/**
 *  @file  maildir.cc
 *  @brief Implementation of the Maildir class.
 *  @author Andreas Aardal Hanssen
 *  @date 2002-2005
 */

#include "maildir.h"

#include "convert.h"
#include "globals.h"
#include "iodevice.h"
#include "iofactory.h"
#include "maildirmessage.h"
#include "pendingupdates.h"
#include "session.h"
#include "status.h"

#include <algorithm>
#include <iomanip>
#include <iostream>

#include <ctype.h>
#include <errno.h>
#include <stdio.h>

#include <dirent.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

using namespace Binc;
using std::endl;
using std::map;
using std::string;

// Used to generate the unique names for Maildir delivery
static int numDeliveries = 0;

Maildir::iterator::iterator(void) {}

Maildir::iterator::iterator(Maildir *home,
                            MessageMap::iterator it,
                            const SequenceSet &_bset,
                            unsigned int _mod)
  : BaseIterator(1)
  , mailbox(home)
  , bset(_bset)
  , mod(_mod)
  , i(it)
{
  uidmax = home->getMaxUid();
  sqnrmax = home->getMaxSqnr();
}

Maildir::iterator::iterator(const iterator &copy)
  : BaseIterator(copy.sqnr)
  , mailbox(copy.mailbox)
  , bset(copy.bset)
  , mod(copy.mod)
  , i(copy.i)
  , uidmax(copy.uidmax)
  , sqnrmax(copy.sqnrmax)
{}

Maildir::iterator &Maildir::iterator::operator=(const iterator &copy)
{
  sqnr = copy.sqnr;
  mailbox = copy.mailbox;
  bset = copy.bset;
  mod = copy.mod;
  i = copy.i;
  uidmax = copy.uidmax;
  sqnrmax = copy.sqnrmax;
  return *this;
}

Maildir::iterator::~iterator(void) {}

MaildirMessage &Maildir::iterator::curMessage(void)
{
  return i->second;
}

Message &Maildir::iterator::operator*(void)
{
  return curMessage();
}

void Maildir::iterator::operator++(void)
{
  ++i;
  ++sqnr;
  reposition();
}

bool Maildir::iterator::operator==(const BaseIterator &a) const
{
  const iterator *b = dynamic_cast<const iterator *>(&a);
  return b ? (i == b->i) : false;
}

bool Maildir::iterator::operator!=(const BaseIterator &a) const
{
  return !((*this) == a);
}

void Maildir::iterator::reposition(void)
{
  for (;;) {
    if (i == mailbox->messages.end()) break;

    Message &message = curMessage();
    if ((mod & SKIP_EXPUNGED) && message.isExpunged()) {
      ++i;
      continue;
    }

    bool inset = false;
    if (mod & SQNR_MODE) {
      if (bset.isInSet(sqnr) || (!bset.isLimited() && sqnr == sqnrmax)) inset = true;
    } else {
      if (bset.isInSet(message.getUID()) || (!bset.isLimited() && message.getUID() == uidmax))
        inset = true;
    }

    if (!inset) {
      ++i;
      if (!message.isExpunged()) ++sqnr;
      continue;
    }

    break;
  }
}

Mailbox::iterator Maildir::begin(const SequenceSet &bset, unsigned int mod) const
{
  beginIterator = iterator(const_cast<Maildir *>(this), messages.begin(), bset, mod);
  beginIterator.reposition();

  return Mailbox::iterator(beginIterator);
}

Mailbox::iterator Maildir::end(void) const
{
  endIterator = iterator(const_cast<Maildir *>(this), messages.end(), endIterator.bset, endIterator.mod);
  return Mailbox::iterator(endIterator);
}

void Maildir::iterator::erase(void)
{
  MessageMap::iterator iter = i;
  ++iter;

  MaildirMessageCache::getInstance().removeStatus(&curMessage());
  mailbox->index.remove(i->second.getUnique());
  mailbox->messages.erase(i);

  i = iter;
  reposition();
}

Maildir::Maildir(void) : Mailbox()
{
  firstscan = true;
  cacheRead = false;
  uidvalidity = 0;
  uidnext = 1;
  selected = false;
  oldrecent = 0;
  oldexists = 0;
}

