#!/bin/sh

# This script installs the Nix package manager on your system by
# downloading a binary distribution and running its installer script
# (which in turn creates and populates /nix).

{ # Prevent execution if this script was only partially downloaded
oops() {
    echo "$0:" "$@" >&2
    exit 1
}

umask 0022

tmpDir="$(mktemp -d -t nix-binary-tarball-unpack.XXXXXXXXXX || \
          oops "Can't create temporary directory for downloading the Nix binary tarball")"
cleanup() {
    rm -rf "$tmpDir"
}
trap cleanup EXIT INT QUIT TERM

require_util() {
    command -v "$1" > /dev/null 2>&1 ||
        oops "you do not have '$1' installed, which I need to $2"
}

case "$(uname -s).$(uname -m)" in
    Linux.x86_64)
        hash=77c8158315d618df41d109b287ec1e1445e9c8f1db4a36f887d8333e5d688f9d
        path=ynqgiwcpgfdwf0mygh0lpydkvb3vknp4/nix-2.18.0-x86_64-linux.tar.xz
        system=x86_64-linux
        ;;
    Linux.i?86)
        hash=13232dd10792f6acb5426639a9930828de654ca257a12c1419b5ef3ab0a0ad72
        path=y73sl25kgw50l7xgffsmlwbz37qghyww/nix-2.18.0-i686-linux.tar.xz
        system=i686-linux
        ;;
    Linux.aarch64)
        hash=ea3e967dc9f0814850d5a8eeb71ae40f0948fcd399a05865b963f949330f7db3
        path=xfbj2b001gjjbldn56zgryawza8bqkzj/nix-2.18.0-aarch64-linux.tar.xz
        system=aarch64-linux
        ;;
    Linux.armv6l)
        hash=233aca3739a50b365250ebeb0fa5cd4cedd916964784ab717f3ea12ab92f7dee
        path=sgdci0diwfpzmzywkqpdsgp8ss2hr6z0/nix-2.18.0-armv6l-linux.tar.xz
        system=armv6l-linux
        ;;
    Linux.armv7l)
        hash=a02e23ab39aaba7a6089eeb0968da84539a77d2efa096bae4d4cb133625893d9
        path=n6hyslq1iqmpbx2zswzwd1l1nh2dcjs9/nix-2.18.0-armv7l-linux.tar.xz
        system=armv7l-linux
        ;;
    Darwin.x86_64)
        hash=6884230bef5ab30da5f794c3a0d324589f3a006f66cffb80ece54be73f674b5d
        path=q1syn782xi16lkhfj232cd3jrhiirc1w/nix-2.18.0-x86_64-darwin.tar.xz
        system=x86_64-darwin
        ;;
    Darwin.arm64|Darwin.aarch64)
        hash=34bbde379219d1a37ced50fc26c6ca8b6757a1e45a9276855fa2bc75a575aab6
        path=307zi6dgjw3jv7fj9cgppw6fdwwliahg/nix-2.18.0-aarch64-darwin.tar.xz
        system=aarch64-darwin
        ;;
    *) oops "sorry, there is no binary distribution of Nix for your platform";;
esac

# Use this command-line option to fetch the tarballs using nar-serve or Cachix
if [ "${1:-}" = "--tarball-url-prefix" ]; then
    if [ -z "${2:-}" ]; then
        oops "missing argument for --tarball-url-prefix"
    fi
    url=${2}/${path}
    shift 2
else
    url=https://mirrors.tuna.tsinghua.edu.cn/nix//nix-2.18.0/nix-2.18.0-$system.tar.xz
fi

tarball=$tmpDir/nix-2.18.0-$system.tar.xz

require_util tar "unpack the binary tarball"
if [ "$(uname -s)" != "Darwin" ]; then
    require_util xz "unpack the binary tarball"
fi

if command -v curl > /dev/null 2>&1; then
    fetch() { curl --fail -L "$1" -o "$2"; }
elif command -v wget > /dev/null 2>&1; then
    fetch() { wget "$1" -O "$2"; }
else
    oops "you don't have wget or curl installed, which I need to download the binary tarball"
fi

echo "downloading Nix 2.18.0 binary tarball for $system from '$url' to '$tmpDir'..."
fetch "$url" "$tarball" || oops "failed to download '$url'"

if command -v sha256sum > /dev/null 2>&1; then
    hash2="$(sha256sum -b "$tarball" | cut -c1-64)"
elif command -v shasum > /dev/null 2>&1; then
    hash2="$(shasum -a 256 -b "$tarball" | cut -c1-64)"
elif command -v openssl > /dev/null 2>&1; then
    hash2="$(openssl dgst -r -sha256 "$tarball" | cut -c1-64)"
else
    oops "cannot verify the SHA-256 hash of '$url'; you need one of 'shasum', 'sha256sum', or 'openssl'"
fi

if [ "$hash" != "$hash2" ]; then
    oops "SHA-256 hash mismatch in '$url'; expected $hash, got $hash2"
fi

unpack=$tmpDir/unpack
mkdir -p "$unpack"
tar -xJf "$tarball" -C "$unpack" || oops "failed to unpack '$url'"

script=$(echo "$unpack"/*/install)

[ -e "$script" ] || oops "installation script is missing from the binary tarball!"
export INVOKED_FROM_INSTALL_IN=1
"$script" "$@"

} # End of wrapping