// Copyright 2009 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "VideoCommon/HiresTextures.h"

#include <algorithm>
#include <memory>
#include <mutex>
#include <string>
#include <string_view>
#include <thread>
#include <unordered_map>
#include <utility>
#include <vector>
#include <xxhash.h>

#include <fmt/format.h>

#include "Common/CommonPaths.h"
#include "Common/FileSearch.h"
#include "Common/FileUtil.h"
#include "Common/Flag.h"
#include "Common/IOFile.h"
#include "Common/Image.h"
#include "Common/Logging/Log.h"
#include "Common/MemoryUtil.h"
#include "Common/StringUtil.h"
#include "Common/Swap.h"
#include "Common/Thread.h"
#include "Common/Timer.h"
#include "Core/Config/GraphicsSettings.h"
#include "Core/ConfigManager.h"
#include "VideoCommon/OnScreenDisplay.h"
#include "VideoCommon/VideoConfig.h"

struct DiskTexture
{
  std::string path;
  bool has_arbitrary_mipmaps;
};

constexpr std::string_view s_format_prefix{"tex1_"};

static std::unordered_map<std::string, DiskTexture> s_textureMap;
static std::unordered_map<std::string, std::shared_ptr<HiresTexture>> s_textureCache;
static std::mutex s_textureCacheMutex;
static Common::Flag s_textureCacheAbortLoading;

static std::thread s_prefetcher;

void HiresTexture::Init()
{
  // Note: Update is not called here so that we handle dynamic textures on startup more gracefully
}

void HiresTexture::Shutdown()
{
  Clear();
}

void HiresTexture::Update()
{
  if (s_prefetcher.joinable())
  {
    s_textureCacheAbortLoading.Set();
    s_prefetcher.join();
  }

  if (!g_ActiveConfig.bHiresTextures)
  {
    Clear();
    return;
  }

  if (!g_ActiveConfig.bCacheHiresTextures)
  {
    s_textureCache.clear();
  }

  const std::string& game_id = SConfig::GetInstance().GetGameID();
  const std::set<std::string> texture_directories =
      GetTextureDirectoriesWithGameId(File::GetUserPath(D_HIRESTEXTURES_IDX), game_id);
  const std::vector<std::string> extensions{".png", ".dds"};

  for (const auto& texture_directory : texture_directories)
  {
    const auto texture_paths =
        Common::DoFileSearch({texture_directory}, extensions, /*recursive*/ true);

    bool failed_insert = false;
    for (auto& path : texture_paths)
    {
      std::string filename;
      SplitPath(path, nullptr, &filename, nullptr);

      if (filename.substr(0, s_format_prefix.length()) == s_format_prefix)
      {
        const size_t arb_index = filename.rfind("_arb");
        const bool has_arbitrary_mipmaps = arb_index != std::string::npos;
        if (has_arbitrary_mipmaps)
          filename.erase(arb_index, 4);

        const auto [it, inserted] =
            s_textureMap.try_emplace(filename, DiskTexture{path, has_arbitrary_mipmaps});
        if (!inserted)
        {
          failed_insert = true;
        }
      }
    }

    if (failed_insert)
    {
      ERROR_LOG_FMT(VIDEO, "One or more textures at path '{}' were already inserted",
                    texture_directory);
    }
  }

  if (g_ActiveConfig.bCacheHiresTextures)
  {
    // remove cached but deleted textures
    auto iter = s_textureCache.begin();
    while (iter != s_textureCache.end())
    {
      if (s_textureMap.find(iter->first) == s_textureMap.end())
      {
        iter = s_textureCache.erase(iter);
      }
      else
      {
        iter++;
      }
    }

    s_textureCacheAbortLoading.Clear();
    s_prefetcher = std::thread(Prefetch);
  }
}

void HiresTexture::Clear()
{
  if (s_prefetcher.joinable())
  {
    s_textureCacheAbortLoading.Set();
    s_prefetcher.join();
  }
  s_textureMap.clear();
  s_textureCache.clear();
}

void HiresTexture::Prefetch()
{
  Common::SetCurrentThreadName("Prefetcher");

  size_t size_sum = 0;
  const size_t sys_mem = Common::MemPhysical();
  const size_t recommended_min_mem = 2 * size_t(1024 * 1024 * 1024);
  // keep 2GB memory for system stability if system RAM is 4GB+ - use half of memory in other cases
  const size_t max_mem =
      (sys_mem / 2 < recommended_min_mem) ? (sys_mem / 2) : (sys_mem - recommended_min_mem);

