--[==[ This module is a Lua implementation of the old ((Portal)) template. As of February 2019 it is used on nearly 7,900,000 articles.
-- Please take care when updating it! It outputs two functions: p.portal, which generates a list of portals, and p.image, which
-- produces the image name for an individual portal.

-- The portal image data is kept in submodules of [[Module:Portal/images]], listed below:
-- [[Module:Portal/images/a]]		- for portal names beginning with "A".
-- [[Module:Portal/images/b]]		- for portal names beginning with "B".
-- [[Module:Portal/images/c]]		- for portal names beginning with "C".
-- [[Module:Portal/images/d]]		- for portal names beginning with "D".
-- [[Module:Portal/images/e]]		- for portal names beginning with "E".
-- [[Module:Portal/images/f]]		- for portal names beginning with "F".
-- [[Module:Portal/images/g]]		- for portal names beginning with "G".
-- [[Module:Portal/images/h]]		- for portal names beginning with "H".
-- [[Module:Portal/images/i]]		- for portal names beginning with "I".
-- [[Module:Portal/images/j]]		- for portal names beginning with "J".
-- [[Module:Portal/images/k]]		- for portal names beginning with "K".
-- [[Module:Portal/images/l]]		- for portal names beginning with "L".
-- [[Module:Portal/images/m]]		- for portal names beginning with "M".
-- [[Module:Portal/images/n]]		- for portal names beginning with "N".
-- [[Module:Portal/images/o]]		- for portal names beginning with "O".
-- [[Module:Portal/images/p]]		- for portal names beginning with "P".
-- [[Module:Portal/images/q]]		- for portal names beginning with "Q".
-- [[Module:Portal/images/r]]		- for portal names beginning with "R".
-- [[Module:Portal/images/s]]		- for portal names beginning with "S".
-- [[Module:Portal/images/t]]		- for portal names beginning with "T".
-- [[Module:Portal/images/u]]		- for portal names beginning with "U".
-- [[Module:Portal/images/v]]		- for portal names beginning with "V".
-- [[Module:Portal/images/w]]		- for portal names beginning with "W".
-- [[Module:Portal/images/x]]		- for portal names beginning with "X".
-- [[Module:Portal/images/y]]		- for portal names beginning with "Y".
-- [[Module:Portal/images/z]]		- for portal names beginning with "Z".
-- [[Module:Portal/images/other]]	- for portal names beginning with any other letters. This includes numbers,
-- 									  letters with diacritics, and letters in non-Latin alphabets.
-- [[Module:Portal/images/aliases]]	- for adding aliases for existing portal names. Use this page for variations
-- 									  in spelling and diacritics, etc., no matter what letter the portal begins with.
--
-- The images data pages are separated by the first letter to reduce server load when images are added, changed, or removed.
-- Previously all the images were on one data page at [[Module:Portal/images]], but this had the disadvantage that all
-- 5,000,000 pages using this module needed to be refreshed every time an image was added or removed.
]==]

local p = {}

-- determine whether we're being called from a sandbox
local isSandbox = mw.getCurrentFrame():getTitle():find('sandbox', 1, true)
local sandbox = isSandbox and '/sandbox' or ''

local function sandboxVersion(s)
	return isSandbox and s..'-sand' or s
end

local templatestyles = 'Module:Portal'..sandbox..'/styles.css'

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

-- List of non-talk namespaces which should not be tracked (Talk pages are never tracked)
local badNamespaces = {'user','template','draft','wikipedia'}

