/**
 *  @file operator-list.cc
 *  @brief Implementation of the LIST command.
 */

#include "convert.h"
#include "depot.h"
#include "iodevice.h"
#include "iofactory.h"
#include "mailbox.h"
#include "operators.h"
#include "recursivedescent.h"
#include "regmatch.h"
#include "session.h"

#include <iostream>
#include <string>

#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>

using namespace Binc;
using std::string;

namespace {
  const time_t LIST_CACHE_TIMEOUT = 10;
}

ListOperator::ListOperator()
{
  cacheTimeout = 0;
}

ListOperator::~ListOperator() {}

const string ListOperator::getName() const
{
  return "LIST";
}

Session::State ListOperator::getState() const
{
  return Session::State(Session::AUTHENTICATED | Session::SELECTED);
}

Operator::ProcessResult ListOperator::process(Depot &depot, Request &command)
{
  Session &session = Session::getInstance();
  const char delim = depot.getDelimiter();

  // special case: if the mailbox argument is empty, then give a
  // hard coded reply.
  string wildcard;
  if ((wildcard = command.getListMailbox()) == "") {
    bincClient << "* LIST (\\Noselect) \"" << delim << "\" \"\"" << std::endl;
    return Operator::ProcessResult::OK;
  }

  // remove leading or trailing delimiter in wildcard
  trim(wildcard, string(&delim, 1));

  // convert wildcard to regular expression
  string regex = toRegex(wildcard, depot.getDelimiter());
  string wildcardLower = regex;
  lowercase(wildcardLower);
  if (wildcardLower.substr(0, 6) == "^inbox")
    regex = "^[iI][nN][bB][oO][xX]" + regex.substr(6);

  // remove leading or trailing delimiter in reference
  string ref = command.getMailbox();
  trim(ref, string(&delim, 1));
  wildcardLower = ref;
  lowercase(wildcardLower);
  if (wildcardLower.substr(0, 6) == "^inbox") ref = "^[iI][nN][bB][oO][xX]" + ref.substr(6);
  if (wildcardLower.substr(0, 5) == "inbox"
      && (wildcardLower.length() == 5 || wildcardLower[5] == delim))
  {
    ref = "INBOX" + ref.substr(5);
  }

  // a map from mailbox name to flags
  std::map<string, unsigned int> mailboxes;

  if (cacheTimeout == 0 || cacheTimeout < time(nullptr) - LIST_CACHE_TIMEOUT
      || session.mailboxchanges)
  {
    session.mailboxchanges = false;

    // read through all entries in depository.
    for (Depot::iterator i = depot.begin("."); i != depot.end(); ++i) {
      const string path = *i;
      const string mpath = depot.filenameToMailbox(path);
      Mailbox *m = nullptr;

      // skip entries that are not identified as mailboxes
      if ((m = depot.get(mpath)) == nullptr) continue;

      // convert file name to mailbox name. skip it if there is no
      // corresponding mailbox name.
      string tmp = toCanonMailbox(depot.filenameToMailbox(path));
      trim(tmp, string(&delim, 1));
      if (tmp == "") {
        continue;
      } else {
        // inherit flags that were already set for this mailbox.
        int flags = DIR_SELECT;
        if (m->isMarked(path)) flags |= DIR_MARKED;
        if (mailboxes.find(tmp) != mailboxes.end()) flags |= mailboxes[tmp];
        mailboxes[tmp] = flags;
      }

      // now add all superior mailboxes with no flags set if not
      // added already.
      string::size_type pos = tmp.rfind(delim);
      while (pos != string::npos) {
        tmp = tmp.substr(0, pos);
        trim(tmp, string(&delim, 1));

        if (mailboxes.find(tmp) == mailboxes.end()) mailboxes[tmp] = 0;

        pos = tmp.rfind(delim);
      }
    }

    // find leaf nodes O(N^2)
    for (auto i = mailboxes.begin(); i != mailboxes.end(); ++i) {
      string mailbox = i->first;
      mailbox += delim;

      bool leaf = true;

      for (auto j = mailboxes.begin(); j != mailboxes.end(); ++j) {
        string::size_type pos = j->first.rfind(delim);
        if (pos == string::npos) continue;

        string base = j->first.substr(0, pos + 1);

        if (mailbox == base) {
          leaf = false;
          break;
        }
      }

      if (leaf) {
        unsigned int flags = i->second;
        flags |= DIR_LEAF;
        i->second = flags;
      }
    }

    cache = mailboxes;
    cacheTimeout = time(nullptr);
  } else {
    mailboxes = cache;
    cacheTimeout = time(nullptr);
  }

  // finally, print all mailbox entries with flags.
  for (auto i = mailboxes.begin(); i != mailboxes.end(); ++i) {
    if (ref == ""
        || (ref.length() <= i->first.length() && ref == i->first.substr(0, ref.length())))
    {
      if (regexMatch(i->first.substr(ref.length()), regex) == 0) {
        bincClient << "* LIST (";
        string sep = "";

        int flags = i->second;
        bool noselect = false;

        if (!(flags & DIR_SELECT)) {
          bincClient << sep << "\\Noselect";
          sep = " ";
          noselect = true;
        }

        if (!noselect) {
          if (flags & DIR_MARKED)
            bincClient << sep << "\\Marked";
          else
            bincClient << sep << "\\Unmarked";
          sep = " ";
        }

        if (flags & DIR_LEAF)
          bincClient << sep << "\\HasNoChildren";
        else
          bincClient << sep << "\\HasChildren";
        sep = " ";

        if (flags & DIR_NOINFERIORS) bincClient << sep << "\\Noinferiors";

        bincClient << ") \"" << depot.getDelimiter() << "\" " << toImapString(i->first)
                   << std::endl;
      }
    }
  }

  return Operator::ProcessResult::OK;
}

Parser::ParseResult ListOperator::parse(Request &c_in, Parser &p)
{
  constexpr auto ACCEPT = Parser::ParseResult::ACCEPT;

  Session &session = Session::getInstance();

  if (c_in.getUidMode()) return Parser::ParseResult::REJECT;

  Parser::ParseResult res;
  if ((res = p.expectSPACE()) != ACCEPT) {
    session.setLastError("Expected SPACE after LIST");
    return res;
  }

  string mailbox;
  if ((res = p.expectMailbox(mailbox)) != ACCEPT) {
    session.setLastError("Expected mailbox after LIST SPACE");
    return res;
  }

  c_in.setMailbox(mailbox);

  if ((res = p.expectSPACE()) != ACCEPT) {
    session.setLastError("Expected SPACE after LIST SPACE mailbox");
    return res;
  }

  string listmailbox;
  if ((res = p.expectListMailbox(listmailbox)) != ACCEPT) {
    session.setLastError("Expected list_mailbox after LIST SPACE"
                         " mailbox SPACE");
    return res;
  }

  if ((res = p.expectCRLF()) != ACCEPT) {
    session.setLastError("Expected CRLF after LIST SPACE mailbox"
                         " SPACE list_mailbox");
    return res;
  }

  c_in.setListMailbox(listmailbox);
  c_in.setName("LIST");
  return ACCEPT;
}