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

ROOT_DIR="$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)"
RUN_DIR="$ROOT_DIR/run"
PID_FILE="$RUN_DIR/hy-app-monitor.pid"
LOG_FILE="$RUN_DIR/hy-app-monitor.log"
ENV_FILE="${APP_ENV_FILE:-$ROOT_DIR/.env}"
SYSTEMD_SERVICE_NAME="hy-app-monitor.service"

if [ -f "$ENV_FILE" ]; then
  set -a
  # shellcheck disable=SC1090
  . "$ENV_FILE"
  set +a
fi

APP_BIND="${APP_BIND:-0.0.0.0}"
APP_PORT="${APP_PORT:-2026}"
TARGETS_FILE="${TARGETS_FILE:-$ROOT_DIR/config/targets.json}"

if [ -x "$ROOT_DIR/.venv/bin/python" ]; then
  PYTHON_BIN_DEFAULT="$ROOT_DIR/.venv/bin/python"
else
  PYTHON_BIN_DEFAULT="python3"
fi

PYTHON_BIN="${PYTHON_BIN:-$PYTHON_BIN_DEFAULT}"

mkdir -p "$RUN_DIR"

read_pid() {
  if [ -f "$PID_FILE" ]; then
    local pid
    pid="$(cat "$PID_FILE")"
    if pid_matches_project "$pid"; then
      echo "$pid"
      return 0
    fi
  fi

  discover_project_pid
}

is_running() {
  local pid
  pid="$(read_pid || true)"
  if [ -z "${pid:-}" ]; then
    rm -f "$PID_FILE"
    return 1
  fi
  if ! kill -0 "$pid" >/dev/null 2>&1; then
    rm -f "$PID_FILE"
    return 1
  fi

  echo "$pid" >"$PID_FILE"
  return 0
}

has_systemd_unit() {
  if ! command -v systemctl >/dev/null 2>&1; then
    return 1
  fi
  systemctl cat "$SYSTEMD_SERVICE_NAME" >/dev/null 2>&1
}

stop_legacy_process() {
  local pid
  pid="$(read_pid || true)"

  if [ -n "${pid:-}" ] && kill -0 "$pid" >/dev/null 2>&1; then
    kill "$pid" >/dev/null 2>&1 || true
    for _ in $(seq 1 10); do
      if ! kill -0 "$pid" >/dev/null 2>&1; then
        break
      fi
      sleep 1
    done
    kill -9 "$pid" >/dev/null 2>&1 || true
  fi

  rm -f "$PID_FILE"
}

discover_project_pid() {
  if ! command -v lsof >/dev/null 2>&1; then
    return 1
  fi

  local pid
  while IFS= read -r pid; do
    if pid_matches_project "$pid"; then
      echo "$pid"
      return 0
    fi
  done < <(lsof -tiTCP:"$APP_PORT" -sTCP:LISTEN 2>/dev/null || true)

  return 1
}

pid_matches_project() {
  local pid="$1"
  if [ -z "${pid:-}" ] || ! kill -0 "$pid" >/dev/null 2>&1; then
    return 1
  fi

  local command
  command="$(ps -p "$pid" -o command= 2>/dev/null || true)"
  if [[ "$command" != *"$ROOT_DIR/server.py"* ]] && [[ "$command" != *" server.py"* ]]; then
    return 1
  fi

  if command -v lsof >/dev/null 2>&1; then
    local cwd
    cwd="$(lsof -a -p "$pid" -d cwd -Fn 2>/dev/null | sed -n 's/^n//p' | head -n 1)"
    if [ -n "$cwd" ] && [ "$cwd" != "$ROOT_DIR" ]; then
      return 1
    fi
  fi

  return 0
}