-- Check whether to do tracking in this namespace
-- Returns true unless the page is one of the banned namespaces
local function checkTracking(title)
	local thisPage = title or mw.title.getCurrentTitle()
	if thisPage.isTalkPage then
		return false
	end
	local ns = thisPage.nsText:lower()
	for _, v in ipairs(badNamespaces) do
		if ns == v then
			return false
		end
	end
	return true
end

local function matchImagePage(s)
	-- Finds the appropriate image subpage given a lower-case
	-- portal name plus the first letter of that portal name.
	if type(s) ~= 'string' or #s < 1 then return end
	local firstLetter = mw.ustring.sub(s, 1, 1)
	local imagePage
	if mw.ustring.find(firstLetter, '^[a-z]') then
		imagePage = 'Module:Portal/images/' .. firstLetter .. sandbox
	else
		imagePage = 'Module:Portal/images/other' .. sandbox
	end
	return mw.loadData(imagePage)[s]
end

local function getAlias(s)
	-- Gets an alias from the image alias data page.
	local aliasData = mw.loadData('Module:Portal/images/aliases'..sandbox)
	for portal, aliases in pairs(aliasData) do
		for _, alias in ipairs(aliases) do
			if alias == s then
				return portal
			end
		end
	end
end

local defaultImage = 'Portal-puzzle.svg|link=|alt='

local function getImageName(s)
	-- Gets the image name for a given string.
	if type(s) ~= 'string' or #s < 1 then
		return defaultImage
	end
	s = mw.ustring.lower(s)
	return matchImagePage(s) or matchImagePage(getAlias(s)) or defaultImage
end
local function exists(title) 
	local success, exists = pcall(function() return title.exists end)
	-- If success = false, then we're out of expensive parser function calls and can't check whether it exists
	-- in that case, don't throw a Lua error
	return not success or exists
end

 -- Function to check argument portals for errors, generate tracking categories if needed
 --     Function first checks for too few/many portals provided
 --     Then checks the portal list to purge any portals that don't exist
 -- Arguments:
 --   portals: raw list of portals
 --   args.tracking: is tracking requested? (will not track on bad titles or namespaces)
 --   args.redlinks: should redlinks be displayed?
 --   args.minPortals: minimum number of portal arguments
 --   args.maxPortals: maximum number of portal arguments
 -- Returns:
 --   portals = list of portals, with redlinks purged (if args.redlinks=false)
 --   trackingCat = possible tracking category
 --   errorMsg = error message
function p._checkPortals(portals, args)
	local trackingCat = ''
	local errMsg = nil
	
	-- Tracking is on by default.
	-- It is disabled if any of the following is true
	-- 1/ the parameter "tracking" is set to 'no, 'n', or 'false'
	-- 2/ the current page fails the namespace or pagename tests 
	local trackingEnabled = args.tracking and checkTracking()
	
	args.minPortals = args.minPortals or 1
	args.maxPortals = args.maxPortals or -1
	-- check for too few portals
	if #portals < args.minPortals then
		errMsg = 'please specify at least '..args.minPortals..' portal'..(args.minPortals > 1 and 's' or '')
		trackingCat = (trackingEnabled and '[[Category:Portal templates with too few portals]]' or '')
		return portals, trackingCat, errMsg
	end
	-- check for too many portals
	if args.maxPortals >= 0 and #portals > args.maxPortals then
		errMsg = 'too many portals (maximum = '..args.maxPortals..')'
		trackingCat = (trackingEnabled and '[[Category:Portal templates with too many portals]]' or '')
		return portals, trackingCat, errMsg
	end
	if not args.redlinks or trackingEnabled then
		-- make new list of portals that exist
		local existingPortals = {}
		for _, portal in ipairs(portals) do
			local portalTitle = mw.title.new(portal,"Portal")
			-- if portal exists, put it into list
			if portalTitle and exists(portalTitle) then
				table.insert(existingPortals,portal)
			-- otherwise set tracking cat
			elseif trackingEnabled then
				trackingCat = "[[Category:Portal templates with redlinked portals]]"
			end
		end
		-- If redlinks is off, use portal list purged of redlinks
		portals = args.redlinks and portals or existingPortals
		-- if nothing left after purge, set tracking cat
		if #portals == 0 and trackingEnabled then
			trackingCat = trackingCat.."[[Category:Pages with empty portal template]]" 
		end
	end
	return portals, trackingCat, errMsg
end

local function portalBox(args)
	return mw.html.create('ul')
		:attr('role', 'navigation')
		:attr('aria-label', 'Portals')
		:addClass('noprint')
		:addClass(args.error and '' or sandboxVersion('portalbox'))
		:addClass(args.border and sandboxVersion('portalborder') or '')
		:addClass(sandboxVersion(args.left and 'portalleft' or 'portalright'))
		:css('margin', args.margin or nil)
		:newline()
end

