src/chess.lua

   1 local realchess = {}
   2 screwdriver = screwdriver or {}
   3
   4 local function index_to_xy(idx)
   5         idx = idx - 1
   6         local x = idx % 8
   7         local y = (idx - x) / 8
   8
   9         return x, y
  10 end
  11
  12 local function xy_to_index(x, y)
  13         return x + y * 8 + 1
  14 end
  15
  16 local function get_square(a, b)
  17         return (a * 8) - (8 - b)
  18 end
  19
  20 local chat_prefix = minetest.colorize("#FFFF00", "[Chess] ")
  21 local letters = {'A','B','C','D','E','F','G','H'}
  22
  23 local function board_to_table(inv)
  24         local t = {}
  25         for i = 1, 64 do
  26                 t[#t + 1] = inv:get_stack("board", i):get_name()
  27         end
  28
  29         return t
  30 end
  31
  32 local piece_values = {
  33         pawn   = 10,
  34         knight = 30,
  35         bishop = 30,
  36         rook   = 50,
  37         queen  = 90,
  38         king   = 900
  39 }
  40
  41 local function get_possible_moves(inv, from_idx)
  42         local piece, color = inv:get_stack("board", from_idx):get_name():match(":(%w+)_(%w+)")
  43         if not piece then return end
  44         local moves = {}
  45         local from_x, from_y = index_to_xy(from_idx)
  46
  47         for i = 1, 64 do
  48                 local stack = inv:get_stack("board", i)
  49                 local stack_name = stack:get_name()
  50
  51                 if stack_name:find((color == "black" and "white" or "black")) or
  52                                 stack:is_empty() then
  53                         moves[i] = 0
  54                 end
  55         end
  56
  57         for to_idx in pairs(moves) do
  58                 local pieceTo    = inv:get_stack("board", to_idx):get_name()
  59                 local to_x, to_y = index_to_xy(to_idx)
  60
  61                 -- PAWN
  62                 if piece == "pawn" then
  63                         if color == "white" then
  64                                 local pawnWhiteMove = inv:get_stack("board", xy_to_index(from_x, from_y - 1)):get_name()
  65                                 -- white pawns can go up only
  66                                 if from_y - 1 == to_y then
  67                                         if from_x == to_x then
  68                                                 if pieceTo ~= "" then
  69                                                         moves[to_idx] = nil
  70                                                 end
  71                                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
  72                                                 if not pieceTo:find("black") then
  73                                                         moves[to_idx] = nil
  74                                                 end
  75                                         else
  76                                                 moves[to_idx] = nil
  77                                         end
  78                                 elseif from_y - 2 == to_y then
  79                                         if pieceTo ~= "" or from_y < 6 or pawnWhiteMove ~= "" then
  80                                                 moves[to_idx] = nil
  81                                         end
  82                                 else
  83                                         moves[to_idx] = nil
  84                                 end
  85
  86                                 --[[
  87                                      if x not changed
  88                                           ensure that destination cell is empty
  89                                      elseif x changed one unit left or right
  90                                           ensure the pawn is killing opponent piece
  91                                      else
  92                                           move is not legal - abort
  93                                 ]]
  94
  95                                 if from_x == to_x then
  96                                         if pieceTo ~= "" then
  97                                                 moves[to_idx] = nil
  98                                         end
  99                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 100                                         if not pieceTo:find("black") then
 101                                                 moves[to_idx] = nil
 102                                         end
 103                                 else
 104                                         moves[to_idx] = nil
 105                                 end
 106
 107                         elseif color == "black" then
 108                                 local pawnBlackMove = inv:get_stack("board", xy_to_index(from_x, from_y + 1)):get_name()
 109                                 -- black pawns can go down only
 110                                 if from_y + 1 == to_y then
 111                                         if from_x == to_x then
 112                                                 if pieceTo ~= "" then
 113                                                         moves[to_idx] = nil
 114                                                 end
 115                                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
 116                                                 if not pieceTo:find("white") then
 117                                                         moves[to_idx] = nil
 118                                                 end
 119                                         else
 120                                                 moves[to_idx] = nil
 121                                         end
 122                                 elseif from_y + 2 == to_y then
 123                                         if pieceTo ~= "" or from_y > 1 or pawnBlackMove ~= "" then
 124                                                 moves[to_idx] = nil
 125                                         end
 126                                 else
 127                                         moves[to_idx] = nil
 128                                 end
 129
 130                                 --[[
 131                                      if x not changed
 132                                           ensure that destination cell is empty
 133                                      elseif x changed one unit left or right
 134                                           ensure the pawn is killing opponent piece
 135                                      else
 136                                           move is not legal - abort
 137                                 ]]
 138
 139                                 if from_x == to_x then
 140                                         if pieceTo ~= "" then
 141                                                 moves[to_idx] = nil
 142                                         end
 143                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 144                                         if not pieceTo:find("white") then
 145                                                 moves[to_idx] = nil
 146                                         end
 147                                 else
 148                                         moves[to_idx] = nil
 149                                 end
 150                         else
 151                                 moves[to_idx] = nil
 152                         end
 153
 154                 -- ROOK
 155                 elseif piece == "rook" then
 156                         if from_x == to_x then
 157                                 -- Moving vertically
 158                                 if from_y < to_y then
 159                                         -- Moving down
 160                                         -- Ensure that no piece disturbs the way
 161                                         for i = from_y + 1, to_y - 1 do
 162                                                 if inv:get_stack("board", xy_to_index(from_x, i)):get_name() ~= "" then
 163                                                         moves[to_idx] = nil
 164                                                 end
 165                                         end
 166                                 else
 167                                         -- Mocing up
 168                                         -- Ensure that no piece disturbs the way
 169                                         for i = to_y + 1, from_y - 1 do
 170                                                 if inv:get_stack("board", xy_to_index(from_x, i)):get_name() ~= "" then
 171                                                         moves[to_idx] = nil
 172                                                 end
 173                                         end
 174                                 end
 175                         elseif from_y == to_y then
 176                                 -- Mocing horizontally
 177                                 if from_x < to_x then
 178                                         -- mocing right
 179                                         -- ensure that no piece disturbs the way
 180                                         for i = from_x + 1, to_x - 1 do
 181                                                 if inv:get_stack("board", xy_to_index(i, from_y)):get_name() ~= "" then
 182                                                         moves[to_idx] = nil
 183                                                 end
 184                                         end
 185                                 else
 186                                         -- Mocing left
 187                                         -- Ensure that no piece disturbs the way
 188                                         for i = to_x + 1, from_x - 1 do
 189                                                 if inv:get_stack("board", xy_to_index(i, from_y)):get_name() ~= "" then
 190                                                         moves[to_idx] = nil
 191                                                 end
 192                                         end
 193                                 end
 194                         else
 195                                 -- Attempt to move arbitrarily -> abort
 196                                 moves[to_idx] = nil
 197                         end
 198
 199                 -- KNIGHT
