// Copyright 2008 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <algorithm>
#include <cinttypes>
#include <cstddef>
#include <cstring>
#include <map>
#include <memory>
#include <optional>
#include <string>
#include <vector>

#include "Common/CommonFuncs.h"
#include "Common/CommonTypes.h"
#include "Common/FileUtil.h"
#include "Common/Logging/Log.h"
#include "Common/MsgHandler.h"
#include "Common/StringUtil.h"
#include "DiscIO/FileSystemGCWii.h"
#include "DiscIO/Filesystem.h"
#include "DiscIO/Volume.h"

namespace DiscIO
{
constexpr u32 FST_ENTRY_SIZE = 4 * 3;  // An FST entry consists of three 32-bit integers

// Set everything manually.
FileInfoGCWii::FileInfoGCWii(const u8* fst, u8 offset_shift, u32 index, u32 total_file_infos)
    : m_fst(fst), m_offset_shift(offset_shift), m_index(index), m_total_file_infos(total_file_infos)
{
}

// For the root object only.
// m_fst and m_index must be correctly set before GetSize() is called!
FileInfoGCWii::FileInfoGCWii(const u8* fst, u8 offset_shift)
    : m_fst(fst), m_offset_shift(offset_shift), m_index(0), m_total_file_infos(GetSize())
{
}

// Copy data that is common to the whole file system.
FileInfoGCWii::FileInfoGCWii(const FileInfoGCWii& file_info, u32 index)
    : FileInfoGCWii(file_info.m_fst, file_info.m_offset_shift, index, file_info.m_total_file_infos)
{
}

FileInfoGCWii::~FileInfoGCWii()
{
}

uintptr_t FileInfoGCWii::GetAddress() const
{
  return reinterpret_cast<uintptr_t>(m_fst + FST_ENTRY_SIZE * m_index);
}

u32 FileInfoGCWii::GetNextIndex() const
{
  return IsDirectory() ? GetSize() : m_index + 1;
}

FileInfo& FileInfoGCWii::operator++()
{
  m_index = GetNextIndex();
  return *this;
}

std::unique_ptr<FileInfo> FileInfoGCWii::clone() const
{
  return std::make_unique<FileInfoGCWii>(*this);
}

FileInfo::const_iterator FileInfoGCWii::begin() const
{
  return const_iterator(std::make_unique<FileInfoGCWii>(*this, m_index + 1));
}

FileInfo::const_iterator FileInfoGCWii::end() const
{
  return const_iterator(std::make_unique<FileInfoGCWii>(*this, GetNextIndex()));
}

u32 FileInfoGCWii::Get(EntryProperty entry_property) const
{
  return Common::swap32(m_fst + FST_ENTRY_SIZE * m_index +
                        sizeof(u32) * static_cast<int>(entry_property));
}

u32 FileInfoGCWii::GetSize() const
{
  u32 result = Get(EntryProperty::FILE_SIZE);

  if (IsDirectory() && result <= m_index)
  {
    // For directories, GetSize is supposed to return the index of the next entry.
    // If a file system is malformed and instead has an index that isn't after this one,
    // we act as if the directory is empty to avoid strange behavior.
    ERROR_LOG(DISCIO, "Invalid folder end in file system");
    return m_index + 1;
  }

  return result;
}

u64 FileInfoGCWii::GetOffset() const
{
  return static_cast<u64>(Get(EntryProperty::FILE_OFFSET)) << m_offset_shift;
}

bool FileInfoGCWii::IsDirectory() const
{
  return (Get(EntryProperty::NAME_OFFSET) & 0xFF000000) != 0;
}

u32 FileInfoGCWii::GetTotalChildren() const
{
  return GetSize() - (m_index + 1);
}

std::string FileInfoGCWii::GetName() const
{
  // TODO: Should we really always use SHIFT-JIS?
  // Some names in Pikmin (NTSC-U) don't make sense without it, but is it correct?
  u32 name_offset = Get(EntryProperty::NAME_OFFSET) & 0xFFFFFF;
  const u8* name = m_fst + FST_ENTRY_SIZE * m_total_file_infos + name_offset;
  return SHIFTJISToUTF8(reinterpret_cast<const char*>(name));
}

std::string FileInfoGCWii::GetPath() const
{
  // The root entry doesn't have a name
  if (m_index == 0)
    return "";

  if (IsDirectory())
  {
    u32 parent_directory_index = Get(EntryProperty::FILE_OFFSET);
    if (parent_directory_index >= m_index)
    {
      // The index of the parent directory is supposed to be smaller than
      // the current index. If an FST is malformed and breaks that rule,
      // there's a risk that parent directory pointers form a loop.
      // To avoid stack overflows, this method returns.
      ERROR_LOG(DISCIO, "Invalid parent offset in file system");
      return "";
    }
    return FileInfoGCWii(*this, parent_directory_index).GetPath() + GetName() + "/";
  }
  else
  {
    // The parent directory can be found by searching backwards
    // for a directory that contains this file.

