#!/usr/bin/env bash

set -euo pipefail

PORT="${PORT:-15124}"
HOST="${HOST:-0.0.0.0}"
APP_MODULE="${APP_MODULE:-app.py}"
PID_FILE="${PID_FILE:-backend.pid}"
LOG_FILE="${LOG_FILE:-backend.log}"

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
cd "$SCRIPT_DIR"

echo "检查端口 ${PORT} ..."
if command -v ss >/dev/null 2>&1; then
  if ss -ltn | awk '{print $4}' | grep -Eq "(^|:)${PORT}$"; then
    echo "错误: 端口 ${PORT} 已被占用，请先释放后再启动。"
    exit 1
  fi
elif command -v netstat >/dev/null 2>&1; then
  if netstat -ltn 2>/dev/null | awk '{print $4}' | grep -Eq "(^|:)${PORT}$"; then
    echo "错误: 端口 ${PORT} 已被占用，请先释放后再启动。"
    exit 1
  fi
else
  echo "警告: 未找到 ss 或 netstat，跳过端口占用检查。"
fi
echo "端口 ${PORT} 未被占用。"
echo "工作目录已切换至: ${SCRIPT_DIR}"

PYTHON_BIN=""
if [[ -x "${SCRIPT_DIR}/venv/bin/python" ]]; then
  PYTHON_BIN="${SCRIPT_DIR}/venv/bin/python"
elif [[ -x "${SCRIPT_DIR}/.venv/bin/python" ]]; then
  PYTHON_BIN="${SCRIPT_DIR}/.venv/bin/python"
elif command -v python3 >/dev/null 2>&1; then
  PYTHON_BIN="$(command -v python3)"
elif command -v python >/dev/null 2>&1; then
  PYTHON_BIN="$(command -v python)"
else
  echo "错误: 未找到可用的 Python，请先安装 Python 3.9+。"
  exit 1
fi

echo "使用 Python: ${PYTHON_BIN}"
"${PYTHON_BIN}" - <<'PY'
import sys
major, minor = sys.version_info[:2]
if (major, minor) < (3, 9):
    print(f"错误: 当前 Python 版本为 {major}.{minor}，项目至少需要 Python 3.9。")
    print("原因: requirement.txt 中的 Flask 3.x、pandas 2.x 等依赖不支持 Python 3.6。")
    raise SystemExit(1)
print(f"Python 版本检查通过: {major}.{minor}")
PY

if [[ ! -f "requirement.txt" ]]; then
  echo "错误: 未找到 requirement.txt。"
  exit 1
fi

echo "检查关键依赖 ..."
if ! "${PYTHON_BIN}" - <<'PY'
import importlib.util
modules = ("flask", "flask_cors", "pymysql", "werkzeug")
missing = [name for name in modules if importlib.util.find_spec(name) is None]
if missing:
    print("缺少依赖: " + ", ".join(missing))
    raise SystemExit(1)
print("关键依赖已安装。")
PY
then
  echo "开始安装 requirement.txt ..."
  "${PYTHON_BIN}" -m pip install --upgrade pip
  "${PYTHON_BIN}" -m pip install -r requirement.txt
fi

if [[ -f "${PID_FILE}" ]]; then
  OLD_PID="$(cat "${PID_FILE}" 2>/dev/null || true)"
  if [[ -n "${OLD_PID}" ]] && kill -0 "${OLD_PID}" 2>/dev/null; then
    echo "错误: 检测到服务已在运行，PID=${OLD_PID}"
    exit 1
  fi
  rm -f "${PID_FILE}"
fi

echo "启动 Flask 服务 ${HOST}:${PORT} ..."
nohup "${PYTHON_BIN}" "${APP_MODULE}" >> "${LOG_FILE}" 2>&1 &
NEW_PID=$!
echo "${NEW_PID}" > "${PID_FILE}"

sleep 2
if kill -0 "${NEW_PID}" 2>/dev/null; then
  echo "启动成功，PID=${NEW_PID}"
  echo "日志文件: ${SCRIPT_DIR}/${LOG_FILE}"
else
  echo "错误: 服务启动失败，请检查日志 ${SCRIPT_DIR}/${LOG_FILE}"
  exit 1
fi