-------------------------------------------------------------------------------

--                       Automatic archive navigator

--

-- This module produces a talk archive banner, together with an automatically-

-- generated list of navigation links to other archives of the talk page in

-- question. It implements {{Automatic archive navigator}} and

-- {{Talk archive navigation}}.

-------------------------------------------------------------------------------



local yesno = require('Module:Yesno')



-------------------------------------------------------------------------------

-- Helper functions

-------------------------------------------------------------------------------



local function makeWikilink(page, display)

	if display then

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

	else

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

	end

end



local function escapePattern(s)

	-- Escape punctuation in a string so it can be used in a Lua pattern.

	s = s:gsub('%p', '%%%0')

	return s

end



-------------------------------------------------------------------------------

-- Navigator class

-------------------------------------------------------------------------------



local Navigator = {}

Navigator.__index = Navigator



function Navigator.new(args, cfg, currentTitle)

	local obj = setmetatable({}, Navigator)

	

	-- Set inputs

	obj.args = args

	obj.cfg = cfg

	obj.currentTitle = currentTitle



	-- Archive prefix

	-- Decode HTML entities so users can enter things like "Archive " from

	-- wikitext.

	obj.archivePrefix = obj.args.prefix or obj:message('archive-prefix')

	obj.archivePrefix = mw.text.decode(obj.archivePrefix)



	-- Current archive number

	do

		local pattern = string.format(

			'^%s([1-9][0-9]*)$',

			escapePattern(obj.archivePrefix)

		)

		obj.currentArchiveNum = obj.currentTitle.subpageText:match(pattern)

		obj.currentArchiveNum = tonumber(obj.currentArchiveNum)

	end

	

	-- Highest archive number

	obj.highestArchiveNum = require('Module:Highest archive number')._main(

		 obj.currentTitle.nsText ..

		 	':' .. 

			obj.currentTitle.baseText .. 

			'/' .. 

			obj.archivePrefix

	)



	return obj

end



function Navigator:message(key, ...)

	local msg = self.cfgkey

	if select('#', ...) > 0 then

		return mw.message.newRawMessage(msg, ...):plain()

	else

		return msg

	end

end



function Navigator:makeBlurb()

	local args = self.args

	if args1 == '1' then

		-- The old template used "|1" to suppress the blurb.

		return ''

	else

		local ret

		if args.text then

			ret = args.text

		else

			local talkPage = self.currentTitle.nsText ..

				':' ..

				self.currentTitle.baseText

			if args.period then

				ret = self:message('blurb-period', talkPage, args.period)

			else

				ret = self:message('blurb-noperiod', talkPage)

			end

		end

		return ret

	end

end



function Navigator:makeMessageBox()

	local args = self.args

	

	local image

	if args.image then

		image = args.image

	else

		local icon = args.icon or self:message('default-icon')

		image = string.format(

			'[[File:%s|%s|alt=|link=]]',

			icon,

			self:message('image-size')

		)

	end



	local mbox = require('Module:Message box').main('tmbox', {

		image = image,

		imageright = args.imageright,

		style = args.style or '',

		textstyle = args.textstyle or 'text-align:center',

		text = self:makeBlurb()

	})



	return mbox

end



function Navigator:getArchiveNums()

	-- Returns an array of the archive numbers to format.

	local noLinks = tonumber(self.args.links) or self:message('default-link-count')

	noLinks = math.floor(noLinks)

	-- If |noredlinks is "yes", true or absent, don't allow red links. If it is 

	-- 'no' or false, allow red links.

	local allowRedLinks = yesno(self.args.noredlinks) == false

	

	local current = self.currentArchiveNum

	local highest = self.highestArchiveNum



	if not current or not highest or noLinks < 1 then

		return {}

	elseif noLinks == 1 then

		return {current}

	end



	local function getNum(i, current)

		-- Gets an archive number given i, the position in the array away from

		-- the current archive, and the current archive number. The first two

		-- offsets are consecutive; the third offset is rounded up to the

		-- nearest 5; and the fourth and subsequent offsets are rounded up to

		-- the nearest 10. The offsets are calculated in such a way that archive

		-- numbers will not be duplicated.

