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/*

  Stockfish, a UCI chess playing engine derived from Glaurung 2.1

  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)

  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad

  Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad

  Stockfish 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 3 of the License, or

  (at your option) any later version.

  Stockfish 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, see <http://www.gnu.org/licenses/>.

*/

#include <cassert>

#include <iostream>

#include <sstream>

#include <string>

#include "evaluate.h"

#include "movegen.h"

#include "position.h"

#include "search.h"

#include "thread.h"

#include "timeman.h"

#include "tt.h"

#include "uci.h"

#include "syzygy/tbprobe.h"

using namespace std;

extern vector<string> setup_bench(const Position&, istream&);

namespace {

  // FEN string of the initial position, normal chess

  const char* StartFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";

  // position() is called when engine receives the "position" UCI command.

  // The function sets up the position described in the given FEN string ("fen")

  // or the starting position ("startpos") and then makes the moves given in the

  // following move list ("moves").

  void position(Position& pos, istringstream& is, StateListPtr& states) {

    Move m;

    string token, fen;

    is >> token;

    if (token == "startpos")

    {

        fen = StartFEN;

        is >> token; // Consume "moves" token if any

    }

    else if (token == "fen")

        while (is >> token && token != "moves")

            fen += token + " ";

    else

        return;

    states = StateListPtr(new std::deque<StateInfo>(1)); // Drop old and create a new one

    pos.set(fen, Options["UCI_Chess960"], &states->back(), Threads.main());

    // Parse move list (if any)

    while (is >> token && (m = UCI::to_move(pos, token)) != MOVE_NONE)

    {

        states->emplace_back();

        pos.do_move(m, states->back());

    }

  }

  // setoption() is called when engine receives the "setoption" UCI command. The

  // function updates the UCI option ("name") to the given value ("value").

  void setoption(istringstream& is) {

    string token, name, value;

    is >> token; // Consume "name" token

    // Read option name (can contain spaces)

    while (is >> token && token != "value")

        name += (name.empty() ? "" : " ") + token;

    // Read option value (can contain spaces)

    while (is >> token)

        value += (value.empty() ? "" : " ") + token;

    if (Options.count(name))

        Options[name] = value;

    else

        sync_cout << "No such option: " << name << sync_endl;

  }

  // go() is called when engine receives the "go" UCI command. The function sets

  // the thinking time and other parameters from the input string, then starts

  // the search.

  void go(Position& pos, istringstream& is, StateListPtr& states) {

    Search::LimitsType limits;

    string token;

    bool ponderMode = false;

    limits.startTime = now(); // As early as possible!

    while (is >> token)

        if (token == "searchmoves")

            while (is >> token)

                limits.searchmoves.push_back(UCI::to_move(pos, token));

        else if (token == "wtime")     is >> limits.time[WHITE];

        else if (token == "btime")     is >> limits.time[BLACK];

        else if (token == "winc")      is >> limits.inc[WHITE];

        else if (token == "binc")      is >> limits.inc[BLACK];

        else if (token == "movestogo") is >> limits.movestogo;

        else if (token == "depth")     is >> limits.depth;

        else if (token == "nodes")     is >> limits.nodes;

        else if (token == "movetime")  is >> limits.movetime;

        else if (token == "mate")      is >> limits.mate;

        else if (token == "perft")     is >> limits.perft;

        else if (token == "infinite")  limits.infinite = 1;

        else if (token == "ponder")    ponderMode = true;

    Threads.start_thinking(pos, states, limits, ponderMode);

  }

  // bench() is called when engine receives the "bench" command. Firstly

  // a list of UCI commands is setup according to bench parameters, then

  // it is run one by one printing a summary at the end.

  void bench(Position& pos, istream& args, StateListPtr& states) {

    string token;

    uint64_t num, nodes = 0, cnt = 1;

    vector<string> list = setup_bench(pos, args);

    num = count_if(list.begin(), list.end(), [](string s) { return s.find("go ") == 0; });

    TimePoint elapsed = now();

    for (const auto& cmd : list)

    {

        istringstream is(cmd);

        is >> skipws >> token;

        if (token == "go")

        {

            cerr << "\nPosition: " << cnt++ << '/' << num << endl;

            go(pos, is, states);

            Threads.main()->wait_for_search_finished();

            nodes += Threads.nodes_searched();

        }

        else if (token == "setoption")  setoption(is);

        else if (token == "position")   position(pos, is, states);

        else if (token == "ucinewgame") Search::clear();

    }

    elapsed = now() - elapsed + 1; // Ensure positivity to avoid a 'divide by zero'

    dbg_print(); // Just before exiting

    cerr << "\n==========================="

         << "\nTotal time (ms) : " << elapsed

         << "\nNodes searched  : " << nodes

         << "\nNodes/second    : " << 1000 * nodes / elapsed << endl;

  }

} // namespace

/// UCI::loop() waits for a command from stdin, parses it and calls the appropriate

/// function. Also intercepts EOF from stdin to ensure gracefully exiting if the

/// GUI dies unexpectedly. When called with some command line arguments, e.g. to

/// run 'bench', once the command is executed the function returns immediately.

