#!/bin/sh
# shellcheck shell=dash

# Installing bitsrun - with code shamelessly referenced from zoxide/install.sh
#
# https://github.com/ajeetdsouza/zoxide/blob/7af4da1dabfcfc9a4b23cc8807150bf2f61a0df6/install.sh
#
# 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.

main() {
  if [ "$KSH_VERSION" = 'Version JM 93t+ 2010-03-05' ]; then
    # The version of ksh93 that ships with many illumos systems does not
    # support the "local" extension.  Print a message rather than fail in
    # subtle ways later on:
    err 'the installer does not work with this ksh93 version; please try bash'
  fi

  set -u

  # Detect and print host target triple.
  ensure get_architecture
  local _arch="$RETVAL"
  assert_nz "$_arch" "arch"
  echo "Detected architecture: $_arch"

  # Create and enter a temporary directory.
  local _tmp_dir
  _tmp_dir="$(mktemp -d)" || err "mktemp: could not create temporary directory"
  cd "$_tmp_dir" || err "cd: failed to enter directory: $_tmp_dir"

  # Download and extract bitsrun.
  ensure download_bitsrun "$_arch"
  local _package="$RETVAL"
  assert_nz "$_package" "package"
  echo "Downloaded package: $_package"
  case "$_package" in
  *.tar.gz)
    need_cmd tar
    ensure tar -xf "$_package"
    ;;
  *.zip)
      need_cmd unzip
      ensure unzip -oq "$_package"
      ;;
  *)
    err "unsupported package format: $_package"
    ;;
  esac

  # Change to the extracted directory.
  local _dir
  _dir="$(find . -maxdepth 1 -type d -name 'bitsrun-*' -print -quit)"
  assert_nz "$_dir" "directory"
  cd "$_dir" || err "cd: failed to enter directory: $_dir"

  # Install binary.
  local _bin_dir="$HOME/.local/bin"
  local _bin_name
  _bin_name="bitsrun"
  ensure mkdir -p "$_bin_dir"
  ensure cp "$_bin_name" "$_bin_dir"
  echo "Installed bitsrun to $_bin_dir"

  # Print success message and check $PATH.
  echo ""
  echo "bitsrun is installed!"
  if ! echo ":$PATH:" | grep -Fq ":$_bin_dir:"; then
    echo "NOTE: $_bin_dir is not on your \$PATH. bitsrun will not work unless it is added to \$PATH."
  fi
}

download_bitsrun() {
  local _arch="$1"

  if check_cmd curl; then
    _dld=curl
  elif check_cmd wget; then
    _dld=wget
  else
    need_cmd 'curl or wget'
  fi
  need_cmd grep

  local _releases_url="https://api.github.com/repos/spencerwooo/bitsrun-rs/releases/latest"
  local _releases
  case "$_dld" in
  curl) _releases="$(curl -sL "$_releases_url")" ||
    err "curl: failed to download $_releases_url" ;;
  wget) _releases="$(wget -qO- "$_releases_url")" ||
    err "wget: failed to download $_releases_url" ;;
  esac

  local _package_url
  _package_url="$(echo "$_releases" | grep "browser_download_url" | cut -d '"' -f 4 | grep "$_arch")" ||
    err "bitsrun has not yet been packaged for your architecture ($_arch), please file an issue at https://github.com/spencerwooo/bitsrun-rs/issues"

  local _ext
  case "$_package_url" in
  *.tar.gz) _ext="tar.gz" ;;
  # *.zip) _ext="zip" ;;
  *) err "unsupported package format: $_package_url" ;;
  esac

  local _package="bitsrun.$_ext"
  case "$_dld" in
  curl) _releases="$(curl -sLo "$_package" "$_package_url")" || err "curl: failed to download $_package_url" ;;
  wget) _releases="$(wget -qO "$_package" "$_package_url")" || err "wget: failed to download $_package_url" ;;
  esac

  RETVAL="$_package"
}

# The below functions have been extracted with minor modifications from the
# Rustup install script:
#
#   https://github.com/rust-lang/rustup/blob/4c1289b2c3f3702783900934a38d7c5f912af787/rustup-init.sh

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

  if [ "$_ostype" = Linux ]; then
    if [ "$(uname -o)" = Android ]; then
      _ostype=Android
    fi
    if ldd --version 2>&1 | grep -q 'musl'; then
      _clibtype="musl"
    fi
  fi

  if [ "$_ostype" = Darwin ] && [ "$_cputype" = i386 ]; then
    # Darwin `uname -m` lies
    if sysctl hw.optional.x86_64 | grep -q ': 1'; then
      _cputype=x86_64
    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

  case "$_ostype" in
  Android)
    _ostype=linux-android
    ;;
  Linux)
    check_proc
    _ostype=unknown-linux-$_clibtype
    _bitness=$(get_bitness)
    ;;
  FreeBSD)
    _ostype=unknown-freebsd
    ;;
  NetBSD)
    _ostype=unknown-netbsd
    ;;
  DragonFly)
    _ostype=unknown-dragonfly
    ;;
  Darwin)
    _ostype=apple-darwin
    ;;
  illumos)
    _ostype=unknown-illumos
    ;;
  MINGW* | MSYS* | CYGWIN* | Windows_NT)
    _ostype=pc-windows-msvc
    ;;
  *)
    err "unrecognized OS type: $_ostype"
    ;;
  esac

