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

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <memory>
#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 "DiscIO/WbfsBlob.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;

static inline u64 align(u64 value, u64 bounds)
{
  return (value + (bounds - 1)) & (~(bounds - 1));
}

WbfsFileReader::WbfsFileReader(const std::string& filename)
    : m_total_files(0), m_size(0), m_good(true)
{
  if (filename.length() < 4 || !OpenFiles(filename) || !ReadHeader())
  {
    m_good = false;
    return;
  }

  // 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;
}

bool WbfsFileReader::OpenFiles(const std::string& filename)
{
  m_total_files = 0;

  while (true)
  {
    auto new_entry = std::make_unique<file_entry>();

    // Replace last character with index (e.g. wbfs = wbf1)
    std::string path = filename;
    if (m_total_files != 0)
    {
      path[path.length() - 1] = '0' + m_total_files;
    }

    if (!new_entry->file.Open(path, "rb"))
    {
      return m_total_files != 0;
    }

    new_entry->base_address = m_size;
    new_entry->size = new_entry->file.GetSize();
    m_size += new_entry->size;

    m_total_files++;
    m_files.emplace_back(std::move(new_entry));
  }
}

bool WbfsFileReader::ReadHeader()
{
  // Read hd size info
  m_files[0]->file.ReadBytes(&m_header, sizeof(WbfsHeader));
  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 =
      align(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)
{
  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 (u32 i = 0; i != m_total_files; i++)
    {
      if (final_address < (m_files[i]->base_address + m_files[i]->size))
      {
        m_files[i]->file.Seek(final_address - m_files[i]->base_address, SEEK_SET);
        if (available)
        {
          u64 till_end_of_file = m_files[i]->size - (final_address - m_files[i]->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 m_files[i]->file;
      }
    }
  }

  PanicAlert("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(const std::string& filename)
{
  auto reader = std::unique_ptr<WbfsFileReader>(new WbfsFileReader(filename));

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

  return reader;
}

bool IsWbfsBlob(const std::string& filename)
{
  File::IOFile f(filename, "rb");

  u8 magic[4] = {0, 0, 0, 0};
  f.ReadBytes(&magic, 4);

  return (magic[0] == 'W') && (magic[1] == 'B') && (magic[2] == 'F') && (magic[3] == 'S');
}

}  // namespace
