-- This module takes a list of dates and adds a marker highlighting the closest

-- date in the future.



local p = {}

local lang = mw.language.getContentLanguage()



local function normalizeDate(timestamp)

	local success, date = pcall(lang.formatDate, lang, 'Y-m-d', timestamp)

	return success and date

end



local function makeData(args)

	local data, unsorted = {}, {}

	for k, v in pairs(args) do

		if type(k) == 'string' then

			local datakey, num = k:match('^(.-)([1-9][0-9]*)$')

			if datakey == 'item' or datakey == 'date' then

				num = tonumber(num)

				unsortednum = unsortednum or {}

				unsortednum][datakey = v

			elseif datakey then

				error(string.format("invalid parameter '%s' detected", k), 3)

			end

		end

	end

	for num, t in pairs(unsorted) do

		if t.item and t.date then

			local date = normalizeDate(t.date)

			if not date then

				error(string.format(

					"invalid date '%s' in parameter 'date%d'",

					t.date, num

				), 3)

			end

			t.date = date

			table.insert(data, t)

		elseif t.item then

			error(string.format(

				"parameter 'item%d' was specified but parameter 'date%d' is missing",

				num, num

			), 3)

		else

			error(string.format(

				"parameter 'date%d' was specified but parameter 'item%d' is missing",

				num, num

			), 3)

		end

	end

	table.sort(data, function (t1, t2)

		return t1.date < t2.date

	end)

	return data

end



local function makeComparisonDate(gracePeriod)

	local timestamp

	if gracePeriod then

		timestamp = 'now - ' .. gracePeriod

	else

		timestamp = 'now'

	end

	local date = normalizeDate(timestamp)

	if date then

		return date

	else

		error(string.format("invalid grace period '%s'", gracePeriod), 3)

	end

end



local function makeHighlighter(color)

	color = color or '#FC6'

	local highlighter = mw.html.create('span')

	highlighter

		:css('background-color', color)

		:wikitext(lang:getArrow('forwards'))

	return tostring(highlighter)

end



function p._main(args)

	local data = makeData(args)

	local comparisonDate = makeComparisonDate(args.graceperiod)

	local highlighter = args.highlighter or makeHighlighter(args.highlightercolor)

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

	root

		:addClass(args.class)

		:cssText(args.style)

	local doneHighlight = false

	for i, t in ipairs(data) do

		local item

		if not doneHighlight and t.date >= comparisonDate then

			doneHighlight = true

			item = highlighter .. ' ' .. t.item

		else

			item = t.item

		end

		root

			:newline()

			:tag('li')

				:wikitext(item)

	end

	root:newline()

	return tostring(root)

end



function p.main(frame)

	local args = require('Module:Arguments').getArgs(frame, {

		wrappers = 'Template:Highlighted date list'

	})

	return p._main(args)

end



return p