Maildir::~Maildir(void) {}

void Maildir::setPath(const string &path_in)
{
  path = path_in;
}

bool Maildir::getUpdates(bool doscan, unsigned int type, PendingUpdates &updates, bool forceScan)
{
  if (doscan && scan(forceScan) != Success) return false;

  unsigned int exists = 0;
  unsigned int recent = 0;
  bool displayExists = false;

  // count messages, find recent
  if (!readOnly && (type & PendingUpdates::EXPUNGE)) {
    Mailbox::iterator i = begin(SequenceSet::all(), INCLUDE_EXPUNGED | SQNR_MODE);

    while (i != end()) {
      Message &message = *i;

      if (message.isExpunged()) {
        updates.addExpunged(i.getSqnr());
        i.erase();
        mailboxchanged = true;
        displayExists = true;
      } else {
        ++i;
      }
    }
  }

  Mailbox::iterator i = begin(SequenceSet::all(), INCLUDE_EXPUNGED | SQNR_MODE);
  for (; i != end(); ++i) {
    Message &message = *i;
    // at this point, there is a message that is not expunged
    ++exists;
    if (message.getStdFlags() & Message::F_RECENT) ++recent;
  }

  if (displayExists || exists != oldexists) updates.setExists(oldexists = exists);

  if (recent != oldrecent) updates.setRecent(oldrecent = recent);

  if (type & PendingUpdates::FLAGS) {
    Mailbox::iterator i = begin(SequenceSet::all(), SQNR_MODE);
    for (; i != end(); ++i) {
      Message &message = *i;
      if (message.hasFlagsChanged()) {
        int flags = message.getStdFlags();

        updates.addFlagUpdates(i.getSqnr(), message.getUID(), flags, message.getCustomFlags());

        message.setFlagsUnchanged();
      }
    }
  }

  return true;
}

bool Maildir::isMailbox(const std::string &s_in) const
{
  struct stat mystat;

  return ((stat((s_in + "/cur").c_str(), &mystat) == 0 && S_ISDIR(mystat.st_mode))
          && (stat((s_in + "/new").c_str(), &mystat) == 0 && S_ISDIR(mystat.st_mode))
          && (stat((s_in + "/tmp").c_str(), &mystat) == 0 && S_ISDIR(mystat.st_mode)));
}

const std::string Maildir::getTypeName(void) const
{
  return "Maildir";
}

void Maildir::bumpUidValidity(const string &s_in) const
{
  unlink((s_in + "/bincimap-uidvalidity").c_str());
  unlink((s_in + "/bincimap-cache").c_str());
}

bool Maildir::isMarked(const std::string &s_in) const
{
  DIR *dirp = opendir((s_in + "/new").c_str());
  if (dirp == nullptr) return false;

  struct dirent *direntp;
  while ((direntp = readdir(dirp)) != nullptr) {
    string s = direntp->d_name;
    if (s[0] != '.' && s.find('/') == string::npos && s.find(':') == string::npos) {
      closedir(dirp);
      return true;
    }
  }

  closedir(dirp);
  return false;
}

unsigned int Maildir::getStatusID(const string &path) const
{
  unsigned int statusid = 0;
  struct stat mystat;
  if (stat((path + "/new/").c_str(), &mystat) == 0) statusid = mystat.st_ctime;

  if (stat((path + "/cur/").c_str(), &mystat) == 0) statusid += mystat.st_ctime;

  if (stat((path + "/bincimap-cache").c_str(), &mystat) == 0) statusid += mystat.st_ctime;

  return statusid;
}

bool Maildir::getStatus(const string &path, Status &s) const
{
  unsigned int messages = 0;
  unsigned int unseen = 0;
  unsigned int recent = 0;

  unsigned int readUidValidity;
  unsigned int readUidNext = 1;
  map<string, bool> mincache;

  const string cachefilename = path + "/bincimap-cache";
  FILE *fp = fopen(cachefilename.c_str(), "r");
  if (fp) {
    do {
      char inputBuffer[512];
      if (!fgets(inputBuffer, sizeof(inputBuffer), fp)) {
        fclose(fp);
        return false;
      }

