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

local randomModule = require('Module:Random')

local yesno = require('Module:Yesno')

local slideshowModule = require('Module:Random slideshow')



p = {}



-- == Utility functions ==

local function getCleanArgs(frame)

	return getArgs(frame, {

		trim = true,

		removeBlanks = true

	})

end



local function wikiError(message)

	return mw.html.create('div'):addClass('error'):wikitext(message)

end



-- replace all newlines in the string with break tags

-- slideshow only supports single line captions

local function replaceNewlines(s)

	return mw.ustring.gsub(s, '%c', '<br />')

end



-- == Argument preparation functions ==

-- Extracts dates, custom images, and subpages from args

local function extractPictures(args)

	local dates = {}

	local images = {}

	local subpages = {}

	for key, value in pairs(args) do

		if value then

			if type(key) == "number" then

				-- positional parameters correspond to POTD dates

				table.insert(dates, value)

			elseif string.sub(key, 1, 1) == "i" then

				-- named parameters with prefixes "i", "title", "credit", and "caption"

				-- correspond to custom images

				local num = string.sub(key, 2)

				local title = args"title" .. num

				local credit = args"credit" .. num

				local caption = args"caption" .. num or ""

				local image = {

					file = value,

					title = title,

					credit = credit,

					caption = caption

				}

				table.insert(images, image)

			end

		end

	end

	local subpageMax = tonumber(args'subpagemax']) or 0

	if subpageMax > 0

	then

		local root = args'demoroot' or (mw.title.getCurrentTitle().rootPageTitle.prefixedText)

		local picturesRoot = root .. '/' .. (args'subpage' or 'Selected picture')

		for i = 1, subpageMax do

			table.insert(subpages, picturesRoot .. '/' .. tostring(i))

		end

	end

	return dates, images, subpages

end



local function getDefaultMoreLink(args)

	local root = args'demoroot' or (mw.title.getCurrentTitle().rootPageTitle.prefixedText)

	local picturesPage = args'subpage' or 'Selected picture'

	return "[[" .. root .. "/" .. picturesPage .. "|More selected pictures]]"

end



-- == Formatting functions ==

-- transclude [[Template:Portal POTD]]

local function formatPortalPotd(frame, potdDate)

	return frame:expandTemplate{

		title = "Portal POTD",

		args = {

			potdDate,

			more = 'no'

		}

	}

end



local function formatMoreHtml(more)

	if not yesno(more, true)

	then

		return ""

	end

	local moreHtml = mw.html.create('div')

		:attr("class", "noprint")

		:attr("style", "margin-top:0.5em; font-weight:bold; width:100%; text-align:right;")

		:wikitext(more)

	return tostring(moreHtml)

end



-- manual recreation of the bottom half of [[Template:Portal POTD]]

local function formatPotdText(frame, titleText, creditText, captionText, moreHtml)

	local res = frame:expandTemplate{

		title = "POTD portal layout/text",

		args = {

			title = titleText,

			credit = creditText,

			caption = captionText,

			'margin-top'='0.5em'

		}

	}

	if moreHtml

	then

		-- ideally, the "more" text should be trancluded _once_ for the whole box

		-- but we do it for _every_ image for compatibility with portals, which use numbered subpages

		res = res .. moreHtml

	end

	return res

end



local function formatFile(filename)

	local html = mw.html.create('div')

		:attr("class", "center")

		:wikitext("[[File:" .. filename .. "|380px]]")

	return tostring(html)

end



-- Extract value named "paramName" from a subpage of [[Template:POTD]]

local function getPotdPart(frame, potdSubpage, paramName)

	return frame:expandTemplate{

		title = potdSubpage,

		args = { paramName }

	}

end



-- bottom half of [[Template:Portal POTD]] for a POTD subpage

local function getPotdText(frame, potdDate, moreHtml)

	local potdText = getPotdPart(frame, "POTD/" .. potdDate, "portal layout/text")

	potdText = replaceNewlines(potdText)

	if moreHtml

	then

		potdText = potdText .. moreHtml

	end

	return potdText

end



-- prepare arguments for [[Module:Random slideshow]]

-- alternating: image1, text1, image2, text2, ...

local function makeSlideShowArgs(frame, dates, images, subpages, more, limit)

	local slideShowArgs = {}

	local moreHtml = formatMoreHtml(more)

	if #dates > 0 then

		local randomDates = randomModule.main('array', {t=dates, limit=limit})

		for _, potdDate in ipairs(randomDates) do

			local image = getPotdPart(frame, "POTD/" .. potdDate, "image")

			local image2 = ''

			if image == '{{{image}}}' then

				image = getPotdPart(frame, "POTD/" .. potdDate, "image1")

				image2 = '[[File:' .. getPotdPart(frame, "POTD/" .. potdDate, "image2") .. '|200px|center]]'

			end

			local text = image2 .. getPotdText(frame, potdDate, moreHtml)

			table.insert(slideShowArgs, image)

			table.insert(slideShowArgs, text)

		end

	end

	if #images > 0 then

		local randomImages = randomModule.main('array', {t=images, limit=limit})

		for _, image in pairs(randomImages) do

			table.insert(slideShowArgs, image'file'])

			local text = formatPotdText(frame, image'title'], image'credit'], image'caption'], moreHtml)

			table.insert(slideShowArgs, text)

		end

	end

	if #subpages > 0 then

		local randomSubpages = randomModule.main('array', {t=subpages, limit=math.floor(limit / 2)})

		for _, subpage in pairs(randomSubpages) do

			table.insert(slideShowArgs, 'Blank.png')

			local subpageContent = replaceNewlines(frame:expandTemplate{ title = subpage })

			table.insert(slideShowArgs, subpageContent)

		end

	end

	return slideShowArgs

end



-- == Main functions ==

-- Create a list gallery of all passed images

local function gallery(frame)

	local args = getCleanArgs(frame)

	local dates, images, subpages = extractPictures(args)

	local texts = {}



	for _, value in pairs(dates) do

		local topText = '<span id="Template:POTD/' .. value .. '"></span>' .. "[[Template:POTD/" .. value .. "]]\n\n"

		table.insert(texts,	topText .. formatPortalPotd(frame, value))

	end

	for _, image in pairs(images) do

		local topText = "[[:File:" .. image'file' .. "]]\n\n"

		local bottomText = formatPotdText(frame, image'title'], image'credit'], image'caption'])

		table.insert(texts, topText .. formatFile(image'file']) .. "\n\n" .. bottomText)

	end

	for _, subpage in pairs(subpages) do

		local topText = "[[:" .. subpage .. "]]\n\n"

		local subpageContent = frame:expandTemplate{ title = subpage }

		table.insert(texts, topText .. subpageContent)

	end

	return frame:preprocess(table.concat(texts, "\n----\n"))

end



-- Create a slideshow of passed images using [[Module:Random slideshow]]

local function slideShow(frame)

	local args = getCleanArgs(frame)

	local more = args"more" or getDefaultMoreLink(args)

	local dates, images, subpages = extractPictures(args)

	local limit = 15



	local slideShowArgs = makeSlideShowArgs(frame, dates, images, subpages, more, limit)



	local slideShow = slideshowModule._main(slideShowArgs, false, 'portalSlideshow-container')

	return frame:extensionTag{ name='templatestyles', args = { src='Module:Random slideshow/styles.css'} } .. frame:preprocess(slideShow)

end



-- entry point for the module

function main(frame)

	local title = mw.title.getCurrentTitle()

	if title.isSubpage

	then

		return gallery(frame)

	else

		return slideShow(frame)

	end

end



p.main = main

p.slideShow = slideShow

p.gallery = gallery



return p