#!/bin/sh
# specsnip installer
#
#   curl -fsSL https://get.specsnip.ru | sh
#   (the same script is also served at https://specsnip.ru/install)
#
# Puts a single file, `specsnip`, into ~/.local/bin after checking its SHA-256 against
# https://specsnip.ru/SHA256SUMS. Needs Node.js 20+ and curl (or wget). No sudo, nothing else is touched.
#
# Options (environment variables):
#   SPECSNIP_VERSION      install a specific version, e.g. 1.0.0 (default: the latest)
#   SPECSNIP_INSTALL_DIR  where to put the file (default: $HOME/.local/bin)
#   SPECSNIP_BASE_URL     where to download from (default: https://specsnip.ru)
#
# Uninstall: rm "$HOME/.local/bin/specsnip"
#
# Everything below runs inside main(), which is called on the very last line: if the download is
# cut short, the shell sees an unfinished function and executes nothing.

main() {
  set -eu

  base="${SPECSNIP_BASE_URL:-https://specsnip.ru}"
  version="${SPECSNIP_VERSION:-latest}"
  dir="${SPECSNIP_INSTALL_DIR:-${HOME:?HOME is not set}/.local/bin}"

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

  # --- requirements -----------------------------------------------------------------------------
  command -v node >/dev/null 2>&1 || fail 'Node.js 20 or newer is required: https://nodejs.org'
  node_major="$(node -p 'process.versions.node.split(".")[0]' 2>/dev/null || echo 0)"
  [ "$node_major" -ge 20 ] 2>/dev/null || fail "Node.js 20 or newer is required, found $(node -v 2>/dev/null || echo 'none')"

  fetch() {
    if command -v curl >/dev/null 2>&1; then
      curl -fsSL "$1"
    elif command -v wget >/dev/null 2>&1; then
      wget -qO- "$1"
    else
      fail 'curl or wget is required'
    fi
  }

  sha256() {
    if command -v sha256sum >/dev/null 2>&1; then
      sha256sum | cut -d' ' -f1
    elif command -v shasum >/dev/null 2>&1; then
      shasum -a 256 | cut -d' ' -f1
    else
      fail 'sha256sum or shasum is required to verify the download'
    fi
  }

  # --- which file -------------------------------------------------------------------------------
  if [ "$version" = latest ]; then
    file='specsnip.mjs'
  else
    case "$version" in
      *[!0-9A-Za-z.+-]* | '') fail "invalid SPECSNIP_VERSION: $version" ;;
    esac
    file="specsnip-$version.mjs"
  fi

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

  # --- download and verify ----------------------------------------------------------------------
  printf 'Downloading %s/%s\n' "$base" "$file"
  fetch "$base/$file" >"$tmp/specsnip" || fail "cannot download $base/$file"
  fetch "$base/SHA256SUMS" >"$tmp/sums" || fail "cannot download $base/SHA256SUMS"

  want="$(awk -v f="$file" '$2 == f { print $1 }' "$tmp/sums")"
  [ -n "$want" ] || fail "$file is not listed in $base/SHA256SUMS (unknown version?)"
  got="$(sha256 <"$tmp/specsnip")"
  [ "$got" = "$want" ] || fail "checksum mismatch for $file: expected $want, got $got. Nothing was installed"
  printf 'Checksum OK (%s)\n' "$(printf '%s' "$want" | cut -c1-12)"

  # --- install ----------------------------------------------------------------------------------
  mkdir -p "$dir" 2>/dev/null || fail "cannot create $dir (set SPECSNIP_INSTALL_DIR to a writable folder)"
  [ -w "$dir" ] || fail "$dir is not writable (set SPECSNIP_INSTALL_DIR to a writable folder)"
  # Copy next to the target and rename: an upgrade never leaves a half-written file behind.
  cp "$tmp/specsnip" "$dir/.specsnip.$$"
  chmod 755 "$dir/.specsnip.$$"
  mv -f "$dir/.specsnip.$$" "$dir/specsnip"

  installed="$("$dir/specsnip" --version 2>/dev/null)" || fail "the installed file does not run: $dir/specsnip --version"
  printf 'Installed specsnip %s to %s/specsnip\n' "$installed" "$dir"

  case ":$PATH:" in
    *":$dir:"*) ;;
    *)
      # в подсказке пишем $HOME, а не длинный абсолютный путь: её копируют в ~/.zshrc как есть
      shown="$dir"
      case "$dir" in "$HOME"/*) shown="\$HOME${dir#"$HOME"}" ;; esac
      printf '\n%s is not in your PATH. Add it, for example:\n\n  export PATH="%s:$PATH"\n\n' "$dir" "$shown"
      printf 'put that line into ~/.zshrc or ~/.bashrc to make it permanent.\n'
      ;;
  esac
  printf '\nTry:  specsnip --help\n'
}

main "$@"