#! /bin/sh -e

usage(){
    echo  >&2 "syntax: nix-prefetch-zip [OPTIONS] [URL [EXPECTED-HASH]]

Options:
      --url         url    The url of the archive to fetch.
      --name        name   The name to use for the store path (defaults to \`basename \$url\`).
      --ext         ext    The file extension (.zip, .tar.gz, ...) to be REMOVED from name
      --hash        hash   The hash of unpacked archive.
      --hash-type   type   Use the specified cryptographic hash algorithm, which can be one of md5, sha1, and sha256.
      --leave-root         Keep the root directory of the archive.
      --help               Show this help text.
"
    exit 1
}


name=""
ext=""
argi=0
argfun=""
for arg; do
  if test -z "$argfun"; then
    case $arg in
      --url) argfun=set_url;;
      --name) argfun=set_name;;
      --ext) argfun=set_ext;;
      --hash) argfun=set_expHash;;
      --hash-type) argfun=set_hashType;;
      --leave-root) leaveRoot=true;;
      --help) usage;;
      *) argi=$(($argi + 1))
         case $argi in
           1) url=$arg;;
           2) rev=$arg;;
           3) expHash=$arg;;
           *) echo "Unexpected argument: $arg" >&2
              usage
              ;;
         esac
         ;;
    esac
  else
    case $argfun in
      set_*)
        var=$(echo $argfun | sed 's,^set_,,')
        eval "$var=\$arg"
        ;;
    esac
    argfun=""
  fi
done

if [ -z "$url" ]; then
  echo "Error: No --url flag given" >&2
  usage
fi

if [ -z "$name" ]; then
  name=$(basename "$url")
fi

if test -z "$hashType"; then
  hashType=sha256
fi

hashFormat="--base32"

tmp=$(mktemp -d 2>/dev/null || mktemp -d -t "$$")
trap "rm -rf '$tmp'" EXIT

dirname=$(basename -s "$ext" "$name")

unpackDirTmp=$tmp/unpacked-tmp/$dirname
mkdir -p $unpackDirTmp

unpackDir=$tmp/unpacked/$dirname
mkdir -p $unpackDir

downloadedFile=$tmp/$(basename "$url")

unpackFile() {
  local curSrc="$1"

  case "$curSrc" in
    *.tar.xz | *.tar.lzma)
      # Don't rely on tar knowing about .xz.
      xz -d < $curSrc | tar xf -
      ;;
    *.tar | *.tar.* | *.tgz | *.tbz2)
      # GNU tar can automatically select the decompression method
      # (info "(tar) gzip").
      tar xf $curSrc
      ;;
    *.zip)
      unzip -qq $curSrc
      ;;
    *)
      echo "source archive $curSrc has unknown type" >&2
      exit 1
      ;;
  esac
}

# If the hash was given, a file with that hash may already be in the
# store.
if test -n "$expHash"; then
  finalPath=$(nix-store --print-fixed-path --recursive "$hashType" "$expHash" "$name")
  if ! nix-store --check-validity "$finalPath" 2> /dev/null; then
    finalPath=
  fi
  hash=$expHash
fi

# If we don't know the hash or a path with that hash doesn't exist,
# download the file and add it to the store.
if test -z "$finalPath"; then
  curl="curl \
   --location --max-redirs 20 \
   --disable-epsv \
   --insecure"

  if ! $curl --fail "$url" --output "$downloadedFile"; then
    echo "error: could not download $url" >&2
    exit 1
  fi

  if [ -z "$leaveRoot" ]; then
    shopt -s dotglob

    cd "$unpackDirTmp"
    unpackFile "$downloadedFile"

    if [ $(ls "$unpackDirTmp" | wc -l) != 1 ]; then
      echo "error: zip file must contain a single file or directory."
      exit 1
    fi

    fn=$(cd "$unpackDirTmp" && echo *)

    if [ -f "$unpackDirTmp/$fn" ]; then
      mv "$unpackDirTmp/$fn" "$unpackDir"
    else
      mv "$unpackDirTmp/$fn/"* "$unpackDir/"
    fi
  else
    cd $unpackDir
    unpackFile "$downloadedFile"
  fi

  # Compute the hash.
  hash=$(nix-hash --type $hashType $hashFormat $unpackDir)
  if ! test -n "$QUIET"; then echo "hash is $hash" >&2; fi

  # Add the downloaded file to the Nix store.
  finalPath=$(nix-store --add-fixed --recursive "$hashType" $unpackDir)

  if test -n "$expHash" -a "$expHash" != "$hash"; then
    echo "hash mismatch for URL \`$url'"
    exit 1
  fi
fi

if ! test -n "$QUIET"; then echo "path is $finalPath" >&2; fi

echo $hash

if test -n "$PRINT_PATH"; then
  echo $finalPath
fi