/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.micode.notes.gtask.remote;

import android.accounts.Account;
import android.accounts.AccountManager;
import android.accounts.AccountManagerFuture;
import android.app.Activity;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;

import net.micode.notes.gtask.data.Node;
import net.micode.notes.gtask.data.Task;
import net.micode.notes.gtask.data.TaskList;
import net.micode.notes.gtask.exception.ActionFailureException;
import net.micode.notes.gtask.exception.NetworkFailureException;
import net.micode.notes.tool.GTaskStringUtils;
import net.micode.notes.ui.NotesPreferenceActivity;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.cookie.Cookie;
import org.apache.http.impl.client.BasicCookieStore;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.List;
import java.util.zip.GZIPInputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;


/**
 * GTaskClient 类负责与 Google Tasks API 进行通信，
 * 处理 HTTP 请求、JSON 解析和认证令牌管理，
 * 是 Google 任务同步功能的核心网络交互层。
 */
public class GTaskClient {
    private static final String TAG = GTaskClient.class.getSimpleName();
    private static final String GTASK_URL = "https://mail.google.com/tasks/";
    private static final String GTASK_GET_URL = "https://mail.google.com/tasks/ig";
    private static final String GTASK_POST_URL = "https://mail.google.com/tasks/r/ig";


    private static GTaskClient mInstance = null;

    private DefaultHttpClient mHttpClient;

    private String mGetUrl;

    private String mPostUrl;

    private long mClientVersion;

    private boolean mLoggedin;

    private long mLastLoginTime;

    private int mActionId;

    private Account mAccount;

    private JSONArray mUpdateArray;

    /**
     * 私有构造函数，确保该类只能通过单例模式创建实例
     */
    private GTaskClient() {
        mHttpClient = null;
        mGetUrl = GTASK_GET_URL;
        mPostUrl = GTASK_POST_URL;
        mClientVersion = -1;
        mLoggedin = false;
        mLastLoginTime = 0;
        mActionId = 1;
        mAccount = null;
        mUpdateArray = null;
    }

    /**
     * 获取 GTaskClient 的单例实例
     *
     * @return GTaskClient 的单例实例
     */
    public static synchronized GTaskClient getInstance() {
        if (mInstance == null) {
            mInstance = new GTaskClient();
        }
        return mInstance;
    }

    /**
     * 用户登录 Google Tasks 服务
     *
     * @param activity 当前活动实例，用于获取账户管理器和认证令牌
     * @return 登录成功返回 true，失败返回 false
     */
    public boolean login(Activity activity) {
        // 假设 cookie 有效期为 5 分钟，超过该时间需要重新登录
        final long interval = 1000 * 60 * 5;
        if (mLastLoginTime + interval < System.currentTimeMillis()) {
            mLoggedin = false;
        }

        // 如果用户切换了账户，需要重新登录
        if (mLoggedin
                && !TextUtils.equals(getSyncAccount().name, NotesPreferenceActivity
                        .getSyncAccountName(activity))) {
            mLoggedin = false;
        }

        // 如果已经登录，直接返回 true
        if (mLoggedin) {
            Log.d(TAG, "already logged in");
            return true;
        }

        // 更新最后登录时间
        mLastLoginTime = System.currentTimeMillis();
        // 登录 Google 账户并获取认证令牌
        String authToken = loginGoogleAccount(activity, false);
        if (authToken == null) {
            Log.e(TAG, "login google account failed");
            return false;
        }

        //  如果使用的是自定义域名的 Google 账户，需要特殊处理登录 URL
        if (!(mAccount.name.toLowerCase().endsWith("gmail.com") || mAccount.name.toLowerCase()
                .endsWith("googlemail.com"))) {
            StringBuilder url = new StringBuilder(GTASK_URL).append("a/");
            int index = mAccount.name.indexOf('@') + 1;
            String suffix = mAccount.name.substring(index);
            url.append(suffix + "/");
            mGetUrl = url.toString() + "ig";
            mPostUrl = url.toString() + "r/ig";

            if (tryToLoginGtask(activity, authToken)) {
                mLoggedin = true;
            }
        }

