/* <!-- 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 "SegmentMan.h"

#include <cassert>
#include <algorithm>
#include <numeric>

#include "util.h"
#include "message.h"
#include "prefs.h"
#include "PiecedSegment.h"
#include "GrowSegment.h"
#include "LogFactory.h"
#include "Logger.h"
#include "PieceStorage.h"
#include "PeerStat.h"
#include "Option.h"
#include "DownloadContext.h"
#include "Piece.h"
#include "FileEntry.h"
#include "wallclock.h"
#include "fmt.h"
#include "WrDiskCacheEntry.h"
#include "DownloadFailureException.h"

namespace aria2 {

SegmentEntry::SegmentEntry(cuid_t cuid, const std::shared_ptr<Segment>& segment)
    : cuid(cuid), segment(segment)
{
}

SegmentEntry::~SegmentEntry() = default;

SegmentMan::SegmentMan(const std::shared_ptr<DownloadContext>& downloadContext,
                       const std::shared_ptr<PieceStorage>& pieceStorage)
    : downloadContext_(downloadContext),
      pieceStorage_(pieceStorage),
      ignoreBitfield_(downloadContext->getPieceLength(),
                      downloadContext->getTotalLength())
{
  ignoreBitfield_.enableFilter();
}

SegmentMan::~SegmentMan() = default;

bool SegmentMan::downloadFinished() const
{
  if (!pieceStorage_) {
    return false;
  }
  else {
    return pieceStorage_->downloadFinished();
  }
}

void SegmentMan::init()
{
  // TODO Do we have to do something about DownloadContext and
  // PieceStorage here?
}

int64_t SegmentMan::getTotalLength() const
{
  if (!pieceStorage_) {
    return 0;
  }
  else {
    return pieceStorage_->getTotalLength();
  }
}

void SegmentMan::setPieceStorage(
    const std::shared_ptr<PieceStorage>& pieceStorage)
{
  pieceStorage_ = pieceStorage;
}

void SegmentMan::setDownloadContext(
    const std::shared_ptr<DownloadContext>& downloadContext)
{
  downloadContext_ = downloadContext;
}

namespace {
void flushWrDiskCache(WrDiskCache* wrDiskCache,
                      const std::shared_ptr<Piece>& piece)
{
  piece->flushWrCache(wrDiskCache);
  if (piece->getWrDiskCacheEntry()->getError() !=
      WrDiskCacheEntry::CACHE_ERR_SUCCESS) {
    piece->clearAllBlock(wrDiskCache);
    throw DOWNLOAD_FAILURE_EXCEPTION2(
        fmt("Write disk cache flush failure index=%lu",
            static_cast<unsigned long>(piece->getIndex())),
        piece->getWrDiskCacheEntry()->getErrorCode());
  }
}
} // namespace

std::shared_ptr<Segment>
SegmentMan::checkoutSegment(cuid_t cuid, const std::shared_ptr<Piece>& piece)
{
  if (!piece) {
    return nullptr;
  }
  A2_LOG_DEBUG(fmt("Attach segment#%lu to CUID#%" PRId64 ".",
                   static_cast<unsigned long>(piece->getIndex()), cuid));

  if (piece->getWrDiskCacheEntry()) {
    // Flush cached data here, because the cached data may be overlapped
    // if BT peers are involved.
    A2_LOG_DEBUG(fmt(
        "Flushing cached data, size=%lu",
        static_cast<unsigned long>(piece->getWrDiskCacheEntry()->getSize())));
    flushWrDiskCache(pieceStorage_->getWrDiskCache(), piece);
  }

