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         return x, y
   9 end
  10
  11 local function xy_to_index(x, y)
  12         return x + y * 8 + 1
  13 end
  14
  15 local function get_square(a, b)
  16         return (a * 8) - (8 - b)
  17 end
  18
  19 local chat_prefix = minetest.colorize("#FFFF00", "[Chess] ")
  20 local letters = {'A','B','C','D','E','F','G','H'}
  21
  22 local rowDirs = {-1, -1, -1, 0, 0, 1, 1, 1}
  23 local colDirs = {-1, 0, 1, -1, 1, -1, 0, 1}
  24
  25 local bishopThreats = {true,  false, true,  false, false, true,  false, true}
  26 local rookThreats   = {false, true,  false, true,  true,  false, true,  false}
  27 local queenThreats  = {true,  true,  true,  true,  true,  true,  true,  true}
  28 local kingThreats   = {true,  true,  true,  true,  true,  true,  true,  true}
  29
  30 local function board_to_table(inv)
  31         local t = {}
  32         for i = 1, 64 do
  33                 t[#t + 1] = inv:get_stack("board", i):get_name()
  34         end
  35
  36         return t
  37 end
  38
  39 local function attacked(color, idx, board)
  40         local threatDetected = false
  41         local kill           = color == "white"
  42         local pawnThreats    = {kill, false, kill, false, false, not kill, false, not kill}
  43
  44         for dir = 1, 8 do
  45                 if not threatDetected then
  46                         local col, row = index_to_xy(idx)
  47                         col, row = col + 1, row + 1
  48
  49                         for step = 1, 8 do
  50                                 row = row + rowDirs[dir]
  51                                 col = col + colDirs[dir]
  52
  53                                 if row >= 1 and row <= 8 and col >= 1 and col <= 8 then
  54                                         local square            = get_square(row, col)
  55                                         local square_name       = board[square]
  56                                         local piece, pieceColor = square_name:match(":(%w+)_(%w+)")
  57
  58                                         if piece then
  59                                                 if pieceColor ~= color then
  60                                                         if piece == "bishop" and bishopThreats[dir] then
  61                                                                 threatDetected = true
  62                                                         elseif piece == "rook" and rookThreats[dir] then
  63                                                                 threatDetected = true
  64                                                         elseif piece == "queen" and queenThreats[dir] then
  65                                                                 threatDetected = true
  66                                                         else
  67                                                                 if step == 1 then
  68                                                                         if piece == "pawn" and pawnThreats[dir] then
  69                                                                                 threatDetected = true
  70                                                                         end
  71                                                                         if piece == "king" and kingThreats[dir] then
  72                                                                                 threatDetected = true
  73                                                                         end
  74                                                                 end
  75                                                         end
  76                                                 end
  77                                                 break
  78                                         end
  79                                 end
  80                         end
  81                 end
  82         end
  83
  84         return threatDetected
  85 end
  86
  87 local function locate_kings(board)
  88         local Bidx, Widx
  89         for i = 1, 64 do
  90                 local piece, color = board[i]:match(":(%w+)_(%w+)")
  91                 if piece == "king" then
  92                         if color == "black" then
  93                                 Bidx = i
  94                         else