 200                 elseif piece == "knight" then
 201                         -- Get relative pos
 202                         local dx = from_x - to_x
 203                         local dy = from_y - to_y
 204
 205                         -- Get absolute values
 206                         if dx < 0 then
 207                                 dx = -dx
 208                         end
 209
 210                         if dy < 0 then
 211                                 dy = -dy
 212                         end
 213
 214                         -- Sort x and y
 215                         if dx > dy then
 216                                 dx, dy = dy, dx
 217                         end
 218
 219                         -- Ensure that dx == 1 and dy == 2
 220                         if dx ~= 1 or dy ~= 2 then
 221                                 moves[to_idx] = nil
 222                         end
 223                         -- Just ensure that destination cell does not contain friend piece
 224                         -- ^ It was done already thus everything ok
 225
 226                 -- BISHOP
 227                 elseif piece == "bishop" then
 228                         -- Get relative pos
 229                         local dx = from_x - to_x
 230                         local dy = from_y - to_y
 231
 232                         -- Get absolute values
 233                         if dx < 0 then
 234                                 dx = -dx
 235                         end
 236
 237                         if dy < 0 then
 238                                 dy = -dy
 239                         end
 240
 241                         -- Ensure dx and dy are equal
 242                         if dx ~= dy then
 243                                 moves[to_idx] = nil
 244                         end
 245
 246                         if from_x < to_x then
 247                                 if from_y < to_y then
 248                                         -- Moving right-down
 249                                         -- Ensure that no piece disturbs the way
 250                                         for i = 1, dx - 1 do
 251                                                 if inv:get_stack(
 252                                                         "board", xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 253                                                         moves[to_idx] = nil
 254                                                 end
 255                                         end
 256                                 else
 257                                         -- Moving right-up
 258                                         -- Ensure that no piece disturbs the way
 259                                         for i = 1, dx - 1 do
 260                                                 if inv:get_stack(
 261                                                         "board", xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 262                                                         moves[to_idx] = nil
 263                                                 end
 264                                         end
 265                                 end
 266                         else
 267                                 if from_y < to_y then
 268                                         -- Moving left-down
 269                                         -- Ensure that no piece disturbs the way
 270                                         for i = 1, dx - 1 do
 271                                                 if inv:get_stack(
 272                                                         "board", xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 273                                                         moves[to_idx] = nil
 274                                                 end
 275                                         end
 276                                 else
 277                                         -- Moving left-up
 278                                         -- ensure that no piece disturbs the way
 279                                         for i = 1, dx - 1 do
 280                                                 if inv:get_stack(
 281                                                         "board", xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 282                                                         moves[to_idx] = nil
 283                                                 end
 284                                         end
 285                                 end
 286                         end
 287
 288                 -- QUEEN
 289                 elseif piece == "queen" then
 290                         local dx = from_x - to_x
 291                         local dy = from_y - to_y
 292
 293                         -- Get absolute values
 294                         if dx < 0 then
 295                                 dx = -dx
 296                         end
 297
 298                         if dy < 0 then
 299                                 dy = -dy
 300                         end
 301
 302                         -- Ensure valid relative move
 303                         if dx ~= 0 and dy ~= 0 and dx ~= dy then
 304                                 moves[to_idx] = nil
 305                         end
 306
 307                         if from_x == to_x then
 308                                 -- Moving vertically
 309                                 if from_y < to_y then
 310                                         -- Moving down
 311                                         -- Ensure that no piece disturbs the way
 312                                         for i = from_y + 1, to_y - 1 do
 313                                                 if inv:get_stack("board", xy_to_index(from_x, i)):get_name() ~= "" then
 314                                                         moves[to_idx] = nil
 315                                                 end
 316                                         end
 317                                 else
 318                                         -- Mocing up
 319                                         -- Ensure that no piece disturbs the way
 320                                         for i = to_y + 1, from_y - 1 do
 321                                                 if inv:get_stack("board", xy_to_index(from_x, i)):get_name() ~= "" then
 322                                                         moves[to_idx] = nil
 323                                                 end
 324                                         end
 325                                 end
 326                         elseif from_x < to_x then
 327                                 if from_y == to_y then
 328                                         -- Goes right
 329                                         -- Ensure that no piece disturbs the way
 330                                         for i = 1, dx - 1 do
 331                                                 if inv:get_stack(
 332                                                         "board", xy_to_index(from_x + i, from_y)):get_name() ~= "" then
 333                                                         moves[to_idx] = nil
 334                                                 end
 335                                         end
 336                                 elseif from_y < to_y then
 337                                         -- Goes right-down
 338                                         -- Ensure that no piece disturbs the way
 339                                         for i = 1, dx - 1 do
 340                                                 if inv:get_stack(
 341                                                         "board", xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 342                                                         moves[to_idx] = nil
 343                                                 end
 344                                         end
 345                                 else
 346                                         -- Goes right-up
 347                                         -- Ensure that no piece disturbs the way
 348                                         for i = 1, dx - 1 do
 349                                                 if inv:get_stack(
 350                                                         "board", xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 351                                                         moves[to_idx] = nil
 352                                                 end
 353                                         end
 354                                 end
 355                         else
 356                                 if from_y == to_y then
 357                                         -- Mocing horizontally
 358                                         if from_x < to_x then
 359                                                 -- mocing right
 360                                                 -- ensure that no piece disturbs the way
 361                                                 for i = from_x + 1, to_x - 1 do
 362                                                         if inv:get_stack("board", xy_to_index(i, from_y)):get_name() ~= "" then
 363                                                                 moves[to_idx] = nil
 364                                                         end
 365                                                 end
 366                                         else
 367                                                 -- Mocing left
 368                                                 -- Ensure that no piece disturbs the way
 369                                                 for i = to_x + 1, from_x - 1 do
 370                                                         if inv:get_stack("board", xy_to_index(i, from_y)):get_name() ~= "" then
 371                                                                 moves[to_idx] = nil
 372                                                         end
 373                                                 end
 374                                         end
 375                                 elseif from_y < to_y then
 376                                         -- Goes left-down
 377                                         -- Ensure that no piece disturbs the way
 378                                         for i = 1, dx - 1 do
