local p = {}

local function image_square( pc, row, col, size )
	local colornames = {
		l = { m = 'белый', f = 'белая' },
		d = { m = 'чёрный', f = 'чёрная' }
	}
	local piecenames = { 
		p = { name = 'пешка', gender = 'f' },
		r = { name = 'ладья', gender = 'f' },
		n = { name = 'конь', gender = 'm' },
		b = { name = 'слон', gender = 'm' },
		q = { name = 'ферзь', gender = 'm' },
		k = { name = 'король', gender = 'm' },
		a = { name = 'архиепископ', gender = 'm' },
		c = { name = 'канцлер', gender = 'm' },
		z = { name = 'чемпион', gender = 'm' },
		w = { name = 'колдун', gender = 'm' },
		t = { name = 'шут', gender = 'm' },
		h = { name = 'перевёрнутая пешка', gender = 'f' },
		m = { name = 'перевёрнутая ладья', gender = 'f' },
		s = { name = 'перевёрнутый конь', gender = 'm' },
		f = { name = 'перевёрнутый король', gender = 'm' },
		e = { name = 'перевёрнутый слон', gender = 'm' },
		g = { name = 'перевёрнутый ферзь', gender = 'm' },
		G = { name = 'жираф', gender = 'm' },
		U = { name = 'единорог', gender = 'm' },
		Z = { name = 'зебра', gender = 'f' }
	}
	local symnames = {
		xx = 'чёрный крест',
		ox = 'белый крест',
		xo = 'чёрный круг',
		oo = 'белый круг',
		ul = 'стрелка вверх-влево',
		ua = 'стрелка вверх',
		ur = 'стрелка вверх-вправо',
		la = 'стрелка влево',
		ra = 'стрелка вправо',
		dl = 'стрелка вниз-влево',
		da = 'стрелка вниз',
		dr = 'стрелка вниз-вправо',
		lr = 'стрелка влево-вправо',
		ud = 'стрелка вверх-вниз',
		x0 = 'ноль',
		x1 = 'один',
		x2 = 'два',
		x3 = 'три',
		x4 = 'четыре',
		x5 = 'пять',
		x6 = 'шесть',
		x7 = 'семь',
		x8 = 'восемь',
		x9 = 'девять',
	}
	local colchar = {'a','b','c','d','e','f','g','h'}
    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]['gender']] .. ' ' .. piecenames[piece]['name']
    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
    
local function innerboard(args, size, rev)
	local root = mw.html.create('div')
	root:addClass('chess-board')
		:css('position', 'relative')
		:wikitext(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 )
               root:tag('div')
               		:css('position', 'absolute')
               		:css('z-index', '3')
               		:css('top', tostring(( trow - 1 ) * size) .. 'px')
               		:css('left', tostring(( tcol - 1 ) * size) .. 'px')
               		:css('width', size .. 'px')
               		:css('height', size .. 'px')
               		:wikitext(img)
            end
        end
    end

    return tostring(root)
end

function chessboard(args, size, rev, letters, numbers, header, footer, align, clear)
    function letters_row( rev, num_lt, num_rt )
        local letters = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'}
        local root = mw.html.create('')
        if num_lt then
        	root:tag('th')
        		:css('vertical-align', 'inherit')
        		:css('padding', '0')
        end
        for k = 1,8 do
        	root:tag('th')
        		:attr('scope', 'col')
        		:css('padding', '0')
        		:css('vartical-align', 'inherit')
        		:css('font-weight', 'normal')
        		:css('height', '18px')
        		:css('width', size .. 'px')
        		:wikitext(rev and letters[9-k] or letters[k])
        end
        if num_rt then
        	root:tag('th')
        		:css('vertical-align', 'inherit')
        		:css('padding', '0')
        end
        return tostring(root)
    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 root = mw.html.create('div')
    	:addClass('thumb')
    	:addClass(align)
    	:css('clear', clear)
    	:css('text-align', 'center')
    local div = root:tag('div')
    	:addClass('thumbinner')
    	:css('width', width .. 'px')
    local b = div:tag('table')
    	:attr('cellpadding', '0')
    	:attr('cellspacing', '0')
    	:css('background', 'white')
    	:css('font-size', '88%')
    	:css('border' , '1px #b0b0b0 solid')
    	:css('padding', '0')
    	:css('margin', 'auto')

	b:tag('caption')
		:css('font-weight', 'normal')
		:css('font-size', '120%')
    	:wikitext(header)

    if ( letters_tp ) then
        b:tag('tr')
        	:css('vertical-align', 'middle')
        	:wikitext(letters_row( rev, numbers_lt, numbers_rt ))
    end
    local tablerow = b:tag('tr'):css('vertical-align','middle')
    if ( numbers_lt ) then 
    	tablerow:tag('td')
    		:css('padding', '0')
    		:css('vertical-align', 'inherit')
    		:css('width', '18px')
    		:css('height', size .. 'px')
    		:wikitext(rev and 1 or 8) 
    end
    local td = tablerow:tag('td')
    	:attr('colspan', 8)
    	:attr('rowspan', 8)
    	:css('padding', '0')
    	:css('vertical-align', 'inherit')
    	:wikitext(innerboard(args, size, rev))
	
    if ( numbers_rt ) then 
    	tablerow:tag('td')
    		:css('padding', '0')
    		:css('vertical-align', 'inherit')
    		:css('width', '18px')
    		:css('height', size .. 'px')
    		:wikitext(rev and 1 or 8) 
    end
    if ( numbers_lt or numbers_rt ) then
       for trow = 2, 8 do
          local idx = rev and trow or ( 9 - trow )
          tablerow = b:tag('tr')
          	:css('vertical-align', 'middle')
          if ( numbers_lt ) then 
          	tablerow:tag('th')
        		:attr('scope', 'row')
          		:css('padding', '0')
          		:css('vertical-align', 'inherit')
        		:css('font-weight', 'normal')
          		:css('height', size .. 'px')
          		:wikitext(idx)
          end
          if ( numbers_rt ) then 
          	tablerow:tag('th')
        		:attr('scope', 'row')
          		:css('padding', '0')
          		:css('vertical-align', 'inherit')
        		:css('font-weight', 'normal')
          		:css('height', size .. 'px')
          		:wikitext(idx)
          end
       end
    end
    if ( letters_bt ) then
        b:tag('tr')
        	:css('vertical-align', 'middle')
        	:wikitext(letters_row( rev, numbers_lt, numbers_rt ))
    end

    if (footer and mw.text.trim(footer) ~= '') then
		div:tag('div')
			:addClass('thumbcaption')
			:wikitext(footer)
	end

    return tostring(root)
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