  piece->setUsedBySegment(true);
  std::shared_ptr<Segment> segment;
  if (piece->getLength() == 0) {
    segment = std::make_shared<GrowSegment>(piece);
  }
  else {
    segment = std::make_shared<PiecedSegment>(
        downloadContext_->getPieceLength(), piece);
  }
  auto entry = std::make_shared<SegmentEntry>(cuid, segment);
  usedSegmentEntries_.push_back(entry);
  A2_LOG_DEBUG(fmt("index=%lu, length=%" PRId64 ", segmentLength=%" PRId64 ","
                   " writtenLength=%" PRId64,
                   static_cast<unsigned long>(segment->getIndex()),
                   segment->getLength(), segment->getSegmentLength(),
                   segment->getWrittenLength()));

  if (piece->getLength() > 0) {
    auto positr = segmentWrittenLengthMemo_.find(segment->getIndex());
    if (positr != segmentWrittenLengthMemo_.end()) {
      const auto writtenLength = (*positr).second;
      A2_LOG_DEBUG(fmt("writtenLength(in memo)=%" PRId64
                       ", writtenLength=%" PRId64,
                       writtenLength, segment->getWrittenLength()));
      //  If the difference between cached writtenLength and segment's
      //  writtenLength is less than one block, we assume that these
      //  missing bytes are already downloaded.
      if (segment->getWrittenLength() < writtenLength &&
          writtenLength - segment->getWrittenLength() <
              piece->getBlockLength()) {
        segment->updateWrittenLength(writtenLength -
                                     segment->getWrittenLength());
      }
    }
  }
  return segment;
}

void SegmentMan::getInFlightSegment(
    std::vector<std::shared_ptr<Segment>>& segments, cuid_t cuid)
{
  for (SegmentEntries::const_iterator itr = usedSegmentEntries_.begin(),
                                      eoi = usedSegmentEntries_.end();
       itr != eoi; ++itr) {
    const std::shared_ptr<SegmentEntry>& segmentEntry = *itr;
    if (segmentEntry->cuid == cuid) {
      segments.push_back(segmentEntry->segment);
    }
  }
}

std::shared_ptr<Segment> SegmentMan::getSegment(cuid_t cuid,
                                                size_t minSplitSize)
{
  std::shared_ptr<Piece> piece = pieceStorage_->getMissingPiece(
      minSplitSize, ignoreBitfield_.getFilterBitfield(),
      ignoreBitfield_.getBitfieldLength(), cuid);
  return checkoutSegment(cuid, piece);
}

void SegmentMan::getSegment(std::vector<std::shared_ptr<Segment>>& segments,
                            cuid_t cuid, size_t minSplitSize,
                            const std::shared_ptr<FileEntry>& fileEntry,
                            size_t maxSegments)
{
  BitfieldMan filter(ignoreBitfield_);
  filter.enableFilter();
  filter.addNotFilter(fileEntry->getOffset(), fileEntry->getLength());
  std::vector<std::shared_ptr<Segment>> pending;
  while (segments.size() < maxSegments) {
    std::shared_ptr<Segment> segment = checkoutSegment(
        cuid,
        pieceStorage_->getMissingPiece(minSplitSize, filter.getFilterBitfield(),
                                       filter.getBitfieldLength(), cuid));
    if (!segment) {
      break;
    }
    if (segment->getPositionToWrite() < fileEntry->getOffset() ||
        fileEntry->getLastOffset() <= segment->getPositionToWrite()) {
      pending.push_back(segment);
    }
    else {
      segments.push_back(segment);
    }
  }
  for (std::vector<std::shared_ptr<Segment>>::const_iterator
           i = pending.begin(),
           eoi = pending.end();
       i != eoi; ++i) {
    cancelSegment(cuid, *i);
  }
}

std::shared_ptr<Segment> SegmentMan::getSegmentWithIndex(cuid_t cuid,
                                                         size_t index)
{
  if (index > 0 && downloadContext_->getNumPieces() <= index) {
    return nullptr;
  }
  return checkoutSegment(cuid, pieceStorage_->getMissingPiece(index, cuid));
}

