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

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

#include "Common/Align.h"
#include "Common/Assert.h"
#include "Common/CommonPaths.h"
#include "Common/CommonTypes.h"
#include "Common/FileUtil.h"
#include "Common/Logging/Log.h"
#include "DiscIO/Blob.h"
#include "DiscIO/Enums.h"
#include "DiscIO/FileMonitor.h"
#include "DiscIO/Volume.h"
#include "DiscIO/VolumeDirectory.h"

namespace DiscIO
{
static u32 ComputeNameSize(const File::FSTEntry& parentEntry);

const size_t CVolumeDirectory::MAX_NAME_LENGTH;
const size_t CVolumeDirectory::MAX_ID_LENGTH;

CVolumeDirectory::CVolumeDirectory(const std::string& _rDirectory, bool _bIsWii,
                                   const std::string& _rApploader, const std::string& _rDOL)
    : m_dataStartAddress(-1), m_diskHeader(DISKHEADERINFO_ADDRESS),
      m_diskHeaderInfo(std::make_unique<SDiskHeaderInfo>()), m_fst_address(0), m_dol_address(0)
{
  m_rootDirectory = ExtractDirectoryName(_rDirectory);

  // create the default disk header
  SetGameID("AGBJ01");
  SetName("Default name");

  if (_bIsWii)
    SetDiskTypeWii();
  else
    SetDiskTypeGC();

  // Don't load the DOL if we don't have an apploader
  if (SetApploader(_rApploader))
    SetDOL(_rDOL);

  BuildFST();
}

CVolumeDirectory::~CVolumeDirectory()
{
}

bool CVolumeDirectory::IsValidDirectory(const std::string& _rDirectory)
{
  return File::IsDirectory(ExtractDirectoryName(_rDirectory));
}

bool CVolumeDirectory::Read(u64 _Offset, u64 _Length, u8* _pBuffer, bool decrypt) const
{
  if (!decrypt && (_Offset + _Length >= 0x400) && m_is_wii)
  {
    // Fully supporting this would require re-encrypting every file that's read.
    // Only supporting the areas that IOS allows software to read could be more feasible.
    // Currently, only the header (up to 0x400) is supported, though we're cheating a bit
    // with it by reading the header inside the current partition instead. Supporting the
    // header is enough for booting games, but not for running things like the Disc Channel.
    return false;
  }

  if (decrypt && !m_is_wii)
    PanicAlertT("Tried to decrypt data from a non-Wii volume");

  // header
  if (_Offset < DISKHEADERINFO_ADDRESS)
  {
    WriteToBuffer(DISKHEADER_ADDRESS, DISKHEADERINFO_ADDRESS, m_diskHeader.data(), _Offset, _Length,
                  _pBuffer);
  }
  // header info
  if (_Offset >= DISKHEADERINFO_ADDRESS && _Offset < APPLOADER_ADDRESS)
  {
    WriteToBuffer(DISKHEADERINFO_ADDRESS, sizeof(m_diskHeaderInfo), (u8*)m_diskHeaderInfo.get(),
                  _Offset, _Length, _pBuffer);
  }
  // apploader
  if (_Offset >= APPLOADER_ADDRESS && _Offset < APPLOADER_ADDRESS + m_apploader.size())
  {
    WriteToBuffer(APPLOADER_ADDRESS, m_apploader.size(), m_apploader.data(), _Offset, _Length,
                  _pBuffer);
  }
  // dol
  if (_Offset >= m_dol_address && _Offset < m_dol_address + m_DOL.size())
  {
    WriteToBuffer(m_dol_address, m_DOL.size(), m_DOL.data(), _Offset, _Length, _pBuffer);
  }
  // fst
  if (_Offset >= m_fst_address && _Offset < m_dataStartAddress)
  {
    WriteToBuffer(m_fst_address, m_FSTData.size(), m_FSTData.data(), _Offset, _Length, _pBuffer);
  }

  if (m_virtualDisk.empty())
    return true;

  // Determine which file the offset refers to
  std::map<u64, std::string>::const_iterator fileIter = m_virtualDisk.lower_bound(_Offset);
  if (fileIter->first > _Offset && fileIter != m_virtualDisk.begin())
    --fileIter;