local function fillBox(root, contents)
	for _, item in ipairs(contents) do
		local entry = root:tag('li')
		entry:addClass(sandboxVersion('portalbox-entry'))
		local image = entry:tag('span')
		image:addClass(sandboxVersion('portalbox-image'))
		image:wikitext(item[1])
		local link = entry:tag('span')
		link:addClass(sandboxVersion('portalbox-link'))
		link:wikitext(item[2])
	end
	return root
end

function p._portal(portals, args)
	-- This function builds the portal box used by the ((portal)) template.
	
	-- Normalize all arguments
	if args.redlinks == 'include' then args.redlinks = true end
	args.addBreak = args['break']
	for key, default in pairs({left=false,tracking=true,nominimum=false,
		                       redlinks=false,addBreak=false,border=true}) do
		if args[key] == nil then args[key] = default end
		args[key] = yesno(args[key], default)
	end

	local root = portalBox(args)

	local trackingCat = ''
	local errMsg = nil
	args.minPortals = args.nominimum and 0 or 1
	args.maxPortals = -1
	portals, trackingCat, errMsg = p._checkPortals(portals, args)
	root:wikitext(trackingCat)
	-- if error message, put it in the box and return
	if errMsg then
		if args.border then -- suppress error message when border=no
			args.error = true  -- recreate box without fancy formatting
			root = portalBox(args)
			root:wikitext(trackingCat)
			local errTag = root:tag('strong')
			errTag:addClass('error')
			errTag:css('padding','0.2em')
			errTag:wikitext('Error: '..errMsg)
		end
		return tostring(root)
	end
	-- if no portals (and no error), just return tracking category
	if #portals == 0 then
		return trackingCat
	end

	local contents = {}
	-- Display the portals specified in the positional arguments.
	local defaultUsed = nil
	for _, portal in ipairs(portals) do
		local portalImage = getImageName(portal)
		if portalImage == defaultImage then
			defaultUsed = portal
		end
		local image = string.format('[[File:%s|32x28px|class=noviewer]]',
			portalImage)
		local link = string.format('[[Portal:%s|%s%sportal]]',
			portal, portal, args.addBreak and '<br />' or ' ')
		table.insert(contents, {image, link})
	end
	if defaultUsed and checkTracking() then
		local cat = string.format('[[Category:Portal templates with default image|%s]]',
			                      defaultUsed)
		root:wikitext(cat)
	end
	return tostring(fillBox(root, contents))
end

function p._demo(imageList, args)
	for key, default in pairs({left=false,border=true}) do
		if args[key] == nil then args[key] = default end
		args[key] = yesno(args[key], default)
	end
	
	local root = portalBox(args)

	local contents = {}
	-- Display the portals specified in the positional arguments.
	for _, fn in ipairs(imageList) do
		local image = string.format('[[File:%s|32x28px|class=noviewer]]',fn)
		local link = string.format('[[:File:%s|%s]]',fn,fn)
		table.insert(contents,{image,link})
	end

	return tostring(fillBox(root,contents))
end

function p._image(portal,keep)
	-- Wrapper function to allow getImageName() to be accessed through #invoke.
	-- backward compatibility: if table passed, take first element
	if type(portal) == 'table' then
		portal = portal[1]
	end
	local name = getImageName(portal)
	-- If keep is yes (or equivalent), then allow all metadata (like image borders) to be returned
	local keepargs = yesno(keep)
	local args = mw.text.split(name, "|", true)
	local result = {args[1]}  -- the filename always comes first
	local category = ''
	-- parse name, looking for category arguments
	for i = 2,#args do
		local m = mw.ustring.match(args[i],  "^%s*category%s*=")
		if keepargs or m then
			table.insert(result, args[i])
		end
	end
	-- reassemble arguments
	return table.concat(result,"|")
end


