#!/bin/sh
set -eu

BASE_URL="https://downloads.poolside.ai/pool"
INSTALL_DIR="${POOL_INSTALL_DIR:-${XDG_BIN_HOME:-$HOME/.local/bin}}"
UPDATE_PATH="${POOL_INSTALL_UPDATE_PATH:-ask}"
SHOW_SPLASH="${POOL_INSTALL_SPLASH:-1}"
ACCEPT_EULA="${POOL_INSTALL_ACCEPT_EULA:-0}"
POOL_PATH_WORKS=0
PATH_RC_FILE=""

main() {
  os="$(detect_os)"
  arch="$(detect_arch)"
  version="$(resolve_version "${1:-latest}")"

  archive="pool-${os}-${arch}.tar.gz"
  url="${BASE_URL}/${version}/${archive}"
  checksum_url="${BASE_URL}/${version}/checksums.txt"

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

  maybe_show_splash "$version"
  confirm_install
  printf "Downloading pool %s (%s/%s)...\n" "$version" "$os" "$arch"
  download "$url" "$tmpdir/$archive"
  download "$checksum_url" "$tmpdir/checksums.txt"

  verify_checksum "$tmpdir" "$archive"

  tar -xzf "$tmpdir/$archive" -C "$tmpdir"
  binary="$tmpdir/pool-${os}-${arch}"
  chmod +x "$binary"

  mkdir -p "$INSTALL_DIR"
  mv "$binary" "$INSTALL_DIR/pool"

  printf "pool %s installed to %s/pool\n" "$version" "$INSTALL_DIR"
  maybe_update_path
  maybe_print_path_hint
  printf '\nRun pool to get started\n'
}

detect_os() {
  case "$(uname -s)" in
    Linux) echo "linux" ;;
    Darwin) echo "darwin" ;;
    *) fatal "unsupported OS: $(uname -s)" ;;
  esac
}

detect_arch() {
  case "$(uname -m)" in
    x86_64|amd64) echo "amd64" ;;
    aarch64|arm64) echo "arm64" ;;
    *) fatal "unsupported architecture: $(uname -m)" ;;
  esac
}

resolve_version() {
  if [ "$1" = "latest" ]; then
    v="$(download_stdout "${BASE_URL}/pool-latest-version.txt")" || fatal "failed to fetch latest version"
    v="$(printf '%s' "$v" | tr -d '[:space:]')"
    [ -n "$v" ] || fatal "empty version from pool-latest-version.txt"
    echo "$v"
  else
    echo "$1"
  fi
}

download() {
  if command -v curl >/dev/null 2>&1; then
    curl -fsSL --retry 3 -o "$2" "$1"
  elif command -v wget >/dev/null 2>&1; then
    wget -qO "$2" "$1"
  else
    fatal "curl or wget is required"
  fi
}

download_stdout() {
  if command -v curl >/dev/null 2>&1; then
    curl -fsSL --retry 3 "$1"
  elif command -v wget >/dev/null 2>&1; then
    wget -qO- "$1"
  else
    fatal "curl or wget is required"
  fi
}

maybe_show_splash() {
  version="$1"

  if [ "$SHOW_SPLASH" != "1" ] || [ ! -t 1 ]; then
    return 0
  fi

  printf '\n'
  printf '                                 ░██ \n'
  printf '                                 ░██ \n'
  printf '░████████   ░███████   ░███████  ░██ \n'
  printf '░██    ░██ ░██    ░██ ░██    ░██ ░██ \n'
  printf '░██    ░██ ░██    ░██ ░██    ░██ ░██ \n'
  printf '░███   ░██ ░██    ░██ ░██    ░██ ░██ \n'
  printf '░██░█████   ░███████   ░███████  ░██ \n'
  printf '░██                                  \n'
  printf '░██                                  \n'
  printf '       %s loading... \n\n' "$version"
  sleep 0.2
}

confirm_install() {
  if [ "$ACCEPT_EULA" = "1" ]; then
    return 0
  fi

  if [ ! -r /dev/tty ] || [ ! -w /dev/tty ]; then
    fatal "interactive confirmation required. Rerun with POOL_INSTALL_ACCEPT_EULA=1 to accept the EULA in headless scenarios."
  fi

  printf 'By installing pool, you agree to the Poolside End User License Agreement: https://poolside.ai/eula\n\n'