  // zero fill to start of file data
  PadToAddress(fileIter->first, _Offset, _Length, _pBuffer);

  while (fileIter != m_virtualDisk.end() && _Length > 0)
  {
    _dbg_assert_(DVDINTERFACE, fileIter->first <= _Offset);
    u64 fileOffset = _Offset - fileIter->first;
    const std::string fileName = fileIter->second;

    File::IOFile file(fileName, "rb");
    if (!file)
      return false;

    u64 fileSize = file.GetSize();

    FileMon::CheckFile(fileName, fileSize);

    if (fileOffset < fileSize)
    {
      u64 fileBytes = std::min(fileSize - fileOffset, _Length);

      if (!file.Seek(fileOffset, SEEK_SET))
        return false;
      if (!file.ReadBytes(_pBuffer, fileBytes))
        return false;

      _Length -= fileBytes;
      _pBuffer += fileBytes;
      _Offset += fileBytes;
    }

    ++fileIter;

    if (fileIter != m_virtualDisk.end())
    {
      _dbg_assert_(DVDINTERFACE, fileIter->first >= _Offset);
      PadToAddress(fileIter->first, _Offset, _Length, _pBuffer);
    }
  }

  return true;
}

std::string CVolumeDirectory::GetGameID() const
{
  return std::string(m_diskHeader.begin(), m_diskHeader.begin() + MAX_ID_LENGTH);
}

void CVolumeDirectory::SetGameID(const std::string& id)
{
  memcpy(m_diskHeader.data(), id.c_str(), std::min(id.length(), MAX_ID_LENGTH));
}

Country CVolumeDirectory::GetCountry() const
{
  return CountrySwitch(m_diskHeader[3]);
}

std::string CVolumeDirectory::GetMakerID() const
{
  // Not implemented
  return "00";
}

std::string CVolumeDirectory::GetInternalName() const
{
  char name[0x60];
  if (Read(0x20, 0x60, (u8*)name, false))
    return DecodeString(name);
  else
    return "";
}

std::map<Language, std::string> CVolumeDirectory::GetLongNames() const
{
  std::string name = GetInternalName();
  if (name.empty())
    return {{}};
  return {{Language::LANGUAGE_UNKNOWN, name}};
}

std::vector<u32> CVolumeDirectory::GetBanner(int* width, int* height) const
{
  // Not implemented
  *width = 0;
  *height = 0;
  return std::vector<u32>();
}

void CVolumeDirectory::SetName(const std::string& name)
{
  size_t length = std::min(name.length(), MAX_NAME_LENGTH);
  memcpy(&m_diskHeader[0x20], name.c_str(), length);
  m_diskHeader[length + 0x20] = 0;
}

u64 CVolumeDirectory::GetFSTSize() const
{
  // Not implemented
  return 0;
}

std::string CVolumeDirectory::GetApploaderDate() const
{
  // Not implemented
  return "VOID";
}

Platform CVolumeDirectory::GetVolumeType() const
{
  return m_is_wii ? Platform::WII_DISC : Platform::GAMECUBE_DISC;
}

BlobType CVolumeDirectory::GetBlobType() const
{
  // VolumeDirectory isn't actually a blob, but it sort of acts
  // like one, so it makes sense that it has its own blob type.
  // It should be made into a proper blob in the future.
  return BlobType::DIRECTORY;
}

u64 CVolumeDirectory::GetSize() const
{
  // Not implemented
  return 0;
}

u64 CVolumeDirectory::GetRawSize() const
{
  // Not implemented
  return 0;
}

std::string CVolumeDirectory::ExtractDirectoryName(const std::string& _rDirectory)
{
  std::string directoryName = _rDirectory;

  size_t lastSep = directoryName.find_last_of(DIR_SEP_CHR);

  if (lastSep != directoryName.size() - 1)
  {
    // TODO: This assumes that file names will always have a dot in them
    //       and directory names never will; both assumptions are often
    //       right but in general wrong.
    size_t extensionStart = directoryName.find_last_of('.');
    if (extensionStart != std::string::npos && extensionStart > lastSep)
    {
      directoryName.resize(lastSep);
    }
  }
  else
  {
    directoryName.resize(lastSep);
  }

