Module:Delink

-- This module de-links most wikitext.

require("strict")

local p = {}

local getArgs

local function delinkReversePipeTrick(s)
 if s:match("^%[%[|.*[|\n]") then -- Check for newlines or multiple pipes.
  return s
 end
 return s:match("%[%[|(.*)%]%]")

end

local function delinkPipeTrick(s)
 -- We need to deal with colons, brackets, and commas, per [[Help:Pipe trick]].
 -- First, remove the text before the first colon, if any.
 if s:match(":") then
  s = s:match("%[%[.-:(.*)|%]%]")
 -- If there are no colons, grab all of the text apart from the square brackets and the pipe.
 else
  s = s:match("%[%[(.*)|%]%]")
 end
 
 -- Next up, brackets and commas.
 if s:match("%(.-%)$") then -- Brackets trump commas.
  s = s:match("(.-) ?%(.-%)$")
 elseif s:match(",") then -- If there are no brackets, display only the text before the first comma.
  s = s:match("(.-),.*$")
 end
 return s
end

-- Return wikilink target |wikilinks=target
local function getDelinkedTarget(s)
 local result = s
 -- Deal with the reverse pipe trick.
 if result:match("%[%[|") then
  return delinkReversePipeTrick(result)
 end
 
 result = mw.uri.decode(result, "PATH") -- decode percent-encoded entities. Leave underscores and plus signs.
 result = mw.text.decode(result, true) -- decode HTML entities.
 
 -- Check for bad titles. To do this we need to find the
 -- title area of the link, i.e. the part before any pipes.
 local target_area
 if result:match("|") then -- Find if we're dealing with a piped link.
  target_area = result:match("^%[%[(.-)|.*%]%]")
 else
  target_area = result:match("^%[%[(.-)%]%]")
 end

 -- Check for bad characters.
 if mw.ustring.match(target_area, "[%[%]<>{}%%%c\n]") and mw.ustring.match(target_area, "[%[%]<>{}%%%c\n]") ~= "?" then
  return s
 end
 
 return target_area
end

local function getDelinkedLabel(s)
 local result = s
 -- Deal with the reverse pipe trick.
 if result:match("%[%[|") then
  return delinkReversePipeTrick(result)
 end

 result = mw.uri.decode(result, "PATH") -- decode percent-encoded entities. Leave underscores and plus signs.
 result = mw.text.decode(result, true) -- decode HTML entities.

 -- Check for bad titles. To do this we need to find the
 -- title area of the link, i.e. the part before any pipes.
 local target_area
 if result:match("|") then -- Find if we're dealing with a piped link.
  target_area = result:match("^%[%[(.-)|.*%]%]")
 else
  target_area = result:match("^%[%[(.-)%]%]")
 end

 -- Check for bad characters.
 if mw.ustring.match(target_area, "[%[%]<>{}%%%c\n]") and mw.ustring.match(target_area, "[%[%]<>{}%%%c\n]") ~= "?" then
  return s
 end

 -- Check for categories, interwikis, and files.
 local colon_prefix = result:match("%[%[(.-):.*%]%]") or "" -- Get the text before the first colon.
 local ns = mw.site.namespaces[colon_prefix] -- see if this is a known namespace
 if mw.language.isKnownLanguageTag(colon_prefix) or (ns and (ns.canonicalName == "File" or ns.canonicalName == "Category")) then
  return ""
 end

 -- Remove the colon if the link is using the [[Help:Colon trick]].
 if result:match("%[%[:") then
  result = "[[" .. result:match("%[%[:(.*%]%])")
 end

 -- Deal with links using the [[Help:Pipe trick]].
 if mw.ustring.match(result, "^%[%[[^|]*|%]%]") then
  return delinkPipeTrick(result)
 end
 
 -- Find the display area of the wikilink
 if result:match("|") then -- Find if we're dealing with a piped link.
  result = result:match("^%[%[.-|(.+)%]%]")
  -- Remove new lines from the display of multiline piped links,
  -- where the pipe is before the first new line.
  result = result:gsub("\n", "")
 else
  result = result:match("^%[%[(.-)%]%]")
 end

 return result
end

local function delinkURL(s)
 -- Assume we have already delinked internal wikilinks, and that
 -- we have been passed some text between two square brackets [foo].
 