  95                                 Widx = i
  96                         end
  97                 end
  98         end
  99
 100         return Bidx, Widx
 101 end
 102
 103 local pieces = {
 104         "realchess:rook_black_1",
 105         "realchess:knight_black_1",
 106         "realchess:bishop_black_1",
 107         "realchess:queen_black",
 108         "realchess:king_black",
 109         "realchess:bishop_black_2",
 110         "realchess:knight_black_2",
 111         "realchess:rook_black_2",
 112         "realchess:pawn_black_1",
 113         "realchess:pawn_black_2",
 114         "realchess:pawn_black_3",
 115         "realchess:pawn_black_4",
 116         "realchess:pawn_black_5",
 117         "realchess:pawn_black_6",
 118         "realchess:pawn_black_7",
 119         "realchess:pawn_black_8",
 120         '','','','','','','','','','','','','','','','',
 121         '','','','','','','','','','','','','','','','',
 122         "realchess:pawn_white_1",
 123         "realchess:pawn_white_2",
 124         "realchess:pawn_white_3",
 125         "realchess:pawn_white_4",
 126         "realchess:pawn_white_5",
 127         "realchess:pawn_white_6",
 128         "realchess:pawn_white_7",
 129         "realchess:pawn_white_8",
 130         "realchess:rook_white_1",
 131         "realchess:knight_white_1",
 132         "realchess:bishop_white_1",
 133         "realchess:queen_white",
 134         "realchess:king_white",
 135         "realchess:bishop_white_2",
 136         "realchess:knight_white_2",
 137         "realchess:rook_white_2"
 138 }
 139
 140 local pieces_str, x = "", 0
 141 for i = 1, #pieces do
 142         local p = pieces[i]:match(":(%w+_%w+)")
 143         if pieces[i]:find(":(%w+)_(%w+)") and not pieces_str:find(p) then
 144                 pieces_str = pieces_str .. x .. "=" .. p .. ".png,"
 145                 x = x + 1
 146         end
 147 end
 148 pieces_str = pieces_str .. "69=mailbox_blank16.png"
 149
 150 local fs = [[
 151         size[14.7,10;]
 152         no_prepend[]
 153         bgcolor[#080808BB;true]
 154         background[0,0;14.7,10;chess_bg.png]
 155         list[context;board;0.3,1;8,8;]
 156         listcolors[#00000000;#00000000;#00000000;#30434C;#FFF]
 157         tableoptions[background=#00000000;highlight=#00000000;border=false]
 158         button[10.5,8.5;2,2;new;New game]
 159 ]] ..  "tablecolumns[image," .. pieces_str ..
 160                 ";text;color;text;color;text;image," .. pieces_str .. "]"
 161
 162 local function get_moves_list(meta, pieceFrom, pieceTo, pieceTo_s, from_x, to_x, from_y, to_y)
 163         local moves           = meta:get_string("moves")
 164         local pieceFrom_s     = pieceFrom:match(":(%w+_%w+)")
 165         local pieceFrom_si_id = pieces_str:match("(%d+)=" .. pieceFrom_s)
 166         local pieceTo_si_id   = pieceTo_s ~= "" and pieces_str:match("(%d+)=" .. pieceTo_s) or ""
 167
 168         local coordFrom = letters[from_x + 1] .. math.abs(from_y - 8)
 169         local coordTo   = letters[to_x   + 1] .. math.abs(to_y   - 8)
 170
 171         local new_moves = pieceFrom_si_id .. "," ..
 172                 coordFrom .. "," ..
 173                         (pieceTo ~= "" and "#33FF33" or "#FFFFFF") .. ", > ,#FFFFFF," ..
 174                 coordTo .. "," ..
 175                 (pieceTo ~= "" and pieceTo_si_id or "69") .. "," ..
 176                 moves
 177
 178         meta:set_string("moves", new_moves)
 179 end
 180
 181 local function get_eaten_list(meta, pieceTo, pieceTo_s)
 182         local eaten = meta:get_string("eaten")
 183         if pieceTo ~= "" then
 184                 eaten = eaten .. pieceTo_s .. ","
 185         end
 186
 187         meta:set_string("eaten", eaten)
 188
 189         local eaten_t   = string.split(eaten, ",")
 190         local eaten_img = ""
 191
 192         local a, b = 0, 0
 193         for i = 1, #eaten_t do
 194                 local is_white = eaten_t[i]:sub(-5,-1) == "white"
 195                 local X = (is_white and a or b) % 4
 196                 local Y = ((is_white and a or b) % 16 - X) / 4
 197
 198                 if is_white then
 199                         a = a + 1
 200                 else
 201                         b = b + 1
 202                 end
 203
 204                 eaten_img = eaten_img ..
 205                         "image[" .. ((X + (is_white and 11.7 or 8.8)) - (X * 0.45)) .. "," ..