      // terminate the buffer
      inputBuffer[sizeof(inputBuffer) - 1] = '\0';

      char cacheFileVersionBuffer[512];

      if (sscanf(inputBuffer, "%s %u %u", cacheFileVersionBuffer, &readUidValidity, &readUidNext) != 3
          || strcmp(cacheFileVersionBuffer, BINC_CACHE) != 0)
      {
        fclose(fp);
        readUidValidity = 0;
        readUidNext = 1;
        mincache.clear();
        break;
      }

      unsigned int readUID;
      unsigned int readSize;
      unsigned int readInternalDate;
      char readUnique[512];
      while (fgets(inputBuffer, sizeof(inputBuffer), fp)) {
        inputBuffer[sizeof(inputBuffer) - 1] = '\0';
        if (sscanf(inputBuffer, "%u %u %u %s", &readUID, &readInternalDate, &readSize, readUnique) != 4)
        {
          fclose(fp);
          readUidValidity = 0;
          readUidNext = 1;
          mincache.clear();
          break;
        }

        mincache[readUnique] = true;
      }

      fclose(fp);

      s.setUidValidity(readUidValidity < 1 ? time(nullptr) : readUidValidity);
    } while (0);
  } else {
    s.setUidValidity(time(nullptr));
  }

  // Scan new
  DIR *dirp = opendir((path + "/new").c_str());
  if (dirp == nullptr) return false;

  struct dirent *direntp;
  while ((direntp = readdir(dirp)) != nullptr) {
    const string filename = direntp->d_name;
    if (filename[0] == '.' || filename.find(':') != string::npos || filename.find('/') != string::npos)
      continue;

    ++recent;
    ++readUidNext;
    ++unseen;
    ++messages;
  }

  closedir(dirp);

  // Scan cur
  if ((dirp = opendir((path + "/cur").c_str())) == nullptr) return false;

  while ((direntp = readdir(dirp)) != nullptr) {
    const string dname = direntp->d_name;
    if (dname[0] == '.') continue;

    ++messages;

    // Add to unseen if it doesn't have the seen flag or if it has no
    // flags.
    const string::size_type pos = dname.find(':');
    if (pos != string::npos) {
      if (mincache.find(dname.substr(0, pos)) == mincache.end()) {
        ++recent;
        ++readUidNext;
      }

      if (dname.substr(pos).find('S') == string::npos) ++unseen;
    } else {
      if (mincache.find(dname) == mincache.end()) {
        ++recent;
        ++readUidNext;
      }

      ++unseen;
    }
  }

  closedir(dirp);

  s.setRecent(recent);
  s.setMessages(messages);
  s.setUnseen(unseen);
  s.setUidNext(uidnext);

  return true;
}

unsigned int Maildir::getMaxUid(void) const
{
  MessageMap::const_iterator i = messages.end();
  if (i == messages.begin()) return 0;

  --i;
  for (;;) {
    const MaildirMessage &message = i->second;
    if (message.isExpunged()) {
      if (i == messages.begin()) return 0;
      --i;
    } else {
      return message.getUID();
    }
  }

  return 0;
}

unsigned int Maildir::getMaxSqnr(void) const
{
  int sqnr = messages.size();
  MessageMap::const_iterator i = messages.end();
  if (i == messages.begin()) return 0;

  --i;
  for (;;) {
    const MaildirMessage &message = i->second;
    if (message.isExpunged()) {
      if (i == messages.begin()) return 0;
      --sqnr;
      --i;
    } else {
      return sqnr;
    }
  }

  return 0;
}

unsigned int Maildir::getUidValidity(void) const
{
  return uidvalidity;
}

unsigned int Maildir::getUidNext(void) const
{
  return uidnext;
}

Message *Maildir::createMessage(const string &mbox, time_t idate)
{
  string sname = mbox + "/tmp/bincimap-XXXXXX";

  int fd = mkstemp(sname.data());
  if (fd == -1) {
    setLastError("Unable to create safe name.");
    return nullptr;
  }