 379                                                 if inv:get_stack(
 380                                                         "board", xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 381                                                         moves[to_idx] = nil
 382                                                 end
 383                                         end
 384                                 else
 385                                         -- Goes left-up
 386                                         -- Ensure that no piece disturbs the way
 387                                         for i = 1, dx - 1 do
 388                                                 if inv:get_stack(
 389                                                         "board", xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 390                                                         moves[to_idx] = nil
 391                                                 end
 392                                         end
 393                                 end
 394                         end
 395
 396                 -- KING
 397                 elseif piece == "king" then
 398                         local dx = from_x - to_x
 399                         local dy = from_y - to_y
 400
 401                         if dx < 0 then
 402                                 dx = -dx
 403                         end
 404
 405                         if dy < 0 then
 406                                 dy = -dy
 407                         end
 408
 409                         if dx > 1 or dy > 1 then
 410                                 moves[to_idx] = nil
 411                         end
 412                 end
 413         end
 414
 415         if not next(moves) then return end
 416
 417         for i in pairs(moves) do
 418                 local stack = inv:get_stack("board", tonumber(i))
 419                 local stack_name = stack:get_name()
 420
 421                 if stack_name ~= "" then
 422                         for p, value in pairs(piece_values) do
 423                                 if stack_name:find(p) then
 424                                         moves[i] = value
 425                                 end
 426                         end
 427                 end
 428         end
 429
 430         return moves
 431 end
 432
 433 local function best_move(moves)
 434         local value, choices = 0, {}
 435
 436         for from, _ in pairs(moves) do
 437         for to, val in pairs(_) do
 438                 if val > value then
 439                         value = val
 440                         choices = {{
 441                                 from = from,
 442                                 to = to
 443                         }}
 444                 elseif val == value then
 445                         choices[#choices + 1] = {
 446                                 from = from,
 447                                 to = to
 448                         }
 449                 end
 450         end
 451         end
 452
 453         local random = math.random(1, #choices)
 454         local choice_from, choice_to = choices[random].from, choices[random].to
 455
 456         return tonumber(choice_from), choice_to
 457 end
 458
 459 local rowDirs = {-1, -1, -1, 0, 0, 1, 1, 1}
 460 local colDirs = {-1, 0, 1, -1, 1, -1, 0, 1}
 461
 462 local rowDirsKnight = { 2,  1, 2, 1, -2, -1, -2, -1}
 463 local colDirsKnight = {-1, -2, 1, 2,  1,  2, -1, -2}
 464
 465 local bishopThreats = {true,  false, true,  false, false, true,  false, true}
 466 local rookThreats   = {false, true,  false, true,  true,  false, true,  false}
 467 local queenThreats  = {true,  true,  true,  true,  true,  true,  true,  true}
 468 local kingThreats   = {true,  true,  true,  true,  true,  true,  true,  true}
 469
 470 local function attacked(color, idx, board)
 471         local threatDetected = false
 472         local kill           = color == "white"
 473         local pawnThreats    = {kill, false, kill, false, false, not kill, false, not kill}
 474
 475         for dir = 1, 8 do
 476                 if not threatDetected then
 477                         local col, row = index_to_xy(idx)
 478                         col, row = col + 1, row + 1
 479
 480                         for step = 1, 8 do
 481                                 row = row + rowDirs[dir]
 482                                 col = col + colDirs[dir]
 483
 484                                 if row >= 1 and row <= 8 and col >= 1 and col <= 8 then
 485                                         local square            = get_square(row, col)
 486                                         local square_name       = board[square]
 487                                         local piece, pieceColor = square_name:match(":(%w+)_(%w+)")
 488
 489                                         if piece then
 490                                                 if pieceColor ~= color then
 491                                                         if piece == "bishop" and bishopThreats[dir] then
 492                                                                 threatDetected = true
 493                                                         elseif piece == "rook" and rookThreats[dir] then
 494                                                                 threatDetected = true
 495                                                         elseif piece == "queen" and queenThreats[dir] then
 496                                                                 threatDetected = true
 497                                                         else
 498                                                                 if step == 1 then
 499                                                                         if piece == "pawn" and pawnThreats[dir] then
 500                                                                                 threatDetected = true
 501                                                                         end
 502                                                                         if piece == "king" and kingThreats[dir] then
 503                                                                                 threatDetected = true
 504                                                                         end
 505                                                                 end
 506                                                         end
 507                                                 end
 508                                                 break
 509                                         end
 510                                 end
 511                         end
 512
 513                         local colK, rowK = index_to_xy(idx)
 514                         colK, rowK = colK + 1, rowK + 1
 515                         rowK = rowK + rowDirsKnight[dir]
 516                         colK = colK + colDirsKnight[dir]
 517
 518                         if rowK >= 1 and rowK <= 8 and colK >= 1 and colK <= 8 then
 519                                 local square            = get_square(rowK, colK)
 520                                 local square_name       = board[square]
 521                                 local piece, pieceColor = square_name:match(":(%w+)_(%w+)")
 522
 523                                 if piece and pieceColor ~= color and piece == "knight" then
 524                                         threatDetected = true
 525                                 end
 526                         end
 527                 end
 528         end
 529
 530         return threatDetected
 531 end
 532
 533 local function locate_kings(board)
 534         local Bidx, Widx
 535         for i = 1, 64 do
 536                 local piece, color = board[i]:match(":(%w+)_(%w+)")
 537                 if piece == "king" then
 538                         if color == "black" then
 539                                 Bidx = i
 540                         else
 541                                 Widx = i
 542                         end
 543                 end
 544         end
 545
 546         return Bidx, Widx
 547 end
 548
 549 local pieces = {
 550         "realchess:rook_black_1",
 551         "realchess:knight_black_1",
 552         "realchess:bishop_black_1",
 553         "realchess:queen_black",
 554         "realchess:king_black",
 555         "realchess:bishop_black_2",
 556         "realchess:knight_black_2",
 557         "realchess:rook_black_2",
 558         "realchess:pawn_black_1",
 559         "realchess:pawn_black_2",
 560         "realchess:pawn_black_3",
 561         "realchess:pawn_black_4",
 562         "realchess:pawn_black_5",
 563         "realchess:pawn_black_6",
 564         "realchess:pawn_black_7",
 565         "realchess:pawn_black_8",
 566         '','','','','','','','','','','','','','','','',
 567         '','','','','','','','','','','','','','','','',
 568         "realchess:pawn_white_1",
 569         "realchess:pawn_white_2",
 570         "realchess:pawn_white_3",
 571         "realchess:pawn_white_4",
 572         "realchess:pawn_white_5",
 573         "realchess:pawn_white_6",
 574         "realchess:pawn_white_7",
 575         "realchess:pawn_white_8",
 576         "realchess:rook_white_1",
 577         "realchess:knight_white_1",
 578         "realchess:bishop_white_1",
 579         "realchess:queen_white",
 580         "realchess:king_white",
 581         "realchess:bishop_white_2",
 582         "realchess:knight_white_2",
 583         "realchess:rook_white_2"
 584 }
 585
 586 local pieces_str, x = "", 0
 587 for i = 1, #pieces do
 588         local p = pieces[i]:match(":(%w+_%w+)")
 589         if pieces[i]:find(":(%w+)_(%w+)") and not pieces_str:find(p) then
 590                 pieces_str = pieces_str .. x .. "=" .. p .. ".png,"
 591                 x = x + 1
 592         end
 593 end
 594 pieces_str = pieces_str .. "69=mailbox_blank16.png"
 595
 596 local fs = [[
 597         size[14.7,10;]
 598         no_prepend[]
 599         bgcolor[#080808BB;true]
 600         background[0,0;14.7,10;chess_bg.png]
 601         list[context;board;0.3,1;8,8;]
 602         listcolors[#00000000;#00000000;#00000000;#30434C;#FFF]
 603         tableoptions[background=#00000000;highlight=#00000000;border=false]
 604         button[10.5,8.5;2,2;new;New game]
 605 ]] ..  "tablecolumns[image," .. pieces_str ..