		if -2 <= i and i <= 2 then

			return current + i

		elseif -3 <= i and i <= 3 then

			return current + 2 - (current + 2) % 5 + (i / 3) * 5

		elseif 4 <= i then

			return current + 7 - (current + 7) % 10 + (i - 3) * 10

		else

			return current + 2 - (current + 2) % 10 + (i + 3) * 10

		end

	end



	local nums = {}



	-- Archive nums lower than the current page.

	for i = -1, -math.floor((noLinks - 1) / 2), -1 do

		local num = getNum(i, current)

		if num <= 1 then

			table.insert(nums, 1, 1)

			break

		else

			table.insert(nums, 1, num)

		end

	end



	-- Current page.

	if nums#nums < current then

		table.insert(nums, current)

	end



	-- Higher archive nums.

	for i = 1, math.ceil((noLinks - 1) / 2) do

		local num = getNum(i, current)

		if num <= highest then

			table.insert(nums, num)

		elseif allowRedLinks and (i <= 2 or i <= 3 and num == nums#nums + 1) then

			-- Only insert one red link, and only if it is consecutive.

			table.insert(nums, highest + 1)

			break

		elseif nums#nums < highest then

			-- Insert the highest archive number if it isn't already there.

			table.insert(nums, highest)

			break

		else

			break

		end

	end



	return nums

end



function Navigator:makeArchiveLinksWikitable()

	local lang = mw.language.getContentLanguage()

	local nums = self:getArchiveNums()

	local noLinks = #nums

	if noLinks < 1 then

		return ''

	end



	-- Make the table of links.

	local links = {}

	local isCompact = noLinks > 7

	local currentIndex

	for i, num in ipairs(nums) do

		local subpage = self.archivePrefix .. tostring(num)

		local display

		if isCompact then

			display = tostring(num)

		else

			display = self:message('archive-link-display', num)

		end

		local link = makeWikilink('../' .. subpage, display)

		if num == self.currentArchiveNum then

			link = string.format('<span style="font-size:115%%;">%s</span>', link)

			currentIndex = i

		end

		table.insert(links, link)

	end



	-- Add the arrows.

	-- We must do the forwards arrow first as we are adding elements to the

	-- links table. If we did the backwards arrow first the index for the

	-- current archive would be wrong.

	currentIndex = currentIndex or math.ceil(#links / 2)

	for i = currentIndex + 1, #links do

		if numsi - numsi - 1 > 1 then

			table.insert(links, i, lang:getArrow('forwards'))

			break

		end

	end

	for i = currentIndex - 1, 1, -1 do

		if numsi + 1 - numsi > 1 then

			table.insert(links, i + 1, lang:getArrow('backwards'))

			break

		end

	end



	-- Output the wikitable.

	local ret = {}

	local width

	if noLinks <= 3 then

		width = string.format('%dem', noLinks * 10)

	elseif noLinks <= 7 then

		width = string.format('%dem', (noLinks + 3) * 5)

	else

		width = '50em'

	end

	ret#ret + 1 = string.format(

		'{| style="width:%s;background:transparent;' ..

			'margin:0 auto 0.5em;text-align:center"',

		width

	)

	for i, s in ipairs(links) do

		if i % 20 == 1 then

			ret#ret + 1 = '\n|-'

		end

		ret#ret + 1 = '\n| '

		ret#ret + 1 = s

	end

	ret#ret + 1 = '\n|}'

	return table.concat(ret)

end



function Navigator:__tostring()

	return self:makeMessageBox() ..

		'\n' .. 

		self:makeArchiveLinksWikitable() .. 

		' __NONEWSECTIONLINK__ __NOEDITSECTION__ __ARCHIVEDTALK__'

end



-------------------------------------------------------------------------------

-- Exports

-------------------------------------------------------------------------------



local p = {}



function p._exportClasses()

	return {

		Navigator = Navigator

	}

end



function p._aan(args, cfg, currentTitle)

	cfg = cfg or mw.loadData('Module:Automatic archive navigator/config')

	currentTitle = currentTitle or mw.title.getCurrentTitle()

	local aan = Navigator.new(args, cfg, currentTitle)

	return tostring(aan)

end



function p.aan(frame)

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

		wrappers = 'Template:Automatic archive navigator',

	})

	return p._aan(args)

end



return p