// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/benchmarks/invalidation_benchmark.h"

#include <stdint.h>

#include <algorithm>
#include <limits>
#include <optional>
#include <string>
#include <utility>

#include "base/notreached.h"
#include "base/rand_util.h"
#include "base/values.h"
#include "cc/base/math_util.h"
#include "cc/layers/layer.h"
#include "cc/layers/picture_layer.h"
#include "cc/trees/draw_property_utils.h"
#include "cc/trees/layer_tree_host.h"
#include "ui/gfx/geometry/rect.h"

namespace cc {

namespace {

const char* kDefaultInvalidationMode = "viewport";

}  // namespace

InvalidationBenchmark::InvalidationBenchmark(
    base::Value::Dict settings,
    MicroBenchmark::DoneCallback callback)
    : MicroBenchmark(std::move(callback)) {
  std::string mode_string = kDefaultInvalidationMode;

  auto* mode_string_from_settings = settings.FindString("mode");
  if (mode_string_from_settings)
    mode_string = *mode_string_from_settings;

  if (mode_string == "fixed_size") {
    mode_ = FIXED_SIZE;
    auto width = settings.FindInt("width");
    auto height = settings.FindInt("height");
    CHECK(width.has_value()) << "Must provide a width for fixed_size mode.";
    CHECK(height.has_value()) << "Must provide a height for fixed_size mode.";
    width_ = *width;
    height_ = *height;
  } else if (mode_string == "layer") {
    mode_ = LAYER;
  } else if (mode_string == "random") {
    mode_ = RANDOM;
  } else if (mode_string == "viewport") {
    mode_ = VIEWPORT;
  } else {
    NOTREACHED() << "Invalid mode: " << mode_string
                 << ". One of {fixed_size, layer, viewport, random} expected.";
  }
}

InvalidationBenchmark::~InvalidationBenchmark() = default;

void InvalidationBenchmark::DidUpdateLayers(LayerTreeHost* layer_tree_host) {
  for (auto* layer : *layer_tree_host)
    layer->RunMicroBenchmark(this);
}

void InvalidationBenchmark::RunOnLayer(PictureLayer* layer) {
  gfx::Rect visible_layer_rect = gfx::Rect(layer->bounds());
  gfx::Transform from_screen =
      layer->ScreenSpaceTransform().InverseOrIdentity();
  gfx::Rect viewport_rect = MathUtil::ProjectEnclosingClippedRect(
      from_screen, layer->layer_tree_host()->device_viewport_rect());
  visible_layer_rect.Intersect(viewport_rect);
  switch (mode_) {
    case FIXED_SIZE: {
      // Invalidation with a random position and fixed size.
      int x = LCGRandom() * (visible_layer_rect.width() - width_);
      int y = LCGRandom() * (visible_layer_rect.height() - height_);
      gfx::Rect invalidation_rect(x, y, width_, height_);
      layer->SetNeedsDisplayRect(invalidation_rect);
      break;
    }
    case LAYER: {
      // Invalidate entire layer.
      layer->SetNeedsDisplay();
      break;
    }
    case RANDOM: {
      // Random invalidation inside the viewport.
      int x_min = LCGRandom() * visible_layer_rect.width();
      int x_max = LCGRandom() * visible_layer_rect.width();
      int y_min = LCGRandom() * visible_layer_rect.height();
      int y_max = LCGRandom() * visible_layer_rect.height();
      if (x_min > x_max)
        std::swap(x_min, x_max);
      if (y_min > y_max)
        std::swap(y_min, y_max);
      gfx::Rect invalidation_rect(x_min, y_min, x_max - x_min, y_max - y_min);
      layer->SetNeedsDisplayRect(invalidation_rect);
      break;
    }
    case VIEWPORT: {
      // Invalidate entire viewport.
      layer->SetNeedsDisplayRect(visible_layer_rect);
      break;
    }
  }
}

bool InvalidationBenchmark::ProcessMessage(base::Value::Dict message) {
  auto notify_done = message.FindBool("notify_done");
  if (notify_done.has_value()) {
    if (notify_done.value()) {
      NotifyDone(base::Value::Dict());
    }
    return true;
  }
  return false;
}

// A simple linear congruential generator. The random numbers don't need to be
// high quality, but they need to be identical in each run. Therefore, we use a
// LCG and keep the state locally in the benchmark.
float InvalidationBenchmark::LCGRandom() {
  constexpr uint32_t a = 1664525;
  constexpr uint32_t c = 1013904223;
  seed_ = a * seed_ + c;
  return static_cast<float>(seed_) /
         static_cast<float>(std::numeric_limits<uint32_t>::max());
}

}  // namespace cc