Module:Archive list

-- This module implements Template:Archive list in Lua, and adds a few -- new features.

-- Process a numeric argument to make sure it is a positive -- integer. local function processNumArg( num )

   if num then
       num = tonumber( num )
       if type( num ) == 'number' then
           num = math.floor( num )
           if num >= 0 then
               return num
           end
       end
   end
   return nil

end

-- Checks whether a page exists, going through pcall -- in case we are over the expensive function limit. local function checkPageExists( title )

   if not title then
       error('No title passed to checkArchiveExists', 2)
   end
   local noError, titleObject = pcall(mw.title.new, title)
   if not noError then
       -- If we are over the expensive function limit then assume
       -- that the page doesn't exist.
       return false
   else
       if titleObject then
           return titleObject.exists
       else
           return false -- Return false if given a bad title.
       end
   end

end

-- Checks every nth archive to see if it exists, and returns the -- number of the first archive that doesn't exist. It is -- necessary to do this in batches because each check is an -- expensive function call, and we want to avoid making too many -- of them so as not to go over the expensive function limit. local function checkArchives( prefix, n, start )

   local i = start
   local exists = true
   while exists do
       exists = checkPageExists( prefix .. tostring( i ) )
       if exists then
           i = i + n
       end
   end
   return i

end

-- Return the biggest archive number, using checkArchives() -- and starting in intervals of 1000. This should get us a -- maximum of 500,000 possible archives before we hit the -- expensive function limit. local function getBiggestArchiveNum( prefix, max )

   -- Return the value for max if it is specified.
   max = processNumArg( max )
   if max then
       return max
   end
   
   -- Otherwise, detect the largest archive number.
   local check1000 = checkArchives( prefix, 1000, 1 )
   if check1000 == 1 then
       return 0 -- Return 0 if no archives were found.
   end
   local check200 = checkArchives( prefix, 200, check1000 - 1000 )
   local check50 = checkArchives( prefix, 50, check200 - 200 )
   local check10 = checkArchives( prefix, 10, check50 - 50 )
   local check1 = checkArchives( prefix, 1, check10 - 10 )
   -- check1 is the first page that doesn't exist, so we want to
   -- subtract it by one to find the biggest existing archive.
   return check1 - 1

end

-- Get the archive link prefix (the title of the archive pages -- minus the number). local function getPrefix( root, prefix, prefixSpace )

   local ret = root or mw.title.getCurrentTitle().prefixedText
   ret = ret .. '/'
   if prefix then
       ret = ret .. prefix
       if prefixSpace == 'yes' then
           ret = ret .. ' '
       end
   else
       ret = ret .. 'Archive '
   end
   return ret

end

-- Get the number of archives to put on one line. Set to -- math.huge if there should be no line breaks. local function getLineNum( links, nobr )

   local linksToNum = tonumber( links )
   local lineNum
   if nobr == 'yes' or (links and not linksToNum) then
       lineNum = math.huge
   -- If links is a number, process it. Negative values and expressions
   -- such as links=8/2 produced some interesting values with the old
   -- template, but we will ignore those for simplicity.
   elseif type(linksToNum) == 'number' and linksToNum >= 0 then
       -- The old template rounded down decimals to the nearest integer.
       lineNum = math.floor( linksToNum )
       if lineNum == 0 then
           -- In the old template, values of links between 0 and 0.999
           -- suppressed line breaks.
           lineNum = math.huge
       end
   else
       lineNum = 10 -- Default to 10 links.
   end
   return lineNum

end

-- Gets the prefix to put before the archive links. local function getLinkPrefix( prefix, space )

