#!/bin/sh
# Flint install — https://flint.nuucognition.com/install.sh
#
#   curl -fsSL https://flint.nuucognition.com/install.sh | bash
#
# This script installs nothing, writes no file, and uses no sudo. It checks
# that this machine runs macOS or Linux and has Claude Code, shows a welcome,
# and starts Claude Code with the Flint setup prompt. Claude Code then sets up
# Flint with you, and asks before each change to your machine.
#
# The whole script is in main(), and the last line calls it. So a partial
# download runs nothing.

set -eu

main() {
  base="${FLINT_SETUP_BASE:-https://flint.nuucognition.com}"
  base="${base%/}"

  if [ -t 1 ] && [ -z "${NO_COLOR:-}" ]; then
    bold=$(printf '\033[1m')
    dim=$(printf '\033[2m')
    accent=$(printf '\033[38;5;209m')
    reset=$(printf '\033[0m')
  else
    bold=""
    dim=""
    accent=""
    reset=""
  fi

  case "$(uname -s 2>/dev/null || echo unknown)" in
    Darwin) os_label="macOS" ;;
    Linux) os_label="Linux" ;;
    *)
      say "Flint supports macOS and Linux. This system is $(uname -s 2>/dev/null || echo unknown)."
      exit 1
      ;;
  esac

  setup_prompt="Set up Flint on this machine. Fetch $base/setup.md with curl and follow it. The Flint install script started you on $os_label ($(uname -m 2>/dev/null || echo unknown))."

  # Under 'curl | bash', stdin is this script. The key press reads /dev/tty, and
  # the agent gets the terminal device (see terminal_input). With no terminal,
  # print the manual start.
  if ! (exec </dev/tty) 2>/dev/null; then
    say "Flint setup needs a terminal, and this run has none."
    say "Open a terminal, start Claude Code, and paste this prompt:"
    say ""
    say "  $setup_prompt"
    exit 1
  fi

  if ! command -v claude >/dev/null 2>&1; then
    say ""
    say "${bold}Flint setup uses Claude Code${reset}, and this machine does not have it."
    say "Install Claude Code, then run the Flint install command again:"
    say ""
    say "  ${accent}curl -fsSL https://claude.ai/install.sh | bash${reset}"
    say ""
    say "${dim}More about Claude Code: https://claude.com/claude-code${reset}"
    exit 1
  fi

  say ""
  say "  ${accent}${bold}Welcome to Flint.${reset}"
  say ""
  say "  An agent will take you through the setup."
  say "  It asks you before each change to this computer."
  say ""
  say "  ${dim}Claude Code first asks whether you trust your home folder."
  say "  Choose \"Yes, I trust this folder\" to continue.${reset}"
  say ""
  say "  Tip: write ${bold}--auto-approve${reset} in the chat, and the agent sets up"
  say "  everything without asking each time. It still asks before it"
  say "  deletes or replaces anything, or needs your password."
  say ""
  printf '  %sPress any key to continue, or Ctrl-C to stop.%s' "$dim" "$reset"
  wait_for_key
  say ""
  say ""

  # Start in the home folder: the Computer Flint goes there, and the setup
  # does not depend on the folder where this command ran.
  cd "$HOME"

  terminal=$(terminal_input)
  exec claude \
    --allowedTools "Bash(curl -fsSL $base/*)" "Bash(flint --version)" "Bash(flint setup handoff check *)" \
    -- "$setup_prompt" <"$terminal"
}

# The terminal input for the agent. Claude Code is a Bun program, and on
# macOS a descriptor that is opened through /dev/tty fails in kqueue
# ("EINVAL: invalid argument, kqueue"). So give it the real terminal device
# (for example /dev/ttys003), else a copy of the terminal on stderr, and use
# /dev/tty only as the last choice.
terminal_input() {
  tty_name=$(ps -o tty= -p $$ 2>/dev/null | tr -d ' ' || true)
  case "$tty_name" in
    '' | '?' | '??') ;;
    *)
      if [ -c "/dev/$tty_name" ] && [ -r "/dev/$tty_name" ]; then
        printf '/dev/%s' "$tty_name"
        return
      fi
      ;;
  esac
  if [ -t 2 ] && [ -e /dev/fd/2 ]; then
    printf '/dev/fd/2'
    return
  fi
  printf '/dev/tty'
}

say() {
  printf '%s\n' "$1"
}

# Read one key from the terminal with no Enter. POSIX: no 'read -n'.
wait_for_key() {
  old_stty=$(stty -g </dev/tty 2>/dev/null || true)
  if [ -n "$old_stty" ]; then
    trap 'stty "$old_stty" </dev/tty 2>/dev/null; exit 130' INT TERM
    stty -icanon -echo min 1 time 0 </dev/tty 2>/dev/null || true
    dd bs=1 count=1 </dev/tty >/dev/null 2>&1 || true
    stty "$old_stty" </dev/tty 2>/dev/null || true
    trap - INT TERM
  else
    # No stty: fall back to Enter.
    read -r _ </dev/tty || true
  fi
}

main "$@"