# Module:Formatnum

-- This module is intended to replace the functionality of Template:Formatnum and related templates.
local p = {}  
function p.main
local args = :getParent.args
local prec = args.prec or ''
local sep = args.sep or ''
local number = args[1] or args.number or ''
local lang = args[2] or args.lang or ''
-- validate the language parameter within MediaWiki's caller
if lang == "arabic-indic" then -- only for back-compatibility ("arabic-indic" is not a SupportedLanguage)
lang = "fa" -- better support than "ks"
elseif lang == '' or not mw.language.isSupportedLanguage(lang) then
-- Note that 'SupportedLanguages' are not necessarily 'BuiltinValidCodes', and so they are not necessarily
-- 'KnownLanguages' (with a language name defined at least in the default localisation of the local wiki).
-- But they all are ValidLanguageCodes (suitable as Wiki subpages or identifiers: no slash, colon, HTML tags, or entities)
-- In addition, they do not contain any capital letter in order to be unique in page titles (restriction inexistant in BCP47),
-- but they may violate the standard format of BCP47 language tags for specific needs in MediaWiki.
-- Empty/unspecified and unsupported languages are treated here in Commons using the user's language,
-- instead of the local 'ContentLanguage' of the Wiki.
lang = :callParserFunction( "int", "lang" ) -- get user's chosen language
end
return p.formatNum(number, lang, prec, sep ~= '')
end  
local digit = { -- substitution of decimal digits for languages not supported by mw.language:formatNum in core Lua libraries for MediaWiki
["ml-old"] = { '൦', '൧', '൨', '൩', '൪', '൫', '൬', '൭', '൮', '൯' },
["mn"] = { '᠐', '᠑', '᠒', '᠓', '᠔', '᠕', '᠖', '᠗', '᠘', '᠙'},
["ta"] = { '௦', '௧', '௨', '௩', '௪', '௫', '௬', '௭', '௮', '௯'},
["te"] = { '౦', '౧', '౨', '౩', '౪', '౫', '౬', '౭', '౮', '౯'},
["th"] = { '๐', '๑', '๒', '๓', '๔', '๕', '๖', '๗', '๘', '๙'}
}  
function p.formatNum(number, lang, prec, compact)  
-- Do not alter the specified value when it is not a valid number, return it as is
local value = tonumber(number)
if value == nil then
return number
end
-- Basic ASCII-only formatting (without paddings)
number = tostring(value)  
-- Check the presence of an exponent (incorrectly managed in mw.language:FormatNum and even forgotten due to an internal bug, e.g. in Hindi)
local exponent
local pos = string.find(number, '[Ee]')
if pos ~= nil then
exponent = string.sub(number, pos + 1, string.len(number))
number = string.sub(number, 1, pos - 1)
else
exponent = ''
end  
-- Check the minimum precision requested
prec = tonumber(prec) -- nil if not specified as a true number
if prec ~= nil then
prec = math.floor(prec)
if prec < 0 then
prec = nil -- discard an incorrect precision (not a positive integer)
elseif prec > 14 then
prec = 14 -- maximum precision supported by tostring(number)
end
end  
-- Preprocess the minimum precision in the ASCII string
local dot
if (prec or 0) > 0 then
pos = string.find(number, '.', 1, true) -- plain search, no regexp
if pos ~= nil then
prec = pos + prec - string.len(number) -- effective number of trailing decimals to add or remove
dot = '' -- already present
else
dot = '.' -- must be added
end
else
dot = '' -- don't add dot
prec = 0 -- don't alter the precision
end  
if lang ~= nil and mw.language.isKnownLanguageTag(lang) == true then
-- Convert number to localized digits, decimal separator, and group separators
local language = mw.getLanguage(lang)
if compact then
number = language:formatNum(tonumber(number), { noCommafy = 'y' }) -- caveat: can load localized resources for up to 20 languages
else
number = language:formatNum(tonumber(number)) -- caveat: can load localized resources for up to 20 languages
end
-- Postprocessing the precision
if prec > 0 then
local zero = language:formatNum(0)
number = number .. dot .. mw.ustring.rep(zero, prec)
elseif prec < 0 then
-- TODO: rounding of last decimal; here only truncate decimals in excess
number = mw.ustring.sub(number, 1, mw.ustring.len(number) + prec)
end  
-- Append the localized base-10 exponent without grouping separators (there's no reliable way to detect a localized leading symbol 'E')
if exponent ~= '' then
number = number .. 'E' .. language:formatNum(tonumber(exponent),{noCommafy=true})
end
else -- not localized, ASCII only
-- Postprocessing the precision
if prec > 0 then
number = number .. dot .. mw.string.rep('0', prec)
elseif prec < 0 then
-- TODO: rounding of last decimal; here only truncate decimals in excess
number = mw.string.sub(number, 1, mw.string.len(number) + prec)
end  
-- Append the base-10 exponent
if exponent ~= '' then
number = number .. 'E' .. exponent
end
end  
-- Special cases for substitution of ASCII digits (missing support in Lua core libraries for some languages)
if digit[lang] then
for i, v in ipairs(digit[lang]) do
number = mw.ustring.gsub(number, tostring(i - 1), v)
end
end  
return number
end  
return p