 206                                     ((Y + 5.56) - (Y * 0.2)) .. ";1,1;" .. eaten_t[i] .. ".png]"
 207         end
 208
 209         meta:set_string("eaten_img", eaten_img)
 210 end
 211
 212 function realchess.init(pos)
 213         local meta = minetest.get_meta(pos)
 214         local inv  = meta:get_inventory()
 215
 216         meta:set_string("formspec", fs)
 217         meta:set_string("infotext", "Chess Board")
 218         meta:set_string("playerBlack", "")
 219         meta:set_string("playerWhite", "")
 220         meta:set_string("lastMove",    "")
 221
 222         meta:set_int("lastMoveTime",   0)
 223         meta:set_int("castlingBlackL", 1)
 224         meta:set_int("castlingBlackR", 1)
 225         meta:set_int("castlingWhiteL", 1)
 226         meta:set_int("castlingWhiteR", 1)
 227
 228         meta:set_string("moves", "")
 229         meta:set_string("eaten", "")
 230
 231         inv:set_list("board", pieces)
 232         inv:set_size("board", 64)
 233 end
 234
 235 function realchess.move(pos, from_list, from_index, to_list, to_index, _, player)
 236         if from_list ~= "board" and to_list ~= "board" then
 237                 return 0
 238         end
 239
 240         local meta        = minetest.get_meta(pos)
 241         local playerName  = player:get_player_name()
 242         local inv         = meta:get_inventory()
 243         local pieceFrom   = inv:get_stack(from_list, from_index):get_name()
 244         local pieceTo     = inv:get_stack(to_list, to_index):get_name()
 245         local lastMove    = meta:get_string("lastMove")
 246         local playerWhite = meta:get_string("playerWhite")
 247         local playerBlack = meta:get_string("playerBlack")
 248         local thisMove    -- Will replace lastMove when move is legal
 249
 250         if pieceFrom:find("white") then
 251                 if playerWhite ~= "" and playerWhite ~= playerName then
 252                         minetest.chat_send_player(playerName, chat_prefix .. "Someone else plays white pieces!")
 253                         return 0
 254                 end
 255
 256                 if lastMove ~= "" and lastMove ~= "black" then
 257                         return 0
 258                 end
 259
 260                 if pieceTo:find("white") then
 261                         -- Don't replace pieces of same color
 262                         return 0
 263                 end
 264
 265                 playerWhite = playerName
 266                 thisMove = "white"
 267
 268         elseif pieceFrom:find("black") then
 269                 if playerBlack ~= "" and playerBlack ~= playerName then
 270                         minetest.chat_send_player(playerName, chat_prefix .. "Someone else plays black pieces!")
 271                         return 0
 272                 end
 273
 274                 if lastMove ~= "" and lastMove ~= "white" then
 275                         return 0
 276                 end
 277
 278                 if pieceTo:find("black") then
 279                         -- Don't replace pieces of same color
 280                         return 0
 281                 end
 282
 283                 playerBlack = playerName
 284                 thisMove = "black"
 285         end
 286
 287         -- MOVE LOGIC
 288
 289         local from_x, from_y = index_to_xy(from_index)
 290         local to_x, to_y     = index_to_xy(to_index)
 291
 292         -- PAWN
 293         if pieceFrom:sub(11,14) == "pawn" then
 294                 if thisMove == "white" then
 295                         local pawnWhiteMove = inv:get_stack(from_list, xy_to_index(from_x, from_y - 1)):get_name()
 296                         -- white pawns can go up only
 297                         if from_y - 1 == to_y then
 298                                 if from_x == to_x then
 299                                         if pieceTo ~= "" then
 300                                                 return 0
 301                                         elseif to_index >= 1 and to_index <= 8 then
 302                                                 inv:set_stack(from_list, from_index, "realchess:queen_white")
 303                                         end
 304                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 305                                         if not pieceTo:find("black") then
 306                                                 return 0
 307                                         elseif to_index >= 1 and to_index <= 8 then
 308                                                 inv:set_stack(from_list, from_index, "realchess:queen_white")
 309                                         end
 310                                 else
 311                                         return 0
 312                                 end
 313                         elseif from_y - 2 == to_y then
 314                                 if pieceTo ~= "" or from_y < 6 or pawnWhiteMove ~= "" then
 315                                         return 0
 316                                 end
 317                         else
 318                                 return 0
 319                         end
 320
 321                         --[[
 322                              if x not changed
 323                                   ensure that destination cell is empty
 324                              elseif x changed one unit left or right
 325                                   ensure the pawn is killing opponent piece
 326                              else
 327                                   move is not legal - abort
 328                         ]]
 329
 330                         if from_x == to_x then
 331                                 if pieceTo ~= "" then
 332                                         return 0
