WechatTicketSystem/src/main/java/love/sola/netsupport/api/APIRouter.java

/*
 * This file is part of WechatTicketSystem.
 *
 * WechatTicketSystem is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * WechatTicketSystem is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with WechatTicketSystem.  If not, see <http://www.gnu.org/licenses/>.
 */

package love.sola.netsupport.api;

import com.google.gson.Gson;
import love.sola.netsupport.enums.Access;
import love.sola.netsupport.enums.Attribute;
import love.sola.netsupport.pojo.Operator;
import love.sola.netsupport.pojo.User;
import love.sola.netsupport.session.WechatSession;
import love.sola.netsupport.session.WxSession;
import love.sola.netsupport.sql.SQLCore;
import org.hibernate.HibernateException;
import org.reflections.Reflections;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.ParseException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * @author Sola {@literal <dev@sola.love>}
 */
@WebServlet(name = "APIRouter", urlPatterns = "/api/*", loadOnStartup = 11)
public class APIRouter extends HttpServlet {

	protected static Gson gson = SQLCore.gson;
	private Map<String, API> nodes = new HashMap<>();

	@Override
	public void init() throws ServletException {
		super.init();
		try {
			Reflections reflections = new Reflections(getClass().getPackage().getName());
			Set<Class<? extends API>> set = reflections.getSubTypesOf(API.class);
			for (Class<? extends API> clz : set) {
				try {
					System.out.println("Loading API: " + clz.getName());
					API obj = clz.newInstance();
					System.out.println("Registered API: " + obj);
					nodes.put(obj.url, obj);
				} catch (InstantiationException | IllegalAccessException e) {
					e.printStackTrace();
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		System.out.println("Total " + nodes.size() + " API(s) loaded.");
	}

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.setCharacterEncoding("utf-8");
		resp.setCharacterEncoding("utf-8");
		resp.addHeader("Content-type", "application/json;charset=utf-8");
		resp.addHeader("Access-Control-Allow-Origin", "*");
		Object obj = null;
		try {
			API api = nodes.get(req.getPathInfo());
			if (api == null) {
				resp.sendError(HttpServletResponse.SC_FORBIDDEN);
				return;
			}
			WxSession session = getSession(req);
			if (session == null) {
				obj = Error.UNAUTHORIZED;
				return;
			}
			if (api.authorize != null) {
				if (session.getAttribute(Attribute.AUTHORIZED) != api.authorize) {
					obj = Error.UNAUTHORIZED;
					return;
				}
				if (api.access == Access.USER) {
					User u = session.getAttribute(Attribute.USER);
					if (u == null) {
						obj = Error.UNAUTHORIZED;
						return;
					}
				}
				if (api.access < Access.USER) {
					Operator op = session.getAttribute(Attribute.OPERATOR);
					if (op == null) {
						obj = Error.UNAUTHORIZED;
						return;
					}
					if (op.getAccess() > api.access) {
						obj = Error.PERMISSION_DENIED;
						return;
					}
				}
			}
			obj = api.process(req, session);
		} catch (ParseException | NumberFormatException e) {
			obj = Error.ILLEGAL_PARAMETER;
		} catch (HibernateException e) {
			e.printStackTrace();
			obj = Error.DATABASE_ERROR;
		} catch (Exception e) {
			e.printStackTrace();
			obj = Error.INTERNAL_ERROR;
		} finally {
			if (!resp.isCommitted()) {
				try (PrintWriter out = resp.getWriter()) {
					out.println(gson.toJson(obj));
				}
			}
		}
	}

	private static WxSession getSession(HttpServletRequest req) {
		String t = req.getParameter("token");
		if (t == null || t.isEmpty()) return null;
		return WechatSession.get(t);
	}

}