/*
  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 <algorithm>
#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"
#ifndef __EMSCRIPTEN__
#include "syzygy/tbprobe.h"
#endif

using namespace std;

#ifndef __EMSCRIPTEN__
extern vector<string> setup_bench(const Position&, istream&);
#endif

namespace {

  // FEN strings of the initial positions
  const string StartFENs[SUBVARIANT_NB] = {
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#ifdef ANTI
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef ATOMIC
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef CRAZYHOUSE
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR[] w KQkq - 0 1",
#endif
#ifdef EXTINCTION
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef GRID
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef HORDE
  "rnbqkbnr/pppppppp/8/1PP2PP1/PPPPPPPP/PPPPPPPP/PPPPPPPP/PPPPPPPP w kq - 0 1",
#endif
#ifdef KOTH
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef LOSERS
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef RACE
  "8/8/8/8/8/8/krbnNBRK/qrbnNBRQ w - - 0 1",
#endif
#ifdef THREECHECK
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 3+3 0 1",
#endif
#ifdef TWOKINGS
  "rnbqkknr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKKNR w KQkq - 0 1",
#endif
#ifdef SUICIDE
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1",
#endif
#ifdef BUGHOUSE
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR[] w KQkq - 0 1",
#endif
#ifdef DISPLACEDGRID
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef LOOP
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR[] w KQkq - 0 1",
#endif
#ifdef PLACEMENT
  "8/pppppppp/8/8/8/8/PPPPPPPP/8[KQRRBBNNkqrrbbnn] w - -",
#endif
#ifdef SLIPPEDGRID
  "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
#endif
#ifdef TWOKINGSSYMMETRIC
  "rnbqkknr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKKNR w KQkq - 0 1",
#endif
  };


  // 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;

    Variant variant = UCI::variant_from_name(Options["UCI_Variant"]);

    is >> token;
    if (token == "startpos")
    {
        fen = StartFENs[variant];
        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"], variant, &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;
        std::transform(name.begin(), name.end(), name.begin(), ::tolower);
        if (name == "uci_variant") {
            Variant variant = UCI::variant_from_name(value);
            sync_cout << "info string variant " << (string)Options["UCI_Variant"] << " startpos " << StartFENs[variant] << sync_endl;
#ifndef __EMSCRIPTEN__
            Tablebases::init(variant, Options["SyzygyPath"]);
#endif
        }
    }
    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.

#ifndef __EMSCRIPTEN__
  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;
  }
#endif

} // 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.

#ifndef __EMSCRIPTEN__
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(StartFENs[CHESS_VARIANT], false, CHESS_VARIANT, &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";
#else
extern "C" void uci_command(const char *c_cmd) {
  static bool initialized = false;
  static Position pos;
  static StateListPtr states(new std::deque<StateInfo>(1));
  static auto uiThread = std::make_shared<Thread>(0);
  if (!initialized) {
    pos.set(StartFENs[CHESS_VARIANT], false, CHESS_VARIANT, &states->back(), uiThread.get());
    initialized = true;
  }

  std::string token, cmd(c_cmd);
#endif  // __EMSCRIPTEN__

      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();
#ifndef __EMSCRIPTEN__
      else if (token == "bench") bench(pos, is, states);
#endif  // __EMSCRIPTEN__
      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;
#ifndef __EMSCRIPTEN__
  } while (token != "quit" && argc == 1); // Command line args are one-shot
#endif
}


/// 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 - 1) / 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));

#ifdef CRAZYHOUSE
  string move = ((type_of(m) == DROP) ? std::string{" PNBRQK  PNBRQK "[dropped_piece(m)], '@'} : UCI::square(from)) + UCI::square(to);
#else
  string move = UCI::square(from) + UCI::square(to);
#endif

  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;
}


Variant UCI::variant_from_name(const string& str) {

  for (Variant v = CHESS_VARIANT; v < SUBVARIANT_NB; ++v)
      if (variants[v] == str)
          return v;

  return CHESS_VARIANT;
}