 333                                 end
 334                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
 335                                 if not pieceTo:find("black") then
 336                                         return 0
 337                                 end
 338                         else
 339                                 return 0
 340                         end
 341
 342                 elseif thisMove == "black" then
 343                         local pawnBlackMove = inv:get_stack(from_list, xy_to_index(from_x, from_y + 1)):get_name()
 344                         -- black pawns can go down only
 345                         if from_y + 1 == to_y then
 346                                 if from_x == to_x then
 347                                         if pieceTo ~= "" then
 348                                                 return 0
 349                                         elseif to_index >= 57 and to_index <= 64 then
 350                                                 inv:set_stack(from_list, from_index, "realchess:queen_black")
 351                                         end
 352                                 elseif from_x - 1 == to_x or from_x + 1 == to_x then
 353                                         if not pieceTo:find("white") then
 354                                                 return 0
 355                                         elseif to_index >= 57 and to_index <= 64 then
 356                                                 inv:set_stack(from_list, from_index, "realchess:queen_black")
 357                                         end
 358                                 else
 359                                         return 0
 360                                 end
 361                         elseif from_y + 2 == to_y then
 362                                 if pieceTo ~= "" or from_y > 1 or pawnBlackMove ~= "" then
 363                                         return 0
 364                                 end
 365                         else
 366                                 return 0
 367                         end
 368
 369                         --[[
 370                              if x not changed
 371                                   ensure that destination cell is empty
 372                              elseif x changed one unit left or right
 373                                   ensure the pawn is killing opponent piece
 374                              else
 375                                   move is not legal - abort
 376                         ]]
 377
 378                         if from_x == to_x then
 379                                 if pieceTo ~= "" then
 380                                         return 0
 381                                 end
 382                         elseif from_x - 1 == to_x or from_x + 1 == to_x then
 383                                 if not pieceTo:find("white") then
 384                                         return 0
 385                                 end
 386                         else
 387                                 return 0
 388                         end
 389                 else
 390                         return 0
 391                 end
 392
 393         -- ROOK
 394         elseif pieceFrom:sub(11,14) == "rook" then
 395                 if from_x == to_x then
 396                         -- Moving vertically
 397                         if from_y < to_y then
 398                                 -- Moving down
 399                                 -- Ensure that no piece disturbs the way
 400                                 for i = from_y + 1, to_y - 1 do
 401                                         if inv:get_stack(from_list, xy_to_index(from_x, i)):get_name() ~= "" then
 402                                                 return 0
 403                                         end
 404                                 end
 405                         else
 406                                 -- Mocing up
 407                                 -- Ensure that no piece disturbs the way
 408                                 for i = to_y + 1, from_y - 1 do
 409                                         if inv:get_stack(from_list, xy_to_index(from_x, i)):get_name() ~= "" then
 410                                                 return 0
 411                                         end
 412                                 end
 413                         end
 414                 elseif from_y == to_y then
 415                         -- Mocing horizontally
 416                         if from_x < to_x then
 417                                 -- mocing right
 418                                 -- ensure that no piece disturbs the way
 419                                 for i = from_x + 1, to_x - 1 do
 420                                         if inv:get_stack(from_list, xy_to_index(i, from_y)):get_name() ~= "" then
 421                                                 return 0
 422                                         end
 423                                 end
 424                         else
 425                                 -- Mocing left
 426                                 -- Ensure that no piece disturbs the way
 427                                 for i = to_x + 1, from_x - 1 do
 428                                         if inv:get_stack(from_list, xy_to_index(i, from_y)):get_name() ~= "" then
 429                                                 return 0
 430                                         end
 431                                 end
 432                         end
 433                 else
 434                         -- Attempt to move arbitrarily -> abort
 435                         return 0
 436                 end