  Common::Timer timer;
  timer.Start();
  for (const auto& entry : s_textureMap)
  {
    const std::string& base_filename = entry.first;

    if (base_filename.find("_mip") == std::string::npos)
    {
      std::unique_lock<std::mutex> lk(s_textureCacheMutex);

      auto iter = s_textureCache.find(base_filename);
      if (iter == s_textureCache.end())
      {
        // unlock while loading a texture. This may result in a race condition where
        // we'll load a texture twice, but it reduces the stuttering a lot.
        lk.unlock();
        std::unique_ptr<HiresTexture> texture = Load(base_filename, 0, 0);
        lk.lock();
        if (texture)
        {
          std::shared_ptr<HiresTexture> ptr(std::move(texture));
          iter = s_textureCache.insert(iter, std::make_pair(base_filename, ptr));
        }
      }
      if (iter != s_textureCache.end())
      {
        for (const Level& l : iter->second->m_levels)
          size_sum += l.data.size();
      }
    }

    if (s_textureCacheAbortLoading.IsSet())
    {
      return;
    }

    if (size_sum > max_mem)
    {
      Config::SetCurrent(Config::GFX_HIRES_TEXTURES, false);

      OSD::AddMessage(
          fmt::format(
              "Custom Textures prefetching after {:.1f} MB aborted, not enough RAM available",
              size_sum / (1024.0 * 1024.0)),
          10000);
      return;
    }
  }

  OSD::AddMessage(fmt::format("Custom Textures loaded, {:.1f} MB in {:.1f}s",
                              size_sum / (1024.0 * 1024.0), timer.ElapsedMs() / 1000.0),
                  10000);
}

std::string HiresTexture::GenBaseName(const TextureInfo& texture_info, bool dump)
{
  if (!dump && s_textureMap.empty())
    return "";

  const auto texture_name_details = texture_info.CalculateTextureName();

  // look for an exact match first
  const std::string full_name = texture_name_details.GetFullName();
  if (dump || s_textureMap.find(full_name) != s_textureMap.end())
    return full_name;

  // else try and find a wildcard
  if (!dump)
  {
    // Single wildcard ignoring the tlut hash
    const std::string texture_name_single_wildcard_tlut =
        fmt::format("{}_{}_$_{}", texture_name_details.base_name, texture_name_details.texture_name,
                    texture_name_details.format_name);
    if (s_textureMap.find(texture_name_single_wildcard_tlut) != s_textureMap.end())
      return texture_name_single_wildcard_tlut;

    // Single wildcard ignoring the texture hash
    const std::string texture_name_single_wildcard_tex =
        fmt::format("{}_${}_{}", texture_name_details.base_name, texture_name_details.tlut_name,
                    texture_name_details.format_name);
    if (s_textureMap.find(texture_name_single_wildcard_tex) != s_textureMap.end())
      return texture_name_single_wildcard_tex;
  }

  return "";
}

u32 HiresTexture::CalculateMipCount(u32 width, u32 height)
{
  u32 mip_width = width;
  u32 mip_height = height;
  u32 mip_count = 1;
  while (mip_width > 1 || mip_height > 1)
  {
    mip_width = std::max(mip_width / 2, 1u);
    mip_height = std::max(mip_height / 2, 1u);
    mip_count++;
  }

  return mip_count;
}

std::shared_ptr<HiresTexture> HiresTexture::Search(const TextureInfo& texture_info)
{
  const std::string base_filename = GenBaseName(texture_info);

  std::lock_guard<std::mutex> lk(s_textureCacheMutex);

  auto iter = s_textureCache.find(base_filename);
  if (iter != s_textureCache.end())
  {
    return iter->second;
  }

  std::shared_ptr<HiresTexture> ptr(
      Load(base_filename, texture_info.GetRawWidth(), texture_info.GetRawHeight()));

  if (ptr && g_ActiveConfig.bCacheHiresTextures)
  {
    s_textureCache[base_filename] = ptr;
  }

  return ptr;
}

std::unique_ptr<HiresTexture> HiresTexture::Load(const std::string& base_filename, u32 width,
                                                 u32 height)
{
  // We need to have a level 0 custom texture to even consider loading.
  auto filename_iter = s_textureMap.find(base_filename);
  if (filename_iter == s_textureMap.end())
    return nullptr;

  // Try to load level 0 (and any mipmaps) from a DDS file.
  // If this fails, it's fine, we'll just load level0 again using SOIL.
  // Can't use make_unique due to private constructor.
  std::unique_ptr<HiresTexture> ret = std::unique_ptr<HiresTexture>(new HiresTexture());
  const DiskTexture& first_mip_file = filename_iter->second;
  ret->m_has_arbitrary_mipmaps = first_mip_file.has_arbitrary_mipmaps;
  LoadDDSTexture(ret.get(), first_mip_file.path);

  // Load remaining mip levels, or from the start if it's not a DDS texture.
  for (u32 mip_level = static_cast<u32>(ret->m_levels.size());; mip_level++)
  {
    std::string filename = base_filename;
    if (mip_level != 0)
      filename += fmt::format("_mip{}", mip_level);

    filename_iter = s_textureMap.find(filename);
    if (filename_iter == s_textureMap.end())
      break;

    // Try loading DDS textures first, that way we maintain compression of DXT formats.
    // TODO: Reduce the number of open() calls here. We could use one fd.
    Level level;
    if (!LoadDDSTexture(level, filename_iter->second.path, mip_level))
    {
      File::IOFile file;
      file.Open(filename_iter->second.path, "rb");
      std::vector<u8> buffer(file.GetSize());
      file.ReadBytes(buffer.data(), file.GetSize());

      if (!LoadTexture(level, buffer))
      {
        ERROR_LOG_FMT(VIDEO, "Custom texture {} failed to load", filename);
        break;
      }
    }

    ret->m_levels.push_back(std::move(level));
  }

  // If we failed to load any mip levels, we can't use this texture at all.
  if (ret->m_levels.empty())
    return nullptr;

