/* <!-- copyright */
/*
 * aria2 - The high speed download utility
 *
 * Copyright (C) 2006 Tatsuhiro Tsujikawa
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 * You must obey the GNU General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
 * version of the file(s), but you are not obligated to do so.  If you
 * do not wish to do so, delete this exception statement from your
 * version.  If you delete this exception statement from all source
 * files in the program, then also delete it here.
 */
/* copyright --> */
#include "MultiDiskAdaptor.h"

#include <cassert>
#include <algorithm>
#include <map>

#include "DefaultDiskWriter.h"
#include "message.h"
#include "util.h"
#include "FileEntry.h"
#include "MultiFileAllocationIterator.h"
#include "DefaultDiskWriterFactory.h"
#include "DlAbortEx.h"
#include "File.h"
#include "fmt.h"
#include "Logger.h"
#include "LogFactory.h"
#include "SimpleRandomizer.h"
#include "WrDiskCacheEntry.h"

namespace aria2 {

DiskWriterEntry::DiskWriterEntry(const std::shared_ptr<FileEntry>& fileEntry)
  : fileEntry_{fileEntry},
    open_{false},
    needsFileAllocation_{false},
    needsDiskWriter_{false}
{}

const std::string& DiskWriterEntry::getFilePath() const
{
  return fileEntry_->getPath();
}

void DiskWriterEntry::initAndOpenFile()
{
  if(diskWriter_) {
    diskWriter_->initAndOpenFile(fileEntry_->getLength());
    open_ = true;
  }
}

void DiskWriterEntry::openFile()
{
  if(diskWriter_) {
    diskWriter_->openFile(fileEntry_->getLength());
    open_ = true;
  }
}

void DiskWriterEntry::openExistingFile()
{
  if(diskWriter_) {
    diskWriter_->openExistingFile(fileEntry_->getLength());
    open_ = true;
  }
}

void DiskWriterEntry::closeFile()
{
  if(open_) {
    diskWriter_->closeFile();
    open_ = false;
  }
}

bool DiskWriterEntry::fileExists()
{
  return fileEntry_->exists();
}

int64_t DiskWriterEntry::size() const
{
  return File(getFilePath()).size();
}

void DiskWriterEntry::setDiskWriter(std::unique_ptr<DiskWriter> diskWriter)
{
  diskWriter_ = std::move(diskWriter);
}

bool DiskWriterEntry::operator<(const DiskWriterEntry& entry) const
{
  return *fileEntry_ < *entry.fileEntry_;
}

MultiDiskAdaptor::MultiDiskAdaptor()
  : pieceLength_{0},
    maxOpenFiles_{DEFAULT_MAX_OPEN_FILES},
    readOnly_{false}
{}

MultiDiskAdaptor::~MultiDiskAdaptor() {}

namespace {
std::unique_ptr<DiskWriterEntry> createDiskWriterEntry
(const std::shared_ptr<FileEntry>& fileEntry)
{
  auto entry = make_unique<DiskWriterEntry>(fileEntry);
  entry->needsFileAllocation(fileEntry->isRequested());
  return entry;
}
} // namespace