 437
 438                 if thisMove == "white" or thisMove == "black" then
 439                         if pieceFrom:sub(-1) == "1" then
 440                                 meta:set_int("castlingWhiteL", 0)
 441                         elseif pieceFrom:sub(-1) == "2" then
 442                                 meta:set_int("castlingWhiteR", 0)
 443                         end
 444                 end
 445
 446         -- KNIGHT
 447         elseif pieceFrom:sub(11,16) == "knight" then
 448                 -- Get relative pos
 449                 local dx = from_x - to_x
 450                 local dy = from_y - to_y
 451
 452                 -- Get absolute values
 453                 if dx < 0 then dx = -dx end
 454                 if dy < 0 then dy = -dy end
 455
 456                 -- Sort x and y
 457                 if dx > dy then dx, dy = dy, dx end
 458
 459                 -- Ensure that dx == 1 and dy == 2
 460                 if dx ~= 1 or dy ~= 2 then
 461                         return 0
 462                 end
 463                 -- Just ensure that destination cell does not contain friend piece
 464                 -- ^ It was done already thus everything ok
 465
 466         -- BISHOP
 467         elseif pieceFrom:sub(11,16) == "bishop" then
 468                 -- Get relative pos
 469                 local dx = from_x - to_x
 470                 local dy = from_y - to_y
 471
 472                 -- Get absolute values
 473                 if dx < 0 then dx = -dx end
 474                 if dy < 0 then dy = -dy end
 475
 476                 -- Ensure dx and dy are equal
 477                 if dx ~= dy then return 0 end
 478
 479                 if from_x < to_x then
 480                         if from_y < to_y then
 481                                 -- Moving right-down
 482                                 -- Ensure that no piece disturbs the way
 483                                 for i = 1, dx - 1 do
 484                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 485                                                 return 0
 486                                         end
 487                                 end
 488                         else
 489                                 -- Moving right-up
 490                                 -- Ensure that no piece disturbs the way
 491                                 for i = 1, dx - 1 do
 492                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 493                                                 return 0
 494                                         end
 495                                 end
 496                         end
 497                 else
 498                         if from_y < to_y then
 499                                 -- Moving left-down
 500                                 -- Ensure that no piece disturbs the way
 501                                 for i = 1, dx - 1 do
 502                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 503                                                 return 0
 504                                         end
 505                                 end
 506                         else
 507                                 -- Moving left-up
 508                                 -- ensure that no piece disturbs the way
 509                                 for i = 1, dx - 1 do
 510                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 511                                                 return 0
 512                                         end
 513                                 end
 514                         end
 515                 end
 516
 517         -- QUEEN
 518         elseif pieceFrom:sub(11,15) == "queen" then
 519                 local dx = from_x - to_x
 520                 local dy = from_y - to_y
 521
 522                 -- Get absolute values
 523                 if dx < 0 then dx = -dx end
 524                 if dy < 0 then dy = -dy end
 525
 526                 -- Ensure valid relative move
 527                 if dx ~= 0 and dy ~= 0 and dx ~= dy then
 528                         return 0
 529                 end
 530
 531                 if from_x == to_x then
 532                         if from_y < to_y then
 533                                 -- Goes down
 534                                 -- Ensure that no piece disturbs the way
 535                                 for i = 1, dx - 1 do
 536                                         if inv:get_stack(from_list, xy_to_index(from_x, from_y + i)):get_name() ~= "" then
 537                                                 return 0
 538                                         end
 539                                 end
 540                         else
 541                                 -- Goes up
 542                                 -- Ensure that no piece disturbs the way
 543                                 for i = 1, dx - 1 do
 544                                         if inv:get_stack(from_list, xy_to_index(from_x, from_y - i)):get_name() ~= "" then
 545                                                 return 0
 546                                         end
 547                                 end
 548                         end
 549                 elseif from_x < to_x then
 550                         if from_y == to_y then
 551                                 -- Goes right
 552                                 -- Ensure that no piece disturbs the way
 553                                 for i = 1, dx - 1 do
 554                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y)):get_name() ~= "" then
 555                                                 return 0
 556                                         end