std::shared_ptr<Segment> SegmentMan::getCleanSegmentIfOwnerIsIdle(cuid_t cuid,
                                                                  size_t index)
{
  if (index > 0 && downloadContext_->getNumPieces() <= index) {
    return nullptr;
  }
  for (SegmentEntries::const_iterator itr = usedSegmentEntries_.begin(),
                                      eoi = usedSegmentEntries_.end();
       itr != eoi; ++itr) {
    const std::shared_ptr<SegmentEntry>& segmentEntry = *itr;
    if (segmentEntry->segment->getIndex() == index) {
      if (segmentEntry->segment->getWrittenLength() > 0) {
        return nullptr;
      }
      if (segmentEntry->cuid == cuid) {
        return segmentEntry->segment;
      }
      cuid_t owner = segmentEntry->cuid;
      std::shared_ptr<PeerStat> ps = getPeerStat(owner);
      if (!ps || ps->getStatus() == NetStat::IDLE) {
        cancelSegment(owner);
        return getSegmentWithIndex(cuid, index);
      }
      else {
        return nullptr;
      }
    }
  }
  return nullptr;
}

void SegmentMan::cancelSegmentInternal(cuid_t cuid,
                                       const std::shared_ptr<Segment>& segment)
{
  A2_LOG_DEBUG(fmt("Canceling segment#%lu",
                   static_cast<unsigned long>(segment->getIndex())));
  const std::shared_ptr<Piece>& piece = segment->getPiece();
  // TODO In PieceStorage::cancelPiece(), WrDiskCacheEntry may be
  // released. Flush first.
  if (piece->getWrDiskCacheEntry()) {
    // Flush cached data here, because the cached data may be overlapped
    // if BT peers are involved.
    A2_LOG_DEBUG(fmt(
        "Flushing cached data, size=%lu",
        static_cast<unsigned long>(piece->getWrDiskCacheEntry()->getSize())));
    flushWrDiskCache(pieceStorage_->getWrDiskCache(), piece);
    // TODO Exception may cause some segments (pieces) are not
    // canceled.
  }
  piece->setUsedBySegment(false);
  pieceStorage_->cancelPiece(piece, cuid);
  segmentWrittenLengthMemo_[segment->getIndex()] = segment->getWrittenLength();
  A2_LOG_DEBUG(fmt("Memorized segment index=%lu, writtenLength=%" PRId64,
                   static_cast<unsigned long>(segment->getIndex()),
                   segment->getWrittenLength()));
}

void SegmentMan::cancelSegment(cuid_t cuid)
{
  for (auto itr = usedSegmentEntries_.begin(), eoi = usedSegmentEntries_.end();
       itr != eoi;) {
    if ((*itr)->cuid == cuid) {
      cancelSegmentInternal(cuid, (*itr)->segment);
      itr = usedSegmentEntries_.erase(itr);
      eoi = usedSegmentEntries_.end();
    }
    else {
      ++itr;
    }
  }
}

void SegmentMan::cancelSegment(cuid_t cuid,
                               const std::shared_ptr<Segment>& segment)
{
  for (auto itr = usedSegmentEntries_.begin(), eoi = usedSegmentEntries_.end();
       itr != eoi;) {
    if ((*itr)->cuid == cuid && *(*itr)->segment == *segment) {
      cancelSegmentInternal(cuid, (*itr)->segment);
      itr = usedSegmentEntries_.erase(itr);
      break;
    }
    else {
      ++itr;
    }
  }
}

void SegmentMan::cancelAllSegments()
{
  for (auto& e : usedSegmentEntries_) {
    cancelSegmentInternal(e->cuid, e->segment);
  }
  usedSegmentEntries_.clear();
}

void SegmentMan::eraseSegmentWrittenLengthMemo()
{
  segmentWrittenLengthMemo_.clear();
}

namespace {
class FindSegmentEntry {
private:
  std::shared_ptr<Segment> segment_;

public:
  FindSegmentEntry(std::shared_ptr<Segment> segment)
      : segment_(std::move(segment))
  {
  }

  bool operator()(const std::shared_ptr<SegmentEntry>& segmentEntry) const
  {
    return segmentEntry->segment->getIndex() == segment_->getIndex();
  }
};
} // namespace