 606                 ";text;color;text;color;text;image," .. pieces_str .. "]"
 607
 608 local function update_formspec(meta)
 609         local black_king_attacked = meta:get_string("blackAttacked") == "true"
 610         local white_king_attacked = meta:get_string("whiteAttacked") == "true"
 611
 612         local playerWhite = meta:get_string("playerWhite")
 613         local playerBlack = meta:get_string("playerBlack")
 614
 615         local moves     = meta:get_string("moves")
 616         local eaten_img = meta:get_string("eaten_img")
 617         local lastMove  = meta:get_string("lastMove")
 618         local turnBlack = minetest.colorize("#000001", (lastMove == "white" and playerBlack ~= "") and
 619                           playerBlack .. "..." or playerBlack)
 620         local turnWhite = minetest.colorize("#000001", (lastMove == "black" and playerWhite ~= "") and
 621                           playerWhite .. "..." or playerWhite)
 622         local check_s   = minetest.colorize("#FF0000", "\\[check\\]")
 623
 624         local formspec = fs ..
 625                 "label[1.9,0.3;"  .. turnBlack .. (black_king_attacked and " " .. check_s or "") .. "]" ..
 626                 "label[1.9,9.15;" .. turnWhite .. (white_king_attacked and " " .. check_s or "") .. "]" ..
 627                 "table[8.9,1.05;5.07,3.75;moves;" .. moves:sub(1,-2) .. ";1]" ..
 628                 eaten_img
 629
 630         meta:set_string("formspec", formspec)
 631 end
 632
 633 local function get_moves_list(meta, pieceFrom, pieceTo, pieceTo_s, from_idx, to_idx)
 634         local from_x, from_y  = index_to_xy(from_idx)
 635         local to_x, to_y      = index_to_xy(to_idx)
 636         local moves           = meta:get_string("moves")
 637         local pieceFrom_s     = pieceFrom:match(":(%w+_%w+)")
 638         local pieceFrom_si_id = pieces_str:match("(%d+)=" .. pieceFrom_s)
 639         local pieceTo_si_id   = pieceTo_s ~= "" and pieces_str:match("(%d+)=" .. pieceTo_s) or ""
 640
 641         local coordFrom = letters[from_x + 1] .. math.abs(from_y - 8)
 642         local coordTo   = letters[to_x   + 1] .. math.abs(to_y   - 8)
 643
 644         local new_moves = pieceFrom_si_id .. "," ..
 645                 coordFrom .. "," ..
 646                         (pieceTo ~= "" and "#33FF33" or "#FFFFFF") .. ", > ,#FFFFFF," ..
 647                 coordTo .. "," ..
 648                 (pieceTo ~= "" and pieceTo_si_id or "69") .. "," ..
 649                 moves
 650
 651         meta:set_string("moves", new_moves)
 652 end
 653
 654 local function get_eaten_list(meta, pieceTo, pieceTo_s)
 655         local eaten = meta:get_string("eaten")
 656         if pieceTo ~= "" then
 657                 eaten = eaten .. pieceTo_s .. ","
 658         end
 659
 660         meta:set_string("eaten", eaten)
 661
 662         local eaten_t   = string.split(eaten, ",")
 663         local eaten_img = ""
 664
 665         local a, b = 0, 0
 666         for i = 1, #eaten_t do
 667                 local is_white = eaten_t[i]:sub(-5,-1) == "white"
 668                 local X = (is_white and a or b) % 4
 669                 local Y = ((is_white and a or b) % 16 - X) / 4
 670
 671                 if is_white then
 672                         a = a + 1
 673                 else
 674                         b = b + 1
 675                 end
 676
 677                 eaten_img = eaten_img ..
 678                         "image[" .. ((X + (is_white and 11.67 or 8.8)) - (X * 0.45)) .. "," ..
 679                                     ((Y + 5.56) - (Y * 0.2)) .. ";1,1;" .. eaten_t[i] .. ".png]"
 680         end
 681
 682         meta:set_string("eaten_img", eaten_img)
 683 end
 684
 685 function realchess.init(pos)
 686         local meta = minetest.get_meta(pos)
 687         local inv  = meta:get_inventory()
 688
 689         meta:set_string("formspec", fs)
 690         meta:set_string("infotext", "Chess Board")
 691         meta:set_string("playerBlack", "")
 692         meta:set_string("playerWhite", "")
 693         meta:set_string("lastMove",    "")
 694         meta:set_string("blackAttacked", "")
 695         meta:set_string("whiteAttacked", "")
 696
 697         meta:set_int("lastMoveTime",   0)
 698         meta:set_int("castlingBlackL", 1)
 699         meta:set_int("castlingBlackR", 1)
 700         meta:set_int("castlingWhiteL", 1)
 701         meta:set_int("castlingWhiteR", 1)
 702
 703         meta:set_string("moves", "")
 704         meta:set_string("eaten", "")
 705
 706         inv:set_list("board", pieces)
 707         inv:set_size("board", 64)
 708 end
 709
 710 function realchess.move(pos, from_list, from_index, to_list, to_index, _, player)
 711         if from_list ~= "board" and to_list ~= "board" then
 712                 return 0
 713         end
 714
 715         local meta        = minetest.get_meta(pos)
 716         local playerName  = player:get_player_name()
 717         local inv         = meta:get_inventory()
 718         local pieceFrom   = inv:get_stack(from_list, from_index):get_name()
 719         local pieceTo     = inv:get_stack(to_list, to_index):get_name()
 720         local lastMove    = meta:get_string("lastMove")
 721         local playerWhite = meta:get_string("playerWhite")
 722         local playerBlack = meta:get_string("playerBlack")
 723         local thisMove    -- Will replace lastMove when move is legal
 724
 725         if pieceFrom:find("white") then
 726                 if playerWhite ~= "" and playerWhite ~= playerName then
 727                         minetest.chat_send_player(playerName, chat_prefix .. "Someone else plays white pieces!")
