-- increment/decrement number in dec/hex/oct format
local lexer = vis.lexers
local lpeg = vis.lpeg
if not lexer or not lpeg then return end

local Cp = lpeg.Cp()
local dec_num = lpeg.S('+-')^-1 * lexer.dec_num
local pattern = lpeg.P{ Cp * (lexer.hex_num + lexer.oct_num + dec_num) * Cp + 1 * lpeg.V(1) }

local change = function(delta)

	local win = vis.win
	local file = win.file
	local count = vis.count
	if not count then count = 1 end
	vis.count = nil -- reset count, otherwise it affects next motion

	for cursor in win:cursors_iterator() do
		-- poor man's continue statement, use break to process next cursor
		repeat
			local pos = cursor.pos
			if not pos then break end
			local word = file:text_object_word(pos);
			if not word then break end
			local data = file:content(word.start, 1024)
			if not data then break end
			local s, e = pattern:match(data)
			if not s then break end
			data = string.sub(data, s, e-1)
			if #data == 0 then break end
			-- align start and end for fileindex
			s = word.start + s - 1
			e = word.start + e - 1
			local base, format, padding = 10, 'd', 0
			if lexer.oct_num:match(data) then
				base = 8
				format = 'o'
				padding = #data
			elseif lexer.hex_num:match(data) then
				base = 16
				format = 'x'
				padding = #data - #"0x"
			end
			local number = tonumber(data, base == 8 and 8 or nil)
			if not number then
				vis:info("Not a number")
				break
			end
			number = number + delta * count
			-- string.format does not support negative hex/oct values
			if base ~= 10 and number < 0 then number = 0 end
			number = string.format((base == 16 and "0x" or "") .. "%0"..padding..format, number)
			if base == 8 and string.sub(number, 0, 1) ~= "0" then
				number = '0' .. number
			end
			file:delete(s, e - s)
			file:insert(s, number)
			cursor.pos = s
		until true
	end
end

vis:map(vis.modes.NORMAL, "<C-a>", function() change( 1) end, "Increment number")
vis:map(vis.modes.NORMAL, "<C-x>", function() change(-1) end, "Decrement number")