-- Artbarte Google Code-in, Date formatting

-- WIP



local p = {}



-- Checks if string is a format and returns format string

-- Takes string | returns format string to be applied to os.date() OR nil

function parseFormat(str)

	local formats = {mdy = "%B %d, %Y",year = "%Y",iso = "%Y-%m-%d",dmy = "%d %B %Y"}

	formats"month and year" = "%B %Y"

	

	return formatsstr

end



-- Checks if string is a month or month abbreviation

-- Takes string | returns integer of month OR nil

function parseMonth(str)

	str = string.lower(str)

	local months = {{"January","jan"},

					{"February","feb"},

					{"March","mar"},

					{"April","apr"},

					{"May","may"},

					{"June","jun"},

					{"July","jul"},

					{"August","aug"},

					{"September","sep"},

					{"October","oct"},

					{"November","nov"},

					{"December","dec"},

					}

					

	for i,v in ipairs(months) do

		if str == string.lower(v1]) or str == v2 then

			return i

		end

	end

	return nil

end

-- Checks if the string includes on of the "circa words"

function checkIfCirca (str)

	local dateString = str

	local circa = false

	

	local circaStrings = {"%(uncertain%)", "sometime ", "around "}

	for i,v in ipairs(circaStrings) do

		dateString, matches = string.gsub(dateString , v, "")

		if  matches >= 1 then

			circa = true

		end

	end

	return circa, dateString

	end



p.parseDate = function (frame)

	local date = frame.args.date or ""

	local format = frame.args.format or ""

	

	-- 

	local circa = false

	circa, date = checkIfCirca(date)

	

	-- Pattern searches for 3 words sperated by spaces, slashes or dashes and puts them into variables: first, second, third

	local first,second,third = string.match(date, "([%w%d]+)[ /-]([%w%d]+)[, /-] ?(%d+)")



	-- If pattern didn't find any proper date format display error message

	local fields = {}

	if first ~= nil then table.insert(fields,first) else return "Invalid input <br>" end

	if second ~= nil then table.insert(fields,second) end

	if third ~= nil then table.insert(fields,third) end

	

	-- Putting fields into proper value

	local day,month,year

	for i,v in ipairs(fields) do

		local parsedMonth = parseMonth(v)

		if parsedMonth ~= nil then

			month = parsedMonth

		elseif tonumber(v) > 31 then -- year only

			year = v

		elseif tonumber(v) > 12 then -- day only

			day = v

		elseif month == nil then

			month = v

		else

			day = v

		end

	end

	

	-- Preparing the return message

	local returnMsg = date

	

	-- If format is specified 

	parsedFormat = parseFormat(format)

	if parsedFormat ~= nil then

		local time = os.time({month=month,day=day,year=year})

		returnMsg = os.date(parsedFormat, time)

	end

	

	if circa then 

	 	returnMsg = "circa " .. returnMsg

	end

	-- Return the message

	return "Input: ".. date .. " Format: " .. format .. "<br>Output: '''" .. returnMsg .. "'''<br>"

end



return p