#!/bin/sh
# shellcheck shell=dash

# If you need an offline install, or you'd prefer to run the binary directly, head to
# https://github.com/DeterminateSystems/nix-installer/releases then pick the version and platform
# most appropriate for your deployment target.
#
# This is just a little script that selects and downloads the right `nix-installer`. It does
# platform detection, downloads the installer, and runs it; that's it.
#
# It runs on Unix shells like {a,ba,da,k,z}sh. It uses the common `local`
# extension. Note: Most shells limit `local` to 1 var per line, contra bash.

# This script is based off https://github.com/rust-lang/rustup/blob/2d429e8e172d5854b6dd7244ecbb0dc3da88a678/rustup-init.sh

# Some versions of ksh have no `local` keyword. Alias it to `typeset`, but
# beware this makes variables global with f()-style function syntax in ksh93.
# mksh has this alias by default.
has_local() {
    # shellcheck disable=SC2034  # deliberately unused
    local _has_local
}

has_local 2>/dev/null || alias local=typeset

is_zsh() {
    [ -n "${ZSH_VERSION-}" ]
}

set -u

# If NIX_INSTALLER_FORCE_ALLOW_HTTP is unset or empty, default it.
NIX_INSTALLER_BINARY_ROOT="${NIX_INSTALLER_BINARY_ROOT:-https://install.determinate.systems/nix}"

main() {
    downloader --check
    need_cmd uname
    need_cmd mktemp
    need_cmd chmod
    need_cmd mkdir
    need_cmd rm
    need_cmd rmdir

    get_architecture || return 1
    local _arch="$RETVAL"
    assert_nz "$_arch" "arch"

    local _ext=""
    case "$_arch" in
        *windows*)
            _ext=".exe"
            ;;
    esac

    local _url="${NIX_INSTALLER_OVERRIDE_URL-${NIX_INSTALLER_BINARY_ROOT}/nix-installer-${_arch}${_ext}}"

    local _dir
    if ! _dir="$(ensure mktemp -d)"; then
        # Because the previous command ran in a subshell, we must manually
        # propagate exit status.
        exit 1
    fi
    local _file="${_dir}/nix-installer${_ext}"

    local _ansi_escapes_are_valid=false
    if [ -t 2 ]; then
        if [ "${TERM+set}" = 'set' ]; then
            case "$TERM" in
                xterm*|rxvt*|urxvt*|linux*|vt*)
                    _ansi_escapes_are_valid=true
                ;;
            esac
        fi
    fi

    # check if we have to use /dev/tty to prompt the user
    local need_tty=yes
    for arg in "$@"; do
        case "$arg" in
            --no-confirm)
                need_tty=no
                ;;
            *)
                continue
                ;;
        esac
    done
    if [ "${NIX_INSTALLER_NO_CONFIRM-}" ]; then
        need_tty=no
    fi

    say 'downloading the Determinate Nix Installer'

    ensure mkdir -p "$_dir"
    ensure downloader "$_url" "$_file" "$_arch"
    ensure chmod u+x "$_file"
    if [ ! -x "$_file" ]; then
        err "Cannot execute $_file (likely because of mounting /tmp as noexec)." 1>&2
        err "Please copy the file to a location where you can execute binaries and run ./nix-installer${_ext}." 1>&2
        exit 1
    fi

    if [ "$need_tty" = "yes" ] && [ ! -t 0 ]; then
        # The installer is going to want to ask for confirmation by
        # reading stdin.  This script was piped into `sh` though and
        # doesn't have stdin to pass to its children. Instead we're going
        # to explicitly connect /dev/tty to the installer's stdin.
        if [ ! -t 1 ]; then
            err "Unable to run interactively. Run with --no-confirm to accept defaults, --help for additional options"
            exit 1;
        fi

        ignore "$_file" "$@" < /dev/tty
    else
        ignore "$_file" "$@"
    fi

    local _retval=$?

    ignore rm "$_file"
    ignore rmdir "$_dir"

    return "$_retval"
}

get_current_exe() {
    # Returns the executable used for system architecture detection
    # This is only run on Linux
    local _current_exe
    if test -L /proc/self/exe ; then
        _current_exe=/proc/self/exe
    else
        warn "Unable to find /proc/self/exe. System architecture detection might be inaccurate."
        if test -n "$SHELL" ; then
            _current_exe=$SHELL
        else
            need_cmd /bin/sh
            _current_exe=/bin/sh
        fi
        warn "Falling back to $_current_exe."
    fi
    echo "$_current_exe"
}

get_architecture() {
    local _ostype _cputype _arch
    _ostype="$(uname -s)"
    _cputype="$(uname -m)"

    if [ "$_ostype" = Linux ]; then
        if [ "$(uname -o)" = Android ]; then
            _ostype=Android
        fi
    fi

    if [ "$_ostype" = Darwin ]; then
        # Darwin `uname -m` can lie due to Rosetta shenanigans. If you manage to
        # invoke a native shell binary and then a native uname binary, you can
        # get the real answer, but that's hard to ensure, so instead we use
        # `sysctl` (which doesn't lie) to check for the actual architecture.
        if [ "$_cputype" = i386 ]; then
            # Handling i386 compatibility mode in older macOS versions (<10.15)
            # running on x86_64-based Macs.
            # Starting from 10.15, macOS explicitly bans all i386 binaries from running.
            # See: <https://support.apple.com/en-us/HT208436>

