import re, os, sys, glob, hashlib, tarfile, shutil, subprocess, tempfile

def scrub(b):
  if sys.version_info >= (3,) and type(b) == bytes:
    return b.decode('ascii')
  else:
    return b

src_dir = scrub(os.getenv("CFG_SRC_DIR"))
if not src_dir:
  raise Exception("missing env var CFG_SRC_DIR")

snapshotfile = os.path.join(src_dir, "src", "snapshots.txt")
download_url_base = "http://dl.rust-lang.org/stage0-snapshots"
download_dir_base = "dl"
download_unpack_base = os.path.join(download_dir_base, "unpack")

snapshot_files = {
    "linux": ["bin/rustc",
              "lib/libcore-*.so",
              "lib/libstd-*.so",
              "lib/librustrt.so",
              "lib/librustllvm.so"],
    "macos": ["bin/rustc",
              "lib/libcore-*.dylib",
              "lib/libstd-*.dylib",
              "lib/librustrt.dylib",
              "lib/librustllvm.dylib"],
    "winnt": ["bin/rustc.exe",
              "lib/core-*.dll",
              "lib/std-*.dll",
              "lib/rustrt.dll",
              "lib/rustllvm.dll"]
    }

def parse_line(n, line):
  global snapshotfile

  if re.match(r"\s*$", line): return None

  if re.match(r"^T\s*$", line): return None

  match = re.match(r"\s+([\w_-]+) ([a-fA-F\d]{40})\s*$", line)
  if match:
    return { "type": "file",
             "platform": match.group(1),
             "hash": match.group(2).lower() }

  match = re.match(r"([ST]) (\d{4}-\d{2}-\d{2}) ([a-fA-F\d]+)\s*$", line);
  if (not match):
    raise Exception("%s:%d:E syntax error" % (snapshotfile, n))
  return {"type": "snapshot",
          "date": match.group(2),
          "rev": match.group(3)}


def partial_snapshot_name(date, rev, platform):
  return ("rust-stage0-%s-%s-%s.tar.bz2"
          % (date, rev, platform))

def full_snapshot_name(date, rev, platform, hsh):
  return ("rust-stage0-%s-%s-%s-%s.tar.bz2"
          % (date, rev, platform, hsh))


def get_kernel(triple):
    os_name = triple.split('-')[-1]
    #scrub(os.getenv("CFG_ENABLE_MINGW_CROSS")):
    if os_name == "nt" or os_name == "mingw32":
        return "winnt"
    if os_name == "darwin":
        return "macos"
    return "linux"

def get_cpu(triple):
    arch = triple.split('-')[0]
    if arch == "i686":
      return "i386"
    return arch

def get_platform(triple):
  return "%s-%s" % (get_kernel(triple), get_cpu(triple))


def cmd_out(cmdline):
    p = subprocess.Popen(cmdline,
                         stdout=subprocess.PIPE)
    return scrub(p.communicate()[0].strip())


def local_rev_info(field):
    return cmd_out(["git", "--git-dir=" + os.path.join(src_dir, ".git"),
                    "log", "-n", "1",
                    "--format=%%%s" % field, "HEAD"])


def local_rev_full_sha():
    return local_rev_info("H").split()[0]


def local_rev_short_sha():
    return local_rev_info("h").split()[0]


def local_rev_committer_date():
    return local_rev_info("ci")

def get_url_to_file(u,f):
  subprocess.check_call(["curl", "-o", f, u])

def snap_filename_hash_part(snap):
  match = re.match(r".*([a-fA-F\d]{40}).tar.bz2$", snap)
  if not match:
    raise Exception("unable to find hash in filename: " + snap)
  return match.group(1)

def hash_file(x):
    h = hashlib.sha1()
    h.update(open(x, "rb").read())
    return scrub(h.hexdigest())


def make_snapshot(stage, triple, flag):
    kernel = get_kernel(triple)
    platform = get_platform(triple)
    rev = local_rev_short_sha()
    date = local_rev_committer_date().split()[0]

    file0 = partial_snapshot_name(date, rev, platform)

    def in_tar_name(fn):
      cs = re.split(r"[\\/]", fn)
      if len(cs) >= 2:
        return os.sep.join(cs[-2:])

    tar = tarfile.open(file0, "w:bz2")
    for name in snapshot_files[kernel]:
      dir = stage
      if stage == "stage1" and re.match(r"^lib/(lib)?std.*", name):
        dir = "stage0"
      fn_glob = os.path.join(triple, dir, name)
      matches = glob.glob(fn_glob)
      if not matches:
        raise Exception("Not found file with name like " + fn_glob)
      if len(matches) == 1:
        tar.add(matches[0], "rust-stage0/" + in_tar_name(matches[0]))
      else:
        raise Exception("Found stale files: \n  %s\n\
Please make a clean build." % "\n  ".join(matches))
    tar.close()

    h = hash_file(file0)
    file1 = full_snapshot_name(date, rev, platform, h)

    shutil.move(file0, file1)

    if flag == "install":
      # FIXME this is an ugly quick hack; pls make it better
      path  = file1
      comps = path.split("-")
      parts = { 'year': comps[2], \
                'month': comps[3], \
                'date': comps[4], \
                'check': comps[5], \
                'plat': comps[6], \
                'arch': comps[7], \
                'sha': comps[8].split(".")[0] }

      shutil.move(path, "dl/" + path)
      shutil.move('src/snapshots.txt', 'src/snapshots-old.txt')

      newf = open('src/snapshots.txt', 'w')
      newf.write("T %(year)s-%(month)s-%(date)s %(check)s\n" % parts)
      newf.write("  %(plat)s-%(arch)s %(sha)s\n\n" % parts)

      oldf = open('src/snapshots-old.txt', 'r')
      for line in oldf:
        newf.write(line)
      oldf.close()

      newf.close()

      os.remove('src/snapshots-old.txt')


    return file1