bool SegmentMan::completeSegment(cuid_t cuid,
                                 const std::shared_ptr<Segment>& segment)
{
  pieceStorage_->completePiece(segment->getPiece());
  pieceStorage_->advertisePiece(cuid, segment->getPiece()->getIndex(),
                                global::wallclock());
  auto itr = std::find_if(usedSegmentEntries_.begin(),
                          usedSegmentEntries_.end(), FindSegmentEntry(segment));
  if (itr == usedSegmentEntries_.end()) {
    return false;
  }
  else {
    usedSegmentEntries_.erase(itr);
    return true;
  }
}

bool SegmentMan::hasSegment(size_t index) const
{
  return pieceStorage_->hasPiece(index);
}

int64_t SegmentMan::getDownloadLength() const
{
  if (!pieceStorage_) {
    return 0;
  }
  else {
    return pieceStorage_->getCompletedLength();
  }
}

void SegmentMan::registerPeerStat(const std::shared_ptr<PeerStat>& peerStat)
{
  peerStats_.push_back(peerStat);
}

std::shared_ptr<PeerStat> SegmentMan::getPeerStat(cuid_t cuid) const
{
  for (auto& e : peerStats_) {
    if (e->getCuid() == cuid) {
      return e;
    }
  }
  return nullptr;
}

namespace {
class PeerStatHostProtoEqual {
private:
  const std::shared_ptr<PeerStat>& peerStat_;

public:
  PeerStatHostProtoEqual(const std::shared_ptr<PeerStat>& peerStat)
      : peerStat_(peerStat)
  {
  }

  bool operator()(const std::shared_ptr<PeerStat>& p) const
  {
    return peerStat_->getHostname() == p->getHostname() &&
           peerStat_->getProtocol() == p->getProtocol();
  }
};
} // namespace

void SegmentMan::updateFastestPeerStat(
    const std::shared_ptr<PeerStat>& peerStat)
{
  auto i = std::find_if(fastestPeerStats_.begin(), fastestPeerStats_.end(),
                        PeerStatHostProtoEqual(peerStat));
  if (i == fastestPeerStats_.end()) {
    fastestPeerStats_.push_back(peerStat);
  }
  else if ((*i)->getAvgDownloadSpeed() < peerStat->getAvgDownloadSpeed()) {
    // *i's SessionDownloadLength must be added to peerStat
    peerStat->addSessionDownloadLength((*i)->getSessionDownloadLength());
    *i = peerStat;
  }
  else {
    // peerStat's SessionDownloadLength must be added to *i
    (*i)->addSessionDownloadLength(peerStat->getSessionDownloadLength());
  }
}

size_t SegmentMan::countFreePieceFrom(size_t index) const
{
  size_t numPieces = downloadContext_->getNumPieces();
  for (size_t i = index; i < numPieces; ++i) {
    if (pieceStorage_->hasPiece(i) || pieceStorage_->isPieceUsed(i)) {
      return i - index;
    }
  }
  return downloadContext_->getNumPieces() - index;
}

void SegmentMan::ignoreSegmentFor(const std::shared_ptr<FileEntry>& fileEntry)
{
  A2_LOG_DEBUG(fmt("ignoring segment for path=%s, offset=%" PRId64
                   ", length=%" PRId64 "",
                   fileEntry->getPath().c_str(), fileEntry->getOffset(),
                   fileEntry->getLength()));
  ignoreBitfield_.addFilter(fileEntry->getOffset(), fileEntry->getLength());
}

void SegmentMan::recognizeSegmentFor(
    const std::shared_ptr<FileEntry>& fileEntry)
{
  ignoreBitfield_.removeFilter(fileEntry->getOffset(), fileEntry->getLength());
}

bool SegmentMan::allSegmentsIgnored() const
{
  return ignoreBitfield_.isAllFilterBitSet();
}

} // namespace aria2