Jump to content

Module:Date converter

From Wikipedia, the free encyclopedia
local p = {}

local month_names = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}

local function d_m_y(day, month, year)
	year = tonumber(year)
	day = tonumber(day)
	month = tonumber(month)
    
	-- Inverts day by year, if the date format is xxxx/xx/xx
	if (day and day > 100) then
		day, year = year, day
	end

	-- Adds two thousand if the date entered is two digits
	if (year and year < 100) then
		year = year + 2000
	end

	-- Inverts day by month, if the date format is month/day/year
	if (month and (month > 12 and month < 32)) then
		day, month = month, day
	end

	-- A few pages had a non-existent index error for the month
	if (month and (month > 12 or month < 1)) then
		month = nil
	end

	if (day and month and year) ~= nil then
		return month_names[month] .. " " .. day .. ", " .. year
	end

	return nil
end

local function m_y(month, year)
	year = tonumber(year)
	month = tonumber(month)
    
	-- Returns nil if none of the numbers are greater than 1000
	if not year or not month or (year < 1000 and month < 1000) then
		return nil
	end
	
	-- Inverts month to year, if the date format is year/month
	if month > 1000 then
		month, year = year, month
	end
	
	-- A few pages had a non-existent index error for the month
	if month > 12 or month < 1 then
		return nil
	end

	if (month and year) ~= nil then
		return month_names[month] .. " " .. year
	end

	return nil
end

function p.main(frame)
	local date = frame.args[1]
	local converted
	local day, month, year = string.match(date, "^(%d+)[/%.%-](%d+)[/%.%-](%d+)$")
	if day then
		converted = d_m_y(day, month, year)
	else
		month, year = string.match(date, "^(%d+)[/%.%-](%d+)$")
		converted = m_y(month, year)
	end
	return converted or date
end

return p