#!/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=e956494f50cc8b8f6c6bf1dc7f60fdbc1e3461778a6ef3ebaac325a15385853d
        path=773l7q13kvqdzfdpyy920n937im7gz3b/nix-2.20.8-x86_64-linux.tar.xz
        system=x86_64-linux
        ;;
    Linux.i?86)
        hash=961af361a0d84d335ab9ecaa760ba335a187f80ea70106ef7eb9d7f543a6faa0
        path=qhh8pvkj4myx1hiib65cd02240zbzk25/nix-2.20.8-i686-linux.tar.xz
        system=i686-linux
        ;;
    Linux.aarch64)
        hash=5549a7726153000463aa85b68ab5fb94d92e86264cfac40f591d3d0ca48e0370
        path=jxhvcg5fxxgm865ihnpza0z2fxjwvxb5/nix-2.20.8-aarch64-linux.tar.xz
        system=aarch64-linux
        ;;
    Linux.armv6l)
        hash=57b8e0fbbd9b2b8bf35f5ae6b3c3351c1a476a7b521ff6580846ba68252b5e97
        path=1rw5bi5i8y3gq49b5j8ah6ibq6kq36vi/nix-2.20.8-armv6l-linux.tar.xz
        system=armv6l-linux
        ;;
    Linux.armv7l)
        hash=74e183c7f45b942d44b897937114ae5dbcaa8265655615217cff93da427dfe50
        path=iypcc89r54d774k6vzmp85871hn5qzas/nix-2.20.8-armv7l-linux.tar.xz
        system=armv7l-linux
        ;;
    Darwin.x86_64)
        hash=7d36d1050cea363f8aed437a0e63e6733ee8d6daeaebb39a4ea2818c644f8fec
        path=f7hxh9jfhc14zjsfapv7agz0kijkr60y/nix-2.20.8-x86_64-darwin.tar.xz
        system=x86_64-darwin
        ;;
    Darwin.arm64|Darwin.aarch64)
        hash=6da9461d91cd71aad53b0d6ee4770fee235d6887a6b379cb2a2a94bf79a46e3d
        path=iyb4i4dfcjz5r6615w0y3ad2lq819l4h/nix-2.20.8-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-2.20.8/nix-2.20.8-$system.tar.xz
fi

tarball=$tmpDir/nix-2.20.8-$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 2.20.8 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