 557                                 end
 558                         elseif from_y < to_y then
 559                                 -- Goes right-down
 560                                 -- Ensure that no piece disturbs the way
 561                                 for i = 1, dx - 1 do
 562                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y + i)):get_name() ~= "" then
 563                                                 return 0
 564                                         end
 565                                 end
 566                         else
 567                                 -- Goes right-up
 568                                 -- Ensure that no piece disturbs the way
 569                                 for i = 1, dx - 1 do
 570                                         if inv:get_stack(from_list, xy_to_index(from_x + i, from_y - i)):get_name() ~= "" then
 571                                                 return 0
 572                                         end
 573                                 end
 574                         end
 575                 else
 576                         if from_y == to_y then
 577                                 -- Goes left
 578                                 -- Ensure that no piece disturbs the way and destination cell does
 579                                 for i = 1, dx - 1 do
 580                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y)):get_name() ~= "" then
 581                                                 return 0
 582                                         end
 583                                 end
 584                         elseif from_y < to_y then
 585                                 -- Goes left-down
 586                                 -- Ensure that no piece disturbs the way
 587                                 for i = 1, dx - 1 do
 588                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y + i)):get_name() ~= "" then
 589                                                 return 0
 590                                         end
 591                                 end
 592                         else
 593                                 -- Goes left-up
 594                                 -- Ensure that no piece disturbs the way
 595                                 for i = 1, dx - 1 do
 596                                         if inv:get_stack(from_list, xy_to_index(from_x - i, from_y - i)):get_name() ~= "" then
 597                                                 return 0
 598                                         end
 599                                 end
 600                         end
 601                 end
 602
 603         -- KING
 604         elseif pieceFrom:sub(11,14) == "king" then
 605                 local dx = from_x - to_x
 606                 local dy = from_y - to_y
 607                 local check = true
 608
 609                 if thisMove == "white" then
 610                         if from_y == 7 and to_y == 7 then
 611                                 if to_x == 1 then
 612                                         local castlingWhiteL = meta:get_int("castlingWhiteL")
 613                                         local idx57 = inv:get_stack(from_list, 57):get_name()
 614
 615                                         if castlingWhiteL == 1 and idx57 == "realchess:rook_white_1" then
 616                                                 for i = 58, from_index - 1 do
 617                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 618                                                                 return 0
 619                                                         end
 620                                                 end
 621                                                 inv:set_stack(from_list, 57, "")
 622                                                 inv:set_stack(from_list, 59, "realchess:rook_white_1")
 623                                                 check = false
 624                                         end
 625                                 elseif to_x == 6 then
 626                                         local castlingWhiteR = meta:get_int("castlingWhiteR")
 627                                         local idx64 = inv:get_stack(from_list, 64):get_name()
 628
 629                                         if castlingWhiteR == 1 and idx64 == "realchess:rook_white_2" then
 630                                                 for i = from_index + 1, 63 do
 631                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 632                                                                 return 0
 633                                                         end
 634                                                 end
 635                                                 inv:set_stack(from_list, 62, "realchess:rook_white_2")
 636                                                 inv:set_stack(from_list, 64, "")
 637                                                 check = false
 638                                         end
 639                                 end
 640                         end
 641                 elseif thisMove == "black" then
 642                         if from_y == 0 and to_y == 0 then
 643                                 if to_x == 1 then
 644                                         local castlingBlackL = meta:get_int("castlingBlackL")
 645                                         local idx1 = inv:get_stack(from_list, 1):get_name()
 646
 647                                         if castlingBlackL == 1 and idx1 == "realchess:rook_black_1" then
 648                                                 for i = 2, from_index - 1 do
 649                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 650                                                                 return 0
