// Copyright 2012 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include "DiscIO/WbfsBlob.h"

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "Common/Align.h"
#include "Common/Assert.h"
#include "Common/CommonTypes.h"
#include "Common/File.h"
#include "Common/MsgHandler.h"
#include "Common/Swap.h"

namespace DiscIO
{
static const u64 WII_SECTOR_SIZE = 0x8000;
static const u64 WII_SECTOR_COUNT = 143432 * 2;
static const u64 WII_DISC_HEADER_SIZE = 256;

WbfsFileReader::WbfsFileReader(File::IOFile file, const std::string& path)
    : m_size(0), m_good(false)
{
  if (!AddFileToList(std::move(file)))
    return;
  OpenAdditionalFiles(path);
  if (!ReadHeader())
    return;
  m_good = true;

  // Grab disc info (assume slot 0, checked in ReadHeader())
  m_wlba_table.resize(m_blocks_per_disc);
  m_files[0].file.Seek(m_hd_sector_size + WII_DISC_HEADER_SIZE /*+ i * m_disc_info_size*/,
                       SEEK_SET);
  m_files[0].file.ReadBytes(m_wlba_table.data(), m_blocks_per_disc * sizeof(u16));
  for (size_t i = 0; i < m_blocks_per_disc; i++)
    m_wlba_table[i] = Common::swap16(m_wlba_table[i]);
}

WbfsFileReader::~WbfsFileReader()
{
}

u64 WbfsFileReader::GetDataSize() const
{
  return WII_SECTOR_COUNT * WII_SECTOR_SIZE;
}

void WbfsFileReader::OpenAdditionalFiles(const std::string& path)
{
  if (path.length() < 4)
    return;

  ASSERT(!m_files.empty());  // The code below gives .wbf0 for index 0, but it should be .wbfs

  while (true)
  {
    // Replace last character with index (e.g. wbfs = wbf1)
    if (m_files.size() >= 10)
      return;
    std::string current_path = path;
    current_path.back() = static_cast<char>('0' + m_files.size());
    if (!AddFileToList(File::IOFile(current_path, "rb")))
      return;
  }
}

bool WbfsFileReader::AddFileToList(File::IOFile file)
{
  if (!file.IsOpen())
    return false;

  const u64 file_size = file.GetSize();
  m_files.emplace_back(std::move(file), m_size, file_size);
  m_size += file_size;

  return true;
}

bool WbfsFileReader::ReadHeader()
{
  // Read hd size info
  m_files[0].file.Seek(0, SEEK_SET);
  m_files[0].file.ReadBytes(&m_header, sizeof(WbfsHeader));
  if (m_header.magic != WBFS_MAGIC)
    return false;

  m_header.hd_sector_count = Common::swap32(m_header.hd_sector_count);
  m_hd_sector_size = 1ull << m_header.hd_sector_shift;

  if (m_size != (m_header.hd_sector_count * m_hd_sector_size))
    return false;

  // Read wbfs cluster info
  m_wbfs_sector_size = 1ull << m_header.wbfs_sector_shift;
  m_wbfs_sector_count = m_size / m_wbfs_sector_size;

  if (m_wbfs_sector_size < WII_SECTOR_SIZE)
    return false;

  m_blocks_per_disc =
      (WII_SECTOR_COUNT * WII_SECTOR_SIZE + m_wbfs_sector_size - 1) / m_wbfs_sector_size;
  m_disc_info_size =
      Common::AlignUp(WII_DISC_HEADER_SIZE + m_blocks_per_disc * sizeof(u16), m_hd_sector_size);

  return m_header.disc_table[0] != 0;
}

bool WbfsFileReader::Read(u64 offset, u64 nbytes, u8* out_ptr)
{
  if (offset + nbytes > GetDataSize())
    return false;

  while (nbytes)
  {
    u64 read_size;
    File::IOFile& data_file = SeekToCluster(offset, &read_size);
    if (read_size == 0)
      return false;
    read_size = std::min(read_size, nbytes);

    if (!data_file.ReadBytes(out_ptr, read_size))
    {
      data_file.Clear();
      return false;
    }

    out_ptr += read_size;
    nbytes -= read_size;
    offset += read_size;
  }

  return true;
}

File::IOFile& WbfsFileReader::SeekToCluster(u64 offset, u64* available)
{
  u64 base_cluster = (offset >> m_header.wbfs_sector_shift);
  if (base_cluster < m_blocks_per_disc)
  {
    u64 cluster_address = m_wbfs_sector_size * m_wlba_table[base_cluster];
    u64 cluster_offset = offset & (m_wbfs_sector_size - 1);
    u64 final_address = cluster_address + cluster_offset;

    for (FileEntry& file_entry : m_files)
    {
      if (final_address < (file_entry.base_address + file_entry.size))
      {
        file_entry.file.Seek(final_address - file_entry.base_address, SEEK_SET);
        if (available)
        {
          u64 till_end_of_file = file_entry.size - (final_address - file_entry.base_address);
          u64 till_end_of_sector = m_wbfs_sector_size - cluster_offset;
          *available = std::min(till_end_of_file, till_end_of_sector);
        }

        return file_entry.file;
      }
    }
  }

  PanicAlertFmt("Read beyond end of disc");
  if (available)
    *available = 0;
  m_files[0].file.Seek(0, SEEK_SET);
  return m_files[0].file;
}

std::unique_ptr<WbfsFileReader> WbfsFileReader::Create(File::IOFile file, const std::string& path)
{
  auto reader = std::unique_ptr<WbfsFileReader>(new WbfsFileReader(std::move(file), path));

  if (!reader->IsGood())
    reader.reset();

  return reader;
}

}  // namespace DiscIO