/// In addition to the UCI ones, also some additional debug commands are supported.

void UCI::loop(int argc, char* argv[]) {

  Position pos;

  string token, cmd;

  StateListPtr states(new std::deque<StateInfo>(1));

  auto uiThread = std::make_shared<Thread>(0);

  pos.set(StartFEN, false, &states->back(), uiThread.get());

  for (int i = 1; i < argc; ++i)

      cmd += std::string(argv[i]) + " ";

  do {

      if (argc == 1 && !getline(cin, cmd)) // Block here waiting for input or EOF

          cmd = "quit";

      istringstream is(cmd);

      token.clear(); // Avoid a stale if getline() returns empty or blank line

      is >> skipws >> token;

      // The GUI sends 'ponderhit' to tell us the user has played the expected move.

      // So 'ponderhit' will be sent if we were told to ponder on the same move the

      // user has played. We should continue searching but switch from pondering to

      // normal search. In case Threads.stopOnPonderhit is set we are waiting for

      // 'ponderhit' to stop the search, for instance if max search depth is reached.

      if (    token == "quit"

          ||  token == "stop"

          || (token == "ponderhit" && Threads.stopOnPonderhit))

          Threads.stop = true;

      else if (token == "ponderhit")

          Threads.ponder = false; // Switch to normal search

      else if (token == "uci")

          sync_cout << "id name " << engine_info(true)

                    << "\n"       << Options

                    << "\nuciok"  << sync_endl;

      else if (token == "setoption")  setoption(is);

      else if (token == "go")         go(pos, is, states);

      else if (token == "position")   position(pos, is, states);

      else if (token == "ucinewgame") Search::clear();

      else if (token == "isready")    sync_cout << "readyok" << sync_endl;

      // Additional custom non-UCI commands, mainly for debugging

      else if (token == "flip")  pos.flip();

      else if (token == "bench") bench(pos, is, states);

      else if (token == "d")     sync_cout << pos << sync_endl;

      else if (token == "eval")  sync_cout << Eval::trace(pos) << sync_endl;

      else

          sync_cout << "Unknown command: " << cmd << sync_endl;

  } while (token != "quit" && argc == 1); // Command line args are one-shot

}

/// UCI::value() converts a Value to a string suitable for use with the UCI

/// protocol specification:

///

/// cp <x>    The score from the engine's point of view in centipawns.

/// mate <y>  Mate in y moves, not plies. If the engine is getting mated

///           use negative values for y.

string UCI::value(Value v) {

  assert(-VALUE_INFINITE < v && v < VALUE_INFINITE);

  stringstream ss;

  if (abs(v) < VALUE_MATE - MAX_PLY)

      ss << "cp " << v * 100 / PawnValueEg;

  else

      ss << "mate " << (v > 0 ? VALUE_MATE - v + 1 : -VALUE_MATE - v) / 2;

  return ss.str();

}

/// UCI::square() converts a Square to a string in algebraic notation (g1, a7, etc.)

std::string UCI::square(Square s) {

  return std::string{ char('a' + file_of(s)), char('1' + rank_of(s)) };

}

/// UCI::move() converts a Move to a string in coordinate notation (g1f3, a7a8q).

/// The only special case is castling, where we print in the e1g1 notation in

/// normal chess mode, and in e1h1 notation in chess960 mode. Internally all

/// castling moves are always encoded as 'king captures rook'.

string UCI::move(Move m, bool chess960) {

  Square from = from_sq(m);

  Square to = to_sq(m);

  if (m == MOVE_NONE)

      return "(none)";

  if (m == MOVE_NULL)

      return "0000";

  if (type_of(m) == CASTLING && !chess960)

      to = make_square(to > from ? FILE_G : FILE_C, rank_of(from));

  string move = UCI::square(from) + UCI::square(to);

  if (type_of(m) == PROMOTION)

      move += " pnbrqk"[promotion_type(m)];

  return move;

}

/// UCI::to_move() converts a string representing a move in coordinate notation

/// (g1f3, a7a8q) to the corresponding legal Move, if any.

Move UCI::to_move(const Position& pos, string& str) {

  if (str.length() == 5) // Junior could send promotion piece in uppercase

      str[4] = char(tolower(str[4]));

  for (const auto& m : MoveList<LEGAL>(pos))

      if (str == UCI::move(m, pos.is_chess960()))

          return m;

  return MOVE_NONE;

}