 651                                                         end
 652                                                 end
 653
 654                                                 inv:set_stack(from_list, 1, "")
 655                                                 inv:set_stack(from_list, 3, "realchess:rook_black_1")
 656                                                 check = false
 657                                         end
 658                                 elseif to_x == 6 then
 659                                         local castlingBlackR = meta:get_int("castlingBlackR")
 660                                         local idx8 = inv:get_stack(from_list, 1):get_name()
 661
 662                                         if castlingBlackR == 1 and idx8 == "realchess:rook_black_2" then
 663                                                 for i = from_index + 1, 7 do
 664                                                         if inv:get_stack(from_list, i):get_name() ~= "" then
 665                                                                 return 0
 666                                                         end
 667                                                 end
 668
 669                                                 inv:set_stack(from_list, 6, "realchess:rook_black_2")
 670                                                 inv:set_stack(from_list, 8, "")
 671                                                 check = false
 672                                         end
 673                                 end
 674                         end
 675                 end
 676
 677                 if check then
 678                         if dx < 0 then
 679                                 dx = -dx
 680                         end
 681
 682                         if dy < 0 then
 683                                 dy = -dy
 684                         end
 685
 686                         if dx > 1 or dy > 1 then
 687                                 return 0
 688                         end
 689                 end
 690
 691                 if thisMove == "white" then
 692                         meta:set_int("castlingWhiteL", 0)
 693                         meta:set_int("castlingWhiteR", 0)
 694
 695                 elseif thisMove == "black" then
 696                         meta:set_int("castlingBlackL", 0)
 697                         meta:set_int("castlingBlackR", 0)
 698                 end
 699         end
 700
 701         local board       = board_to_table(inv)
 702         board[to_index]   = board[from_index]
 703         board[from_index] = ""
 704
 705         local black_king_idx, white_king_idx = locate_kings(board)
 706         local blackAttacked = attacked("black", black_king_idx, board)
 707         local whiteAttacked = attacked("white", white_king_idx, board)
 708
 709         if (thisMove == "black" and blackAttacked) or
 710            (thisMove == "white" and whiteAttacked) then
 711                 return 0
 712         end
 713
 714         lastMove = thisMove
 715
 716         meta:set_string("lastMove", lastMove)
 717         meta:set_int("lastMoveTime", minetest.get_gametime())
 718         meta:set_string("playerWhite", playerWhite)
 719         meta:set_string("playerBlack", playerBlack)
 720
 721         local pieceTo_s = pieceTo ~= "" and pieceTo:match(":(%w+_%w+)") or ""
 722         get_moves_list(meta, pieceFrom, pieceTo, pieceTo_s, from_x, to_x, from_y, to_y)
 723         get_eaten_list(meta, pieceTo, pieceTo_s)
 724
 725         return 1
 726 end
 727
 728 function realchess.on_move(pos, from_list, from_index)
 729         local meta = minetest.get_meta(pos)
 730         local inv  = meta:get_inventory()
 731         inv:set_stack(from_list, from_index, '')
 732
 733         local board = board_to_table(inv)
 734         local black_king_idx, white_king_idx = locate_kings(board)
 735         local black_king_attacked = attacked("black", black_king_idx, board)
 736         local white_king_attacked = attacked("white", white_king_idx, board)
 737
 738         local playerWhite = meta:get_string("playerWhite")
 739         local playerBlack = meta:get_string("playerBlack")
 740
 741         local moves       = meta:get_string("moves")
 742         local eaten_img   = meta:get_string("eaten_img")
 743         local lastMove    = meta:get_string("lastMove")
 744         local turnBlack   = minetest.colorize("#000001", (lastMove == "white" and playerBlack ~= "") and
 745                             playerBlack .. "..." or playerBlack)
 746         local turnWhite   = minetest.colorize("#000001", (lastMove == "black" and playerWhite ~= "") and
 747                             playerWhite .. "..." or playerWhite)
 748         local check_s     = minetest.colorize("#FF0000", "\\[check\\]")
 749
 750         local formspec = fs ..
 751                 "label[1.9,0.3;"  .. turnBlack .. (black_king_attacked and " " .. check_s or "") .. "]" ..
 752                 "label[1.9,9.15;" .. turnWhite .. (white_king_attacked and " " .. check_s or "") .. "]" ..
 753                 "table[8.9,1.05;5.07,3.75;moves;" .. moves:sub(1,-2) .. ";1]" ..
 754                 eaten_img
 755
 756         meta:set_string("formspec", formspec)
 757
 758         return false
 759 end
 760
 761 local function timeout_format(timeout_limit)
 762         local time_remaining = timeout_limit - minetest.get_gametime()
 763         local minutes        = math.floor(time_remaining / 60)
 764         local seconds        = time_remaining % 60
 765
 766         if minutes == 0 then
 767                 return seconds .. " sec."
 768         end
 769
 770         return minutes .. " min. " .. seconds .. " sec."