 728                         return 0
 729                 end
 730
 731                 if lastMove ~= "" and lastMove ~= "black" then
 732                         return 0
 733                 end
 734
 735                 if pieceTo:find("white") then
 736                         -- Don't replace pieces of same color
 737                         return 0
 738                 end
 739
 740                 playerWhite = playerName
 741                 thisMove = "white"
 742
 743         elseif pieceFrom:find("black") then
 744                 if playerBlack ~= "" and playerBlack ~= playerName then
 745                         minetest.chat_send_player(playerName, chat_prefix .. "Someone else plays black pieces!")
 746                         return 0
 747                 end
 748
 749                 if lastMove ~= "" and lastMove ~= "white" then
 750                         return 0
 751                 end
 752
 753                 if pieceTo:find("black") then
 754                         -- Don't replace pieces of same color
 755                         return 0
 756                 end
 757
 758                 playerBlack = playerName
 759                 thisMove = "black"
 760         end
 761
 762         -- MOVE LOGIC
 763
 764         local from_x, from_y = index_to_xy(from_index)
 765         local to_x, to_y     = index_to_xy(to_index)
 766
 767         -- PAWN
 768         if pieceFrom:sub(11,14) == "pawn" then
 769                 if thisMove == "white" then
 770                         local pawnWhiteMove = inv:get_stack(from_list, xy_to_index(from_x, from_y - 1)):get_name()
 771                         -- white pawns can go up only
 772                         if from_y - 1 == to_y then
 773                                 if from_x == to_x then
 774                                         if pieceTo ~= "" then
 775                                                 return 0
 776                                         elseif to_index >= 1 and to_index <= 8 then
 777                                                 inv:set_stack(from_list, from_index, "realchess:queen_white")
 778                                         end
 779                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 780                                         if not pieceTo:find("black") then
 781                                                 return 0
 782                                         elseif to_index >= 1 and to_index <= 8 then
 783                                                 inv:set_stack(from_list, from_index, "realchess:queen_white")
 784                                         end
 785                                 else
 786                                         return 0
 787                                 end
 788                         elseif from_y - 2 == to_y then
 789                                 if pieceTo ~= "" or from_y < 6 or pawnWhiteMove ~= "" then
 790                                         return 0
 791                                 end
 792                         else
 793                                 return 0
 794                         end
 795
 796                         --[[
 797                              if x not changed
 798                                   ensure that destination cell is empty
 799                              elseif x changed one unit left or right
 800                                   ensure the pawn is killing opponent piece
 801                              else
 802                                   move is not legal - abort
 803                         ]]
 804
 805                         if from_x == to_x then
 806                                 if pieceTo ~= "" then
 807                                         return 0
 808                                 end
 809                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
 810                                 if not pieceTo:find("black") then
 811                                         return 0
 812                                 end
 813                         else
 814                                 return 0
 815                         end
 816
 817                 elseif thisMove == "black" then
 818                         local pawnBlackMove = inv:get_stack(from_list, xy_to_index(from_x, from_y + 1)):get_name()
 819                         -- black pawns can go down only
 820                         if from_y + 1 == to_y then
 821                                 if from_x == to_x then
 822                                         if pieceTo ~= "" then
 823                                                 return 0
 824                                         elseif to_index >= 57 and to_index <= 64 then
 825                                                 inv:set_stack(from_list, from_index, "realchess:queen_black")
 826                                         end
 827                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 828                                         if not pieceTo:find("white") then
 829                                                 return 0
 830                                         elseif to_index >= 57 and to_index <= 64 then
 831                                                 inv:set_stack(from_list, from_index, "realchess:queen_black")
 832                                         end
 833                                 else
 834                                         return 0
 835                                 end
 836                         elseif from_y + 2 == to_y then
 837                                 if pieceTo ~= "" or from_y > 1 or pawnBlackMove ~= "" then
 838                                         return 0
 839                                 end
 840                         else
 841                                 return 0
 842                         end
 843
 844                         --[[
 845                              if x not changed
 846                                   ensure that destination cell is empty
 847                              elseif x changed one unit left or right
 848                                   ensure the pawn is killing opponent piece
 849                              else
 850                                   move is not legal - abort
 851                         ]]
 852
 853                         if from_x == to_x then
 854                                 if pieceTo ~= "" then
 855                                         return 0
 856                                 end
 857                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
 858                                 if not pieceTo:find("white") then
 859                                         return 0
 860                                 end
 861                         else
 862                                 return 0
 863                         end
 864                 else
 865                         return 0
 866                 end
 867
 868         -- ROOK
 869         elseif pieceFrom:sub(11,14) == "rook" then
 870                 if from_x == to_x then
 871                         -- Moving vertically
 872                         if from_y < to_y then
 873                                 -- Moving down
 874                                 -- Ensure that no piece disturbs the way
 875                                 for i = from_y + 1, to_y - 1 do
 876                                         if inv:get_stack(from_list, xy_to_index(from_x, i)):get_name() ~= "" then
 877                                                 return 0
 878                                         end
 879                                 end
 880                         else
 881                                 -- Mocing up
 882                                 -- Ensure that no piece disturbs the way
 883                                 for i = to_y + 1, from_y - 1 do
 884                                         if inv:get_stack(from_list, xy_to_index(from_x, i)):get_name() ~= "" then
 885                                                 return 0
 886                                         end
 887                                 end
 888                         end
 889                 elseif from_y == to_y then
 890                         -- Mocing horizontally
 891                         if from_x < to_x then
 892                                 -- mocing right
 893                                 -- ensure that no piece disturbs the way
 894                                 for i = from_x + 1, to_x - 1 do
 895                                         if inv:get_stack(from_list, xy_to_index(i, from_y)):get_name() ~= "" then
 896                                                 return 0
 897                                         end
 898                                 end
 899                         else
 900                                 -- Mocing left
 901                                 -- Ensure that no piece disturbs the way
 902                                 for i = to_x + 1, from_x - 1 do
 903                                         if inv:get_stack(from_list, xy_to_index(i, from_y)):get_name() ~= "" then
 904                                                 return 0
 905                                         end
 906                                 end
 907                         end
 908                 else
 909                         -- Attempt to move arbitrarily -> abort
