{stdenv, fetchurl, which, file, perl, curl, python27, makeWrapper}:

/* Rust's build process has a few quirks :

- It requires some patched in llvm that haven't landed upstream, so it
  compiles its own llvm. This might change in the future, so at some
  point we may be able to switch to nix's llvm.

- The Rust compiler is written is Rust, so it requires a bootstrap
  compiler, which is downloaded during the build. To make the build
  pure, we download it ourself before and put it where it is
  expected. Once the language is stable (1.0) , we might want to
  switch it to use nix's packaged rust compiler.

*/

with if stdenv.system == "i686-linux" then {
  platform = "linux-i386";
  snapshot = "03e60be1f1b90dddd15f3597bc45ec8d9626b35d";
  snapshot_sha = "1v1l082gj7d2d4p53xgsxz2k965jcgqhw4cyxmjxc6yh5fw0idx6";
  target = "i686-unknown-linux-gnu";
} else if stdenv.system == "x86_64-linux" then {
  platform = "linux-x86_64";
  snapshot = "aa8fbbacdb1d8a078f3a3fe3478dcbc506bd4090";
  snapshot_sha = "17inc23jpznqp0vnskvznm74mm24c1nffhz2bkadhvp2ww0vpjjx";
  target = "x86_64-unknown-linux-gnu";
} else if stdenv.system == "x86_64-darwin" then {
  platform = "macos-x86_64";
  snapshot = "ec746585cb20d1f9edffec74f6ff8be6e93a75f7";
  snapshot_sha = "0r8f8x3x8jb1hm40pbgj4i9ll2y5dgjgvj24qg7mp4crbqcqhkd2";
} else {};
let snapshotDate = "2014-01-05";
    snapshotRev = "a6d3e57";
    snapshotName = "rust-stage0-${snapshotDate}-${snapshotRev}-${platform}-${snapshot}.tar.bz2"; in
stdenv.mkDerivation {
  name = "rust-0.9";

  src = fetchurl {
    url = http://static.rust-lang.org/dist/rust-0.9.tar.gz;
    sha256 = "1lfmgnn00wrc30nf5lgg52w58ir3xpsnpmzk2v5a35xp8lsir4f0";
  };

  # We need rust to build rust. If we don't provide it, configure will try to download it
  snapshot = fetchurl {
    url = "http://static.rust-lang.org/stage0-snapshots/${snapshotName}";
    sha256 = snapshot_sha;
  };

  # Put the snapshot where it is expected
  postUnpack = ''
    mkdir $sourceRoot/dl
    ln -s $snapshot $sourceRoot/dl/${snapshotName}
  '';

  # The compiler requires cc, so we patch the source to tell it where to find it
  patches = [ ./hardcode_paths.patch ];
  postPatch = ''
    substituteInPlace src/librustc/back/link.rs \
      --subst-var-by "gccPath" ${stdenv.gcc}/bin/cc \
      --subst-var-by "binutilsPath" ${stdenv.gcc.binutils}/bin/ar
  '';

  # Modify the snapshot compiler so that is can be executed
  preBuild = if stdenv.isLinux then ''
    make ${target}/stage0/bin/rustc
    patchelf --interpreter ${stdenv.glibc}/lib/${stdenv.gcc.dynamicLinker} \
             --set-rpath ${stdenv.gcc.gcc}/lib/:${stdenv.gcc.gcc}/lib64/ \
             ${target}/stage0/bin/rustc
  '' else null;

  buildInputs = [ which file perl curl python27 makeWrapper ];
  enableParallelBuilding = true;

  meta = {
    homepage = http://www.rust-lang.org/;
    description = "A safe, concurrent, practical language";
    maintainers = [ stdenv.lib.maintainers.madjar ];
    license = map (builtins.getAttr "shortName") [ stdenv.lib.licenses.mit stdenv.lib.licenses.asl20 ];
    # platforms as per http://static.rust-lang.org/doc/master/tutorial.html#getting-started
    platforms = [ "i686-linux" "x86_64-linux" "x86_64-darwin" ];
  };
}