-- Forked from [[Module:Sandbox/Bawolff/Chessboard]]
----------------------------------------------------

local Calculator = require('Module:Sandbox/SD0001/Calculator')
local p = {}

local cfg, nrows, ncols
cfg = {}

-- From Module:Chessboard/Chess
function cfg.dims()
	return 8, 8
end

function cfg.letters()
	return { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h' }
end

function cfg.image_board(size)
	return string.format('[[File:Chessboard480.svg|%dx%dpx|link=|class=notpageimage]]', 8 * size, 8 * size)
end

function cfg.image_square(pc, row, col, size)
	local colornames = { l = 'white', d = 'black', u = 'unknown color' }
	local piecenames = {
		p = 'pawn',
		r = 'rook',
		n = 'knight',
		b = 'bishop',
		q = 'queen',
		k = 'king',
		a = 'archbishop',
		c = 'chancellor',
		z = 'champion',
		w = 'wizard',
		t = 'fool',
		M = 'mann',
		h = 'upside-down pawn',
		m = 'upside-down rook',
		B = 'upside-down bishop',
		N = 'upside-down knight',
		f = 'upside-down king',
		g = 'upside-down queen',
		e = 'elephant',
		s = 'boat',
		G = 'giraffe',
		U = 'unicorn',
		Z = 'zebra'
	}
	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',
		db = 'up-right and down-left arrow',
		dw = 'up-left and down-right arrow',
		x0 = 'zero',
		x1 = 'one',
		x2 = 'two',
		x3 = 'three',
		x4 = 'four',
		x5 = 'five',
		x6 = 'six',
		x7 = 'seven',
		x8 = 'eight',
		x9 = 'nine'
	}
	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 .. ' '
	local alt = ''

	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|link=|class=notpageimage|top]]', piece, color, size, size, alt, alt)

end

-- End Module:Chessboard/Chess

-- From Module:Pgn

local BLACK = "black"
local WHITE = "white"

local PAWN = "P"
local ROOK = "R"
local KNIGHT = "N"
local BISHOP = "B"
local QUEEN = "Q"
local KING = "K"

local KINGSIDE = 7
local QUEENSIDE = 12

local DEFAULT_BOARD = 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR'

local bit32 = bit32 or require('bit32')

-- in lua 5.3, unpack is not a first class citizen anymore, but - assign table.unpack
local unpack = unpack or table.unpack

local function apply(f, ...)
	res = {}
	targ = { ... }
	for ind = 1, #targ do
		res[ind] = f(targ[ind])
	end
	return unpack(res)
end

local function empty(s)
	return not s or mw.text.trim(s) == ''
end

local function falseIfEmpty(s)
	return not empty(s) and s
end

local function charToFile(ch)
	return falseIfEmpty(ch) and string.byte(ch) - string.byte('a')
end

local function charToRow(ch)
	return falseIfEmpty(ch) and tonumber(ch) - 1
end

local function indexToCoords(index)
	return index % 8, math.floor(index / 8)
end

local function coordsToIndex(file, row)
	return row * 8 + file
end

local function charToPiece(letter)
	local piece = mw.ustring.upper(letter)
	return piece, piece == letter and WHITE or BLACK
end

local function pieceToChar(piece, color)
	return color == WHITE and piece or mw.ustring.lower(piece)
end

local function ambigToIndex(file, row)
	if row == nil then
		return file
	end
	return coordsToIndex(file, row)
end

local function enPasantRow(color)
	return color == WHITE and 5 or 2
end

local function sign(a)
	return a < 0 and -1
		or a > 0 and 1
		or 0
end

local function pieceAt(board, fileOrInd, row)
	-- called with 2 params, fileOrInd is the index, otherwise it's the file.
	local letter = board[ambigToIndex(fileOrInd, row)]
	if not letter then
		return
	end
	return charToPiece(letter)
end

local function findPieces(board, piece, color)
	local result = {}
	local lookFor = pieceToChar(piece, color)
	for index = 0, 63 do
		local letter = board[index]
		if letter == lookFor then
			table.insert(result, index)
		end
	end
	return result
end

