#!/bin/sh
# Installs the latest XTermium release from GitHub, on Linux (x64) or macOS:
#
#   curl -fsSL https://xtermium.com/install.sh | sh
#
# Linux takes the package your system installs: the .deb where apt is, the .rpm where dnf, yum or
# zypper is, else the AppImage as ~/.local/bin/xtermium. XTERMIUM_PACKAGE=deb, rpm or appimage
# picks one. macOS takes the universal .dmg into /Applications. Every download is checked against
# the sha256 GitHub publishes for it before anything is installed.
set -eu

repo=xtermium/xtermium
say() { printf 'xtermium: %s\n' "$*" >&2; }
die() { say "$*"; exit 1; }

command -v curl >/dev/null 2>&1 || die "needs curl"
release=$(curl -fsL -H 'Accept: application/vnd.github+json' "https://api.github.com/repos/$repo/releases/latest") ||
  die "no public release yet; see https://xtermium.com/#downloads"

# The download address and sha256 of the first asset whose address ends in $1 (an awk regex;
# write a dot as [.]). Splitting on commas puts one JSON field on a line, pretty-printed or not;
# an asset's digest comes before its address.
asset() {
  printf '%s' "$release" | tr ',' '\n' | awk -F'"' -v want="$1" '
    $2 == "digest" { sum = $4; sub(/^sha256:/, "", sum) }
    $2 == "browser_download_url" { if ($4 ~ want "$") { print $4, sum; exit } sum = "" }'
}

tmp=$(mktemp -d)
trap 'rm -rf "$tmp"' EXIT

# Downloads the asset matching $1 into $tmp, checks its sha256 and prints its path; says $2 and
# stops when the release has no such asset.
fetch() {
  found=$(asset "$1")
  [ -n "$found" ] || die "$2"
  url=${found%% *} sum=${found#* }
  file=$tmp/${url##*/}
  say "downloading ${url##*/}"
  curl -fL --progress-bar -o "$file" "$url"
  if [ "$sum" = "$url" ] || [ -z "$sum" ]; then
    die "GitHub publishes no sha256 for ${url##*/}; not installing it unchecked"
  fi
  if command -v sha256sum >/dev/null 2>&1; then got=$(sha256sum "$file"); else got=$(shasum -a 256 "$file"); fi
  [ "${got%% *}" = "$sum" ] || die "sha256 mismatch for ${url##*/}; not installing it"
  say "sha256 checked"
  printf '%s\n' "$file"
}

as_root() {
  if [ "$(id -u)" -eq 0 ]; then "$@"
  elif command -v sudo >/dev/null 2>&1; then sudo "$@"
  else die "needs root, or sudo, to install a package"
  fi
}

case $(uname -s) in
Linux)
  [ "$(uname -m)" = x86_64 ] || die "builds are x64 only, and this is $(uname -m)"
  kind=${XTERMIUM_PACKAGE:-}
  if [ -z "$kind" ]; then
    if command -v apt-get >/dev/null 2>&1; then kind=deb
    elif command -v dnf >/dev/null 2>&1 || command -v yum >/dev/null 2>&1 || command -v zypper >/dev/null 2>&1; then kind=rpm
    else kind=appimage
    fi
  fi
  case $kind in
  deb)
    file=$(fetch '_amd64[.]deb' "this release has no .deb") || exit 1
    as_root apt-get install -y "$file" ;;
  rpm)
    file=$(fetch '[.]x86_64[.]rpm' "this release has no .rpm") || exit 1
    if command -v dnf >/dev/null 2>&1; then as_root dnf install -y "$file"
    elif command -v zypper >/dev/null 2>&1; then as_root zypper --non-interactive install --allow-unsigned-rpm "$file"
    else as_root yum install -y "$file"
    fi ;;
  appimage)
    file=$(fetch '_amd64[.]AppImage' "this release has no AppImage") || exit 1
    mkdir -p "$HOME/.local/bin"
    cp "$file" "$HOME/.local/bin/xtermium"
    chmod 755 "$HOME/.local/bin/xtermium"
    say "installed as ~/.local/bin/xtermium" ;;
  *) die "XTERMIUM_PACKAGE is deb, rpm or appimage, not $kind" ;;
  esac ;;
Darwin)
  file=$(fetch '_universal[.]dmg' "the macOS build is coming soon; see https://xtermium.com/#downloads") || exit 1
  hdiutil attach -nobrowse -quiet -mountpoint "$tmp/dmg" "$file"
  app=$(find "$tmp/dmg" -maxdepth 1 -name '*.app' | head -n 1)
  if [ -z "$app" ]; then hdiutil detach -quiet "$tmp/dmg"; die "no app in ${file##*/}"; fi
  # /Applications is writable by admins only; anyone else gets their own ~/Applications.
  dest=/Applications
  [ -w "$dest" ] || { dest=$HOME/Applications; mkdir -p "$dest"; }
  rm -rf "$dest/${app##*/}"
  ditto "$app" "$dest/${app##*/}"
  hdiutil detach -quiet "$tmp/dmg"
  say "installed to $dest/${app##*/}" ;;
*) die "no build for $(uname -s); see https://xtermium.com/#downloads" ;;
esac
say "done"