 910                         return 0
 911                 end
 912
 913                 if thisMove == "white" or thisMove == "black" then
 914                         if pieceFrom:sub(-1) == "1" then
 915                                 meta:set_int("castlingWhiteL", 0)
 916                         elseif pieceFrom:sub(-1) == "2" then
 917                                 meta:set_int("castlingWhiteR", 0)
 918                         end
 919                 end
 920
 921         -- KNIGHT
 922         elseif pieceFrom:sub(11,16) == "knight" then
 923                 -- Get relative pos
 924                 local dx = from_x - to_x
 925                 local dy = from_y - to_y
 926
 927                 -- Get absolute values
 928                 if dx < 0 then dx = -dx end
 929                 if dy < 0 then dy = -dy end
 930
 931                 -- Sort x and y
 932                 if dx > dy then dx, dy = dy, dx end
 933
 934                 -- Ensure that dx == 1 and dy == 2
 935                 if dx ~= 1 or dy ~= 2 then
 936                         return 0
 937                 end
 938                 -- Just ensure that destination cell does not contain friend piece
 939                 -- ^ It was done already thus everything ok
 940
 941         -- BISHOP
 942         elseif pieceFrom:sub(11,16) == "bishop" then
 943                 -- Get relative pos
 944                 local dx = from_x - to_x
 945                 local dy = from_y - to_y
 946
 947                 -- Get absolute values
 948                 if dx < 0 then dx = -dx end
 949                 if dy < 0 then dy = -dy end
 950
 951                 -- Ensure dx and dy are equal
 952                 if dx ~= dy then return 0 end
 953
 954                 if from_x < to_x then
 955                         if from_y < to_y then
 956                                 -- Moving right-down
 957                                 -- Ensure that no piece disturbs the way
 958                                 for i = 1, dx - 1 do
 959                                         if inv:get_stack(
 960                                                 from_list, xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 961                                                 return 0
 962                                         end
 963                                 end
 964                         else
 965                                 -- Moving right-up
 966                                 -- Ensure that no piece disturbs the way
 967                                 for i = 1, dx - 1 do
 968                                         if inv:get_stack(
 969                                                 from_list, xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 970                                                 return 0
 971                                         end
 972                                 end
 973                         end
 974                 else
 975                         if from_y < to_y then
 976                                 -- Moving left-down
 977                                 -- Ensure that no piece disturbs the way
 978                                 for i = 1, dx - 1 do
 979                                         if inv:get_stack(
 980                                                 from_list, xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 981                                                 return 0
 982                                         end
 983                                 end
 984                         else
 985                                 -- Moving left-up
 986                                 -- ensure that no piece disturbs the way
 987                                 for i = 1, dx - 1 do
 988                                         if inv:get_stack(
 989                                                 from_list, xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 990                                                 return 0
 991                                         end
 992                                 end
 993                         end
 994                 end
 995
 996         -- QUEEN
 997         elseif pieceFrom:sub(11,15) == "queen" then
 998                 local dx = from_x - to_x
 999                 local dy = from_y - to_y
1000
1001                 -- Get absolute values
1002                 if dx < 0 then dx = -dx end
1003                 if dy < 0 then dy = -dy end
1004
1005                 -- Ensure valid relative move
1006                 if dx ~= 0 and dy ~= 0 and dx ~= dy then
1007                         return 0
1008                 end
1009
1010                 if from_x == to_x then
1011                         if from_y < to_y then
1012                                 -- Goes down
1013                                 -- Ensure that no piece disturbs the way
1014                                 for i = 1, dx - 1 do
1015                                         if inv:get_stack(
1016                                                 from_list, xy_to_index(from_x, from_y + i)):get_name() ~= "" then
1017                                                 return 0
1018                                         end
1019                                 end
1020                         else
1021                                 -- Goes up
1022                                 -- Ensure that no piece disturbs the way
1023                                 for i = 1, dx - 1 do
1024                                         if inv:get_stack(
1025                                                 from_list, xy_to_index(from_x, from_y - i)):get_name() ~= "" then
1026                                                 return 0
1027                                         end
1028                                 end
1029                         end
1030                 elseif from_x < to_x then
1031                         if from_y == to_y then
1032                                 -- Goes right
1033                                 -- Ensure that no piece disturbs the way
1034                                 for i = 1, dx - 1 do
1035                                         if inv:get_stack(
1036                                                 from_list, xy_to_index(from_x + i, from_y)):get_name() ~= "" then
1037                                                 return 0
1038                                         end
1039                                 end
1040                         elseif from_y < to_y then
1041                                 -- Goes right-down
1042                                 -- Ensure that no piece disturbs the way
1043                                 for i = 1, dx - 1 do
1044                                         if inv:get_stack(
1045                                                 from_list, xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
1046                                                 return 0
1047                                         end
1048                                 end
1049                         else
1050                                 -- Goes right-up
1051                                 -- Ensure that no piece disturbs the way
1052                                 for i = 1, dx - 1 do
1053                                         if inv:get_stack(
1054                                                 from_list, xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
1055                                                 return 0
1056                                         end
1057                                 end
1058                         end
1059                 else
1060                         if from_y == to_y then
1061                                 -- Goes left
1062                                 -- Ensure that no piece disturbs the way and destination cell does
1063                                 for i = 1, dx - 1 do
1064                                         if inv:get_stack(
1065                                                 from_list, xy_to_index(from_x - i, from_y)):get_name() ~= "" then
1066                                                 return 0
1067                                         end
1068                                 end
1069                         elseif from_y < to_y then
1070                                 -- Goes left-down
1071                                 -- Ensure that no piece disturbs the way
1072                                 for i = 1, dx - 1 do
1073                                         if inv:get_stack(
1074                                                 from_list, xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
1075                                                 return 0
1076                                         end
1077                                 end
1078                         else
1079                                 -- Goes left-up
1080                                 -- Ensure that no piece disturbs the way
1081                                 for i = 1, dx - 1 do
1082                                         if inv:get_stack(
1083                                                 from_list, xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
1084                                                 return 0
1085                                         end
1086                                 end
