Module:Portal

--[==[ 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 args.tracking 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