    FileInfoGCWii potential_parent(*this, m_index - 1);
    while (!(potential_parent.IsDirectory() && potential_parent.GetSize() > m_index))
    {
      if (potential_parent.m_index == 0)
      {
        // This can happen if an FST has a root with a size that's too small
        ERROR_LOG(DISCIO, "The parent of %s couldn't be found", GetName().c_str());
        return "";
      }
      potential_parent = FileInfoGCWii(*this, potential_parent.m_index - 1);
    }
    return potential_parent.GetPath() + GetName();
  }
}

FileSystemGCWii::FileSystemGCWii(const Volume* _rVolume, const Partition& partition)
    : FileSystem(_rVolume, partition), m_Valid(false), m_offset_shift(0), m_root(nullptr, 0, 0, 0)
{
  // Check if this is a GameCube or Wii disc
  if (m_rVolume->ReadSwapped<u32>(0x18, m_partition) == u32(0x5D1C9EA3))
    m_offset_shift = 2;  // Wii file system
  else if (m_rVolume->ReadSwapped<u32>(0x1c, m_partition) == u32(0xC2339F3D))
    m_offset_shift = 0;  // GameCube file system
  else
    return;

  const std::optional<u32> fst_offset_unshifted = m_rVolume->ReadSwapped<u32>(0x424, m_partition);
  const std::optional<u32> fst_size_unshifted = m_rVolume->ReadSwapped<u32>(0x428, m_partition);
  if (!fst_offset_unshifted || !fst_size_unshifted)
    return;
  const u64 fst_offset = static_cast<u64>(*fst_offset_unshifted) << m_offset_shift;
  const u64 fst_size = static_cast<u64>(*fst_size_unshifted) << m_offset_shift;
  if (fst_size < FST_ENTRY_SIZE)
  {
    ERROR_LOG(DISCIO, "File system is too small");
    return;
  }

  // 128 MiB is more than the total amount of RAM in a Wii.
  // No file system should use anywhere near that much.
  static const u32 ARBITRARY_FILE_SYSTEM_SIZE_LIMIT = 128 * 1024 * 1024;
  if (fst_size > ARBITRARY_FILE_SYSTEM_SIZE_LIMIT)
  {
    // Without this check, Dolphin can crash by trying to allocate too much
    // memory when loading a disc image with an incorrect FST size.

    ERROR_LOG(DISCIO, "File system is abnormally large! Aborting loading");
    return;
  }

  // Read the whole FST
  m_file_system_table.resize(fst_size);
  if (!m_rVolume->Read(fst_offset, fst_size, m_file_system_table.data(), m_partition))
  {
    ERROR_LOG(DISCIO, "Couldn't read file system table");
    return;
  }

  // Create the root object
  m_root = FileInfoGCWii(m_file_system_table.data(), m_offset_shift);
  if (!m_root.IsDirectory())
  {
    ERROR_LOG(DISCIO, "File system root is not a directory");
    return;
  }

  // If we haven't returned yet, everything succeeded
  m_Valid = true;
}

FileSystemGCWii::~FileSystemGCWii()
{
}

const FileInfo& FileSystemGCWii::GetRoot() const
{
  return m_root;
}

std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(const std::string& path) const
{
  if (!IsValid())
    return nullptr;

  return FindFileInfo(path, m_root);
}

std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(const std::string& path,
                                                        const FileInfo& file_info) const
{
  // Given a path like "directory1/directory2/fileA.bin", this function will
  // find directory1 and then call itself to search for "directory2/fileA.bin".

  if (path.empty() || path == "/")
    return file_info.clone();

  // It's only possible to search in directories. Searching in a file is an error
  if (!file_info.IsDirectory())
    return nullptr;

  size_t first_dir_separator = path.find('/');
  const std::string searching_for = path.substr(0, first_dir_separator);
  const std::string rest_of_path =
      (first_dir_separator != std::string::npos) ? path.substr(first_dir_separator + 1) : "";

  for (const FileInfo& child : file_info)
  {
    if (child.GetName() == searching_for)
    {
      // A match is found. The rest of the path is passed on to finish the search.
      std::unique_ptr<FileInfo> result = FindFileInfo(rest_of_path, child);

      // If the search wasn't successful, the loop continues, just in case there's a second
      // file info that matches searching_for (which probably won't happen in practice)
      if (result)
        return result;
    }
  }

  return nullptr;
}

std::unique_ptr<FileInfo> FileSystemGCWii::FindFileInfo(u64 disc_offset) const
{
  if (!IsValid())
    return nullptr;

  // Build a cache (unless there already is one)
  if (m_offset_file_info_cache.empty())
  {
    u32 fst_entries = m_root.GetSize();
    for (u32 i = 0; i < fst_entries; i++)
    {
      FileInfoGCWii file_info(m_root, i);
      if (!file_info.IsDirectory())
        m_offset_file_info_cache.emplace(file_info.GetOffset() + file_info.GetSize(), i);
    }
  }

