#!/bin/sh
set -e

REPO="xs-lang0/xs"
INSTALL_DIR="${XS_INSTALL_DIR:-/usr/local/bin}"
TMP_DIR="$(mktemp -d)"

cleanup() { rm -rf "$TMP_DIR" 2>/dev/null; }
trap cleanup EXIT

err() { echo "error: $1" >&2; exit 1; }
need() { command -v "$1" >/dev/null 2>&1 || err "need '$1' (not found)"; }

main() {
  need curl
  need uname

  os=$(uname -s | tr '[:upper:]' '[:lower:]')
  arch=$(uname -m)

  case "$os" in
    linux)  os="linux" ;;
    darwin) os="macos" ;;
    *) err "unsupported OS: $os" ;;
  esac

  case "$arch" in
    x86_64|amd64) arch="x86_64" ;;
    aarch64|arm64)
      echo "note: no native arm64 build yet; falling back to x86_64 (rosetta on apple silicon)" >&2
      arch="x86_64"
      ;;
    *) err "unsupported arch: $arch" ;;
  esac

  asset="xs-${os}-${arch}"
  url="https://github.com/${REPO}/releases/latest/download/${asset}"

  echo "installing xs..."
  echo "  os:   $os"
  echo "  arch: $arch"
  echo ""

  echo "  downloading binary..."
  curl -fsSL "$url" -o "$TMP_DIR/xs" || err "download failed: $url"

  echo "  verifying..."
  curl -fsSL "$url.sha256" -o "$TMP_DIR/xs.sha256" || err "checksum download failed"
  expected=$(awk '{print $1}' "$TMP_DIR/xs.sha256")
  if command -v sha256sum >/dev/null 2>&1; then
    actual=$(cd "$TMP_DIR" && sha256sum xs | awk '{print $1}')
  else
    actual=$(cd "$TMP_DIR" && shasum -a 256 xs | awk '{print $1}')
  fi
  [ "$expected" = "$actual" ] || err "checksum mismatch (got $actual, expected $expected)"

  chmod +x "$TMP_DIR/xs"

  echo "  installing to $INSTALL_DIR..."
  if [ -w "$INSTALL_DIR" ]; then
    mv "$TMP_DIR/xs" "$INSTALL_DIR/xs"
  else
    sudo mv "$TMP_DIR/xs" "$INSTALL_DIR/xs"
  fi

  echo ""
  echo "installed."
  echo "run: xs --version"
  echo "upgrade later: xs upgrade"
}

main