#!/usr/bin/env bash
# Install or upgrade CST-Agent on Linux, WSL or macOS. Safe to rerun: an
# existing checkout is fast-forwarded, rebuilt and reinstalled.
#
#   bootstrap_linux.sh [DIR] [--no-pull] [--release] [--source]
#   cst-agent-update            (installed by this script; same as rerunning it)
#
# --release downloads the static musl tarball for this host (fast; no compile).
# --source (default) builds from the checkout. CST_INSTALL_MODE=release|source
# overrides the flag.
#
# Env: CST_AGENT_PREFIX (install prefix, default ~/.local), CST_AGENT_DIR
# (checkout, default: current checkout or ~/CST-agent), CST_AGENT_REPO,
# CST_AGENT_VERSION (pin a release; default: cst_version.h or latest tag).
set -euo pipefail

ROOT_HINT="$(cd "$(dirname "$0")/.." 2>/dev/null && pwd || true)"

deps_hint() {
  echo "==> deps: gcc/clang make pkg-config libcurl ncursesw"
  if [[ "$(uname -s)" == Darwin ]]; then
    echo "    macOS: xcode-select --install && brew install ncurses curl pkg-config"
  elif command -v pacman >/dev/null 2>&1; then
    echo "    Arch: sudo pacman -S --needed base-devel curl ncurses"
  elif command -v apt-get >/dev/null 2>&1; then
    echo "    Debian/Ubuntu/WSL: sudo apt install build-essential pkg-config libcurl4-openssl-dev libncurses-dev"
  elif command -v dnf >/dev/null 2>&1; then
    echo "    Fedora: sudo dnf install gcc make pkgconf libcurl-devel ncurses-devel"
  elif command -v apk >/dev/null 2>&1; then
    echo "    Alpine: sudo apk add build-base pkgconf curl-dev ncurses-dev"
  fi
}

# On NixOS (outside a nix shell) build inside shell.nix.
run_make() {
  if [[ -z "${IN_NIX_SHELL:-}" ]] && command -v nix-shell >/dev/null 2>&1 &&
    [[ -f shell.nix ]]; then
    nix-shell --run "make $*"
  else
    make "$@"
  fi
}

install_bin() {
  local prefix="$1" bin="$2"
  mkdir -p "$prefix/bin"
  install -m 0755 "$bin" "$prefix/bin/cst-agent"
}

install_helpers() {
  local prefix="$1" dir="$2"
  mkdir -p "$prefix/bin"
  cat >"$prefix/bin/cst-agent-update" <<EOF
#!$(command -v bash)
export CST_AGENT_PREFIX="\${CST_AGENT_PREFIX:-$prefix}"
exec bash "$dir/scripts/bootstrap_linux.sh" "$dir" "\$@"
EOF
  chmod 0755 "$prefix/bin/cst-agent-update"
  cat >"$prefix/bin/cst-agent-service" <<EOF
#!$(command -v bash)
# Manage the parliament seat service (foreground under systemd, or --service).
set -euo pipefail
BIN="$prefix/bin/cst-agent"
cmd="\${1:-status}"
case "\$cmd" in
status)
  "\$BIN" --version
  if command -v systemctl >/dev/null 2>&1 && systemctl --user is-active cst-agent-parliament.service >/dev/null 2>&1; then
    systemctl --user status cst-agent-parliament.service --no-pager
  else
    "\$BIN" --service-stop >/dev/null 2>&1 || true
    echo "parliament service: not managed by systemd --user (use --login / --service)"
  fi
  ;;
install-unit)
  make -C "$dir" install-service PREFIX="$prefix"
  ;;
start) systemctl --user start cst-agent-parliament.service ;;
stop) systemctl --user stop cst-agent-parliament.service; "\$BIN" --service-stop || true ;;
restart) systemctl --user restart cst-agent-parliament.service ;;
*)
  echo "usage: cst-agent-service {status|install-unit|start|stop|restart}" >&2
  exit 2
  ;;
esac
EOF
  chmod 0755 "$prefix/bin/cst-agent-service"
}

# Fast path: fetch static release tarball for this machine.
install_from_release() {
  local prefix="$1" dir="$2"
  # shellcheck source=lib_release.sh
  . "$dir/scripts/lib_release.sh"
  ROOT="$dir"
  local arch
  arch="$(cst_host_release_arch)" || {
    echo "no prebuilt release for $(uname -m); use --source" >&2
    return 1
  }
  local ver="${CST_AGENT_VERSION:-}"
  if [[ -z "$ver" ]]; then
    ver="$(cst_version)"
  fi
  local name="cst-agent-$ver-linux-$arch.tar.gz"
  local tmp
  tmp="$(mktemp -d /tmp/cst-rel.XXXXXX)"
  # shellcheck disable=SC2046
  if ! cst_fetch "$tmp/$name" $(cst_release_asset_urls "$ver" "$name"); then
    echo "release download failed for $name; falling back to source build" >&2
    rm -rf "$tmp"
    return 1
  fi
  tar -C "$tmp" -xzf "$tmp/$name"
  local bin
  bin="$(find "$tmp" -type f -name cst-agent | head -1)"
  [[ -x "$bin" ]] || { echo "tarball missing cst-agent" >&2; rm -rf "$tmp"; return 1; }
  install_bin "$prefix" "$bin"
  rm -rf "$tmp"
  echo "==> installed release $ver ($arch) -> $prefix/bin/cst-agent"
}