void MultiDiskAdaptor::resetDiskWriterEntries()
{
  diskWriterEntries_.clear();
  if(getFileEntries().empty()) {
    return;
  }
  for(auto& fileEntry: getFileEntries()) {
    diskWriterEntries_.push_back(createDiskWriterEntry(fileEntry));
  }
  // TODO Currently, pieceLength_ == 0 is used for unit testing only.
  if(pieceLength_ > 0) {
    // Check shared piece forward
    int64_t lastOffset = 0;
    for(auto& dwent : diskWriterEntries_) {
      auto& fileEntry = dwent->getFileEntry();
      if(fileEntry->isRequested()) {
        // zero length file does not affect lastOffset.
        if(fileEntry->getLength() > 0) {
          lastOffset = (fileEntry->getLastOffset()-1)/pieceLength_
            * pieceLength_ + pieceLength_;
        }
      } else if(fileEntry->getOffset() < lastOffset) {
        // The files which shares last piece are not needed to be
        // allocated. They just requre DiskWriter
        A2_LOG_DEBUG(fmt("%s needs DiskWriter",
                         fileEntry->getPath().c_str()));
        dwent->needsDiskWriter(true);
      }
    }
    // Check shared piece backword
    lastOffset = std::numeric_limits<int64_t>::max();
    for(auto i = diskWriterEntries_.rbegin(), eoi = diskWriterEntries_.rend();
        i != eoi; ++i) {
      auto& fileEntry = (*i)->getFileEntry();
      if(fileEntry->isRequested()) {
        lastOffset = fileEntry->getOffset()/pieceLength_*pieceLength_;
      } else if(lastOffset <= fileEntry->getOffset() || // length == 0 case
                lastOffset < fileEntry->getLastOffset()) {
        // We needs last part of the file, so file allocation is
        // required, especially for file system which does not support
        // sparse files.
        A2_LOG_DEBUG(fmt("%s needs file allocation",
                         fileEntry->getPath().c_str()));
        (*i)->needsFileAllocation(true);
      }
    }
  }
  DefaultDiskWriterFactory dwFactory;
  for(auto& dwent : diskWriterEntries_) {
    if(dwent->needsFileAllocation() ||
       dwent->needsDiskWriter() ||
       dwent->fileExists()) {
      A2_LOG_DEBUG(fmt("Creating DiskWriter for filename=%s",
                       dwent->getFilePath().c_str()));
      dwent->setDiskWriter(dwFactory.newDiskWriter(dwent->getFilePath()));
      if(readOnly_) {
        dwent->getDiskWriter()->enableReadOnly();
      }
      // TODO mmap is not enabled at this moment. Call enableMmap()
      // after this function call.
    }
  }
}

void MultiDiskAdaptor::openIfNot
(DiskWriterEntry* entry, void (DiskWriterEntry::*open)())
{
  if(!entry->isOpen()) {
    //     A2_LOG_DEBUG(fmt("DiskWriterEntry: Cache MISS. offset=%s",
    //            util::itos(entry->getFileEntry()->getOffset()).c_str()));
    int numOpened = openedDiskWriterEntries_.size();
    (entry->*open)();
    if(numOpened >= maxOpenFiles_) {
      // Cache is full.
      // Choose one DiskWriterEntry randomly and close it.
      size_t index =
        SimpleRandomizer::getInstance()->getRandomNumber(numOpened);
      auto i = std::begin(openedDiskWriterEntries_);
      std::advance(i, index);
      (*i)->closeFile();
      *i = entry;
    } else {
      openedDiskWriterEntries_.push_back(entry);
    }
  } else {
    //     A2_LOG_DEBUG(fmt("DiskWriterEntry: Cache HIT. offset=%s",
    //            util::itos(entry->getFileEntry()->getOffset()).c_str()));
  }
}

void MultiDiskAdaptor::openFile()
{
  resetDiskWriterEntries();
  // util::mkdir() is called in AbstractDiskWriter::createFile(), so
  // we don't need to call it here.

  // Call DiskWriterEntry::openFile to make sure that zero-length files are
  // created.
  for(auto& dwent : diskWriterEntries_) {
    openIfNot(dwent.get(), &DiskWriterEntry::openFile);
  }
}

void MultiDiskAdaptor::initAndOpenFile()
{
  resetDiskWriterEntries();
  // util::mkdir() is called in AbstractDiskWriter::createFile(), so
  // we don't need to call it here.

  // Call DiskWriterEntry::initAndOpenFile to make files truncated.
  for(auto& dwent : diskWriterEntries_) {
    openIfNot(dwent.get(), &DiskWriterEntry::initAndOpenFile);
  }
}

void MultiDiskAdaptor::openExistingFile()
{
  resetDiskWriterEntries();
  // Not need to call openIfNot here.
}

void MultiDiskAdaptor::closeFile()
{
  openedDiskWriterEntries_.clear();
  for(auto& dwent : diskWriterEntries_) {
    dwent->closeFile();
  }
}

namespace {
bool isInRange(DiskWriterEntry* entry, int64_t offset)
{
  return entry->getFileEntry()->getOffset() <= offset &&
    offset < entry->getFileEntry()->getLastOffset();
}
} // namespace

namespace {
ssize_t calculateLength(DiskWriterEntry* entry,
                        int64_t fileOffset, ssize_t rem)
{
  if(entry->getFileEntry()->getLength() < fileOffset+rem) {
    return entry->getFileEntry()->getLength()-fileOffset;
  } else {
    return rem;
  }
}
} // namespace

namespace {
class OffsetCompare {
public:
  bool operator()(int64_t offset, const std::unique_ptr<DiskWriterEntry>& dwe)
  {
    return offset < dwe->getFileEntry()->getOffset();
  }
};
} // namespace