   -- Get the link prefix.
   local ret = 
   if type(prefix) == 'string' then
       ret = prefix
       if space == 'yes' then
           ret = ret .. ' '
       end
   end
   return ret

end

-- Get the number to start listing archives from. local function getStart( start )

   start = processNumArg( start )
   if start then
       return start
   else
       return 1
   end

end

-- Process the separator parameter. local function getSeparator( sep )

   if sep and type(sep) == 'string' then
       if sep == 'dot' 
           or sep =='pipe'
           or sep == 'comma'
           or sep == 'tpt-languages' then
           return mw.message.new( sep .. '-separator' ):plain()
       else
           return sep
       end
   else
       return nil
   end

end

-- Generates the list of archive links. glargs.max must be either zero (for -- no archives) or a positive integer value. local function generateLinks( glargs )

   if type( glargs ) ~= 'table' or not glargs.max or not glargs.prefix then
       error('insufficient arguments passed to generateLinks', 2)
   end
   -- If there are no archives yet, return a message and a
   -- link to create Archive one.
   if glargs.max == 0 then
       return 'no archives yet (create)'
   end
   -- Return an html error if the start number is greater than the 
   -- maximum number.
   local start = glargs.start or 1
   if start > glargs.max then
       return ''
   end
   local linkPrefix = glargs.linkPrefix or 
   local sep = glargs.sep or mw.message.new( 'comma-separator' ):plain()
   local lineNum = glargs.lineNum or 10
   local lineSep = glargs.lineSep or '
'

   -- Generate the archive links.
   local lineCounter = 1 -- The counter to see whether we need a line break or not.
   local ret = {} -- A table containing the strings to be returned.
   for archiveNum = start, glargs.max do
       local link = mw.ustring.format(
           '%s%d',
           glargs.prefix, archiveNum, linkPrefix, archiveNum
       )
       table.insert( ret, link )
       -- If we don't need a new line, output a comma. We don't need
       -- a comma after the last link. 
       if lineCounter < lineNum and archiveNum < glargs.max then
           table.insert( ret, sep )
           lineCounter = lineCounter + 1
       -- Output new lines if needed. We don't need a new line after
       -- the last link.
       elseif lineCounter >= lineNum and archiveNum < glargs.max then
           table.insert( ret, lineSep )
           lineCounter = 1
       end
   end
   return table.concat( ret )

end

-- Get the archive data and pass it to generateLinks(). local function _main( args )

   local prefix = getPrefix( args.root, args.prefix, args.prefixspace )
   local max = getBiggestArchiveNum( prefix, args.max )
   local lineNum = getLineNum( args.links, args.nobr )
   local linkPrefix = getLinkPrefix( args.linkprefix, args.linkprefixspace )
   local start = getStart( args.start )
   local sep = getSeparator( args.sep )
   local lineSep = getSeparator( args.linesep )
   local glargs = {
       start = start,
       max = max,
       prefix = prefix,
       linkPrefix = linkPrefix,
       sep = sep,
       lineNum = lineNum,
       lineSep = lineSep
   }
   return generateLinks( glargs )

end

-- A wrapper function to make getBiggestArchiveNum() available from -- #invoke. local function _count( args )

   local prefix = getPrefix( args.root, args.prefix, args.prefixspace )
   local archiveMax = getBiggestArchiveNum( prefix )
   return archiveMax

end

function makeWrapper( func )

   return function( frame )
       -- If we are being called from #invoke, get the args from #invoke
       -- if they exist, or else get the arguments passed to the parent
       -- frame. Otherwise, assume the arguments are being passed directly
       -- in from another module or from the debug console.
       local origArgs
       if frame == mw.getCurrentFrame() then
           origArgs = frame:getParent().args
           for k, v in pairs( frame.args ) do
               origArgs = frame.args
               break
           end
       else
           origArgs = frame
       end
       
       -- Ignore blank values for parameters other than "links",
       -- which functions differently depending on whether it is
       -- blank or absent.
       local args = {}
       for k, v in pairs( origArgs ) do
           if k == 'links' or v ~=  then
               args[k] = v
           end
       end
       
       return func( args )
   end

end

return {

   main = makeWrapper( _main ),
   count = makeWrapper( _count )

}