// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/renderer_host/navigation_transitions/navigation_transition_config.h"

#include "base/android/callback_android.h"
#include "base/auto_reset.h"
#include "base/byte_size.h"
#include "base/debug/crash_logging.h"
#include "base/numerics/safe_conversions.h"
#include "base/system/sys_info.h"
#include "base/time/time.h"
#include "base/types/pass_key.h"
#include "content/public/common/content_features.h"
#include "third_party/blink/public/common/features.h"
#include "ui/display/screen.h"

namespace content {
namespace {

const int kMaxScreenshotCount = 20;

static int g_min_required_physical_ram_mb = 7200;

const double kPercentageOfRamToUse = 0.5;

const base::TimeDelta kInvisibleCacheCleanupDelay = base::Minutes(7);

size_t GetMaxCacheSizeInBytes() {
  constexpr int kLowEndMax = 32 * 1024 * 1024;  // 32MB
  constexpr int kOtherMax = 128 * 1024 * 1024;  // 128MB
  return base::SysInfo::IsLowEndDevice() ? kLowEndMax : kOtherMax;
}

}  // namespace

// static
bool NavigationTransitionConfig::SupportsBackForwardTransitions(
    base::PassKey<ContentBrowserClient>) {
  return base::SysInfo::AmountOfTotalPhysicalMemory() >=
         base::MiB(
             base::checked_cast<uint64_t>(g_min_required_physical_ram_mb));
}

// static
size_t NavigationTransitionConfig::ComputeCacheSizeInBytes() {
  // TODO(crbug.com/429140103): Convert the return type to ByteSize.

  // Assume 4 bytes per pixel. This value estimates the max number of bytes of
  // the physical screen's uncompressed bitmap.
  // Assume one pixel for unit tests that don't have or need a screen.
  size_t display_size_in_bytes = 4;
  if (auto* screen = display::Screen::Get(); screen) {
    for (const auto& display : display::Screen::Get()->GetAllDisplays()) {
      display_size_in_bytes =
          std::max(display_size_in_bytes,
                   static_cast<size_t>(4 * display.GetSizeInPixel().Area64()));
    }
  }

  size_t memory_required_for_max_screenshots =
      display_size_in_bytes * kMaxScreenshotCount;

  size_t physical_memory_budget =
      (base::SysInfo::AmountOfTotalPhysicalMemory().InBytes() *
       kPercentageOfRamToUse) /
      100;
  physical_memory_budget =
      std::min(physical_memory_budget, GetMaxCacheSizeInBytes());
  physical_memory_budget =
      std::min(physical_memory_budget, memory_required_for_max_screenshots);

  // We should at least be able to cache one uncompressed screenshot.
  physical_memory_budget =
      std::max(display_size_in_bytes, physical_memory_budget);

  static auto* const display_size_key = base::debug::AllocateCrashKeyString(
      "dnt_display_size_bytes", base::debug::CrashKeySize::Size32);
  static auto* const budget_key = base::debug::AllocateCrashKeyString(
      "dnt_budget_bytes", base::debug::CrashKeySize::Size32);

  base::debug::SetCrashKeyString(display_size_key,
                                 base::NumberToString(display_size_in_bytes));
  base::debug::SetCrashKeyString(budget_key,
                                 base::NumberToString(physical_memory_budget));

  return physical_memory_budget;
}

// static
base::TimeDelta
NavigationTransitionConfig::GetCleanupDelayForInvisibleCaches() {
  return kInvisibleCacheCleanupDelay;
}

// static
base::AutoReset<int>
NavigationTransitionConfig::SetMinRequiredPhysicalRamMbForTesting(int mb) {
  return base::AutoReset<int>(&g_min_required_physical_ram_mb, mb);
}

}  // namespace content