local p = {}  function chessboard(args, size, rev, letters, numbers, header, footer, align, clear)  function image_square( pc, row, col, size )  local colornames = { l = 'white', d = 'black' }  local piecenames = {  p = 'pawn',  r = 'rook',  n = 'knight',  b = 'bishop',  q = 'queen',  k = 'king',  a = 'archbishop',  c = 'chancelor',  z = 'champion',  w = 'wizard',  t = 'fool',  h = 'upside-down pawn',  m = 'upside-down rook',  s = 'upside-down knight',  f = 'upside-down king',  e = 'upside-down bishop',  g = 'upside-down queen',  }  local symnames = {  xx = 'black cross',  ox = 'white cross',  xo = 'black circle',  oo = 'white circle',  ul = 'up-left arrow',  ua = 'up arrow',  ur = 'up-right arrow',  la = 'left arrow',  ra = 'right arrow',  dl = 'down-left arrow',  da = 'down arrow',  dr = 'down-right arrow',  lr = 'left-right arrow',  ud = 'up-down arrow',  x0 = 'zero',  x1 = 'one',  x2 = 'two',  x3 = 'three',  x4 = 'four',  x5 = 'five',  x6 = 'six',  x7 = 'seven',  x8 = 'eight',  x9 = 'nine',  }   function colchar( col )  return ( 'abcdefgh' ):sub( col, col )  end   local color = mw.ustring.gsub( pc, '^.*(%w)(%w).*$', '%2' ) or ''  local piece = mw.ustring.gsub( pc, '^.*(%w)(%w).*$', '%1' ) or ''  local alt = colchar( col ) .. row .. ' '  if colornames[color] and piecenames[piece] then  alt = alt .. colornames[color] .. ' ' .. piecenames[piece]  else  alt = alt .. ( symnames[piece .. color] or piece .. ' ' .. color )  end   return string.format( '[[File:Chess %s%st45.svg|%dx%dpx|alt=%s|%s]]', piece, color, size, size, alt, alt )  end   function letters_row( rev, num_lt, num_rt )  local td = '<td style="padding: 0; vertical-align: inherit;height:18px;width:' .. size .. 'px;">'  local legends = 'abcdefgh'  local l = mw.text.split( rev and legends:reverse() or legends, '' )  return '<tr style="vertical-align:middle">\n'  .. ( num_lt and '<td style="vertical-align: inherit; padding: 0"></td>' or '' )  .. td  .. table.concat( l, '</td>' .. td )  .. '</td>'  .. ( num_rt and '<td style="vertical-align: inherit; padding: 0"></td>' or '' )  .. '\n</tr>'  end  local letters_tp = letters:match( 'both' ) or letters:match( 'top' )  local letters_bt = letters:match( 'both' ) or letters:match( 'bottom' )  local numbers_lt = numbers:match( 'both' ) or numbers:match( 'left' )  local numbers_rt = numbers:match( 'both' ) or numbers:match( 'right' )  local width = 8 * size + 2  if ( numbers_lt ) then width = width + 18 end  if ( numbers_rt ) then width = width + 18 end   local b = ''  local caption = ''   if ( letters_tp ) then b = b .. letters_row( rev, numbers_lt, numbers_rt ) .. '\n' end  b = b .. '<tr style="vertical-align:middle">'  if ( numbers_lt ) then b = b .. '<td style="padding: 0; vertical-align: inherit; width:18px;height:' .. size .. 'px">' .. (rev and 1 or 8) .. '</td>' end  b = b .. '<td colspan=8 rowspan=8 style="padding: 0; vertical-align: inherit;"><div class="chess-board" style="position:relative;">'  b = b .. string.format( '[[File:Chessboard480.svg|%dx%dpx|link=]]', 8 * size, 8 * size )  for trow = 1,8 do  local row = rev and trow or ( 9 - trow )  for tcol = 1,8 do  local col = rev and ( 9 - tcol ) or tcol  local piece = args[8 * ( 8 - row ) + col + 2] or ''  if piece:match( '%w%w' ) then  local img = image_square(piece:match('%w%w'), row, col, size )  b = b .. string.format(  '<div style="position:absolute;z-index:3;top:%dpx;left:%dpx;width:' .. size .. 'px;height:' .. size .. 'px;">%s</div>\n',  ( trow - 1 ) * size, ( tcol - 1 ) * size, img )  end  end  end  b = b .. '</div></td>'  if ( numbers_rt ) then b = b .. '<td style="width:18px;height:' .. size ..'px;padding:0">' .. (rev and 1 or 8) .. '</td>' end  b = b .. '</tr>'  if ( numbers_lt or numbers_rt ) then  for trow = 2, 8 do  local row = rev and trow or ( 9 - trow )  b = b .. '<tr style="vertical-align:middle">'  if ( numbers_lt ) then b = b .. '<td style="padding: 0; vertical-align: inherit;height:' .. size .. 