true /* instrumentation enabled */);
  {
    // Preroll the Flutter layer tree. This allows Flutter to perform pre-paint
    // optimizations.
    TRACE_EVENT0("flutter", "Preroll");
    layer_tree->Preroll(frame, session_connection_->metrics().get());
  }

  {
    // Traverse the Flutter layer tree so that the necessary session ops to
    // represent the frame are enqueued in the underlying session.
    TRACE_EVENT0("flutter", "UpdateScene");
    layer_tree->UpdateScene(session_connection_->scene_update_context(),
                            session_connection_->root_node());
  }

  {
    // Flush all pending session ops.
    TRACE_EVENT0("flutter", "SessionPresent");
    session_connection_->Present(
        frame, [callback = std::move(callback)]() { callback(); });
  }
}

}  // namespace flutter_runner