Module:Percentage

--
-- This module implements [[Template:Percentage]]
--
local p = {}

local math_module = require( "Module:Math" )
local precision = math_module._precision
local sortkey = require( "Module:Sortkey" )

local function rnd(num, digits)
 -- This function implements {{rnd}}
 return math_module._precision_format(tostring(num), digits)
end

local function oom(num)
 -- This function implements {{order of magnitude}}
 return math_module._order(tostring(num))
end

function _nonscinote(num)
 -- This function undoes scientific notation
 if mw.ustring.match(num or '', '^%s*(%d)%.(%d+)<span[^<>]*>×</span>10<sup>([%-−]*)(%d)</sup>%s*$') then
  local a,b,c,d = mw.ustring.match(num or '', '^%s*(%d)%.(%d+)<span[^<>]*>×</span>10<sup>([%-−]*)(%d)</sup>%s*$')
  d = tonumber(d) or 1
  if c ~= '' then
   return '0.' .. mw.ustring.rep('0', d - 1) .. a .. b
  else
   return a .. mw.ustring.sub(b .. mw.ustring.rep('0', d ), 1, d)
  end
 end
 return num
end

local function fmtout(num,snote)
 if snote then
  return _nonscinote(num)
 else
  return num
 end
end

function _percentage(n1, n2, prec, suffix, pad, sigfig, sn)
 local pct = 100*n1/n2
 skey = '<span data-sort-value="'
   .. sortkey._sortKeyForNumber(pct) .. '♠" style="display:none"></span>'

 -- prec = math.floor(prec)

 if sigfig ~= '' then
  if pct ~= 0 then
   return skey .. fmtout(rnd(pct, tonumber(sigfig) - oom(pct) - 1), sn) .. suffix
  else
   return skey .. fmtout(rnd(pct, tonumber(sigfig) - 3), sn) .. suffix
  end
 end
 if pad ~= '' then
  return skey .. fmtout(rnd(pct, prec), sn) .. suffix
 end
 
 prec = (prec < 0) and 0 or prec
 if pct ~= 0 then
  pct = ((pct < 0) and -1 or 1)*math.floor(math.abs(pct * 10^prec) + 0.5) / 10^prec
 end
 
 return skey .. fmtout(pct, sn) .. suffix
end

function p.main(frame)
 local args = frame.args[1] and frame.args or frame:getParent().args
 local yesno = require('Module:Yesno')
 return _percentage(
  tonumber(args[1]) or 0,
  tonumber(args[2]) or 100,
  tonumber(args[3]) or tonumber(args['pad']) or 0,
  args['%'] or '%', args['pad'] or '',
  args['sigfig'] or '',
  yesno(args['nonscinote'] or 'no')
  )
end

return p