install-component

#!/bin/sh
set -eu

repository="chasebryan/centl"
channel="oasis"
component=""
release_version="latest"
prefix=${CENTL_PREFIX:-}
archive_path=""

usage() {
  cat <<'EOF'
Install exactly one CENTL scientific command on GNU/Linux x86_64.

Usage: ./install-component --component centl|physics|sci
                           [--channel oasis|mirage]
                           [--version VERSION]
                           [--prefix PATH]
                           [--archive PATH]

Components:
  centl     exact mathematics engine only
  physics   CENTL Physics command only
  sci       CENTL-SCi interpreter only

The component installer downloads a component-specific archive. It does not
first download the full CENTL product bundle.

Environment:
  CENTL_PREFIX   same as --prefix
EOF
}

fail() {
  printf 'centl component install: %s\n' "$1" >&2
  exit 1
}

while [ "$#" -gt 0 ]; do
  case "$1" in
    --component)
      [ "$#" -ge 2 ] || fail "--component needs a value"
      component=$2
      shift 2
      ;;
    --channel)
      [ "$#" -ge 2 ] || fail "--channel needs a value"
      channel=$2
      shift 2
      ;;
    --version)
      [ "$#" -ge 2 ] || fail "--version needs a value"
      release_version=$2
      shift 2
      ;;
    --prefix)
      [ "$#" -ge 2 ] || fail "--prefix needs a path"
      prefix=$2
      shift 2
      ;;
    --archive)
      [ "$#" -ge 2 ] || fail "--archive needs a path"
      archive_path=$2
      shift 2
      ;;
    --help|-h)
      usage
      exit 0
      ;;
    *) fail "unknown option: $1" ;;
  esac
done

case "$component" in
  centl)
    command_name=centl
    asset="centl-only-linux-x86_64.tar.gz"
    ;;
  physics)
    command_name=centl-physics
    asset="centl-physics-only-linux-x86_64.tar.gz"
    ;;
  sci)
    command_name=centl-sci
    asset="centl-sci-only-linux-x86_64.tar.gz"
    ;;
  '') fail "choose --component centl, physics, or sci" ;;
  *) fail "--component must be centl, physics, or sci" ;;
esac

case "$channel" in
  oasis|mirage) ;;
  *) fail "--channel must be oasis or mirage" ;;
esac

case $(uname -s) in
  Linux) ;;
  Darwin) fail "use CENTL-Marsa on macOS; see docs/MATHEMATICIANS.md or docs/PHYSICISTS.md" ;;
  *) fail "this component installer is for GNU/Linux; use CENTL-Marsa for Windows" ;;
esac
case $(uname -m) in
  x86_64|amd64) ;;
  *) fail "component archives currently support GNU/Linux x86_64 only: $(uname -m)" ;;
esac

[ -n "$prefix" ] || {
  [ -n "${HOME:-}" ] || fail "HOME is not set; use --prefix PATH"
  prefix="$HOME/.local"
}
case "$prefix" in
  /*) ;;
  *) prefix="$(pwd)/$prefix" ;;
esac

command -v tar >/dev/null 2>&1 || fail "tar is required"
if command -v sha256sum >/dev/null 2>&1; then
  hash_command=sha256sum
elif command -v shasum >/dev/null 2>&1; then
  hash_command="shasum -a 256"
else
  fail "sha256sum or shasum is required"
fi

temporary=$(mktemp -d "${TMPDIR:-/tmp}/centl-component.XXXXXXXX")
trap 'rm -rf "$temporary"' EXIT HUP INT TERM
archive="$temporary/$asset"
checksum="$temporary/$asset.sha256"
requested_release=""

if [ -n "$archive_path" ]; then
  [ -f "$archive_path" ] || fail "archive not found: $archive_path"
  [ -f "$archive_path.sha256" ] || fail "checksum not found: $archive_path.sha256"
  cp "$archive_path" "$archive"
  cp "$archive_path.sha256" "$checksum"
else
  command -v curl >/dev/null 2>&1 || fail "curl is required to download CENTL"
  channel_root="https://raw.githubusercontent.com/$repository/distribution/channels/$channel"
  if [ "$channel" = oasis ]; then
    if [ "$release_version" = latest ]; then
      curl --fail --silent --show-error --location \
        "$channel_root/LATEST" --output "$temporary/LATEST"
      requested_release=$(sed -n '1p' "$temporary/LATEST")
    else
      requested_release=${release_version#v}
    fi
    case "$requested_release" in
      ''|*/*|*..*|*[!0-9A-Za-z.+_-]*) fail "invalid Oasis version" ;;
    esac
    base_url="$channel_root/v$requested_release"
  else
    if [ "$release_version" = latest ]; then
      base_url="$channel_root/latest"
    else
      requested_release=${release_version#v}
      case "$requested_release" in
        ''|*/*|*..*|*[!0-9A-Za-z.+_-]*) fail "invalid Mirage build" ;;
      esac
      base_url="$channel_root/builds/$requested_release"
    fi
  fi
  printf 'Downloading only %s from CENTL %s...\n' "$command_name" "$channel"
  curl --fail --silent --show-error --location "$base_url/$asset" --output "$archive"
  curl --fail --silent --show-error --location "$base_url/$asset.sha256" --output "$checksum"
fi