        //尝试使用自定义域名 URL 登录 Google Tasks
        if (!mLoggedin) {
            mGetUrl = GTASK_GET_URL;
            mPostUrl = GTASK_POST_URL;
            if (!tryToLoginGtask(activity, authToken)) {
                return false;
            }
        }

        mLoggedin = true;
        return true;
    }

    /**
     * 登录 Google 账户并获取认证令牌
     *
     * @param activity        当前活动实例，用于获取账户管理器
     * @param invalidateToken 是否使现有认证令牌失效
     * @return 认证令牌，如果获取失败则返回 null
     */
    private String loginGoogleAccount(Activity activity, boolean invalidateToken) {
        String authToken;
        AccountManager accountManager = AccountManager.get(activity);
        Account[] accounts = accountManager.getAccountsByType("com.google");

        // 如果没有可用的 Google 账户，返回 null
        if (accounts.length == 0) {
            Log.e(TAG, "there is no available google account");
            return null;
        }

        // 获取用户设置的同步账户名
        String accountName = NotesPreferenceActivity.getSyncAccountName(activity);
        Account account = null;
        // 遍历所有账户，找到与设置中相同名称的账户
        for (Account a : accounts) {
            if (a.name.equals(accountName)) {
                account = a;
                break;
            }
        }
        if (account != null) {
            mAccount = account;
        } else {
            Log.e(TAG, "unable to get an account with the same name in the settings");
            return null;
        }

        // 获取认证令牌
        AccountManagerFuture<Bundle> accountManagerFuture = accountManager.getAuthToken(account,
                "goanna_mobile", null, activity, null, null);
        try {
            Bundle authTokenBundle = accountManagerFuture.getResult();
            authToken = authTokenBundle.getString(AccountManager.KEY_AUTHTOKEN);
            if (invalidateToken) {
                accountManager.invalidateAuthToken("com.google", authToken);
                // 使现有令牌失效后，重新获取令牌
                loginGoogleAccount(activity, false);
            }
        } catch (Exception e) {
            Log.e(TAG, "get auth token failed");
            authToken = null;
        }

        return authToken;
    }

    /**
     * 尝试登录 Google Tasks 服务
     *
     * @param activity  当前活动实例，用于重新获取认证令牌
     * @param authToken 认证令牌
     * @return 登录成功返回 true，失败返回 false
     */
    private boolean tryToLoginGtask(Activity activity, String authToken) {
        if (!loginGtask(authToken)) {
            //如果登录失败，可能是认证令牌过期，使令牌失效并重新获取
            authToken = loginGoogleAccount(activity, true);
            if (authToken == null) {
                Log.e(TAG, "login google account failed");
                return false;
            }

            // 再次尝试登录 Google Tasks
            if (!loginGtask(authToken)) {
                Log.e(TAG, "login gtask failed");
                return false;
            }
        }
        return true;
    }

    /**
     * 使用认证令牌登录 Google Tasks 服务
     *
     * @param authToken 认证令牌
     * @return 登录成功返回 true，失败返回 false
     */
    private boolean loginGtask(String authToken) {
        int timeoutConnection = 10000;
        int timeoutSocket = 15000;
        HttpParams httpParameters = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
        HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
        // 创建一个新的 HttpClient 实例
        mHttpClient = new DefaultHttpClient(httpParameters);
        BasicCookieStore localBasicCookieStore = new BasicCookieStore();
        mHttpClient.setCookieStore(localBasicCookieStore);
        HttpProtocolParams.setUseExpectContinue(mHttpClient.getParams(), false);

        //  尝试登录 Google Tasks
        try {
            String loginUrl = mGetUrl + "?auth=" + authToken;
            HttpGet httpGet = new HttpGet(loginUrl);
            HttpResponse response = null;
            response = mHttpClient.execute(httpGet);

            // 获取 cookie 信息
            List<Cookie> cookies = mHttpClient.getCookieStore().getCookies();
            boolean hasAuthCookie = false;
            for (Cookie cookie : cookies) {
                if (cookie.getName().contains("GTL")) {
                    hasAuthCookie = true;
                }
            }
            if (!hasAuthCookie) {
                Log.w(TAG, "it seems that there is no auth cookie");
            }