  return directoryName;
}

void CVolumeDirectory::SetDiskTypeWii()
{
  Write32(0x5d1c9ea3, 0x18, &m_diskHeader);
  memset(&m_diskHeader[0x1c], 0, 4);

  m_is_wii = true;
  m_addressShift = 2;
}

void CVolumeDirectory::SetDiskTypeGC()
{
  memset(&m_diskHeader[0x18], 0, 4);
  Write32(0xc2339f3d, 0x1c, &m_diskHeader);

  m_is_wii = false;
  m_addressShift = 0;
}

bool CVolumeDirectory::SetApploader(const std::string& _rApploader)
{
  if (!_rApploader.empty())
  {
    std::string data;
    if (!File::ReadFileToString(_rApploader, data))
    {
      PanicAlertT("Apploader unable to load from file");
      return false;
    }
    size_t apploaderSize = 0x20 + Common::swap32(*(u32*)&data.data()[0x14]) +
                           Common::swap32(*(u32*)&data.data()[0x18]);
    if (apploaderSize != data.size())
    {
      PanicAlertT("Apploader is the wrong size...is it really an apploader?");
      return false;
    }
    m_apploader.resize(apploaderSize);
    std::copy(data.begin(), data.end(), m_apploader.begin());

    // 32byte aligned (plus 0x20 padding)
    m_dol_address = Common::AlignUp(APPLOADER_ADDRESS + m_apploader.size() + 0x20, 0x20ull);
    return true;
  }
  else
  {
    m_apploader.resize(0x20);
    // Make sure BS2 HLE doesn't try to run the apploader
    *(u32*)&m_apploader[0x10] = (u32)-1;
    return false;
  }
}

void CVolumeDirectory::SetDOL(const std::string& rDOL)
{
  if (!rDOL.empty())
  {
    std::string data;
    File::ReadFileToString(rDOL, data);
    m_DOL.resize(data.size());
    std::copy(data.begin(), data.end(), m_DOL.begin());

    Write32((u32)(m_dol_address >> m_addressShift), 0x0420, &m_diskHeader);

    // 32byte aligned (plus 0x20 padding)
    m_fst_address = Common::AlignUp(m_dol_address + m_DOL.size() + 0x20, 0x20ull);
  }
}

void CVolumeDirectory::BuildFST()
{
  m_FSTData.clear();

  File::FSTEntry rootEntry = File::ScanDirectoryTree(m_rootDirectory, true);
  u32 name_table_size = ComputeNameSize(rootEntry);

  m_fstNameOffset = rootEntry.size * ENTRY_SIZE;  // offset of name table in FST
  m_FSTData.resize(m_fstNameOffset + name_table_size);

  // if FST hasn't been assigned (ie no apploader/dol setup), set to default
  if (m_fst_address == 0)
    m_fst_address = APPLOADER_ADDRESS + 0x2000;

  // 4 byte aligned start of data on disk
  m_dataStartAddress = Common::AlignUp(m_fst_address + m_FSTData.size(), 0x8000ull);
  u64 curDataAddress = m_dataStartAddress;

  u32 fstOffset = 0;   // Offset within FST data
  u32 nameOffset = 0;  // Offset within name table
  u32 rootOffset = 0;  // Offset of root of FST

  // write root entry
  WriteEntryData(fstOffset, DIRECTORY_ENTRY, 0, 0, rootEntry.size);

  for (auto& entry : rootEntry.children)
  {
    WriteEntry(entry, fstOffset, nameOffset, curDataAddress, rootOffset);
  }

  // overflow check
  _dbg_assert_(DVDINTERFACE, nameOffset == name_table_size);

  // write FST size and location
  Write32((u32)(m_fst_address >> m_addressShift), 0x0424, &m_diskHeader);
  Write32((u32)(m_FSTData.size() >> m_addressShift), 0x0428, &m_diskHeader);
  Write32((u32)(m_FSTData.size() >> m_addressShift), 0x042c, &m_diskHeader);
}

void CVolumeDirectory::WriteToBuffer(u64 _SrcStartAddress, u64 _SrcLength, const u8* _Src,
                                     u64& _Address, u64& _Length, u8*& _pBuffer) const
{
  if (_Length == 0)
    return;

