Module:Singles

local p = {}

-- Ripped from Module:Infobox. TODO: Make a utility module that can do this kind of thing
local function getArgNums(args, prefix)
    -- Returns a table containing the numbers of the arguments that exist
    -- for the specified prefix. For example, if the prefix were to be 'data', and
    -- 'data1', 'data2', and 'data5' were to exist, it would return {1, 2, 5}.
    local nums = {}
    for k, v in pairs(args) do
        local num = tostring(k):match('^' .. prefix .. '([1-9]%d*)$')
        if num then table.insert(nums, tonumber(num)) end
    end
    table.sort(nums)
    return nums
end

-- Forked from Module:Unsubst-infobox

local specialParams = {
 ['$B'] = 'template content'
}

p[''] = function ( frame )
 if not frame.args['$B'] then
  error( '{{#invoke:Singles|}} requires parameter $B (template content)' )
 end

 if mw.isSubsting() then
  ---- substing
  -- Passed args
  local args = {}
  for k, v in pairs( frame:getParent().args ) do
   args[k] = v
  end

  -- Build an equivalent template invocation
  -- First, find the title to use
  local titleobj = mw.title.new(frame:getParent():getTitle())
  local title
  if titleobj.namespace == 10 then -- NS_TEMPLATE
   title = titleobj.text
  elseif titleobj.namespace == 0 then -- NS_MAIN
   title = ':' .. titleobj.text
  else
   title = titleobj.prefixedText
  end

  -- Remove empty fields
  for k, v in pairs( args ) do
   if v == '' then args[k] = nil end
  end

  -- Pull aliases
  local nums = getArgNums(args, '[Ss]ingle ?')
  for _, num in ipairs(nums) do
   args['single' .. num] = args['single' .. num] or args['single ' .. num] or args['Single ' .. num]
   args['single' .. num .. 'date'] = args['single' .. num .. 'date'] or args['single ' .. num .. ' date'] or args['Single ' .. num .. ' date'] or ''
   args['single ' .. num], args['Single ' .. num], args['single ' .. num .. ' date'], args['Single ' .. num .. ' date'] = nil, nil, nil, nil
  end
  for k, v in pairs( {Type = 'type', Name = 'name'} ) do
   if args[k] and not args[v] then args[v], args[k] = args[k], nil end
  end

  -- Build the invocation body
  local ret = '{{' .. title

  -- Make parameter list
  local params = {'name', 'type'}
  for _, num in ipairs( nums ) do table.insert( params, 'single' .. num ); table.insert( params, 'single' .. num .. 'date' ) end

  -- Align parameters correctly and remove extra ones
  local maxlength = 0
  for k, v in ipairs( params ) do
   local tmp = mw.ustring.len( v )
   if tmp > maxlength then maxlength = tmp end
  end

  for k, v in ipairs( params ) do
   ret = ret .. '\n | ' .. v .. string.rep(' ', (maxlength - mw.ustring.len( v ))) .. ' = ' .. (args[v] or '')
  end

  ret = ret .. '\n}}'

  ret = mw.ustring.gsub(ret, '%s+\n', '\n')

  return ret
 else
  -- Not substing
  -- Just return the "body"
  return frame.args['$B']
 end
end

function p.main(frame)
 local args = require('Module:Arguments').getArgs(frame, {wrappers = 'Template:Singles'})
 local out = ''
 local nums = getArgNums(args, '[Ss]ingle ?')
 for _, num in ipairs(nums) do
  out = out .. '\n# <span class="item"><span class="fn">"' .. (args['single' .. num] or args['single ' .. num] or args['Single ' .. num]) .. '"</span>'
  local date = args['single' .. num .. 'date'] or args['single ' .. num .. ' date'] or args['Single ' .. num .. ' date']
  if date then
   out = out .. '<br />Released: ' .. date
  end
  out = out .. '</span>'
 end
 
 if out ~= '' then
  if mw.ustring.match(out, '</?t[drh][ >]') then out = out .. ' [[Category:Music infoboxes with malformed table placement|R]]' end
  return '<div style="text-align:left">' .. out .. '\n</div>'
 end
 
 return out
end

return p