#! @shell@ -e

url=$1
expHash=$2

# to prevent doing more than 1 chroot
unset NIX_ROOT

# needed to make it work on NixOS
export PATH=$PATH:@coreutils@

hashType=$NIX_HASH_ALGO
if test -z "$hashType"; then
    hashType=md5
fi

hashFormat=
if test "$hashType" != "md5"; then
    hashFormat=--base32
fi

if test -z "$url"; then
    echo "syntax: nix-prefetch-url URL [EXPECTED-HASH]" >&2
    exit 1
fi

name=$(basename "$url")
if test -z "$name"; then echo "invalid url"; exit 1; fi


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


# If we don't know the hash or a file with that hash doesn't exist,
# download the file and add it to the store.
if test -z "$finalPath"; then

    tmpPath=/tmp/nix-prefetch-url-$$ # !!! security?
    tmpFile=$tmpPath/$name
    mkdir $tmpPath

    # Perform the download.
    @curl@ --fail --location --max-redirs 20 --disable-epsv "$url" > $tmpFile

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

    # Add the downloaded file to the Nix store.
    finalPath=$(@bindir@/nix-store --add-fixed "$hashType" $tmpFile)

    if test -n "$tmpPath"; then rm -rf $tmpPath || true; fi

    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