-- This module implements {{find sources}} and other similar templates, and -- also provides a mechanism to easily create new source-finding templates.  -- Define constants local ROOT_PAGE = 'Module:Find sources' local TEMPLATE_ROOT = ROOT_PAGE .. '/templates/' -- for template config modules local LINK_ROOT = ROOT_PAGE .. '/links/' -- for link config modules local CONFIG_PAGE = ROOT_PAGE .. '/config' -- for global config  -- Load required modules local checkType = require('libraryUtil').checkType local cfg = mw.loadData(CONFIG_PAGE)  local p = {}  local function maybeLoadData(page)  local success, data = pcall(mw.loadData, page)  return success and data end  local function substituteParams(msg, ...)  return mw.message.newRawMessage(msg, ...):plain() end  local function renderSearchString(searchTerms, separator, transformFunc)  -- This takes a table of search terms and turns it into a search string  -- that can be used in a URL or in a display value. The transformFunc  -- parameter can be used to transform each search term in some way (for  -- example, URL-encoding them).  local searchStrings = {}  for i, s in ipairs(searchTerms) do  searchStrings[i] = s  end  if transformFunc then  for i, s in ipairs(searchStrings) do  searchStrings[i] = transformFunc(s)  end  end  return table.concat(searchStrings, separator) end  function p._renderLink(code, searchTerms, display)  -- Renders the external link wikicode for one link, given the link code,  -- a table of search terms, and an optional display value.   -- Get link config.  local linkCfg = maybeLoadData(LINK_ROOT .. code)  if not linkCfg then  error(string.format(  "invalid link code '%s'; no link config found at [[%s]]",  code,  LINK_ROOT .. code  ))  end   -- Make URL.  local url  do  local separator = linkCfg.separator or "+"  local searchString = renderSearchString(  searchTerms,  separator,  mw.uri.encode  )  url = substituteParams(linkCfg.url, searchString)  end   return string.format('[%s %s]', url, display or linkCfg.display) end  function p._main(template, args)  -- The main access point from Lua.  checkType('_main', 1, template, 'string')  checkType('_main', 2, args, 'table', true)  args = args or {}  local title = mw.title.getCurrentTitle()   -- Get the template config.  local templateCfgPage = TEMPLATE_ROOT .. template  local templateCfg = maybeLoadData(templateCfgPage)  if not templateCfg then  error(string.format(  "invalid template name '%s'; no template config found at [[%s]]",  template, templateCfgPage  ))  end   -- Namespace check.  if not templateCfg.isUsedInMainspace and title.namespace == 0 then  local formatString = '<strong class="error">%s</strong>'  if cfg['namespace-error-category'] then  formatString = formatString .. '[[%s:%s]]'  end  return string.format(  formatString,  cfg['namespace-error'],  mw.site.namespaces[14].name,  cfg['namespace-error-category']  )  end   -- Get the search terms from the arguments.  local searchTerms = {}  for i, s in ipairs(args) do  searchTerms[i] = s  end  if not searchTerms[1] then  -- Use the current subpage name as the default search term. If the page  -- uses a disambiguator like "Foo (bar)", make "Foo" the first term and  -- "bar" the second.  local term, dab = title.subpageText:match('^(.*) (%b())$')  if dab then  dab = dab:sub(2, -2) -- Remove parens  end  if term and dab then  searchTerms[1] = term  searchTerms[2] = dab  else  searchTerms[1] = title.subpageText  end  end  searchTerms[1] = '"' .. searchTerms[1] .. '"'   -- Make the intro link  local introLink  if templateCfg.introLink then  local code = templateCfg.introLink.code  local display = templateCfg.introLink.display or renderSearchString(  searchTerms,  '&nbsp;'  )  introLink = p._renderLink(code, searchTerms, display)  else  introLink = ''  end   -- Make the other links  local links = {}  local separator = templateCfg.separator or cfg['default-separator']  local sep = ''  for i, t in ipairs(templateCfg.links) do  links[i] = sep .. p._renderLink(t.code, searchTerms, t.display) ..  (t.afterDisplay or '')  sep = t.separator or separator  end  links = table.concat(links)   -- Make the blurb.  local blurb = substituteParams(templateCfg.blurb, introLink, links)  local span = mw.html.create('span')  span  :addClass('plainlinks')  :addClass(templateCfg.class)  :cssText(templateCfg.style)  :wikitext(blurb)   return tostring(span) end  setmetatable(p, { __index = function(t, template)  -- The main access point from #invoke.  -- Invocations will look like {{#invoke:Find sources|template name}},  -- where "template name" is a subpage of [[Module:Find sources/templates]].  local tname = template  if tname:sub(-8) == '/sandbox' then  -- This makes {{Find sources/sandbox|Albert Einstein}} work.  tname = tname:sub(1, -9)  end  return function(frame)  local args = require('Module:Arguments').getArgs(frame, {  wrappers = mw.site.namespaces[10].name .. ':' .. tname  })  return t._main(template, args)  end end})  return p