  case "$_cputype" in
  i386 | i486 | i686 | i786 | x86)
    _cputype=i686
    ;;
  xscale | arm)
    _cputype=arm
    if [ "$_ostype" = "linux-android" ]; then
      _ostype=linux-androideabi
    fi
    ;;
  armv6l)
    _cputype=arm
    if [ "$_ostype" = "linux-android" ]; then
      _ostype=linux-androideabi
    else
      _ostype="${_ostype}eabihf"
    fi
    ;;
  armv7l | armv8l)
    _cputype=armv7
    if [ "$_ostype" = "linux-android" ]; then
      _ostype=linux-androideabi
    else
      _ostype="${_ostype}eabihf"
    fi
    ;;
  aarch64 | arm64)
    _cputype=aarch64
    ;;
  x86_64 | x86-64 | x64 | amd64)
    _cputype=x86_64
    ;;
  mips)
    _cputype=$(get_endianness mips '' el)
    ;;
  mips64)
    if [ "$_bitness" -eq 64 ]; then
      # only n64 ABI is supported for now
      _ostype="${_ostype}abi64"
      _cputype=$(get_endianness mips64 '' el)
    fi
    ;;
  ppc)
    _cputype=powerpc
    ;;
  ppc64)
    _cputype=powerpc64
    ;;
  ppc64le)
    _cputype=powerpc64le
    ;;
  s390x)
    _cputype=s390x
    ;;
  riscv64)
    _cputype=riscv64gc
    ;;
  *)
    err "unknown CPU type: $_cputype"
    ;;
  esac

  # Detect 64-bit linux with 32-bit userland
  if [ "${_ostype}" = unknown-linux-musl ] && [ "${_bitness}" -eq 32 ]; then
    case $_cputype in
    x86_64)
      # 32-bit executable for amd64 = x32
      if is_host_amd64_elf; then {
        echo "x32 userland is unsupported" 1>&2
        exit 1
      }; else
        _cputype=i686
      fi
      ;;
    mips64)
      _cputype=$(get_endianness mips '' el)
      ;;
    powerpc64)
      _cputype=powerpc
      ;;
    aarch64)
      _cputype=armv7
      if [ "$_ostype" = "linux-android" ]; then
        _ostype=linux-androideabi
      else
        _ostype="${_ostype}eabihf"
      fi
      ;;
    riscv64gc)
      err "riscv64 with 32-bit userland unsupported"
      ;;
    esac
  fi

  # Detect armv7 but without the CPU features Rust needs in that build,
  # and fall back to arm.
  # See https://github.com/rust-lang/rustup.rs/issues/587.
  if [ "$_ostype" = "unknown-linux-musleabihf" ] && [ "$_cputype" = armv7 ]; then
    if ensure grep '^Features' /proc/cpuinfo | grep -q -v neon; then
      # At least one processor does not have NEON.
      _cputype=arm
    fi
  fi

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

get_bitness() {
  need_cmd head
  # Architecture detection without dependencies beyond coreutils.
  # ELF files start out "\x7fELF", and the following byte is
  #   0x01 for 32-bit and
  #   0x02 for 64-bit.
  # The printf builtin on some shells like dash only supports octal
  # escape sequences, so we use those.
  local _current_exe_head
  _current_exe_head=$(head -c 5 /proc/self/exe)
  if [ "$_current_exe_head" = "$(printf '\177ELF\001')" ]; then
    echo 32
  elif [ "$_current_exe_head" = "$(printf '\177ELF\002')" ]; then
    echo 64
  else
    err "unknown platform bitness"
  fi
}

get_endianness() {
  local cputype=$1
  local suffix_eb=$2
  local suffix_el=$3

  # detect endianness without od/hexdump, like get_bitness() does.
  need_cmd head
  need_cmd tail

  local _current_exe_endianness
  _current_exe_endianness="$(head -c 6 /proc/self/exe | tail -c 1)"
  if [ "$_current_exe_endianness" = "$(printf '\001')" ]; then
    echo "${cputype}${suffix_el}"
  elif [ "$_current_exe_endianness" = "$(printf '\002')" ]; then
    echo "${cputype}${suffix_eb}"
  else
    err "unknown platform endianness"
  fi
}

is_host_amd64_elf() {
  need_cmd head
  need_cmd tail
  # ELF e_machine detection without dependencies beyond coreutils.
  # Two-byte field at offset 0x12 indicates the CPU,
  # but we're interested in it being 0x3E to indicate amd64, or not that.
  local _current_exe_machine
  _current_exe_machine=$(head -c 19 /proc/self/exe | tail -c 1)
  [ "$_current_exe_machine" = "$(printf '\076')" ]
}

check_proc() {
  # Check for /proc by looking for the /proc/self/exe link.
  # This is only run on Linux.
  if ! test -L /proc/self/exe; then
    err "unable to find /proc/self/exe. Is /proc mounted? Installation cannot proceed without /proc."
  fi
}

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

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

# 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: $*"; fi
}

assert_nz() {
  if [ -z "$1" ]; then err "found empty string: $2"; fi
}

err() {
  echo "Error: $1" >&2
  exit 1
}

# This is put in braces to ensure that the script does not run until it is
# downloaded completely.
{
  main "$@" || exit 1
}