local function roadIsClear(board, ind1, ind2)
	if ind1 == ind2 then
		error('call to roadIsClear with identical indices', ind1)
	end
	local file1, row1 = indexToCoords(ind1)
	local file2, row2 = indexToCoords(ind2)
	if (file1 - file2) * (row1 - row2) * (math.abs(row1 - row2) - math.abs(file1 - file2)) ~= 0 then
		error('sent two indices to roadIsClear which are not same row, col, or diagonal: ', ind1, ind2)
	end
	local hdelta = sign(file2 - file1)
	local vdelta = sign(row2 - row1)
	local row, file = row1 + vdelta, file1 + hdelta
	while row ~= row2 or file ~= file2 do
		if pieceAt(board, file, row) then
			return false
		end
		row = row + vdelta
		file = file + hdelta
	end
	return true
end

local function pawnCanMove(board, color, startFile, startRow, file, row, capture)
	local hor, ver = file - startFile, row - startRow
	local absVer = math.abs(ver)
	if capture then
		local ok = hor * hor == 1 and (
			color == WHITE and ver == 1 or
				color == BLACK and ver == -1
		)

		local enpassant = ok and
			row == enPasantRow(color) and
			pieceAt(board, file, row) == nil
		return ok, enpassant
	else
		if hor ~= 0 then
			return false
		end
	end
	if absVer == 2 then
		if not roadIsClear(board, coordsToIndex(startFile, startRow), coordsToIndex(file, row)) then
			return false
		end
		return color == WHITE and startRow == 1 and ver == 2 or
			color == BLACK and startRow == 6 and ver == -2
	end
	return color == WHITE and ver == 1 or color == BLACK and ver == -1
end

local function canMove(board, start, dest, capture, verbose)
	local startFile, startRow = indexToCoords(start)
	local file, row = indexToCoords(dest)
	local piece, color = pieceAt(board, startFile, startRow)
	if piece == PAWN then
		return pawnCanMove(board, color, startFile, startRow, file, row, capture)
	end
	local dx, dy = math.abs(startFile - file), math.abs(startRow - row)
	return piece == KNIGHT and dx * dy == 2
		or piece == KING and bit32.bor(dx, dy) == 1
		or (
		piece == ROOK and dx * dy == 0
			or piece == BISHOP and dx == dy
			or piece == QUEEN and dx * dy * (dx - dy) == 0
	) and roadIsClear(board, start, dest, verbose)
end

local function exposed(board, color)
	-- only test for queen, rook, bishop.
	local king = findPieces(board, KING, color)[1]
	for ind = 1, 63 do
		local letter = board[ind]
		if letter then
			local _, pcolor = charToPiece(letter)
			if pcolor ~= color and canMove(board, ind, king, true) then
				return true
			end
		end
	end
end

local function clone(orig)
	local res = {}
	for k, v in pairs(orig) do
		res[k] = v
	end
	return res
end

local function place(board, piece, color, file, row)
	-- in case of chess960, we have to search
	board[ambigToIndex(file, row)] = pieceToChar(piece, color)
	return board
end

local function clear(board, file, row)
	board[ambigToIndex(file, row)] = nil
	return board
end

local function doCastle(board, color, side)
	local row = color == WHITE and 0 or 7
	local startFile, step = 0, 1
	local kingDestFile, rookDestFile = 2, 3
	local king = findPieces(board, KING, color)[1]
	local rook
	if side == KINGSIDE then
		startFile, step = 7, -1
		kingDestFile, rookDestFile = 6, 5
	end
	for file = startFile, 7 - startFile, step do
		local piece = pieceAt(board, file, row)
		if piece == ROOK then
			rook = coordsToIndex(file, row)
			break
		end
	end
	board = clear(board, king)
	board = clear(board, rook)
	board = place(board, KING, color, kingDestFile, row)
	board = place(board, ROOK, color, rookDestFile, row)
	return board
end

local function doEnPassant(board, pawn, file, row)
	local _, color = pieceAt(board, pawn)
	board = clear(board, pawn)
	board = place(board, PAWN, color, file, row)
	if row == 5 then
		board = clear(board, file, 4)
	end
	if row == 2 then
		board = clear(board, file, 3)
	end
	return board
end

local function generateFen(board)
	local res = ''
	for row = 7, 0, -1 do
		for file = 0, 7 do
			piece = board[coordsToIndex(file, row)]
			res = res .. (piece or '1')
		end
		if row > 0 then
			res = res .. '/'
		end
	end
	return mw.ustring.gsub(res, '1+', function(s)
		return #s
	end)
end