1087                         end
1088                 end
1089
1090         -- KING
1091         elseif pieceFrom:sub(11,14) == "king" then
1092                 local dx = from_x - to_x
1093                 local dy = from_y - to_y
1094                 local check = true
1095
1096                 if thisMove == "white" then
1097                         if from_y == 7 and to_y == 7 then
1098                                 if to_x == 1 then
1099                                         local castlingWhiteL = meta:get_int("castlingWhiteL")
1100                                         local idx57 = inv:get_stack(from_list, 57):get_name()
1101
1102                                         if castlingWhiteL == 1 and idx57 == "realchess:rook_white_1" then
1103                                                 for i = 58, from_index - 1 do
1104                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
1105                                                                 return 0
1106                                                         end
1107                                                 end
1108
1109                                                 inv:set_stack(from_list, 57, "")
1110                                                 inv:set_stack(from_list, 59, "realchess:rook_white_1")
1111                                                 check = false
1112                                         end
1113                                 elseif to_x == 6 then
1114                                         local castlingWhiteR = meta:get_int("castlingWhiteR")
1115                                         local idx64 = inv:get_stack(from_list, 64):get_name()
1116
1117                                         if castlingWhiteR == 1 and idx64 == "realchess:rook_white_2" then
1118                                                 for i = from_index + 1, 63 do
1119                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
1120                                                                 return 0
1121                                                         end
1122                                                 end
1123
1124                                                 inv:set_stack(from_list, 62, "realchess:rook_white_2")
1125                                                 inv:set_stack(from_list, 64, "")
1126                                                 check = false
1127                                         end
1128                                 end
1129                         end
1130                 elseif thisMove == "black" then
1131                         if from_y == 0 and to_y == 0 then
1132                                 if to_x == 1 then
1133                                         local castlingBlackL = meta:get_int("castlingBlackL")
1134                                         local idx1 = inv:get_stack(from_list, 1):get_name()
1135
1136                                         if castlingBlackL == 1 and idx1 == "realchess:rook_black_1" then
1137                                                 for i = 2, from_index - 1 do
1138                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
1139                                                                 return 0
1140                                                         end
1141                                                 end
1142
1143                                                 inv:set_stack(from_list, 1, "")
1144                                                 inv:set_stack(from_list, 3, "realchess:rook_black_1")
1145                                                 check = false
1146                                         end
1147                                 elseif to_x == 6 then
1148                                         local castlingBlackR = meta:get_int("castlingBlackR")
1149                                         local idx8 = inv:get_stack(from_list, 1):get_name()
1150
1151                                         if castlingBlackR == 1 and idx8 == "realchess:rook_black_2" then
1152                                                 for i = from_index + 1, 7 do
1153                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
1154                                                                 return 0
1155                                                         end
1156                                                 end
1157
1158                                                 inv:set_stack(from_list, 6, "realchess:rook_black_2")
1159                                                 inv:set_stack(from_list, 8, "")
1160                                                 check = false
1161                                         end
1162                                 end
1163                         end
1164                 end
1165
1166                 if check then
1167                         if dx < 0 then
1168                                 dx = -dx
1169                         end
1170
1171                         if dy < 0 then
1172                                 dy = -dy
1173                         end
1174
1175                         if dx > 1 or dy > 1 then
1176                                 return 0
1177                         end
1178                 end
1179
1180                 if thisMove == "white" then
1181                         meta:set_int("castlingWhiteL", 0)
1182                         meta:set_int("castlingWhiteR", 0)
1183
1184                 elseif thisMove == "black" then
1185                         meta:set_int("castlingBlackL", 0)
1186                         meta:set_int("castlingBlackR", 0)
1187                 end
1188         end
1189
1190         local board       = board_to_table(inv)
1191         board[to_index]   = board[from_index]
1192         board[from_index] = ""
1193
1194         local black_king_idx, white_king_idx = locate_kings(board)
1195         local blackAttacked = attacked("black", black_king_idx, board)
1196         local whiteAttacked = attacked("white", white_king_idx, board)
1197
1198         if blackAttacked then
1199                 if thisMove == "black" then
1200                         --[(*)[ and meta:get_string("blackAttacked") == "true" ]] then
1201                         return 0
1202                 else
1203                         meta:set_string("blackAttacked", "true")
1204                 end
1205         else
1206                 meta:set_string("blackAttacked", "")
1207         end
1208
1209         if whiteAttacked then
1210                 if thisMove == "white" then
1211                         --[(*)[ and meta:get_string("whiteAttacked") == "true" ]] then
1212                         return 0
1213                 else
1214                         meta:set_string("whiteAttacked", "true")
1215                 end
1216         else
1217                 meta:set_string("whiteAttacked", "")
1218         end
1219
1220         --(*) Allow a piece to move and put its king in check. Maybe not in the chess rules though?
1221
1222         lastMove = thisMove
1223         meta:set_string("lastMove", lastMove)
1224         meta:set_int("lastMoveTime", minetest.get_gametime())
1225
1226         if meta:get_string("playerWhite") == "" then
1227                 meta:set_string("playerWhite", playerWhite)
1228         elseif meta:get_string("playerBlack") == "" then
1229                 meta:set_string("playerBlack", playerBlack)
1230         end
1231
1232         local pieceTo_s = pieceTo ~= "" and pieceTo:match(":(%w+_%w+)") or ""
1233         get_moves_list(meta, pieceFrom, pieceTo, pieceTo_s, from_index, to_index)
1234         get_eaten_list(meta, pieceTo, pieceTo_s)
1235
1236         --print("from_index: " .. from_index)
1237         --print("to_index: " .. to_index)
1238
1239         return 1
1240 end
1241
1242 function realchess.on_move(pos, from_list, from_index)
1243         local meta = minetest.get_meta(pos)
1244         local inv  = meta:get_inventory()
1245         inv:set_stack(from_list, from_index, "")
1246
1247         local lastMove = meta:get_string("lastMove")
1248         if lastMove == "white" then
1249                 update_formspec(meta)
1250                 local moves = {}
1251
1252                 for i = 1, 64 do
1253                         local possibleMoves = get_possible_moves(inv, i)
1254                         local stack_name    = inv:get_stack("board", i):get_name()
1255
1256                         if stack_name:find("black") then
1257                                 moves[tostring(i)] = possibleMoves
1258                         end
1259                 end
1260
1261                 --minetest.log("warning", "moves: " .. dump(moves))
1262
1263                 local choice_from, choice_to = best_move(moves)
1264                 local pieceFrom = inv:get_stack("board", choice_from):get_name()
1265                 local pieceTo   = inv:get_stack("board", choice_to):get_name()
1266                 local pieceTo_s = pieceTo ~= "" and pieceTo:match(":(%w+_%w+)") or ""
1267
1268                 local board          = board_to_table(inv)
1269                 local black_king_idx = locate_kings(board)
1270                 local blackAttacked  = attacked("black", black_king_idx, board)
1271                 local kingSafe       = true
1272                 local bestMoveSaveFrom, bestMoveSaveTo
1273
1274                 if blackAttacked then
