/*
Copyright (C) 2012 Sebastian Herbord. All rights reserved.

This file is part of Mod Organizer.

Mod Organizer is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Mod Organizer is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Mod Organizer.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "dummybsa.h"
#include <QFile>
#include <stdexcept>
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#else
#ifndef MAX_PATH
#define MAX_PATH 260
#endif
#endif

static void writeUlong(unsigned char* buffer, int offset, unsigned long value)
{
  union
  {
    unsigned long ulValue;
    unsigned char cValue[4];
  };
  ulValue = value;
  memcpy(buffer + offset, cValue, 4);
}

static void writeUlonglong(unsigned char* buffer, int offset, unsigned long long value)
{
  union
  {
    unsigned long long ullValue;
    unsigned char cValue[8];
  };
  ullValue = value;
  memcpy(buffer + offset, cValue, 8);
}

static unsigned long genHashInt(const unsigned char* pos, const unsigned char* end)
{
  unsigned long hash = 0;
  for (; pos < end; ++pos) {
    hash *= 0x1003f;
    hash += *pos;
  }
  return hash;
}

static unsigned long long genHash(const char* fileName)
{
  char fileNameLower[MAX_PATH + 1];
  int i = 0;
  for (; i < MAX_PATH && fileName[i] != '\0'; ++i) {
    fileNameLower[i] = static_cast<char>(tolower(fileName[i]));
    if (fileNameLower[i] == '\\') {
      fileNameLower[i] = '/';
    }
  }
  fileNameLower[i] = '\0';

  unsigned char* fileNameLowerU = reinterpret_cast<unsigned char*>(fileNameLower);

  char* ext = strrchr(fileNameLower, '.');
  if (ext == nullptr) {
    ext = fileNameLower + strlen(fileNameLower);
  }
  unsigned char* extU = reinterpret_cast<unsigned char*>(ext);

  int length = ext - fileNameLower;

  unsigned long long hash = 0ULL;

  if (length > 0) {
    hash = *(extU - 1) | ((length > 2 ? *(ext - 2) : 0) << 8) | (length << 16) |
           (fileNameLowerU[0] << 24);
  }

  if (strlen(ext) > 0) {
    if (strcmp(ext + 1, "kf") == 0) {
      hash |= 0x80;
    } else if (strcmp(ext + 1, "nif") == 0) {
      hash |= 0x8000;
    } else if (strcmp(ext + 1, "dds") == 0) {
      hash |= 0x8080;
    } else if (strcmp(ext + 1, "wav") == 0) {
      hash |= 0x80000000;
    }

    unsigned long long temp =
        static_cast<unsigned long long>(genHashInt(fileNameLowerU + 1, extU - 2));
    temp += static_cast<unsigned long long>(genHashInt(extU, extU + strlen(ext)));

    hash |= (temp & 0xFFFFFFFF) << 32;
  }
  return hash;
}

DummyBSA::DummyBSA(unsigned long bsaVersion)
    : m_Version(bsaVersion), m_FolderName(""), m_FileName("dummy.dds"),
      m_TotalFileNameLength(0)
{}

void DummyBSA::writeHeader(QFile& file)
{
  unsigned char header[] = {
      'B',  'S',  'A',  '\0',  // magic string
      0xDE, 0xAD, 0xBE, 0xEF,  // version - insert later
      0x24, 0x00, 0x00, 0x00,  // offset to folder recors. header size is static
      0xDE, 0xAD, 0xBE, 0xEF,  // archive flags - insert later
      0x01, 0x00, 0x00, 0x00,  // folder count
      0x01, 0x00, 0x00, 0x00,  // file count
      0xDE, 0xAD, 0xBE, 0xEF,  // total folder names length - insert later
      0xDE, 0xAD, 0xBE, 0xEF,  // total file names length - insert later
      0xDE, 0xAD, 0xBE, 0xEF   // file flags - insert later
  };

  writeUlong(header, 4, m_Version);
  writeUlong(header, 12, 0x01 | 0x02);  // has directories and has files.
  writeUlong(header, 24,
             static_cast<unsigned long>(m_FolderName.length()) +
                 1);                              // empty folder name
  writeUlong(header, 28, m_TotalFileNameLength);  // single character file name

  writeUlong(header, 32, 2);  // has dds

  file.write(reinterpret_cast<char*>(header), sizeof(header));
}

void DummyBSA::writeFolderRecord(QFile& file, const std::string& folderName)
{
  unsigned char folderRecord[] = {
      0xDE, 0xAD, 0xBE, 0xEF, 0xDE, 0xAD, 0xBE, 0xEF,  // folder hash
      0x01, 0x00, 0x00, 0x00,                          // file count
      0xDE, 0xAD, 0xBE, 0xEF,                          // offset to folder name
  };
  // we'd usually have to sort folders be the hash value generated here
  writeUlonglong(folderRecord, 0, genHash(folderName.c_str()));
  writeUlong(folderRecord, 12,
             0x34 + m_TotalFileNameLength);  // TODO: this should be calculated properly

  file.write(reinterpret_cast<char*>(folderRecord), sizeof(folderRecord));
}

void DummyBSA::writeFileRecord(QFile& file, const std::string& fileName)
{
  unsigned char fileRecord[] = {
      0xDE, 0xAD, 0xBE, 0xEF, 0xDE, 0xAD, 0xBE, 0xEF,  // file name hash
      0xDE, 0xAD, 0xBE, 0xEF,                          // size
      0xDE, 0xAD, 0xBE, 0xEF,                          // offset to file data
  };

  // we'd usually have to sort files by the value generated here
  writeUlonglong(fileRecord, 0, genHash(fileName.c_str()));
  writeUlong(fileRecord, 8, 0);
  writeUlong(
      fileRecord, 12,
      0x44 + static_cast<unsigned long>(fileName.length() + 1) +
          4);  // after this record we expect the filename and 4 bytes of file size

  file.write(reinterpret_cast<char*>(fileRecord), sizeof(fileRecord));
}

void DummyBSA::writeFileRecordBlocks(QFile& file, const std::string& folderName)
{
  file.write(folderName.c_str(), folderName.length() + 1);

  writeFileRecord(file, m_FileName);
}

void DummyBSA::write(const QString& fileName)
{
  QFile file(fileName);
  if (!file.open(QIODevice::WriteOnly)) {
    throw std::runtime_error(
        QString("failed to open dummy BSA for writing: %1").arg(fileName).toStdString());
  }

  m_TotalFileNameLength = static_cast<unsigned long>(m_FileName.length() + 1);

  writeHeader(file);
  writeFolderRecord(file, m_FolderName);
  writeFileRecordBlocks(file, m_FolderName);
  file.write(m_FileName.c_str(), m_FileName.length() + 1);
  char fileSize[] = {0x00, 0x00, 0x00, 0x00};
  file.write(fileSize, sizeof(fileSize));
  file.close();
}