  MaildirMessage message(*this);

  message.setFile(fd);
  message.setSafeName(sname);
  message.setInternalDate(idate);

  newMessages.push_back(message);
  return &newMessages.back();
}

bool Maildir::commitNewMessages(const string &mbox)
{
  Session &session = Session::getInstance();

  std::vector<MaildirMessage>::iterator i = newMessages.begin();
  map<MaildirMessage *, string> committedMessages;

  struct timeval youngestFile = {0, 0};

  bool abort = false;
  while (!abort && i != newMessages.end()) {
    MaildirMessage &m = *i;

    if (m.getInternalFlags() & MaildirMessage::Committed) {
      ++i;
      continue;
    }

    m.setInternalFlag(MaildirMessage::Committed);

    string safeName = m.getSafeName();

    for (int attempt = 0; !abort && attempt < 1000; ++attempt) {
      struct timeval tv;
      gettimeofday(&tv, nullptr);
      youngestFile = tv;

      // Generate Maildir conformant file name
      BincStream ssid;
      ssid << (int)tv.tv_sec << "."
           << "R" << rand() << "M" << (int)tv.tv_usec << "P" << session.getPid() << "Q"
           << numDeliveries++ << "." << session.getEnv("TCPLOCALHOST");

      BincStream ss;
      ss << mbox << "/new/" << ssid.str();

      string fileName = ss.str();

      if (link(safeName.c_str(), fileName.c_str()) == 0) {
        unlink(safeName.c_str());
        m.setInternalDate(tv.tv_sec);
        m.setUnique(ssid.str());
        m.setUID(0);
        committedMessages[&m] = fileName;
        break;
      }

      if (errno == EEXIST) continue;

      bincWarning << "link(" << toImapString(safeName) << ", " << toImapString(fileName)
                  << ") failed: " << strerror(errno) << endl;

      session.setResponseCode("TRYCREATE");
      session.setLastError("failed, internal error.");
      abort = true;
      break;
    }

    ++i;
  }

  // abort means to make an attempt to restore the mailbox to its original state.
  if (abort) {
    // Fixme: Messages that are in committedMessages should be skipped
    // here.
    for (const auto &i : newMessages)
      unlink(i.getSafeName().c_str());

    for (const auto &[_, second] : committedMessages) {
      if (unlink(second.c_str()) != 0) {
        if (errno == ENOENT) {
          // FIXME: The message was probably moves away from new/ by
          // another IMAP session.
          bincWarning << "error rollbacking after failed commit to " << toImapString(mbox)
                      << ", failed to unlink " << toImapString(second) << ": " << strerror(errno)
                      << endl;
        } else {
          bincWarning << "error rollbacking after failed commit to " << toImapString(mbox)
                      << ", failed to unlink " << toImapString(second) << ": " << strerror(errno)
                      << endl;
          newMessages.clear();
          return false;
        }
      }
    }

    newMessages.clear();
    return false;
  }

  // cover the extremely unlikely event that another concurrent
  // Maildir accessor has just made a file with the same timestamp and
  // random number by spinning until the timestamp has changed before
  // moving the message into cur.
  struct timeval tv;
  gettimeofday(&tv, nullptr);
  while (tv.tv_sec == youngestFile.tv_sec && tv.tv_usec == youngestFile.tv_usec)
    gettimeofday(&tv, nullptr);

  for (auto &j : committedMessages) {
    string basename = j.second.substr(j.second.rfind('/') + 1);

    int flags = j.first->getStdFlags();
    string flagStr;
    if (flags & Message::F_DRAFT) flagStr += "D";
    if (flags & Message::F_FLAGGED) flagStr += "F";
    if (flags & Message::F_ANSWERED) flagStr += "R";
    if (flags & Message::F_SEEN) flagStr += "S";
    if (flags & Message::F_DELETED) flagStr += "T";

    string dest = mbox + "/cur/" + basename + ":2," + flagStr;
    if (rename(j.second.c_str(), dest.c_str()) == 0) continue;