local function findCandidate(board, piece, color, oldFile, oldRow, file, row, capture, notation)
	local enpassant = {}
	local candidates, newCands = findPieces(board, piece, color), {} -- all black pawns or white kings etc.
	if oldFile or oldRow then
		local newCands = {}
		for _, cand in ipairs(candidates) do
			local file, row = indexToCoords(cand)
			if file == oldFile then
				table.insert(newCands, cand)
			end
			if row == oldRow then
				table.insert(newCands, cand)
			end
		end
		candidates, newCands = newCands, {}
	end
	local dest = coordsToIndex(file, row)
	for _, candidate in ipairs(candidates) do
		local can
		can, enpassant[candidate] = canMove(board, candidate, dest, capture)
		if can then
			table.insert(newCands, candidate)
		end
	end

	candidates, newCands = newCands, {}
	if #candidates == 1 then
		return candidates[1], enpassant[candidates[1]]
	end
	if #candidates == 0 then
		error('could not find a piece that can execute ' .. notation)
	end
	-- we have more than one candidate. this means that all but one of them can't really move, b/c it will expose the king
	-- test for it by creating a new board with this candidate removed, and see if the king became exposed
	for _, candidate in ipairs(candidates) do
		local cloneBoard = clone(board) -- first, clone the board
		cloneBoard = clear(cloneBoard, candidate) -- now, remove the piece
		if not exposed(cloneBoard, color) then
			table.insert(newCands, candidate)
		end
	end
	candidates, newCands = newCands, {}
	if #candidates == 1 then
		return candidates[1]
	end
	error(mw.ustring.format('too many (%d, expected 1) pieces can execute %s at board %s', #candidates, notation, generateFen(board)))
end

local function move(board, notation, color)
	local endGame = { ['1-0'] = true, ['0-1'] = true, ['1/2-1/2'] = true, ['*'] = true }

	local cleanNotation = mw.ustring.gsub(notation, '[!?+# ]', '')

	if cleanNotation == 'O-O' then
		return doCastle(board, color, KINGSIDE)
	end
	if cleanNotation == 'O-O-O' then
		return doCastle(board, color, QUEENSIDE)
	end
	if endGame[cleanNotation] then
		return board, true
	end

	local pattern = '([RNBKQ]?)([a-h]?)([1-8]?)(x?)([a-h])([1-8])(=?[RNBKQ]?)'
	local _, _, piece, oldFile, oldRow, isCapture, file, row, promotion = mw.ustring.find(cleanNotation, pattern)
	oldFile, file = apply(charToFile, oldFile, file)
	oldRow, row = apply(charToRow, oldRow, row)
	piece = falseIfEmpty(piece) or PAWN
	promotion = falseIfEmpty(promotion)
	isCapture = falseIfEmpty(isCapture)
	local candidate, enpassant = findCandidate(board, piece, color, oldFile, oldRow, file, row, isCapture, notation) -- findCandidates should panic if # != 1
	if enpassant then
		return doEnPassant(board, candidate, file, row)
	end
	board[coordsToIndex(file, row)] = promotion and pieceToChar(promotion:sub(-1), color) or board[candidate]
	board = clear(board, candidate)
	return board
end

local function create(fen)
	-- converts FEN notation to 64 entry array of positions. copied from enwiki Module:Chessboard (in some distant past i prolly wrote it)
	local res = {}
	local row = 8
	-- Loop over rows, which are delimited by /
	for srow in string.gmatch("/" .. fen, "/%w+") do
		srow = srow:sub(2)
		row = row - 1
		local ind = row * 8
		-- Loop over all letters and numbers in the row
		for piece in srow:gmatch("%w") do
			if piece:match("%d") then
				-- if a digit
				ind = ind + piece
			else
				-- not a digit
				res[ind] = piece
				ind = ind + 1
			end
		end
	end
	return res
end

local function processMeta(grossMeta)
	res = {}
	-- process grossMEta here
	for item in mw.ustring.gmatch(grossMeta or '', '%[([^%]]*)%]') do
		key, val = item:match('([^"]+)"([^"]*)"')
		if key and val then
			res[mw.text.trim(key)] = mw.text.trim(val) -- add mw.text.trim()
		else
			error('strange item detected: ' .. item .. #items) -- error later
		end
	end
	return res
end

local function analyzePgn(pgn)
	local grossMeta = pgn:match('%[(.*)%]') -- first open to to last bracket
	pgn = string.gsub(pgn, '%[(.*)%]', '')
	local steps = mw.text.split(pgn, '%s*%d+%.%s*')
	local moves = {}
	for _, step in ipairs(steps) do
		if mw.ustring.len(mw.text.trim(step)) then
			ssteps = mw.text.split(step, '%s+')
			for _, sstep in ipairs(ssteps) do
				if sstep and not mw.ustring.match(sstep, '^%s*$') then
					table.insert(moves, sstep)
				end
			end
		end
	end
	return processMeta(grossMeta), moves
end

local function pgn2fen(pgn)
	local metadata, notationList = analyzePgn(pgn)
	local fen = metadata.fen or DEFAULT_BOARD
	local board = create(fen)
	local res = { fen }
	local colors = { BLACK, WHITE }
	for step, notation in ipairs(notationList) do
		local color = colors[step % 2 + 1]
		board = move(board, notation, color)
		local fen = generateFen(board)
		table.insert(res, fen)
	end
	return res, metadata
end

