/*
 * Juick
 * Copyright (C) 2008-2013, Ugnich Anton
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.juick.www.controllers;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.juick.service.CrosspostService;
import com.juick.service.UserService;
import com.juick.www.Utils;
import com.juick.www.facebook.Graph;
import org.apache.commons.lang3.CharEncoding;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.inject.Inject;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.UUID;

/**
 *
 * @author Ugnich Anton
 */
@Controller
public class FacebookLogin {

    private static final Logger logger = LoggerFactory.getLogger(FacebookLogin.class);

    private final String FACEBOOK_APPID;
    private final String FACEBOOK_SECRET;
    private final String FACEBOOK_REDIRECT = "http://juick.com/_fblogin";
    private final ObjectMapper mapper;

    @Inject
    CrosspostService crosspostService;
    @Inject
    UserService userService;

    @Inject
    public FacebookLogin(Environment env) {
        FACEBOOK_APPID = env.getProperty("facebook_appid");
        FACEBOOK_SECRET = env.getProperty("facebook_secret");

        mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_DEFAULT);
    }

    @RequestMapping(value = "/_fblogin", method = RequestMethod.GET)
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws UnsupportedEncodingException {
        String fbstate;

        String code = request.getParameter("code");
        if (StringUtils.isBlank(code)) {
            fbstate = UUID.randomUUID().toString();

            Cookie c = new Cookie("fbstate", fbstate);
            response.addCookie(c);

            response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
            response.setHeader("Location", "https://www.facebook.com/dialog/oauth?scope=publish_stream&client_id=" + FACEBOOK_APPID + "&redirect_uri=" + URLEncoder.encode(FACEBOOK_REDIRECT, CharEncoding.UTF_8) + "&state=" + fbstate);
            return;
        }

        fbstate = Utils.getCookie(request, "fbstate");
        if (fbstate == null || fbstate.isEmpty() || !fbstate.equals(request.getParameter("state"))) {
            response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            return;
        } else {
            Cookie c = new Cookie("fbstate", "-");
            c.setMaxAge(0);
            response.addCookie(c);
        }

        String token = Utils.fetchURL("https://graph.facebook.com/oauth/access_token?client_id=" + FACEBOOK_APPID + "&redirect_uri=" + URLEncoder.encode(FACEBOOK_REDIRECT, CharEncoding.UTF_8) + "&client_secret=" + FACEBOOK_SECRET + "&code=" + URLEncoder.encode(code, CharEncoding.UTF_8));
        if (token == null || token.isEmpty() || !token.startsWith("access_token=")) {
            logger.error("FACEBOOK TOKEN ERROR: {}", token);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
        token = token.substring(13); // access_token=...
        int tokenamp = token.indexOf('&'); // &expires=
        if (tokenamp > 0) {
            token = token.substring(0, tokenamp);
        }

        String graph = Utils.fetchURL("https://graph.facebook.com/me?access_token=" + token);
        if (graph == null || graph.isEmpty()) {
            logger.error("FACEBOOK GRAPH ERROR");
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        try {
            Graph fb = mapper.readValue(graph, Graph.class);

            long fbID = NumberUtils.toLong(fb.getId(), 0);
            if (fbID == 0 || StringUtils.isBlank(fb.getName()) || StringUtils.isBlank(fb.getLink())) {
                throw new Exception();
            }

            int uid = crosspostService.getUIDbyFBID(fbID);
            if (uid > 0) {
                if (!crosspostService.updateFacebookUser(fbID, token, fb.getName(), fb.getLink())) {
                    throw new Exception();
                }
                Cookie c = new Cookie("hash", userService.getHashByUID(uid));
                c.setMaxAge(50 * 24 * 60 * 60);
                response.addCookie(c);
                response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
                response.setHeader("Location", "/");
            } else if (fb.getVerified()) {
                String loginhash = UUID.randomUUID().toString();
                if (!crosspostService.createFacebookUser(fbID, loginhash, token, fb.getName(), fb.getLink())) {
                    throw new Exception();
                }
                response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
                response.setHeader("Location", "/signup?type=fb&hash=" + loginhash);
            } else {
                throw new Exception();
            }
        } catch (Exception e) {
            logger.error("fb error", e);
            response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }
    }
}