/-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import init.system.platform
import init.data.string.basic

namespace System
namespace FilePath
open Platform

/-- The character that separates directories. In the case where more than one character is possible, `pathSeparator` is the 'ideal' one. -/
def pathSeparator : Char :=
if isWindows then '\\' else '/'

/-- The list of all possible separators. -/
def pathSeparators : List Char :=
if isWindows then ['\\', '/'] else ['/']

/-- The character that is used to separate the entries in the $PATH environment variable. -/
def searchPathSeparator : Char :=
if isWindows then ';' else ':'

/-- File extension character -/
def extSeparator : Char :=
'.'

/-- Case-insensitive file system -/
def isCaseInsensitive : Bool :=
isWindows || isOSX

def normalizePath (fname : String) : String :=
if pathSeparators.length == 1 && !isCaseInsensitive then fname
else fname.map (fun c =>
  if pathSeparators.any (fun c' => c == c') then pathSeparator
  else if isCaseInsensitive then c.toLower
  else c)

def dirName (fname : String) : String :=
let fname := normalizePath fname;
match fname.revPosOf pathSeparator with
| none => "."
| some pos => { Substring . str := fname, startPos := 0, stopPos := pos }.toString

end FilePath
end System