-- End Module:Pgn

-- start Module:Chessboard


local function innerboard(definedPieces, pieceInfo, size, rev)
	pattern = cfg.pattern or '%w%w'
	local root = mw.html.create('div')
	root:addClass('chess-pieces notheme')
		:css('position', 'relative')
		:wikitext(cfg.image_board(size))

	for piece in pairs(definedPieces) do
		if piece:match(pattern) then
			local img = cfg.image_square(piece:match(pattern), row, col, size)
			local curPos = pieceInfo[1][piece] or { -1, -1 }
			root:tag('div')
				:css('top', 'calc(var(--calculator-top_piece' .. piece .. ',' .. curPos[1] .. ')*1px)')
				:css('left', 'calc(var(--calculator-left_piece' .. piece .. ',' .. curPos[2] .. ')*1px)')
				:css('z-index', 'min(var(--calculator-top_piece' .. piece .. ',' .. curPos[1] .. '),0)')
				:wikitext(img)
		end
	end

	return tostring(root)
end

local function getPositions(args, size, rev)
	pattern = cfg.pattern or '%w%w'
	local pieceInfo = {}
	local definedPieces = {}

	for moveIndex, move in ipairs(args) do
		pieceInfo[moveIndex] = {}
		local layout = convertFenToArgs(move)
		for trow = 1, nrows do
			local row = rev and trow or (1 + nrows - trow)
			for tcol = 1, ncols do
				local col = rev and (1 + ncols - tcol) or tcol
				local piece = layout[ncols * (nrows - row) + col + 2] or ''
				local pieceName = piece:match(pattern)
				if pieceName then
					-- Maximum number of pieces of the same type and color is 10
					-- (eg. 2 rooks + 8 pawns each promoted to a rook)
					local pieceIdx = 1
					for i = 1, 10 do
						if not pieceInfo[moveIndex][pieceName .. i] then
							pieceIdx = i
							break
						end
					end
					definedPieces[pieceName .. pieceIdx] = true
					pieceInfo[moveIndex][pieceName .. pieceIdx] = { (trow - 1) * size, (tcol - 1) * size }
				end
			end
		end
	end

	return definedPieces, pieceInfo
end

function chessboard(definedPieces, pieceInfo, size, rev, letters, numbers, header, footer, align, clear)
	function letters_row(rev, num_lt, num_rt)
		local letters = cfg.letters()
		local root = mw.html.create('')
		if num_lt then
			root:tag('td')
		end
		for k = 1, ncols do
			root:tag('td')
				:css('height', '18px')
				:css('width', size .. 'px')
				:wikitext(rev and letters[1 + ncols - k] or letters[k])
		end
		if num_rt then
			root:tag('td')
		end
		return tostring(root)
	end

	local letters_top = letters:match('both') or letters:match('top')
	local letters_bottom = letters:match('both') or letters:match('bottom')
	local numbers_left = numbers:match('both') or numbers:match('left')
	local numbers_right = numbers:match('both') or numbers:match('right')
	local width = ncols * size + 2
	if (numbers_left) then
		width = width + 18
	end
	if (numbers_right) then
		width = width + 18
	end

	local root = mw.html.create('div')
				   :addClass('chessboard')
				   :addClass('calculator-container')
				   :addClass('thumb')
				   :addClass('noviewer')
				   :addClass(align)
	if (header and header ~= '') then
		root:tag('div')
			:addClass('center')
			:css('line-height', '130%')
			:css('margin', '0 auto')
			:css('max-width', (width + ncols) .. 'px')
			:wikitext(header)
	end
	local div = root:tag('div')
					:addClass('thumbinner')
					:css('width', width .. 'px')
	local b = div:tag('table')
				 :attr('cellpadding', '0')
				 :attr('cellspacing', '0')
				 :addClass('calculator-field')
				 :attr('data-calculator-type', 'passthru')
				 :attr('data-calculator-formula', 'rotate')

