{-# OPTIONS_GHC -cpp #-}
{-
Copyright (C) 2004 David Roundy

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
-}

module Darcs.URL (
    is_file, is_url, is_ssh, is_relative, is_absolute,
    is_ssh_nopath
  ) where

import Data.Maybe ( isNothing, isJust )

import Text.Regex ( Regex, mkRegex, matchRegex )
#include "impossible.h"

{-
  Path resolving:
    * A URL contains the sequence "://".
    * A local filepath does not contain colons, except
      as second character (windows drives).
    * A path that is neither a URL nor a local file
      is an ssh-path.

  Examples:
    /usr/repo/foo                 - local file
    c:/src/darcs                  - local file
    http://darcs.net/             - URL
    peter@host:/path              - ssh
    host:/path                    - ssh


  This means that single-letter hosts in ssh-paths doesn't work,
  unless a username is provided.

  Perhaps ssh-paths should use "ssh://user@host/path"-syntax instead?
-}

match_not_file :: Regex
match_not_file = mkRegex "..+:.+"
match_url :: Regex
match_url = mkRegex ".+://.+"
match_ssh_nopath :: Regex
match_ssh_nopath = mkRegex "^[^:]{2,}:$"

is_relative :: String -> Bool
is_absolute :: String -> Bool
is_file :: String -> Bool
is_url :: String -> Bool
is_ssh :: String -> Bool
is_ssh_nopath :: String -> Bool

is_relative (_:':':_) = False
is_relative f@(c:_) = is_file f && c /= '/' && c /= '~'
is_relative "" = bug "Empty filename in is_relative"

is_absolute f = is_file f && (not $ is_relative f)

is_file fou = isNothing $ matchRegex match_not_file fou
is_url s = isJust $ matchRegex match_url s
is_ssh s = not (is_file s || is_url s)
is_ssh_nopath s = isJust $ matchRegex match_ssh_nopath s