            # Avoid `sysctl: unknown oid` stderr output and/or non-zero exit code.
            if (sysctl hw.optional.x86_64 2> /dev/null || true) | grep -q ': 1'; then
                _cputype=x86_64
            fi
        elif [ "$_cputype" = x86_64 ]; then
            # Handling x86-64 compatibility mode (a.k.a. Rosetta 2)
            # in newer macOS versions (>=11) running on arm64-based Macs.
            # Rosetta 2 is built exclusively for x86-64 and cannot run i386 binaries.

            # Avoid `sysctl: unknown oid` stderr output and/or non-zero exit code.
            if (sysctl hw.optional.arm64 2> /dev/null || true) | grep -q ': 1'; then
                _cputype=arm64
            fi
        fi
    fi

    if [ "$_ostype" = SunOS ]; then
        # Both Solaris and illumos presently announce as "SunOS" in "uname -s"
        # so use "uname -o" to disambiguate.  We use the full path to the
        # system uname in case the user has coreutils uname first in PATH,
        # which has historically sometimes printed the wrong value here.
        if [ "$(/usr/bin/uname -o)" = illumos ]; then
            _ostype=illumos
        fi

        # illumos systems have multi-arch userlands, and "uname -m" reports the
        # machine hardware name; e.g., "i86pc" on both 32- and 64-bit x86
        # systems.  Check for the native (widest) instruction set on the
        # running kernel:
        if [ "$_cputype" = i86pc ]; then
            _cputype="$(isainfo -n)"
        fi
    fi

    local _current_exe
    case "$_ostype" in
        Linux)
            _current_exe=$(get_current_exe)
            _ostype=linux
            ;;

        Darwin)
            _ostype=darwin
            ;;

        *)
            err "unrecognized OS type: $_ostype"
            exit 1
            ;;

    esac

    case "$_cputype" in
        aarch64 | arm64)
            _cputype=aarch64
            ;;

        x86_64 | x86-64 | x64 | amd64)
            _cputype=x86_64
            ;;

        *)
            err "unknown CPU type: $_cputype"
            ;;

    esac

    _arch="${_cputype}-${_ostype}"

    RETVAL="$_arch"
}

__print() {
    if $_ansi_escapes_are_valid; then
        printf '\33[1m%s:\33[0m %s\n' "$1" "$2" >&2
    else
        printf '%s: %s\n' "$1" "$2" >&2
    fi
}

warn() {
    __print 'warn' "$1" >&2
}

say() {
    __print 'info' "$1" >&2
}

# NOTE: you are required to exit yourself
# we don't do it here because of multiline errors
err() {
    __print 'error' "$1" >&2
}

need_cmd() {
    if ! check_cmd "$1"; then
        err "need '$1' (command not found)"
        exit 1
    fi
}

check_cmd() {
    command -v "$1" > /dev/null 2>&1
}

assert_nz() {
    if [ -z "$1" ]; then
        err "assert_nz $2"
        exit 1
    fi
}

# Run a command that should never fail. If the command fails execution
# will immediately terminate with an error showing the failing
# command.
ensure() {
    if ! "$@"; then
        err "command failed: $*"
        exit 1
    fi
}

# This is just for indicating that commands' results are being
# intentionally ignored. Usually, because it's being executed
# as part of error handling.
ignore() {
    "$@"
}

# This wraps curl or wget. Try curl first, if not installed,
# use wget instead.
downloader() {
    # zsh does not split words by default, Required for curl retry arguments below.
    is_zsh && setopt local_options shwordsplit

    local _dld
    local _ciphersuites
    local _err
    local _status
    local _retry
    if check_cmd curl; then
        # Check if we have a broken snap curl
        # https://github.com/boukendesho/curl-snap/issues/1
        _curl_path=$(command -v curl)
        if echo "$_curl_path" | grep "/snap/" > /dev/null 2>&1; then
            if check_cmd wget; then
                _dld=wget
            else
                err "curl installed with snap cannot be used to install Rust"
                err "due to missing permissions. Please uninstall it and"
                err "reinstall curl with a different package manager (e.g., apt)."
                err "See https://github.com/boukendesho/curl-snap/issues/1"
                exit 1
            fi
        else
            _dld=curl
        fi
    elif check_cmd wget; then
        _dld=wget
    else
        _dld='curl or wget' # to be used in error message of need_cmd
    fi

