--[[
* Modulo a supporto del template Avviso archivio.
]]--

require('strict')

local getArgs = require('Modulo:Arguments').getArgs

-- =============================================================================
--                           classe TitleBuilder
-- =============================================================================

local TitleBuilder = {
	currTitle = mw.title.getCurrentTitle(),
	existingBasePageTitle = nil,
	splitTitle = nil
}

function TitleBuilder:new()
	local self = {}
	local lazyFields = {
		existingBasePageTitle = TitleBuilder.getExistingBasePageTitle,
		splitTitle = TitleBuilder.getSplitTitle
	}

	setmetatable(self, {
		__index = function (t, key)
			if lazyFields[key] then
				return lazyFields[key](self)
			else
				return TitleBuilder[key]
			end
		end
	})

	self.number = nil
	self.subpageText = nil

	return self
end

function TitleBuilder:getExistingBasePageTitle()
	local basePageTitle = self.currTitle.basePageTitle

	while TitleBuilder.existingBasePageTitle == nil do
		if basePageTitle and basePageTitle.exists then
			TitleBuilder.existingBasePageTitle = basePageTitle
		elseif not basePageTitle or basePageTitle == basePageTitle.basePageTitle then
			TitleBuilder.existingBasePageTitle = self.currTitle
		else
			basePageTitle = basePageTitle.basePageTitle
		end
	end

	return TitleBuilder.existingBasePageTitle
end

function TitleBuilder:getSplitTitle()
	if TitleBuilder.splitTitle == nil then
		local pre, post = self.currTitle.prefixedText:match('^(.-)(%d+)$')
		TitleBuilder.splitTitle = { pre = pre, post = post }
	end

	return TitleBuilder.splitTitle
end

function TitleBuilder:setSubpageText(subpageText)
	self.subpageText = subpageText
	return self
end

function TitleBuilder:setNumber(distance)
	if self.splitTitle.post then
		local currNumber = tonumber(self.splitTitle.post)

		if currNumber + distance >= 1 then
			self.number = currNumber + distance
		end
	end

	return self
end

function TitleBuilder:build()
	local title

	if self.subpageText then
		title = self.existingBasePageTitle:subPageTitle(self.subpageText)
	else
		local titleTexts = {}

		if self.number and self.splitTitle.pre and self.splitTitle.post then
			local newPost = tostring(self.number)
			local pad0 = string.rep('0', #self.splitTitle.post - #newPost)
			table.insert(titleTexts, self.splitTitle.pre .. pad0 .. newPost)
			table.insert(titleTexts, self.splitTitle.pre .. newPost)
		end

		for _, titleText in ipairs(titleTexts) do
			local possibleTitle = mw.title.new(titleText)

			if possibleTitle.exists then
				title = possibleTitle
				break
			end
		end
	end

	if title then
		local wlLabel

		if #title.text > #self.existingBasePageTitle.text + 1 then
			wlLabel = title.text:sub(#self.existingBasePageTitle.text + 2)
		else
			wlLabel = title.subpageText
		end

		local customTitleFields = {
			wikilink = string.format('[[%s|%s]]', title.prefixedText, wlLabel)
		}

		return setmetatable(customTitleFields, { __index = title })
	end
end

-- =============================================================================
--                            Funzioni esportate
-- =============================================================================

local p = {}

-- Genera i link di navigazione tra le pagine di archiviazione
function p.navlinks(frame)
	local args = getArgs(frame, { parentOnly = true })
	local noRedLinks = args.noredlinks == 'y'
	local wikilinks = {}
	local wikilinkConf = {
		{ subpageText = args.prima, distance = -1 },
		{ subpageText = args.dopo, distance = 1 }
	}

	for i, item in ipairs(wikilinkConf) do
		local titleBuilder = TitleBuilder:new()

		if item.subpageText then
			titleBuilder:setSubpageText(item.subpageText)
		else
			titleBuilder:setNumber(item.distance)
		end

		local title = titleBuilder:build()

		if title and (noRedLinks == false or title.exists) then
			wikilinks[i] = title.wikilink
		end
	end

	if next(wikilinks) then
		local div = mw.html.create('div')

		div
			:css('margin', 'auto')
			:css('min-width', '20em')
			:css('width', 'fit-content')
			:wikitext(frame:expandTemplate{
				title = 'Precedente e successivo',
				args = wikilinks
			})

		return tostring(div)
	end
end

return p