namespace {
DiskWriterEntries::const_iterator findFirstDiskWriterEntry
(const DiskWriterEntries& diskWriterEntries, int64_t offset)
{
  auto first = std::upper_bound(std::begin(diskWriterEntries),
                                std::end(diskWriterEntries),
                                offset, OffsetCompare());
  --first;
  // In case when offset is out-of-range
  if(!isInRange((*first).get(), offset)) {
    throw DL_ABORT_EX
      (fmt(EX_FILE_OFFSET_OUT_OF_RANGE, static_cast<int64_t>(offset)));
  }
  return first;
}
} // namespace

namespace {
void throwOnDiskWriterNotOpened(DiskWriterEntry* e, int64_t offset)
{
  throw DL_ABORT_EX
    (fmt("DiskWriter for offset=%" PRId64 ", filename=%s is not opened.",
         static_cast<int64_t>(offset),
         e->getFilePath().c_str()));
}
} // namespace

void MultiDiskAdaptor::writeData(const unsigned char* data, size_t len,
                                 int64_t offset)
{
  auto first = findFirstDiskWriterEntry(diskWriterEntries_, offset);
  ssize_t rem = len;
  int64_t fileOffset = offset-(*first)->getFileEntry()->getOffset();
  for(auto i = first, eoi = diskWriterEntries_.cend(); i != eoi; ++i) {
    ssize_t writeLength = calculateLength((*i).get(), fileOffset, rem);
    openIfNot((*i).get(), &DiskWriterEntry::openFile);
    if(!(*i)->isOpen()) {
      throwOnDiskWriterNotOpened((*i).get(), offset+(len-rem));
    }

    (*i)->getDiskWriter()->writeData(data+(len-rem), writeLength, fileOffset);
    rem -= writeLength;
    fileOffset = 0;
    if(rem == 0) {
      break;
    }
  }
}

ssize_t MultiDiskAdaptor::readData
(unsigned char* data, size_t len, int64_t offset)
{
  auto first = findFirstDiskWriterEntry(diskWriterEntries_, offset);
  ssize_t rem = len;
  ssize_t totalReadLength = 0;
  int64_t fileOffset = offset-(*first)->getFileEntry()->getOffset();
  for(auto i = first, eoi = diskWriterEntries_.cend(); i != eoi; ++i) {
    ssize_t readLength = calculateLength((*i).get(), fileOffset, rem);
    openIfNot((*i).get(), &DiskWriterEntry::openFile);
    if(!(*i)->isOpen()) {
      throwOnDiskWriterNotOpened((*i).get(), offset+(len-rem));
    }
    totalReadLength +=
      (*i)->getDiskWriter()->readData(data+(len-rem), readLength, fileOffset);
    rem -= readLength;
    fileOffset = 0;
    if(rem == 0) {
      break;
    }
  }
  return totalReadLength;
}