  _dbg_assert_(DVDINTERFACE, _Address >= _SrcStartAddress);

  u64 srcOffset = _Address - _SrcStartAddress;

  if (srcOffset < _SrcLength)
  {
    u64 srcBytes = std::min(_SrcLength - srcOffset, _Length);

    memcpy(_pBuffer, _Src + srcOffset, (size_t)srcBytes);

    _Length -= srcBytes;
    _pBuffer += srcBytes;
    _Address += srcBytes;
  }
}

void CVolumeDirectory::PadToAddress(u64 _StartAddress, u64& _Address, u64& _Length,
                                    u8*& _pBuffer) const
{
  if (_StartAddress > _Address && _Length > 0)
  {
    u64 padBytes = std::min(_StartAddress - _Address, _Length);
    memset(_pBuffer, 0, (size_t)padBytes);
    _Length -= padBytes;
    _pBuffer += padBytes;
    _Address += padBytes;
  }
}

void CVolumeDirectory::Write32(u32 data, u32 offset, std::vector<u8>* const buffer)
{
  (*buffer)[offset++] = (data >> 24);
  (*buffer)[offset++] = (data >> 16) & 0xff;
  (*buffer)[offset++] = (data >> 8) & 0xff;
  (*buffer)[offset] = (data)&0xff;
}

void CVolumeDirectory::WriteEntryData(u32& entryOffset, u8 type, u32 nameOffset, u64 dataOffset,
                                      u64 length)
{
  m_FSTData[entryOffset++] = type;

  m_FSTData[entryOffset++] = (nameOffset >> 16) & 0xff;
  m_FSTData[entryOffset++] = (nameOffset >> 8) & 0xff;
  m_FSTData[entryOffset++] = (nameOffset)&0xff;

  Write32((u32)(dataOffset >> m_addressShift), entryOffset, &m_FSTData);
  entryOffset += 4;

  Write32((u32)length, entryOffset, &m_FSTData);
  entryOffset += 4;
}

void CVolumeDirectory::WriteEntryName(u32& nameOffset, const std::string& name)
{
  strncpy((char*)&m_FSTData[nameOffset + m_fstNameOffset], name.c_str(), name.length() + 1);

  nameOffset += (u32)(name.length() + 1);
}

void CVolumeDirectory::WriteEntry(const File::FSTEntry& entry, u32& fstOffset, u32& nameOffset,
                                  u64& dataOffset, u32 parentEntryNum)
{
  if (entry.isDirectory)
  {
    u32 myOffset = fstOffset;
    u32 myEntryNum = myOffset / ENTRY_SIZE;
    WriteEntryData(fstOffset, DIRECTORY_ENTRY, nameOffset, parentEntryNum,
                   myEntryNum + entry.size + 1);
    WriteEntryName(nameOffset, entry.virtualName);

    for (const auto& child : entry.children)
    {
      WriteEntry(child, fstOffset, nameOffset, dataOffset, myEntryNum);
    }
  }
  else
  {
    // put entry in FST
    WriteEntryData(fstOffset, FILE_ENTRY, nameOffset, dataOffset, entry.size);
    WriteEntryName(nameOffset, entry.virtualName);

    // write entry to virtual disk
    _dbg_assert_(DVDINTERFACE, m_virtualDisk.find(dataOffset) == m_virtualDisk.end());
    m_virtualDisk.emplace(dataOffset, entry.physicalName);

    // 4 byte aligned
    dataOffset = Common::AlignUp(dataOffset + std::max<u64>(entry.size, 1ull), 0x8000ull);
  }
}

static u32 ComputeNameSize(const File::FSTEntry& parentEntry)
{
  u32 nameSize = 0;
  for (const File::FSTEntry& entry : parentEntry.children)
  {
    if (entry.isDirectory)
      nameSize += ComputeNameSize(entry);

    nameSize += (u32)entry.virtualName.length() + 1;
  }
  return nameSize;
}

}  // namespace