-- This module renders the calendar seen on [[Portal:Current events]].



--[[

	Incoming expected variables:

		frame.args.year = Integer value for year

		frame.args.month = Integer value for month, 1 based.

--]]



local p = {}



local function makeWikilink(link, display)

	if display then

		return string.format('[[%s|%s]]', link, display)

	else

		return string.format('[[%s]]', link)

	end

end



local function getDateStuff(argsDate)

--[[

	Note: This function takes advantage of the formatDate's second argument to

	create data for the archival calendars. If the second arg (argsDate) is nil,

	then formatDate assumes the current date/time.

--]]



	local lang = mw.language.getContentLanguage()

	local firstOfMonth = lang:formatDate('01-m-Y', argsDate)

	return {

		argsDate = argsDate,

		year = tonumber(lang:formatDate('Y', argsDate)),

		month = lang:formatDate('F', argsDate),

		monthAndYear = lang:formatDate('F Y', argsDate),

		previousMonthAndYear = lang:formatDate('F Y', firstOfMonth .. ' -1 month'),

		nextMonthAndYear = lang:formatDate('F Y', firstOfMonth .. ' +1 month'),

		day = tonumber(lang:formatDate('j', argsDate)),

		daysInMonth = tonumber(lang:formatDate('j', firstOfMonth .. ' +1 month -1 day')),

		-- Weekday of the first day of the month

		-- Make compatible with Lua tables so we add 1. Sunday = 1, Saturday = 7.

		firstWeekday = tonumber(lang:formatDate('w', firstOfMonth)) + 1

	}

end



local function isLinkworthy(day, currentDay)

	-- Returns true if the calendar day should be linked, and false if not. Days

	-- should be linked if they are the current day or if they are within the six

	-- preceding days, as that is the number of items on the current events page.

	return currentDay - 6 <= day and day <= currentDay

end



local function makeDayStrings(dateStuff)

	local calStrings = {}

	local currentDay = dateStuff.day

	local currentMonth = dateStuff.month

	local currentYear = dateStuff.year

	for day = 1, dateStuff.daysInMonth do

		if dateStuff.argsDate or isLinkworthy(day, currentDay) then

			table.insert(calStrings, string.format(

				"[[#%d %s %d|%d]]",

				currentYear,

				currentMonth,

				day,

				day

			))

		else

			table.insert(calStrings, tostring(day))

		end

	end

	return calStrings

end



local function export(dayStrings, dateStuff)

	-- Generates the calendar HTML.

	local monthAndYear = dateStuff.monthAndYear

	local root = mw.html.create('table')

	root

		:addClass('current-events-calendar')

		-- Make the table-layout-based Archive pages look good. When the Archives

		-- have been converted to a grid-based layout, this logic can be removed,

		-- and the corressponding CSS margin attribute can be simplified.

		:addClass(dateStuff.argsDate and 'current-events-calendar-archive')

		-- Headings

		:tag('caption')

			:tag('span')

				:addClass('noprint')

				:wikitext(makeWikilink(

					'Portal:Current events/' .. dateStuff.previousMonthAndYear,

					'◀'

				))

				:done()

			:tag('span')

				:wikitext(makeWikilink(

					'Portal:Current events/' .. monthAndYear,

					monthAndYear

				))

				:done()

			:tag('span')

				:addClass('noprint')

				:wikitext(makeWikilink(

					'Portal:Current events/' .. dateStuff.nextMonthAndYear,

					'▶'

				))



	-- Day of week headings

	local dayHeadingRow = root:tag('tr')

	local weekdays = {'S', 'M', 'T', 'W', 'T', 'F', 'S'}

	for _, weekday in ipairs(weekdays) do

		dayHeadingRow:tag('th'):wikitext(weekday)

	end



	-- Days

	-- Tracks the number of day cells. Negative values used for initial blank cells.

	local cellCount = 1 - dateStuff.firstWeekday

	while cellCount < #dayStrings do -- Weekly rows

		local weeklyRow = root:tag('tr')

		for i = 1, 7 do -- Always make 7 cells.

			cellCount = cellCount + 1

			-- Use a blank cell if there is no corresponding dateString

			local dayString = dayStringscellCount or ''

			weeklyRow:tag('td'):wikitext(dayString)

		end

	end



	-- Footer

	if not dateStuff.argsDate then -- No footer necessary on Archive pages.

		root:tag('tr')

			:addClass('current-events-calendar-footer')

		    :addClass('noprint')

			:tag('td')

				:attr('colspan', '7')

				:wikitext(makeWikilink(

					'Portal:Current events/' .. monthAndYear,

					'More ' .. monthAndYear .. ' events...&nbsp;&nbsp;&nbsp;'

				))

	end

	

	return tostring(root)

end



function p.main(frame)

	local argsDate = nil

	if frame and frame.args and frame.args.year and frame.args.month then

		-- If a date is passed in, assume that the display page is an Archive page.

		-- If no date passed in, assume that the display page is the current Current Events page

		-- Construct a date, YYY-M-DD format.

		argsDate = frame.args.year .. "-" .. frame.args.month .. "-01"

	end

	local dateStuff = getDateStuff(argsDate)

	return frame:extensionTag{

		name = 'templatestyles',

		args = { src = 'Module:Current events calendar/styles.css' }

	} .. export(makeDayStrings(dateStuff), dateStuff)

end



return p