#!/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=8a650e25b171628bd780abffef3d2711dc5077ced25471a4047d72a900682ceb
        path=243jv4rx227zcjp14d6x3acjywmnsava/nix-2.20.2-x86_64-linux.tar.xz
        system=x86_64-linux
        ;;
    Linux.i?86)
        hash=50242d2728dc52ac23804d4d0b7f6de8f63a633d99e4a1cb8664634ca98dc8ef
        path=yvypbpafc2i1zkldkbfpk2wycc7c247g/nix-2.20.2-i686-linux.tar.xz
        system=i686-linux
        ;;
    Linux.aarch64)
        hash=42033c90681964bfddf4e996f72b9fd60a8d422172a00a6d99b0bc7ae2d3f2c3
        path=4svzqj0z6121xfn4ifnyhy8pdwhzn7sr/nix-2.20.2-aarch64-linux.tar.xz
        system=aarch64-linux
        ;;
    Linux.armv6l)
        hash=2e2e4c16e02cbb5e44b0b5c50bd9ef58346b04355ab2a3ed89d41bddf84a1daa
        path=grgrq2s7jn8kwrva5ywl3kn131blh66q/nix-2.20.2-armv6l-linux.tar.xz
        system=armv6l-linux
        ;;
    Linux.armv7l)
        hash=8fecd5a970c3e826ca00201e23fb446a330c43329e3f21ff7c0dd1fde432d2eb
        path=b832cn8n32ag3a8zxs4fyvgwjp7r6rpz/nix-2.20.2-armv7l-linux.tar.xz
        system=armv7l-linux
        ;;
    Darwin.x86_64)
        hash=8df8064905a0b6fb21dbe56c61353f1793674919fe806c69df24f96e6de68d4b
        path=9702lsmbn8fr5pjbjv6jyz0m1vl90vwz/nix-2.20.2-x86_64-darwin.tar.xz
        system=x86_64-darwin
        ;;
    Darwin.arm64|Darwin.aarch64)
        hash=ab5f14561d894ffd60ff6cf9c55ce22a5a16ebb395bd92c26ee5dc2bccaa9b4d
        path=3i2s6awfzli66iczw3d5kiw9lbs52kll/nix-2.20.2-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-2.20.2/nix-2.20.2-$system.tar.xz
fi

tarball=$tmpDir/nix-2.20.2-$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 2.20.2 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