void MultiDiskAdaptor::writeCache(const WrDiskCacheEntry* entry)
{
  // Write cached data in 4KiB aligned offset. This reduces disk
  // activity especially on Windows 7 NTFS.
  unsigned char buf[16*1024];
  size_t buflen = 0;
  size_t buffoffset = 0;
  auto& dataSet = entry->getDataSet();
  if(dataSet.empty()) {
    return;
  }
  auto dent =
    findFirstDiskWriterEntry(diskWriterEntries_, (*dataSet.begin())->goff),
    eod = diskWriterEntries_.cend();
  auto i = std::begin(dataSet), eoi = std::end(dataSet);
  size_t celloff = 0;
  for(; dent != eod; ++dent) {
    int64_t lstart = 0, lp = 0;
    auto& fent = (*dent)->getFileEntry();
    for(; i != eoi;) {
      if(std::max(fent->getOffset(),
                  static_cast<int64_t>((*i)->goff + celloff)) <
         std::min(fent->getLastOffset(),
                  static_cast<int64_t>((*i)->goff + (*i)->len))) {
        openIfNot((*dent).get(), &DiskWriterEntry::openFile);
        if(!(*dent)->isOpen()) {
          throwOnDiskWriterNotOpened((*dent).get(), (*i)->goff + celloff);
        }
      } else {
        A2_LOG_DEBUG(fmt("%s Cache flush loff=%" PRId64 ", len=%lu",
                         fent->getPath().c_str(),
                         lstart,
                         static_cast<unsigned long>(buflen-buffoffset)));
        (*dent)->getDiskWriter()->
          writeData(buf + buffoffset, buflen - buffoffset, lstart);
        buflen = buffoffset = 0;
        break;
      }
      int64_t loff = fent->gtoloff((*i)->goff + celloff);
      if(static_cast<int64_t>(lstart + buflen) < loff) {
        A2_LOG_DEBUG(fmt("%s Cache flush loff=%" PRId64 ", len=%lu",
                         fent->getPath().c_str(),
                         lstart,
                         static_cast<unsigned long>(buflen-buffoffset)));
        (*dent)->getDiskWriter()->
          writeData(buf + buffoffset, buflen - buffoffset, lstart);
        lstart = lp = loff;
        buflen = buffoffset = 0;
      }
      // If the position of the cache data is not aligned, offset
      // buffer so that next write can be aligned.
      if(buflen == 0) {
        buflen = buffoffset = loff & 0xfff;
      }
      assert((*i)->len > celloff);
      for(;;) {
        size_t wlen = std::min(static_cast<int64_t>((*i)->len - celloff),
                               fent->getLength() - lp);
        wlen = std::min(wlen, sizeof(buf) - buflen);
        memcpy(buf + buflen, (*i)->data + (*i)->offset + celloff, wlen);
        buflen += wlen;
        celloff += wlen;
        lp += wlen;
        if(lp == fent->getLength() || buflen == sizeof(buf)) {
          A2_LOG_DEBUG(fmt("%s Cache flush loff=%" PRId64 ", len=%lu",
                           fent->getPath().c_str(),
                           lstart,
                           static_cast<unsigned long>(buflen-buffoffset)));
          (*dent)->getDiskWriter()->
            writeData(buf + buffoffset, buflen - buffoffset, lstart);
          lstart += buflen - buffoffset;
          lp = lstart;
          buflen = buffoffset = 0;
        }
        if(lp == fent->getLength() || celloff == (*i)->len) {
          break;
        }
      }
      if(celloff == (*i)->len) {
        ++i;
        celloff = 0;
      }
    }
    if(i == eoi) {
      A2_LOG_DEBUG(fmt("%s Cache flush loff=%" PRId64 ", len=%lu",
                       fent->getPath().c_str(),
                       lstart,
                       static_cast<unsigned long>(buflen - buffoffset)));
      (*dent)->getDiskWriter()->
        writeData(buf + buffoffset, buflen - buffoffset, lstart);
      break;
    }
  }
  assert(i == eoi);
}

bool MultiDiskAdaptor::fileExists()
{
  return std::find_if(std::begin(getFileEntries()),
                      std::end(getFileEntries()),
                      std::mem_fn(&FileEntry::exists)) !=
    std::end(getFileEntries());
}

int64_t MultiDiskAdaptor::size()
{
  int64_t size = 0;
  for(auto& fe : getFileEntries()) {
    size += File(fe->getPath()).size();
  }
  return size;
}

std::unique_ptr<FileAllocationIterator>
MultiDiskAdaptor::fileAllocationIterator()
{
  return make_unique<MultiFileAllocationIterator>(this);
}

void MultiDiskAdaptor::enableReadOnly()
{
  readOnly_ = true;
}

void MultiDiskAdaptor::disableReadOnly()
{
  readOnly_ = false;
}

void MultiDiskAdaptor::enableMmap()
{
  for(auto& dwent : diskWriterEntries_) {
    auto& dw = dwent->getDiskWriter();
    if(dw) {
      dw->enableMmap();
    }
  }
}

void MultiDiskAdaptor::cutTrailingGarbage()
{
  for(auto& dwent : diskWriterEntries_) {
    int64_t length = dwent->getFileEntry()->getLength();
    if(File(dwent->getFilePath()).size() > length) {
      // We need open file before calling DiskWriter::truncate(int64_t)
      openIfNot(dwent.get(), &DiskWriterEntry::openFile);
      dwent->getDiskWriter()->truncate(length);
    }
  }
}

void MultiDiskAdaptor::setMaxOpenFiles(int maxOpenFiles)
{
  maxOpenFiles_ = maxOpenFiles;
}

size_t MultiDiskAdaptor::utime(const Time& actime, const Time& modtime)
{
  size_t numOK = 0;
  for(auto& fe : getFileEntries()) {
    if(fe->isRequested()) {
      File f{fe->getPath()};
      if(f.isFile() && f.utime(actime, modtime)) {
        ++numOK;
      }
    }
  }
  return numOK;
}

} // namespace aria2