#!/usr/bin/env bash
# dev.sh — start/stop the frontend (Nuxt) and backend (Express) together.
#
# Usage:
#   ./dev.sh                     Start both in the foreground (Ctrl+C stops both)
#   ./dev.sh start               Start both dev servers in the background
#   ./dev.sh stop                Stop both dev servers
#   ./dev.sh restart             Stop then start
#   ./dev.sh status              Show which services are running
#   ./dev.sh logs [service]      Follow logs (all, backend, or frontend)

set -euo pipefail

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PID_DIR="$ROOT/.pids"
LOG_DIR="$ROOT/.logs"
SERVICES=("backend" "frontend")

pid_of() {
  local pid_file="$PID_DIR/$1.pid"
  [[ -f "$pid_file" ]] && cat "$pid_file" || true
}

is_running() {
  local pid
  pid="$(pid_of "$1")"
  [[ -n "$pid" ]] && kill -0 "$pid" 2>/dev/null
}

start_service() {
  local name="$1"
  if is_running "$name"; then
    echo "$name is already running (PID $(pid_of "$name"))"
    return
  fi
  mkdir -p "$PID_DIR" "$LOG_DIR"
  # setsid puts each service in its own process group so `stop` can kill
  # npm and all of its child processes (node --watch, nuxt, ...) cleanly.
  setsid bash -c 'cd "$1" && exec npm run dev' _ "$ROOT/$name" \
    > "$LOG_DIR/$name.log" 2>&1 &
  local pid=$!
  echo "$pid" > "$PID_DIR/$name.pid"
  echo "started $name (PID $pid) — log: $LOG_DIR/$name.log"
}

stop_service() {
  local name="$1"
  local pid
  pid="$(pid_of "$name")"

  if ! is_running "$name"; then
    echo "$name is not running"
    rm -f "$PID_DIR/$name.pid"
    return
  fi

  # Negative PID kills the whole process group (npm + its children).
  kill -TERM -- "-$pid" 2>/dev/null || kill -TERM "$pid" 2>/dev/null || true
  # Wait up to 5s for a graceful shutdown, then force-kill.
  for _ in {1..50}; do
    kill -0 "$pid" 2>/dev/null || break
    sleep 0.1
  done
  if kill -0 "$pid" 2>/dev/null; then
    kill -KILL -- "-$pid" 2>/dev/null || kill -KILL "$pid" 2>/dev/null || true
  fi
  rm -f "$PID_DIR/$name.pid"
  echo "stopped $name (PID $pid)"
}

status() {
  for name in "${SERVICES[@]}"; do
    if is_running "$name"; then
      echo "$name: running (PID $(pid_of "$name"))"
    else
      echo "$name: stopped"
    fi
  done
}

FG_PIDS=()
SHUTTING=0

# Stop all foreground services (and their process groups). A second call
# (e.g. pressing Ctrl+C again while shutting down) escalates to SIGKILL.
fg_stop_all() {
  local name pid sig=TERM
  if [[ $SHUTTING -eq 1 ]]; then sig=KILL; else
    SHUTTING=1
    echo
    echo "stopping frontend + backend..."
  fi
  for pid in "${FG_PIDS[@]:-}"; do
    kill -"$sig" -- "-$pid" 2>/dev/null || kill -"$sig" "$pid" 2>/dev/null || true
  done
  wait 2>/dev/null || true
  for name in "${SERVICES[@]}"; do rm -f "$PID_DIR/$name.pid"; done
  exit 0
}

foreground() {
  local name
  for name in "${SERVICES[@]}"; do
    if is_running "$name"; then
      echo "$name is already running (PID $(pid_of "$name")); run '$0 stop' first" >&2
      exit 1
    fi
  done
  mkdir -p "$PID_DIR"
  for name in "${SERVICES[@]}"; do
    # setsid puts each service in its own process group (PID == PGID) so the
    # output prefix pipeline survives the shutdown; sed -u tags every line.
    setsid bash -c 'cd "$1" && exec npm run dev' _ "$ROOT/$name" \
      > >(sed -u "s/^/[$name] /") 2>&1 &
    local pid=$!
    FG_PIDS+=("$pid")
    echo "$pid" > "$PID_DIR/$name.pid"
  done
  trap 'fg_stop_all' INT TERM
  echo "frontend + backend running — press Ctrl+C to stop both"
  # Exit as soon as either service dies, so they always run/stop together.
  wait -n
  echo "a dev server exited — stopping the other one..."
  fg_stop_all
}

case "${1:-dev}" in
  dev)
    foreground
    ;;
  start)
    for name in "${SERVICES[@]}"; do start_service "$name"; done
    echo
    echo "backend:  http://localhost:5000"
    echo "frontend: http://localhost:3000"
    ;;
  stop)
    for name in "${SERVICES[@]}"; do stop_service "$name"; done
    ;;
  restart)
    for name in "${SERVICES[@]}"; do stop_service "$name"; done
    for name in "${SERVICES[@]}"; do start_service "$name"; done
    ;;
  status)
    status
    ;;
  logs)
    case "${2:-all}" in
      all)      tail -f "$LOG_DIR"/*.log ;;
      backend|frontend) tail -f "$LOG_DIR/$2.log" ;;
      *) echo "usage: $0 logs [all|backend|frontend]"; exit 1 ;;
    esac
    ;;
  *)
    echo "usage: $0 [dev|start|stop|restart|status|logs [all|backend|frontend]]  (default: dev)"
    exit 1
    ;;
esac