    if [ "$1" = --check ]; then
        need_cmd "$_dld"
    elif [ "$_dld" = curl ]; then
        check_curl_for_retry_support
        _retry="$RETVAL"
        get_ciphersuites_for_curl
        _ciphersuites="$RETVAL"
        if [ -n "$_ciphersuites" ]; then
            # shellcheck disable=SC2086
            _err=$(curl $_retry --proto '=https' --tlsv1.2 --ciphers "$_ciphersuites" --silent --show-error --fail --location "$1" --output "$2" 2>&1)
            _status=$?
        else
            warn "Not enforcing strong cipher suites for TLS, this is potentially less secure"
            if ! check_help_for "$3" curl --proto --tlsv1.2; then
                warn "Not enforcing TLS v1.2, this is potentially less secure"
                # shellcheck disable=SC2086
                _err=$(curl $_retry --silent --show-error --fail --location "$1" --output "$2" 2>&1)
                _status=$?
            else
                # shellcheck disable=SC2086
                _err=$(curl $_retry --proto '=https' --tlsv1.2 --silent --show-error --fail --location "$1" --output "$2" 2>&1)
                _status=$?
            fi
        fi
        if [ -n "$_err" ]; then
            warn "$_err"
            if echo "$_err" | grep -q 404$; then
                err "installer for platform '$3' not found, this may be unsupported"
                exit 1
            fi
        fi
        return $_status
    elif [ "$_dld" = wget ]; then
        if [ "$(wget -V 2>&1|head -2|tail -1|cut -f1 -d" ")" = "BusyBox" ]; then
            warn "using the BusyBox version of wget.  Not enforcing strong cipher suites for TLS or TLS v1.2, this is potentially less secure"
            _err=$(wget "$1" -O "$2" 2>&1)
            _status=$?
        else
            get_ciphersuites_for_wget
            _ciphersuites="$RETVAL"
            if [ -n "$_ciphersuites" ]; then
                _err=$(wget --https-only --secure-protocol=TLSv1_2 --ciphers "$_ciphersuites" "$1" -O "$2" 2>&1)
                _status=$?
            else
                warn "Not enforcing strong cipher suites for TLS, this is potentially less secure"
                if ! check_help_for "$3" wget --https-only --secure-protocol; then
                    warn "Not enforcing TLS v1.2, this is potentially less secure"
                    _err=$(wget "$1" -O "$2" 2>&1)
                    _status=$?
                else
                    _err=$(wget --https-only --secure-protocol=TLSv1_2 "$1" -O "$2" 2>&1)
                    _status=$?
                fi
            fi
        fi
        if [ -n "$_err" ]; then
            warn "$_err"
            if echo "$_err" | grep -q ' 404 Not Found$'; then
                err "installer for platform '$3' not found, this may be unsupported"
                exit 1
            fi
        fi
        return $_status
    else
        err "Unknown downloader"   # should not reach here
        exit 1
    fi
}

check_help_for() {
    local _arch
    local _cmd
    local _arg
    _arch="$1"
    shift
    _cmd="$1"
    shift

    local _category
    if "$_cmd" --help | grep -q '"--help all"'; then
      _category="all"
    else
      _category=""
    fi

    case "$_arch" in

        *darwin*)
        if check_cmd sw_vers; then
            local _os_version
            local _os_major
            _os_version=$(sw_vers -productVersion)
            _os_major=$(echo "$_os_version" | cut -d. -f1)
            case $_os_major in
                10)
                    # If we're running on macOS, older than 10.13, then we always
                    # fail to find these options to force fallback
                    if [ "$(echo "$_os_version" | cut -d. -f2)" -lt 13 ]; then
                        # Older than 10.13
                        warn "Detected macOS platform older than 10.13"
                        return 1
                    fi
                    ;;
                *)
                    if ! { [ "$_os_major" -eq "$_os_major" ] 2>/dev/null && [ "$_os_major" -ge 11 ]; }; then
                        # Unknown product version, warn and continue
                        warn "Detected unknown macOS major version: $_os_version"
                        warn "TLS capabilities detection may fail"
                    fi
                    ;; # We assume that macOS v11+ will always be okay.
            esac
        fi
        ;;

    esac

    for _arg in "$@"; do
        if ! "$_cmd" --help "$_category" | grep -q -- "$_arg"; then
            return 1
        fi
    done

    true # not strictly needed
}

# Check if curl supports the --retry flag, then pass it to the curl invocation.
# Note that --speed-limit and --speed-time were in the very first commit of curl.
# So this should be pretty much ubiquitously safe.
check_curl_for_retry_support() {
  local _retry_part=""
  local _continue_part=""
  local _speed_limit_part=""

  # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
  if check_help_for "notspecified" "curl" "--retry"; then
      _retry_part="--retry 3"

      if check_help_for "notspecified" "curl" "--continue-at"; then
          # "-C -" tells curl to automatically find where to resume the download when retrying.
          _continue_part="--continue-at -"
      fi

      if check_help_for "notspecified" "curl" "--speed-limit" \
          && check_help_for "notspecified" "curl" "--speed-time"; then
        # 250000 is approximately 20% of the bandwidth of typical DSL
        # these limits mean users below these limits will see failures.
        _speed_limit_part="--speed-limit 250000 --speed-time 15"
      fi
  fi

  RETVAL="$_retry_part $_continue_part $_speed_limit_part"
}


# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
# if support by local tools is detected. Detection currently supports these curl backends:
# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
get_ciphersuites_for_curl() {
    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
        # user specified custom cipher suites, assume they know what they're doing
        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
        return
    fi

    local _openssl_syntax="no"
    local _gnutls_syntax="no"
    local _backend_supported="yes"
    if curl -V | grep -q ' OpenSSL/'; then
        _openssl_syntax="yes"
    elif curl -V | grep -iq ' LibreSSL/'; then
        _openssl_syntax="yes"
    elif curl -V | grep -iq ' BoringSSL/'; then
        _openssl_syntax="yes"
    elif curl -V | grep -iq ' GnuTLS/'; then
        _gnutls_syntax="yes"
    else
        _backend_supported="no"
    fi

    local _args_supported="no"
    if [ "$_backend_supported" = "yes" ]; then
        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
        if check_help_for "notspecified" "curl" "--tlsv1.2" "--ciphers" "--proto"; then
            _args_supported="yes"
        fi
    fi

    local _cs=""
    if [ "$_args_supported" = "yes" ]; then
        if [ "$_openssl_syntax" = "yes" ]; then
            _cs=$(get_strong_ciphersuites_for "openssl")
        elif [ "$_gnutls_syntax" = "yes" ]; then
            _cs=$(get_strong_ciphersuites_for "gnutls")
        fi
    fi

    RETVAL="$_cs"
}

# Return cipher suite string specified by user, otherwise return strong TLS 1.2-1.3 cipher suites
# if support by local tools is detected. Detection currently supports these wget backends:
# GnuTLS and OpenSSL (possibly also LibreSSL and BoringSSL). Return value can be empty.
get_ciphersuites_for_wget() {
    if [ -n "${RUSTUP_TLS_CIPHERSUITES-}" ]; then
        # user specified custom cipher suites, assume they know what they're doing
        RETVAL="$RUSTUP_TLS_CIPHERSUITES"
        return
    fi

    local _cs=""
    if wget -V | grep -q '\-DHAVE_LIBSSL'; then
        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
            _cs=$(get_strong_ciphersuites_for "openssl")
        fi
    elif wget -V | grep -q '\-DHAVE_LIBGNUTLS'; then
        # "unspecified" is for arch, allows for possibility old OS using macports, homebrew, etc.
        if check_help_for "notspecified" "wget" "TLSv1_2" "--ciphers" "--https-only" "--secure-protocol"; then
            _cs=$(get_strong_ciphersuites_for "gnutls")
        fi
    fi

    RETVAL="$_cs"
}

# Return strong TLS 1.2-1.3 cipher suites in OpenSSL or GnuTLS syntax. TLS 1.2
# excludes non-ECDHE and non-AEAD cipher suites. DHE is excluded due to bad
# DH params often found on servers (see RFC 7919). Sequence matches or is
# similar to Firefox 68 ESR with weak cipher suites disabled via about:config.
# $1 must be openssl or gnutls.
get_strong_ciphersuites_for() {
    if [ "$1" = "openssl" ]; then
        # OpenSSL is forgiving of unknown values, no problems with TLS 1.3 values on versions that don't support it yet.
        echo "TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384"
    elif [ "$1" = "gnutls" ]; then
        # GnuTLS isn't forgiving of unknown values, so this may require a GnuTLS version that supports TLS 1.3 even if wget doesn't.
        # Begin with SECURE128 (and higher) then remove/add to build cipher suites. Produces same 9 cipher suites as OpenSSL but in slightly different order.
        echo "SECURE128:-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-DTLS-ALL:-CIPHER-ALL:-MAC-ALL:-KX-ALL:+AEAD:+ECDHE-ECDSA:+ECDHE-RSA:+AES-128-GCM:+CHACHA20-POLY1305:+AES-256-GCM"
    fi
}

main "$@" || exit 1