main() {
  local repo_url="${CST_AGENT_REPO:-https://git.whcself.xyz/WHC/CST-agent.git}"
  local prefix="${CST_AGENT_PREFIX:-$HOME/.local}"
  local dir="" pull=1 changed=0 mode="${CST_INSTALL_MODE:-source}" arg
  for arg in "$@"; do
    case "$arg" in
    --no-pull) pull=0 ;;
    --release) mode=release ;;
    --source) mode=source ;;
    --rebuilt) changed=1 ;; # internal: re-exec after a pull
    -h | --help)
      sed -n '2,16p' "$0"
      return 0
      ;;
    *) dir="$arg" ;;
    esac
  done
  if [[ -z "$dir" ]]; then
    if [[ -n "${CST_AGENT_DIR:-}" ]]; then
      dir="$CST_AGENT_DIR"
    elif [[ -f Makefile && -f src/main.c && -d .git ]]; then
      dir="$(pwd)"
    elif [[ -n "$ROOT_HINT" && -f "$ROOT_HINT/Makefile" ]]; then
      dir="$ROOT_HINT"
    else
      dir="$HOME/CST-agent"
    fi
  fi

  local old="" new=""
  if [[ ! -f "$dir/Makefile" ]]; then
    echo "==> git clone $repo_url -> $dir"
    git clone "$repo_url" "$dir"
    changed=1
  elif ((pull)); then
    old="$(git -C "$dir" rev-parse HEAD)"
    if git -C "$dir" diff --quiet && git -C "$dir" diff --cached --quiet; then
      echo "==> git pull ($dir)"
      git -C "$dir" pull --ff-only
    else
      echo "warning: $dir has local changes; skipping git pull" >&2
    fi
    new="$(git -C "$dir" rev-parse HEAD)"
    if [[ "$old" != "$new" ]]; then
      echo "    $(git -C "$dir" log --oneline "$old..$new" | wc -l) new commit(s)"
      # The script itself may have changed: continue with the new version.
      exec bash "$dir/scripts/bootstrap_linux.sh" "$dir" --no-pull --rebuilt \
        ${mode:+--$mode}
    fi
  fi
  cd "$dir"
  dir="$(pwd)"

  if [[ "$mode" == release ]]; then
    if install_from_release "$prefix" "$dir"; then
      install_helpers "$prefix" "$dir"
      echo
      echo "OK: $("$prefix/bin/cst-agent" --version) (release install)"
      case ":$PATH:" in
      *":$prefix/bin:"*) ;;
      *) echo "Add to PATH: export PATH=\"$prefix/bin:\$PATH\"" ;;
      esac
      echo "Upgrade: cst-agent-update --release   Rebuild from source: --source"
      return 0
    fi
    echo "==> continuing with source build"
  fi

  local jobs
  jobs="$(nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || echo 4)"
  echo "==> build (incremental, -j$jobs)"
  # Prefer incremental rebuilds. Set CST_AGENT_CLEAN=1 to force a clean tree.
  if [[ "${CST_AGENT_CLEAN:-0}" == "1" ]]; then
    run_make clean >/dev/null 2>&1 || true
  fi
  : "${changed:=0}"
  if ! run_make -j"$jobs"; then
    deps_hint
    return 1
  fi
  if [[ "${CST_AGENT_SKIP_CHECK:-0}" != "1" ]]; then
    run_make -j"$jobs" check >/dev/null 2>&1 || echo "warning: some tests failed (run 'make check')"
  fi

  echo "==> install to $prefix/bin"
  install_bin "$prefix" "$dir/cst-agent"
  install_helpers "$prefix" "$dir"

  echo
  echo "OK: $("$prefix/bin/cst-agent" --version)"
  case ":$PATH:" in
  *":$prefix/bin:"*) ;;
  *) echo "Add to PATH: export PATH=\"$prefix/bin:\$PATH\"" ;;
  esac
  echo "Run 'cst-agent' inside a project directory; upgrade with 'cst-agent-update'."
  echo "Fast upgrade from Release: 'cst-agent-update --release'."
  echo "Parliament seat service helper: 'cst-agent-service status|install-unit'."
  echo "The first start asks for the provider and its API key and saves them."
}

main "$@"