local function getAllImageTable()
	-- Returns an array containing all image subpages (minus aliases) as loaded by mw.loadData.
	local images = {}
	for i, subpage in ipairs{'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'other'} do
		local imageTable = mw.loadData('Module:Portal/images/' .. subpage .. sandbox)
		for portal, image in pairs(imageTable) do
			local args = mw.text.split(image,"|")
			images[portal] = args[1] -- just use image filename
		end
	end
	return images
end

function p._displayAll(portals, args)
	-- This function displays all portals that have portal images. This function is for maintenance purposes and should not be used in
	-- articles, for two reasons: 1) there are over 1500 portals with portal images, and 2) the module doesn't record how the portal
	-- names are capitalized, so the portal links may be broken.
	local lang = mw.language.getContentLanguage()
	portals = portals or {}
	for portal in pairs(getAllImageTable()) do
		table.insert(portals,lang:ucfirst(portal))
	end
	table.sort(portals)
	args.redlinks = args.redlinks or "yes"
	return p._portal(portals, args)
end

function p._imageDupes()
	-- This function searches the image subpages to find duplicate images. If duplicate images exist, it is not necessarily a bad thing,
	-- as different portals might just happen to choose the same image. However, this function is helpful in identifying images that
	-- should be moved to a portal alias for ease of maintenance.
	local exists, dupes = {}, {}
	for portal, image in pairs(getAllImageTable()) do
		if not exists[image] then
			exists[image] = portal
		else
			table.insert(dupes, string.format('The image "[[:File:%s|%s]]" is used for both portals "%s" and "%s".', image, image, exists[image], portal))
		end
	end
	if #dupes < 1 then
		return 'No duplicate images found.'
	else
		return 'The following duplicate images were found:\n* ' .. table.concat(dupes, '\n* ')
	end
end

local function processPortalArgs(args)
	-- This function processes a table of arguments and returns two tables: an array of portal names for processing by ipairs, and a table of
	-- the named arguments that specify style options, etc. We need to use ipairs because we want to list all the portals in the order
	-- they were passed to the template, but we also want to be able to deal with positional arguments passed explicitly, for example
	-- ((portal|2=Politics)). The behaviour of ipairs is undefined if nil values are present, so we need to make sure they are all removed.
	args = type(args) == 'table' and args or {}
	local portals = {}
	local namedArgs = {}
	for k, v in pairs(args) do
		if type(k) == 'number' and type(v) == 'string' then -- Make sure we have no non-string portal names.
			table.insert(portals, k)
		elseif type(k) ~= 'number' then
			namedArgs[k] = v
		end
	end
	table.sort(portals)
	for i, v in ipairs(portals) do
		portals[i] = args[v]
	end
	return portals, namedArgs
end

-- Entry point for sorting portals from other named arguments
function p._processPortalArgs(args)
	return processPortalArgs(args)
end

function p.image(frame)
	local origArgs = getArgs(frame)
	local portals, args = processPortalArgs(origArgs)
	return p._image(portals[1],args.border)
end

function p.demo(frame)
	local args = getArgs(frame)
	local styles = frame:extensionTag{ name = 'templatestyles', args = { src = templatestyles} }
	return styles..p._demo(args,args)
end

local function makeWrapper(funcName)
	-- Processes external arguments and sends them to the other functions.
	return function (frame)
		-- If called via #invoke, use the args passed into the invoking
		-- template, or the args passed to #invoke if any exist. Otherwise
		-- assume args are being passed directly in from the debug console
		-- or from another Lua module. 
		-- Also: trim whitespace and remove blank arguments
		local origArgs = getArgs(frame)
		-- create two tables to pass to func: an array of portal names, and a table of named arguments.
		local portals, args = processPortalArgs(origArgs)
		local results = ''
		if funcName == '_portal' or funcName == '_displayAll' then
			results = frame:extensionTag{ name = 'templatestyles', args = { src = templatestyles} }
		end
		return results .. p[funcName](portals, args) 
	end
end

for _, funcName in ipairs{'portal', 'imageDupes', 'displayAll'} do
	p[funcName] = makeWrapper('_' .. funcName)
end

return p