Modul:URLutil

---

--[=[
URLutil: Utilities for URL etc.
* getAuthority()
* getHost()
* getScheme()
* isIP()
* isIPv4()
* isIPv6()
* isMailAddress()
Only [[dotted decimal]] notation for IPv4 supported.
Does not support dotted hexadecimal, dotted octal, or single-number formats.

Functions are not "local",
so other modules can require this module and call them directly.
We return an object with small stub functions to call the real ones
so that the functions can be called from templates also.
----
Based upon   w:en:Special:Permalink/542839577?title=Module:IPAddress   2013-03-01
Unit tests at :en:Module:IPAddress/tests
]=]




function _getAuthority( url )
    if type( url ) == "string" then
        local host, colon, port = mw.ustring.match( url .. "/", "^%s*%w*:?//([%w%.%%-]+)(:?)([%d]*)/" )
        if isHost( host ) then
            host = mw.ustring.lower( host )
            if colon == ":" then
                if port:match( "^[1-9]" ) then
                    return ( host .. ":" .. port )
                end
            elseif #port == 0 then
                return host
            end
        end
    end
    return false
end -- _getAuthority()



function _getHost( url )
    if type( url ) == "string" then
        local auth = _getAuthority( url )
        if type( auth ) == "string" then
            return mw.ustring.match( auth, "^([%w%.%%-]+):?[%d]*$" )
        end
    end
    return false
end -- _getHost()



function _getScheme( url )
    if type( url ) == "string" then
        local prot, colon, slashes = url:match( "^%s*([a-zA-Z]*)(:?)(//)" )
        if slashes == "//" then
           if colon == ":" then
               if #prot > 2 then
                   return prot:lower() .. "://"
               end
           elseif #prot == 0 then
               return "//"
           end
        end
    end
    return false
end -- _getScheme()



function isHost( s )
    -- internal only
    if type( s ) == "string" then
        if _isIP( s ) then
            return s
        elseif type( mw.ustring.match( s, "^([%w%.%%-]+%w)%.[a-zA-Z][a-zA-Z]+$" ) ) == "string" then
            if mw.ustring.match( s, "^%w" ) then
                if mw.ustring.find( s, "..", 1, true ) then
                    return false
                else
                    return s
                end
            end
        end
    end
    return false
end -- isHost()



function _isIP( s )
    return _isIPv4( s ) and "4" or _isIPv6( s ) and "6"
end -- _isIP()



function _isIPv4( s )
    local function legal( n )
              return ( tonumber( n ) or 256 ) < 256
                     and not n:match( "^0%d" )
          end -- in lua 0 is true!
    if type( s ) ~= "string" then
        return false
    end
    local p1, p2, p3, p4 = s:match( "^%s*(%d+)%.(%d+)%.(%d+)%.(%d+)%s*$" )
    return legal( p1 ) and legal( p2 ) and legal( p3 ) and legal( p4 )
end -- _isIPv4()



function _isIPv6( s )
    local dcolon, groups
    if type( s ) ~= "string"
        or s:len() == 0
        or s:find( "[^:%x]" ) -- only colon and hex digits are legal chars
        or s:find( "^:[^:]" ) -- can begin or end with :: but not with single :
        or s:find( "[^:]:$" )
        or s:find( ":::" )
    then
        return false
    end
    s = mw.text.trim( s )
    s, dcolon = s:gsub( "::", ":" )
    if dcolon > 1 then
        return false
    end -- at most one ::
    s = s:gsub( "^:?", ":" ) -- prepend : if needed, upper
    s, groups = s:gsub( ":%x%x?%x?%x?", "" ) -- remove valid groups, and count them
    return ( ( dcolon == 1 and groups < 8 ) or
             ( dcolon == 0 and groups == 8 ) )
        and ( s:len() == 0 or ( dcolon == 1 and s == ":" ) ) -- might be one dangling : if original ended with ::
end -- _isIPv6()



function _isMailAddress( s )
    if type( s ) == "string" then
         s = mw.ustring.match( s, "^%s*[%w%.%%_-]+@([%w%.%%-]+)%s*" )
         return isHost( s )
    end
    return false
end -- _isMailAddress()



-- Provide template access

local p = {}

function p.getAuthority( frame )
    return _getAuthority( frame.args[ 1 ] ) or ""
end
function p.getHost( frame )
    return _getHost( frame.args[ 1 ] ) or ""
end
function p.getScheme( frame )
    return _getScheme( frame.args[ 1 ] ) or ""
end
function p.isIP( frame )
    return _isIP( frame.args[ 1 ] ) or ""
end
function p.isIPv4( frame )
    return _isIPv4( frame.args[ 1 ] ) and "1" or "0"
end
function p.isIPv6( frame )
    return _isIPv6( frame.args[ 1 ] ) and "1" or "0"
end
function p.isMailAddress( frame )
    return _isMailAddress( frame.args[ 1 ] ) and "1" or "0"
end

return p