 771 end
 772
 773 function realchess.fields(pos, _, fields, sender)
 774         local playerName    = sender:get_player_name()
 775         local meta          = minetest.get_meta(pos)
 776         local timeout_limit = meta:get_int("lastMoveTime") + 300
 777         local playerWhite   = meta:get_string("playerWhite")
 778         local playerBlack   = meta:get_string("playerBlack")
 779         local lastMoveTime  = meta:get_int("lastMoveTime")
 780         if fields.quit then return end
 781
 782         -- Timeout is 5 min. by default for resetting the game (non-players only)
 783         if fields.new then
 784                 if (playerWhite == playerName or playerBlack == playerName) then
 785                         realchess.init(pos)
 786
 787                 elseif lastMoveTime ~= 0 then
 788                         if minetest.get_gametime() >= timeout_limit and
 789                                         (playerWhite ~= playerName or playerBlack ~= playerName) then
 790                                 realchess.init(pos)
 791                         else
 792                                 minetest.chat_send_player(playerName, chat_prefix ..
 793                                         "You can't reset the chessboard, a game has been started. " ..
 794                                         "If you aren't a current player, try again in " ..
 795                                         timeout_format(timeout_limit))
 796                         end
 797                 end
 798         end
 799 end
 800
 801 function realchess.dig(pos, player)
 802         if not player then
 803                 return false
 804         end
 805
 806         local meta          = minetest.get_meta(pos)
 807         local playerName    = player:get_player_name()
 808         local timeout_limit = meta:get_int("lastMoveTime") + 300
 809         local lastMoveTime  = meta:get_int("lastMoveTime")
 810
 811         -- Timeout is 5 min. by default for digging the chessboard (non-players only)
 812         return (lastMoveTime == 0 and minetest.get_gametime() > timeout_limit) or
 813                 minetest.chat_send_player(playerName, chat_prefix ..
 814                                 "You can't dig the chessboard, a game has been started. " ..
 815                                 "Reset it first if you're a current player, or dig it again in " ..
 816                                 timeout_format(timeout_limit))
 817 end
 818
 819 minetest.register_node(":realchess:chessboard", {
 820         description = "Chess Board",
 821         drawtype = "nodebox",
 822         paramtype = "light",
 823         paramtype2 = "facedir",
 824         inventory_image = "chessboard_top.png",
 825         wield_image = "chessboard_top.png",
 826         tiles = {"chessboard_top.png", "chessboard_top.png", "chessboard_sides.png"},
 827         groups = {choppy=3, oddly_breakable_by_hand=2, flammable=3},
 828         sounds = default.node_sound_wood_defaults(),
 829         node_box = {type = "fixed", fixed = {-.375, -.5, -.375, .375, -.4375, .375}},
 830         sunlight_propagates = true,
 831         on_rotate = screwdriver.rotate_simple,
 832         can_dig = realchess.dig,
 833         on_construct = realchess.init,
 834         on_receive_fields = realchess.fields,
 835         allow_metadata_inventory_move = realchess.move,
 836         on_metadata_inventory_move = realchess.on_move,
 837         allow_metadata_inventory_take = function() return 0 end
 838 })
 839
 840 local function register_piece(name, count)
 841         for _, color in pairs({"black", "white"}) do
 842         if not count then
 843                 minetest.register_craftitem(":realchess:" .. name .. "_" .. color, {
 844                         description = color:gsub("^%l", string.upper) .. " " .. name:gsub("^%l", string.upper),
 845                         inventory_image = name .. "_" .. color .. ".png",
 846                         stack_max = 1,
 847                         groups = {not_in_creative_inventory=1}
 848                 })
 849         else
 850                 for i = 1, count do
 851                         minetest.register_craftitem(":realchess:" .. name .. "_" .. color .. "_" .. i, {
 852                                 description = color:gsub("^%l", string.upper) .. " " .. name:gsub("^%l", string.upper),
 853                                 inventory_image = name .. "_" .. color .. ".png",
 854                                 stack_max = 1,
 855                                 groups = {not_in_creative_inventory=1}
 856                         })
 857                 end
 858         end
 859         end
 860 end
 861
 862 register_piece("pawn", 8)
 863 register_piece("rook", 2)
 864 register_piece("knight", 2)
 865 register_piece("bishop", 2)
 866 register_piece("queen")
 867 register_piece("king")
 868
 869 -- Recipes
 870
 871 minetest.register_craft({
 872         output = "realchess:chessboard",
 873         recipe = {
 874                 {"dye:black", "dye:white", "dye:black"},
 875                 {"stairs:slab_wood", "stairs:slab_wood", "stairs:slab_wood"}
 876         }
 877 })