#!/usr/bin/env bash
set -uo pipefail

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
PORT="${WEB_UI_PORT:-8765}"
LOG_FILE="$ROOT_DIR/work/web_ui.log"
SERVER_PID_FILE="$ROOT_DIR/work/web_ui.pid"
WATCHDOG_PID_FILE="$ROOT_DIR/work/web_ui_watchdog.pid"

mkdir -p "$ROOT_DIR/work"
echo $$ > "$WATCHDOG_PID_FILE"

cd "$ROOT_DIR"

start_server() {
  echo "[$(date '+%Y-%m-%d %H:%M:%S')] [watchdog] starting web_ui.py" >> "$LOG_FILE"
  python3 -u scripts/web_ui.py >> "$LOG_FILE" 2>&1 &
  echo "$!" > "$SERVER_PID_FILE"
}

stop_server() {
  if [[ -f "$SERVER_PID_FILE" ]]; then
    local pid
    pid="$(cat "$SERVER_PID_FILE" 2>/dev/null || true)"
    if [[ -n "$pid" ]] && kill -0 "$pid" 2>/dev/null; then
      kill "$pid" 2>/dev/null || true
    fi
  fi
}

trap 'stop_server; rm -f "$WATCHDOG_PID_FILE"; exit 0' INT TERM EXIT

while true; do
  if ! curl -fsS --max-time 2 "http://127.0.0.1:$PORT/" >/dev/null 2>&1; then
    pids="$(lsof -tiTCP:"$PORT" -sTCP:LISTEN 2>/dev/null || true)"
    if [[ -n "$pids" ]]; then
      echo "[$(date '+%Y-%m-%d %H:%M:%S')] [watchdog] clearing stale listener: $pids" >> "$LOG_FILE"
      kill $pids 2>/dev/null || true
      sleep 1
    fi
    start_server || true
    sleep 2
  fi
  sleep 5
done