  // Verify that the aspect ratio of the texture hasn't changed, as this could have side-effects.
  const Level& first_mip = ret->m_levels[0];
  if (first_mip.width * height != first_mip.height * width)
  {
    ERROR_LOG_FMT(VIDEO,
                  "Invalid custom texture size {}x{} for texture {}. The aspect differs "
                  "from the native size {}x{}.",
                  first_mip.width, first_mip.height, first_mip_file.path, width, height);
  }

  // Same deal if the custom texture isn't a multiple of the native size.
  if (width != 0 && height != 0 && (first_mip.width % width || first_mip.height % height))
  {
    ERROR_LOG_FMT(VIDEO,
                  "Invalid custom texture size {}x{} for texture {}. Please use an integer "
                  "upscaling factor based on the native size {}x{}.",
                  first_mip.width, first_mip.height, first_mip_file.path, width, height);
  }

  // Verify that each mip level is the correct size (divide by 2 each time).
  u32 current_mip_width = first_mip.width;
  u32 current_mip_height = first_mip.height;
  for (u32 mip_level = 1; mip_level < static_cast<u32>(ret->m_levels.size()); mip_level++)
  {
    if (current_mip_width != 1 || current_mip_height != 1)
    {
      current_mip_width = std::max(current_mip_width / 2, 1u);
      current_mip_height = std::max(current_mip_height / 2, 1u);

      const Level& level = ret->m_levels[mip_level];
      if (current_mip_width == level.width && current_mip_height == level.height)
        continue;

      ERROR_LOG_FMT(
          VIDEO, "Invalid custom texture size {}x{} for texture {}. Mipmap level {} must be {}x{}.",
          level.width, level.height, first_mip_file.path, mip_level, current_mip_width,
          current_mip_height);
    }
    else
    {
      // It is invalid to have more than a single 1x1 mipmap.
      ERROR_LOG_FMT(VIDEO, "Custom texture {} has too many 1x1 mipmaps. Skipping extra levels.",
                    first_mip_file.path);
    }

    // Drop this mip level and any others after it.
    while (ret->m_levels.size() > mip_level)
      ret->m_levels.pop_back();
  }

  // All levels have to have the same format.
  if (std::any_of(ret->m_levels.begin(), ret->m_levels.end(),
                  [&ret](const Level& l) { return l.format != ret->m_levels[0].format; }))
  {
    ERROR_LOG_FMT(VIDEO, "Custom texture {} has inconsistent formats across mip levels.",
                  first_mip_file.path);

    return nullptr;
  }

  return ret;
}

bool HiresTexture::LoadTexture(Level& level, const std::vector<u8>& buffer)
{
  if (!Common::LoadPNG(buffer, &level.data, &level.width, &level.height))
    return false;

  if (level.data.empty())
    return false;

  // Loaded PNG images are converted to RGBA.
  level.format = AbstractTextureFormat::RGBA8;
  level.row_length = level.width;
  return true;
}

std::set<std::string> GetTextureDirectoriesWithGameId(const std::string& root_directory,
                                                      const std::string& game_id)
{
  std::set<std::string> result;
  const std::string texture_directory = root_directory + game_id;

  if (File::Exists(texture_directory))
  {
    result.insert(texture_directory);
  }
  else
  {
    // If there's no directory with the region-specific ID, look for a 3-character region-free one
    const std::string region_free_directory = root_directory + game_id.substr(0, 3);

    if (File::Exists(region_free_directory))
    {
      result.insert(region_free_directory);
    }
  }

  const auto match_gameid_or_all = [game_id](const std::string& filename) {
    std::string basename;
    SplitPath(filename, nullptr, &basename, nullptr);
    return basename == game_id || basename == game_id.substr(0, 3) || basename == "all";
  };

  // Look for any other directories that might be specific to the given gameid
  const auto files = Common::DoFileSearch({root_directory}, {".txt"}, true);
  for (const auto& file : files)
  {
    if (match_gameid_or_all(file))
    {
      // The following code is used to calculate the top directory
      // of a found gameid.txt file
      // ex:  <root directory>/My folder/gameids/<gameid>.txt
      // would insert "<root directory>/My folder"
      const auto directory_path = file.substr(root_directory.size());
      const std::size_t first_path_separator_position = directory_path.find_first_of(DIR_SEP_CHR);
      result.insert(root_directory + directory_path.substr(0, first_path_separator_position));
    }
  }

  return result;
}

HiresTexture::~HiresTexture()
{
}

AbstractTextureFormat HiresTexture::GetFormat() const
{
  return m_levels.at(0).format;
}

bool HiresTexture::HasArbitraryMipmaps() const
{
  return m_has_arbitrary_mipmaps;
}