 -- If the text contains a line break it is not formatted as a URL, regardless of other content.
 if s:match("\n") then
  return s
 end
 
 -- Check if the text has a valid URL prefix and at least one valid URL character.
 local valid_url_prefixes = {"//", "http://", "https://", "ftp://", "gopher://", "mailto:", "news:", "irc://"} 
 local url_prefix
 for _ ,v in ipairs(valid_url_prefixes) do
  if mw.ustring.match(s, '^%[' .. v ..'[^"%s].*%]' ) then
   url_prefix = v
   break
  end
 end
 
 -- Get display text
 if not url_prefix then
  return s
 end
 s = s:match("^%[" .. url_prefix .. "(.*)%]") -- Grab all of the text after the URL prefix and before the final square bracket.
 s = s:match('^.-(["<> ].*)') or "" -- Grab all of the text after the first URL separator character ("<> ).
 s = mw.ustring.match(s, "^%s*(%S.*)$") or "" -- If the separating character was a space, trim it off.
 
 local s_decoded = mw.text.decode(s, true)
 if mw.ustring.match(s_decoded, "%c") then
  return s
 end

 return s_decoded

end

local function delinkLinkClass(text, pattern, delinkFunction)
 if type(text) ~= "string" then
  error("Attempt to de-link non-string input.", 2)
 end
 if type(pattern) ~= "string" or mw.ustring.sub(pattern, 1, 1) ~= "^" then
  error('Invalid pattern detected. Patterns must begin with "^".', 2)
 end
 -- Iterate over the text string, and replace any matched text. using the 
 -- delink function. We need to iterate character by character rather 
 -- than just use gsub, otherwise nested links aren't detected properly.
 local result = ""
 while text ~= "" do
  -- Replace text using one iteration of gsub.
  text = mw.ustring.gsub(text, pattern, delinkFunction, 1)
  -- Append the left-most character to the result string.
  result = result .. mw.ustring.sub(text, 1, 1)
  text = mw.ustring.sub(text, 2, -1)
 end
 return result
end

function p._delink(args)
 local text = args[1] or ""
 if args.refs == "yes" then
  -- Remove any [[Help:Strip markers]] representing ref tags. In most situations 
  -- this is not a good idea - only use it if you know what you are doing!
  text = mw.ustring.gsub(text, "UNIQ%w*%-ref%-%d*%-QINU", "")
 end
 if args.comments ~= "no" then
  text = text:gsub("<!%-%-.-%-%->", "") -- Remove html comments.
 end

 if args.wikilinks ~= "no" and args.wikilinks ~= "target" then
  -- De-link wikilinks and return the label portion of the wikilink.
  text = delinkLinkClass(text, "^%[%[.-%]%]", getDelinkedLabel)
 elseif args.wikilinks == "target" then
  -- De-link wikilinks and return the target portions of the wikilink.
  text = delinkLinkClass(text, "^%[%[.-%]%]", getDelinkedTarget)
 end
 if args.urls ~= "no" then
  text = delinkLinkClass(text, "^%[.-%]", delinkURL) -- De-link URLs.
 end
 if args.whitespace ~= "no" then
  -- Replace single new lines with a single space, but leave double new lines
  -- and new lines only containing spaces or tabs before a second new line.
  text = mw.ustring.gsub(text, "([^\n \t][ \t]*)\n([ \t]*[^\n \t])", "%1 %2")
  text = text:gsub("[ \t]+", " ") -- Remove extra tabs and spaces.
 end
 return text
end

function p.delink(frame)
 if not getArgs then
  getArgs = require('Module:Arguments').getArgs
 end
 return p._delink(getArgs(frame, {wrappers = 'Template:Delink'}))
end

return p