  // Get the first file that ends after disc_offset
  const auto it = m_offset_file_info_cache.upper_bound(disc_offset);
  if (it == m_offset_file_info_cache.end())
    return nullptr;
  std::unique_ptr<FileInfo> result(std::make_unique<FileInfoGCWii>(m_root, it->second));

  // If the file's start isn't after disc_offset, success
  if (result->GetOffset() <= disc_offset)
    return result;

  return nullptr;
}

u64 FileSystemGCWii::ReadFile(const FileInfo* file_info, u8* _pBuffer, u64 _MaxBufferSize,
                              u64 _OffsetInFile) const
{
  if (!file_info || file_info->IsDirectory())
    return 0;

  if (_OffsetInFile >= file_info->GetSize())
    return 0;

  u64 read_length = std::min(_MaxBufferSize, file_info->GetSize() - _OffsetInFile);

  DEBUG_LOG(DISCIO, "Reading %" PRIx64 " bytes at %" PRIx64 " from file %s. Offset: %" PRIx64
                    " Size: %" PRIx32,
            read_length, _OffsetInFile, file_info->GetPath().c_str(), file_info->GetOffset(),
            file_info->GetSize());

  m_rVolume->Read(file_info->GetOffset() + _OffsetInFile, read_length, _pBuffer, m_partition);
  return read_length;
}

bool FileSystemGCWii::ExportFile(const FileInfo* file_info,
                                 const std::string& _rExportFilename) const
{
  if (!file_info || file_info->IsDirectory())
    return false;

  u64 remainingSize = file_info->GetSize();
  u64 fileOffset = file_info->GetOffset();

  File::IOFile f(_rExportFilename, "wb");
  if (!f)
    return false;

  bool result = true;

  while (remainingSize)
  {
    // Limit read size to 128 MB
    size_t readSize = (size_t)std::min(remainingSize, (u64)0x08000000);

    std::vector<u8> buffer(readSize);

    result = m_rVolume->Read(fileOffset, readSize, &buffer[0], m_partition);

    if (!result)
      break;

    f.WriteBytes(&buffer[0], readSize);

    remainingSize -= readSize;
    fileOffset += readSize;
  }

  return result;
}

bool FileSystemGCWii::ExportApploader(const std::string& _rExportFolder) const
{
  std::optional<u32> apploader_size = m_rVolume->ReadSwapped<u32>(0x2440 + 0x14, m_partition);
  const std::optional<u32> trailer_size = m_rVolume->ReadSwapped<u32>(0x2440 + 0x18, m_partition);
  constexpr u32 header_size = 0x20;
  if (!apploader_size || !trailer_size)
    return false;
  *apploader_size += *trailer_size + header_size;
  DEBUG_LOG(DISCIO, "Apploader size -> %x", *apploader_size);

  std::vector<u8> buffer(*apploader_size);
  if (m_rVolume->Read(0x2440, *apploader_size, buffer.data(), m_partition))
  {
    std::string exportName(_rExportFolder + "/apploader.img");

    File::IOFile AppFile(exportName, "wb");
    if (AppFile)
    {
      AppFile.WriteBytes(buffer.data(), *apploader_size);
      return true;
    }
  }

  return false;
}

std::optional<u64> FileSystemGCWii::GetBootDOLOffset() const
{
  std::optional<u32> offset = m_rVolume->ReadSwapped<u32>(0x420, m_partition);
  return offset ? static_cast<u64>(*offset) << m_offset_shift : std::optional<u64>();
}

std::optional<u32> FileSystemGCWii::GetBootDOLSize(u64 dol_offset) const
{
  u32 dol_size = 0;

  // Iterate through the 7 code segments
  for (u8 i = 0; i < 7; i++)
  {
    const std::optional<u32> offset =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0x00 + i * 4, m_partition);
    const std::optional<u32> size =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0x90 + i * 4, m_partition);
    if (!offset || !size)
      return {};
    dol_size = std::max(*offset + *size, dol_size);
  }

  // Iterate through the 11 data segments
  for (u8 i = 0; i < 11; i++)
  {
    const std::optional<u32> offset =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0x1c + i * 4, m_partition);
    const std::optional<u32> size =
        m_rVolume->ReadSwapped<u32>(dol_offset + 0xac + i * 4, m_partition);
    if (!offset || !size)
      return {};
    dol_size = std::max(*offset + *size, dol_size);
  }

  return dol_size;
}

bool FileSystemGCWii::ExportDOL(const std::string& _rExportFolder) const
{
  std::optional<u64> dol_offset = GetBootDOLOffset();
  if (!dol_offset)
    return false;
  std::optional<u32> dol_size = GetBootDOLSize(*dol_offset);
  if (!dol_size)
    return false;

  std::vector<u8> buffer(*dol_size);
  if (m_rVolume->Read(*dol_offset, *dol_size, &buffer[0], m_partition))
  {
    std::string exportName(_rExportFolder + "/boot.dol");

    File::IOFile DolFile(exportName, "wb");
    if (DolFile)
    {
      DolFile.WriteBytes(&buffer[0], *dol_size);
      return true;
    }
  }

  return false;
}

}  // namespace