'px">' .. row .. '</td>' end  if ( numbers_rt ) then b = b .. '<td style="padding: 0; vertical-align: inherit;height:' .. size .. 'px">' .. row .. '</td>' end  b = b .. '</tr>\n'  end  end  if ( letters_bt ) then b = b .. letters_row( rev, numbers_lt, numbers_rt ) .. '\n' end   if footer:match( '^%s*$' )  then  else  caption = '<div class="thumbcaption">' .. footer .. '</div>\n'  end   return '<div class="thumb ' .. align .. '" style="clear:' .. clear .. '; text-align:center;">'  .. header .. '\n<div class="thumbinner" style="width:' .. width .. 'px;">\n'  .. '<table cellpadding=0 cellspacing=0 style="background:white; font-size:88%; border:1px #b0b0b0 solid; padding:0; '  .. 'margin:auto;">\n' .. b .. '\n</table>\n' .. caption .. '</div></div>' end  function convertFenToArgs( fen )  -- converts FEN notation to 64 entry array of positions, offset by 2  local res = { ' ', ' ' }  -- Loop over rows, which are delimited by /  for srow in string.gmatch( "/" .. fen, "/%w+" ) do  -- Loop over all letters and numbers in the row  for piece in srow:gmatch( "%w" ) do  if piece:match( "%d" ) then -- if a digit  for k=1,piece do  table.insert(res,' ')  end  else -- not a digit  local color = piece:match( '%u' ) and 'l' or 'd'  piece = piece:lower()  table.insert( res, piece .. color )  end  end  end   return res end  function convertArgsToFen( args, offset )  function nullOrWhitespace( s ) return not s or s:match( '^%s*(.-)%s*$' ) == '' end  function piece( s )  return nullOrWhitespace( s ) and 1  or s:gsub( '%s*(%a)(%a)%s*', function( a, b ) return b == 'l' and a:upper() or a end )  end   local res = ''  offset = offset or 0  for row = 1, 8 do  for file = 1, 8 do  res = res .. piece( args[8*(row - 1) + file + offset] )  end  if row < 8 then res = res .. '/' end  end  return mw.ustring.gsub(res, '1+', function( s ) return #s end ) end  function p.board(frame)  local args = frame.args  local pargs = frame:getParent().args  local size = args.size or pargs.size or '26'  local reverse = ( args.reverse or pargs.reverse or '' ):lower() == "true"  local letters = ( args.letters or pargs.letters or 'both' ):lower()  local numbers = ( args.numbers or pargs.numbers or 'both' ):lower()  local header = args[2] or pargs[2] or ''  local footer = args[67] or pargs[67] or ''  local align = ( args[1] or pargs[1] or 'tright' ):lower()  local clear = args.clear or pargs.clear or ( align:match('tright') and 'right' ) or 'none'  local fen = args.fen or pargs.fen   size = mw.ustring.match( size, '[%d]+' ) or '26' -- remove px from size  if (fen) then  align = args.align or pargs.align or 'tright'  clear = args.clear or pargs.clear or ( align:match('tright') and 'right' ) or 'none'  header = args.header or pargs.header or ''  footer = args.footer or pargs.footer or ''  return chessboard( convertFenToArgs( fen ), size, reverse, letters, numbers, header, footer, align, clear )  end  if args[3] then  return chessboard(args, size, reverse, letters, numbers, header, footer, align, clear)  else  return chessboard(pargs, size, reverse, letters, numbers, header, footer, align, clear)  end end  function p.fen2ascii(frame)  -- {{#invoke:Chessboard|fen2ascii|fen=...}}  local b = convertFenToArgs( frame.args.fen )  local res = '|=\n'  local offset = 2  for row = 1,8 do  local n = (9 - row)  res = res .. n .. ' |' ..  table.concat(b, '|', 8*(row-1) + 1 + offset, 8*(row-1) + 8 + offset) .. '|=\n'  end  res = mw.ustring.gsub( res,'\| \|', '| |' )  res = mw.ustring.gsub( res,'\| \|', '| |' )  res = res .. ' a b c d e f g h'  return res end  function p.ascii2fen( frame )  -- {{#invoke:Chessboard|ascii2fen|kl| | |....}}  return convertArgsToFen( frame.args, frame.args.offset or 1 ) end  return p