1275                         kingSafe = false
1276                         meta:set_string("blackAttacked", "true")
1277                         local save_moves = {}
1278
1279                         for from_idx, _ in pairs(moves) do
1280                         for to_idx, value in pairs(_) do
1281                                 from_idx = tonumber(from_idx)
1282                                 local from_idx_bak, to_idx_bak = board[from_idx], board[to_idx]
1283                                 board[to_idx]   = board[from_idx]
1284                                 board[from_idx] = ""
1285                                 black_king_idx  = locate_kings(board)
1286
1287                                 if black_king_idx then
1288                                         blackAttacked = attacked("black", black_king_idx, board)
1289                                         if not blackAttacked then
1290                                                 save_moves[from_idx] = save_moves[from_idx] or {}
1291                                                 save_moves[from_idx][to_idx] = value
1292                                         end
1293                                 end
1294
1295                                 board[from_idx], board[to_idx] = from_idx_bak, to_idx_bak
1296                         end
1297                         end
1298
1299                         if next(save_moves) then
1300                                 bestMoveSaveFrom, bestMoveSaveTo = best_move(save_moves)
1301                         end
1302                 end
1303
1304                 minetest.after(1.0, function()
1305                         local lastMoveTime = meta:get_int("lastMoveTime")
1306                         if lastMoveTime > 0 then
1307                                 if not kingSafe then
1308                                         if bestMoveSaveTo then
1309                                                 inv:set_stack("board", bestMoveSaveTo, board[bestMoveSaveFrom])
1310                                                 inv:set_stack("board", bestMoveSaveFrom, "")
1311                                                 meta:set_string("blackAttacked", "")
1312                                         else
1313                                                 return
1314                                         end
1315                                 else
1316                                         inv:set_stack("board", choice_to, pieceFrom)
1317                                         inv:set_stack("board", choice_from, "")
1318                                 end
1319
1320                                 board = board_to_table(inv)
1321                                 local _, white_king_idx = locate_kings(board)
1322                                 local whiteAttacked = attacked("white", white_king_idx, board)
1323
1324                                 if whiteAttacked then
1325                                         meta:set_string("whiteAttacked", "true")
1326                                 end
1327
1328                                 if meta:get_string("playerBlack") == "" then
1329                                         meta:set_string("playerBlack", "Dumb AI")
1330                                 end
1331
1332                                 meta:set_string("lastMove", "black")
1333                                 meta:set_int("lastMoveTime", minetest.get_gametime())
1334
1335                                 get_moves_list(meta, pieceFrom, pieceTo, pieceTo_s, choice_from, choice_to)
1336                                 get_eaten_list(meta, pieceTo, pieceTo_s)
1337
1338                                 update_formspec(meta)
1339                         end
1340                 end)
1341         else
1342                 update_formspec(meta)
1343         end
1344
1345         return false
1346 end
1347
1348 local function timeout_format(timeout_limit)
1349         local time_remaining = timeout_limit - minetest.get_gametime()
1350         local minutes        = math.floor(time_remaining / 60)
1351         local seconds        = time_remaining % 60
1352
1353         if minutes == 0 then
1354                 return seconds .. " sec."
1355         end
1356
1357         return minutes .. " min. " .. seconds .. " sec."
1358 end
1359
1360 function realchess.fields(pos, _, fields, sender)
1361         local playerName    = sender:get_player_name()
1362         local meta          = minetest.get_meta(pos)
1363         local timeout_limit = meta:get_int("lastMoveTime") + 300
1364         local playerWhite   = meta:get_string("playerWhite")
1365         local playerBlack   = meta:get_string("playerBlack")
1366         local lastMoveTime  = meta:get_int("lastMoveTime")
1367         if fields.quit then return end
1368
1369         -- Timeout is 5 min. by default for resetting the game (non-players only)
1370         if fields.new then
1371                 if (playerWhite == playerName or playerBlack == playerName) then
1372                         realchess.init(pos)
1373
1374                 elseif lastMoveTime > 0 then
1375                         if minetest.get_gametime() >= timeout_limit and
1376                                         (playerWhite ~= playerName or playerBlack ~= playerName) then
1377                                 realchess.init(pos)
1378                         else
1379                                 minetest.chat_send_player(playerName, chat_prefix ..
1380                                         "You can't reset the chessboard, a game has been started. " ..
1381                                         "If you aren't a current player, try again in " ..
1382                                         timeout_format(timeout_limit))
1383                         end
1384                 end
1385         end
1386 end
1387
1388 function realchess.dig(pos, player)
1389         if not player then
1390                 return false
1391         end
1392
1393         local meta          = minetest.get_meta(pos)
1394         local playerName    = player:get_player_name()
1395         local timeout_limit = meta:get_int("lastMoveTime") + 300
1396         local lastMoveTime  = meta:get_int("lastMoveTime")
1397
1398         -- Timeout is 5 min. by default for digging the chessboard (non-players only)
1399         return (lastMoveTime == 0 and minetest.get_gametime() > timeout_limit) or
1400                 minetest.chat_send_player(playerName, chat_prefix ..
1401                                 "You can't dig the chessboard, a game has been started. " ..
1402                                 "Reset it first if you're a current player, or dig it again in " ..
1403                                 timeout_format(timeout_limit))
1404 end
1405
1406 minetest.register_node(":realchess:chessboard", {
1407         description = "Chess Board",
1408         drawtype = "nodebox",
1409         paramtype = "light",
1410         paramtype2 = "facedir",
1411         inventory_image = "chessboard_top.png",
1412         wield_image = "chessboard_top.png",
1413         tiles = {"chessboard_top.png", "chessboard_top.png", "chessboard_sides.png"},
1414         groups = {choppy=3, oddly_breakable_by_hand=2, flammable=3},
1415         sounds = default.node_sound_wood_defaults(),
1416         node_box = {type = "fixed", fixed = {-.375, -.5, -.375, .375, -.4375, .375}},
1417         sunlight_propagates = true,
1418         on_rotate = screwdriver.rotate_simple,
1419         can_dig = realchess.dig,
1420         on_construct = realchess.init,
1421         on_receive_fields = realchess.fields,
1422         allow_metadata_inventory_move = realchess.move,
1423         on_metadata_inventory_move = realchess.on_move,
1424         allow_metadata_inventory_take = function() return 0 end
1425 })
1426
1427 local function register_piece(name, count)
1428         for _, color in pairs({"black", "white"}) do
1429         if not count then
1430                 minetest.register_craftitem(":realchess:" .. name .. "_" .. color, {
1431                         description = color:gsub("^%l", string.upper) .. " " .. name:gsub("^%l", string.upper),
1432                         inventory_image = name .. "_" .. color .. ".png",
1433                         stack_max = 1,
1434                         groups = {not_in_creative_inventory=1}
1435                 })
1436         else
1437                 for i = 1, count do
1438                         minetest.register_craftitem(":realchess:" .. name .. "_" .. color .. "_" .. i, {
1439                                 description = color:gsub("^%l", string.upper) .. " " .. name:gsub("^%l", string.upper),
1440                                 inventory_image = name .. "_" .. color .. ".png",
1441                                 stack_max = 1,
1442                                 groups = {not_in_creative_inventory=1}
1443                         })
1444                 end
1445         end
1446         end
1447 end
1448
1449 register_piece("pawn", 8)
1450 register_piece("rook", 2)
1451 register_piece("knight", 2)
1452 register_piece("bishop", 2)
1453 register_piece("queen")
1454 register_piece("king")
1455
1456 -- Recipes
1457
1458 minetest.register_craft({
1459         output = "realchess:chessboard",
1460         recipe = {
1461                 {"dye:black", "dye:white", "dye:black"},
1462                 {"stairs:slab_wood", "stairs:slab_wood", "stairs:slab_wood"}
1463         }
1464 })