  while :; do
    printf 'Continue? [Y/n] '
    IFS= read -r reply </dev/tty || fatal "installation canceled"

    case "$reply" in
      ""|[Yy])
        return 0
        ;;
      [Nn])
        fatal "installation canceled"
        ;;
      *)
        printf 'Please answer y or n.\n'
        ;;
    esac
  done
}

maybe_update_path() {
  if path_has_dir "$INSTALL_DIR"; then
    return 0
  fi

  case "$UPDATE_PATH" in
    1) ;;
    0) return 0 ;;
    ask)
      if ! should_prompt_for_path_update; then
        return 0
      fi
      if ! confirm_path_update; then
        return 0
      fi
      ;;
    *)
      fatal "invalid POOL_INSTALL_UPDATE_PATH value: $UPDATE_PATH"
      ;;
  esac

  rc_file="$(choose_rc_file)"
  if [ -z "$rc_file" ]; then
    return 0
  fi

  mkdir -p "$(dirname "$rc_file")"
  touch "$rc_file"

  line="export PATH=\"$INSTALL_DIR:\$PATH\""
  if ! grep -Fqx "$line" "$rc_file"; then
    printf '\n%s\n' "$line" >> "$rc_file"
    POOL_PATH_WORKS=1
    PATH_RC_FILE="$rc_file"
    printf "Added %s to PATH in %s\n" "$INSTALL_DIR" "$rc_file"
    return 0
  fi

  POOL_PATH_WORKS=1
  PATH_RC_FILE="$rc_file"
}

maybe_print_path_hint() {
  if path_has_dir "$INSTALL_DIR"; then
    return 0
  fi

  printf '\n'

  if [ "$POOL_PATH_WORKS" = "1" ]; then
    printf 'pool will be on your PATH in new shells.\n'
    printf 'Use it now with:\n'
    printf '  export PATH="%s:$PATH"\n' "$INSTALL_DIR"
    printf 'Or reload your shell config:\n'
    printf '  . "%s"\n' "$PATH_RC_FILE"
    return 0
  fi

  printf 'pool is not on your PATH yet.\n'
  printf 'Add it for this shell with:\n'
  printf '  export PATH="%s:$PATH"\n' "$INSTALL_DIR"
  printf 'Or rerun with POOL_INSTALL_UPDATE_PATH=1 to update your shell config automatically.\n'
}

choose_rc_file() {
  shell_name="$(basename "${SHELL:-}")"

  case "$shell_name" in
    zsh)
      printf '%s\n' "$HOME/.zshrc"
      ;;
    bash)
      printf '%s\n' "$HOME/.bashrc"
      ;;
    *)
      printf '%s\n' "$HOME/.profile"
      ;;
  esac
}

path_has_dir() {
  case ":${PATH:-}:" in
    *":$INSTALL_DIR:"*) return 0 ;;
    *) return 1 ;;
  esac
}

should_prompt_for_path_update() {
  [ -t 0 ] && [ -t 1 ]
}

confirm_path_update() {
  rc_file="$(choose_rc_file)"
  if [ -z "$rc_file" ]; then
    return 1
  fi

  printf '\nAdd %s to PATH in %s? [Y/n] ' "$INSTALL_DIR" "$rc_file" >&2
  if ! IFS= read -r answer; then
    printf '\n' >&2
    return 1
  fi

  case "$answer" in
    ""|y|Y|yes|YES|Yes) return 0 ;;
    *) return 1 ;;
  esac
}

verify_checksum() {
  dir="$1"
  file="$2"
  expected="$(grep "$file" "$dir/checksums.txt" | awk '{print $1}')"
  [ -n "$expected" ] || fatal "no checksum found for $file"

  if command -v sha256sum >/dev/null 2>&1; then
    actual="$(cd "$dir" && sha256sum "$file" | awk '{print $1}')"
  elif command -v shasum >/dev/null 2>&1; then
    actual="$(cd "$dir" && shasum -a 256 "$file" | awk '{print $1}')"
  else
    printf "Warning: no sha256sum or shasum found, skipping checksum verification\n" >&2
    return 0
  fi

  if [ "$actual" != "$expected" ]; then
    fatal "checksum mismatch for $file: expected $expected, got $actual"
  fi
}

fatal() {
  printf "Error: %s\n" "$1" >&2
  exit 1
}

main "$@"