expected=$(awk 'NR == 1 {print $1}' "$checksum")
case "$expected" in
  ''|*[!0-9a-fA-F]*) fail "component checksum is malformed" ;;
esac
[ "${#expected}" -eq 64 ] || fail "component checksum is malformed"
expected=$(printf '%s' "$expected" | tr 'A-F' 'a-f')
if [ "$hash_command" = sha256sum ]; then
  actual=$(sha256sum "$archive" | awk '{print $1}')
else
  actual=$(shasum -a 256 "$archive" | awk '{print $1}')
fi
[ "$actual" = "$expected" ] || fail "component checksum verification failed"

tar -tzf "$archive" | while IFS= read -r member; do
  case "$member" in
    /*|../*|*/../*|*/..) fail "component archive contains an unsafe path" ;;
    centl|centl/*) ;;
    *) fail "component archive has an unexpected layout" ;;
  esac
done

extracted="$temporary/extracted"
mkdir "$extracted"
tar --no-same-owner --no-same-permissions -xzf "$archive" -C "$extracted"
package="$extracted/centl"
[ -f "$package/VERSION" ] || fail "component archive has no VERSION"
[ -f "$package/COMPONENT" ] || fail "component archive has no COMPONENT identity"
[ "$(sed -n '1p' "$package/COMPONENT")" = "$component" ] || fail "component archive identity mismatch"
[ -x "$package/bin/$command_name" ] || fail "component launcher is missing"
[ -x "$package/libexec/$command_name" ] || fail "component executable is missing"

for other in centl centl-physics centl-sci; do
  if [ "$other" != "$command_name" ]; then
    [ ! -e "$package/bin/$other" ] || fail "component archive unexpectedly contains $other"
    [ ! -e "$package/libexec/$other" ] || fail "component archive unexpectedly contains $other"
  fi
done

version=$(sed -n '1p' "$package/VERSION")
case "$version" in
  ''|*/*|*..*|*[!0-9A-Za-z.+_-]*) fail "component version is invalid" ;;
esac
if [ "$channel" = oasis ] && [ -n "$requested_release" ]; then
  [ "$version" = "$requested_release" ] || fail "requested $requested_release but archive contains $version"
fi

case "$component" in
  centl)
    smoke=$("$package/bin/centl" '0.1 + 0.2' 2>&1) || fail "centl component cannot run: $smoke"
    [ "$smoke" = '3/10' ] || fail "centl component failed exact arithmetic smoke test"
    ;;
  physics)
    smoke=$("$package/bin/centl-physics" convert 100 cm m 2>&1) || fail "physics component cannot run: $smoke"
    [ "$smoke" = '1' ] || fail "physics component failed unit conversion smoke test"
    ;;
  sci)
    smoke=$("$package/bin/centl-sci" 'What is 0.1 plus 0.2?' 2>&1) || fail "SCi component cannot run: $smoke"
    [ "$smoke" = '3/10' ] || fail "SCi component failed exact arithmetic smoke test"
    ;;
esac

hash_short=$(printf '%s' "$actual" | cut -c1-12)
if [ "$channel" = oasis ]; then
  install_id=$version
else
  install_id="$version-$hash_short"
fi
component_root="$prefix/share/centl/components/$channel/$install_id/$component"
bin_directory="$prefix/bin"
mkdir -p "$(dirname "$component_root")" "$bin_directory"
[ ! -e "$component_root" ] || fail "$component is already installed at $component_root"
mv "$package" "$component_root"

channel_link="$bin_directory/$channel-$command_name"
ln -sfn "$component_root/bin/$command_name" "$channel_link"
if [ "$channel" = oasis ]; then
  ln -sfn "$component_root/bin/$command_name" "$bin_directory/$command_name"
fi

printf 'Installed only %s from CENTL %s.\n' "$command_name" "$channel"
printf 'Location: %s\n' "$component_root"
case ":${PATH:-}:" in
  *":$bin_directory:"*) ;;
  *) printf 'Add %s to PATH to use %s.\n' "$bin_directory" "$command_name" ;;
esac