	if (letters_top) then
		b:tag('tr')
		 :wikitext(letters_row(rev, numbers_left, numbers_right))
	end
	local tablerow = b:tag('tr')
	if (numbers_left) then
		tablerow:tag('td')
				:css('width', '18px')
				:css('height', size .. 'px')
				:wikitext(rev and 1 or nrows)
	end
	local td = tablerow:tag('td')
					   :attr('colspan', ncols)
					   :attr('rowspan', nrows)
					   :addClass('pieces')
					   :wikitext(innerboard(definedPieces, pieceInfo, size, rev))

	if (numbers_right) then
		tablerow:tag('td')
				:css('width', '18px')
				:css('height', size .. 'px')
				:wikitext(rev and 1 or nrows)
	end
	if (numbers_left or numbers_right) then
		for trow = 2, nrows do
			local idx = rev and trow or (1 + nrows - trow)
			tablerow = b:tag('tr')
			if (numbers_left) then
				tablerow:tag('td')
						:css('height', size .. 'px')
						:wikitext(idx)
			end
			if (numbers_right) then
				tablerow:tag('td')
						:css('height', size .. 'px')
						:wikitext(idx)
			end
		end
	end
	if (letters_bottom) then
		b:tag('tr')
		 :wikitext(letters_row(rev, numbers_left, numbers_right))
	end

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

	return tostring(root) ..
		mw.getCurrentFrame():extensionTag('templatestyles', '', { src = 'Module:Chessboard/styles.css' })
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

local function getPieceMoves(definedPieces, pieceInfo)
	local calc = Calculator:new { scoped = false }
	for piece in pairs(definedPieces) do
		local curTop = -1
		local curLeft = -1
		local switchTop = 'switch(move,'
		local switchLeft = 'switch(move,'
		for moveNumber, move in ipairs(pieceInfo) do
			if (move[piece] and move[piece][1] or -1) ~= curTop then
				switchTop = switchTop .. (moveNumber - 1) .. ',' .. curTop .. ','
				curTop = (move[piece] and move[piece][1] or -1)
			end
			if (move[piece] and move[piece][2] or -1) ~= curLeft then
				switchLeft = switchLeft .. (moveNumber - 1) .. ',' .. curLeft .. ','
				curLeft = (move[piece] and move[piece][2] or -1)
			end
		end
		switchTop = switchTop .. curTop .. ')'
		switchLeft = switchLeft .. curLeft .. ')'

		calc:hidden {
			id = 'top_piece' .. piece,
			formula = switchTop
		}
		calc:hidden {
			id = 'left_piece' .. piece,
			formula = switchLeft
		}
	end
	return tostring(calc)
end

function p.board(frame)
	local args = frame.args
	local pargs = frame:getParent().args
	nrows, ncols = cfg.dims()

	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[nrows * ncols + 3] or pargs[nrows * ncols + 3] 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 pgn = args.pgn or pargs.pgn
	local moves, metadata
	local definedPieces, pieceInfo

	size = mw.ustring.match(size, '[%d]+') or '26' -- remove px from size

	assert(pgn, "pgn argument required")
	moves, metadata = pgn2fen(pgn)
	definedPieces, pieceInfo = getPositions(moves, size, reverse)

	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 ''
	if args.animate or pargs.animate then
		align = align .. ' animate'
	end
	local controls = Calculator:new { scoped = false, noJSFallback = '' }
	controls:button { text = '|←', ['for'] = 'move', type = 'default', formula = 1 }
	controls:button { text = '←', ['for'] = 'move', type = 'default', formula = 'max(1, move-1)' }
	controls:button { text = '☯', ['for'] = 'rotate', type = 'default', formula = '(rotate+1)%2' }
	controls:button { text = '→', ['for'] = 'move', type = 'default', formula = 'min('.. #moves..', move+1)' }
	controls:button { text = '→|', ['for'] = 'move', type = 'default', formula = #moves }
	controls:hidden { id = 'move', default = 1 }
	controls:hidden { id = 'rotate', default = 0 }

	header = header .. tostring(controls)
	footer = footer
		.. frame:extensionTag('templatestyles', '', { src = 'Module:Sandbox/SD0001/Chess3/animations.css' })
		.. getPieceMoves(definedPieces, pieceInfo)
	return chessboard(definedPieces, pieceInfo, size, reverse, letters, numbers, header, footer, align, clear)
end

return p