    if (errno != ENOENT) {
      bincWarning << "when setting flags on: " << j.second << ": " << strerror(errno) << endl;
    }
  }

  committedMessages.clear();
  return true;
}

bool Maildir::rollBackNewMessages(void)
{
  // Fixme: Messages that are in committedMessages should be skipped here.
  for (const auto &i : newMessages)
    unlink(i.getSafeName().c_str());

  newMessages.clear();
  return true;
}

bool Maildir::fastCopy(Message &m, Mailbox &desttype, const std::string &destname)
{
  // At this point, fastCopy is broken because the creation time is
  // equal for the two clones. The new clone must have a new creation
  // time. Symlinks are a possibility, but they break if other Maildir
  // accessors rename mailboxes.
  //  return false;

  Session &session = Session::getInstance();

  MaildirMessage *message = dynamic_cast<MaildirMessage *>(&m);
  if (!message) return false;

  string mfilename = message->getFileName();
  if (mfilename == "") return false;

  Maildir *mailbox = dynamic_cast<Maildir *>(&desttype);
  if (!mailbox) return false;

  for (int attempt = 0; attempt < 1000; ++attempt) {
    struct timeval tv;
    gettimeofday(&tv, nullptr);

    // Generate Maildir conformant file name
    BincStream ssid;
    ssid << (int)tv.tv_sec << "."
         << "R" << (int)rand() << "M" << (int)tv.tv_usec << "P" << (int)session.getPid() << "Q"
         << numDeliveries++ << "." << session.getEnv("TCPLOCALHOST");

    BincStream ss;
    ss << destname << "/tmp/" << ssid.str();

    string fileName = ss.str();

    if (link((path + "/cur/" + mfilename).c_str(), fileName.c_str()) == 0) {
      MaildirMessage newmess = *message;
      newmess.setSafeName(fileName);
      newmess.setUnique(ssid.str());
      newmess.setInternalDate(tv.tv_sec);
      newmess.setUID(0);
      newMessages.push_back(newmess);
      break;
    }

    if (errno == EEXIST) continue;

    bincWarning << "Warning: link(" << toImapString(path + "/cur/" + mfilename) << ", "
                << toImapString(fileName) << ") failed: " << strerror(errno) << endl;

    session.setResponseCode("TRYCREATE");
    session.setLastError("failed, internal error.");
    return false;
  }

  return true;
}

MaildirMessage *Maildir::get(const std::string &id)
{
  MaildirIndexItem *item = index.find(id);
  if (!item) return nullptr;

  unsigned int uid = item->uid;
  if (messages.find(uid) == messages.end()) return nullptr;

  return &messages.find(uid)->second;
}

void Maildir::add(MaildirMessage &m)
{
  MessageMap::iterator it = messages.find(m.getUID());
  if (it != messages.end()) messages.erase(it);
  messages.insert(std::make_pair(m.getUID(), m));
  index.insert(m.getUnique(), m.getUID());
}

unsigned int MaildirIndex::getSize(void) const
{
  return idx.size();
}

void MaildirIndex::insert(const string &unique, unsigned int uid, const string &fileName)
{
  if (idx.find(unique) == idx.end()) {
    MaildirIndexItem item;
    item.uid = uid;
    item.fileName = fileName;
    idx[unique] = item;
  } else {
    MaildirIndexItem &item = idx[unique];
    if (uid != 0) item.uid = uid;
    if (fileName != "") item.fileName = fileName;
  }
}

void MaildirIndex::remove(const string &unique)
{
  map<string, MaildirIndexItem>::iterator it = idx.find(unique);
  if (it != idx.end()) idx.erase(it);
}

MaildirIndexItem *MaildirIndex::find(const string &unique)
{
  map<string, MaildirIndexItem>::iterator it = idx.find(unique);
  if (it != idx.end()) return &it->second;

  return nullptr;
}

void MaildirIndex::clear(void)
{
  idx.clear();
}

void MaildirIndex::clearUids(void)
{
  for (auto &it : idx)
    it.second.uid = 0;
}

void MaildirIndex::clearFileNames(void)
{
  for (auto &it : idx)
    it.second.fileName = "";
}