            // 解析响应内容，获取客户端版本号
            String resString = getResponseContent(response.getEntity());
            String jsBegin = "_setup(";
            String jsEnd = ")}</script>";
            int begin = resString.indexOf(jsBegin);
            int end = resString.lastIndexOf(jsEnd);
            String jsString = null;
            if (begin != -1 && end != -1 && begin < end) {
                jsString = resString.substring(begin + jsBegin.length(), end);
            }
            JSONObject js = new JSONObject(jsString);
            mClientVersion = js.getLong("v");
        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            return false;
        } catch (Exception e) {
            //  捕获所有异常，记录错误日志并返回 false
            Log.e(TAG, "httpget gtask_url failed");
            return false;
        }

        return true;
    }

    /**
      获取下一个操作 ID
      @return 操作 ID
     **/
    private int getActionId() {
        return mActionId++;
    }

    /**
      创建一个 HttpPost 请求对象
      @return HttpPost 请求对象
     **/
    private HttpPost createHttpPost() {
        HttpPost httpPost = new HttpPost(mPostUrl);
        httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
        httpPost.setHeader("AT", "1");
        return httpPost;
    }

    /**
      从 HTTP 响应实体中获取响应内容
      @param entity HTTP 响应实体
      @return 响应内容的字符串表示
      @throws IOException 读取响应内容时可能抛出的异常
     */
    private String getResponseContent(HttpEntity entity) throws IOException {
        String contentEncoding = null;
        if (entity.getContentEncoding() != null) {
            contentEncoding = entity.getContentEncoding().getValue();
            Log.d(TAG, "encoding: " + contentEncoding);
        }

        InputStream input = entity.getContent();
        // 如果响应内容使用 gzip 压缩，使用 GZIPInputStream 进行解压缩
        if (contentEncoding != null && contentEncoding.equalsIgnoreCase("gzip")) {
            input = new GZIPInputStream(entity.getContent());
        } else if (contentEncoding != null && contentEncoding.equalsIgnoreCase("deflate")) {
            Inflater inflater = new Inflater(true);
            input = new InflaterInputStream(entity.getContent(), inflater);
        }

        try {
            InputStreamReader isr = new InputStreamReader(input);
            BufferedReader br = new BufferedReader(isr);
            StringBuilder sb = new StringBuilder();

            while (true) {
                String buff = br.readLine();
                if (buff == null) {
                    return sb.toString();
                }
                sb = sb.append(buff);
            }
        } finally {
            input.close();
        }
    }

    /**
      发送 POST 请求并返回响应的 JSON 对象
      @param js 要发送的 JSON 请求对象
      @return 响应的 JSON 对象
     @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    private JSONObject postRequest(JSONObject js) throws NetworkFailureException {
        if (!mLoggedin) {
            Log.e(TAG, "please login first");
            throw new ActionFailureException("not logged in");
        }

        HttpPost httpPost = createHttpPost();
        try {
            LinkedList<BasicNameValuePair> list = new LinkedList<BasicNameValuePair>();
            list.add(new BasicNameValuePair("r", js.toString()));
            UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, "UTF-8");
            httpPost.setEntity(entity);

            // 执行 POST 请求
            HttpResponse response = mHttpClient.execute(httpPost);
            String jsString = getResponseContent(response.getEntity());
            return new JSONObject(jsString);

        } catch (ClientProtocolException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new NetworkFailureException("postRequest failed");
        } catch (IOException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new NetworkFailureException("postRequest failed");
        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("unable to convert response content to jsonobject");
        } catch (Exception e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("error occurs when posting request");
        }
    }

    /**
      创建一个新的任务
      @param task 要创建的任务对象
      @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public void createTask(Task task) throws NetworkFailureException {
        // 提交之前的更新操作
        commitUpdate();
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();

            //添加创建任务的操作到操作列表
            actionList.put(task.getCreateAction(getActionId()));
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            // 设置客户端版本号
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            //发送 POST 请求
            JSONObject jsResponse = postRequest(jsPost);
            JSONObject jsResult = (JSONObject) jsResponse.getJSONArray(
                    GTaskStringUtils.GTASK_JSON_RESULTS).get(0);
            // 设置任务的 Google ID
            task.setGid(jsResult.getString(GTaskStringUtils.GTASK_JSON_NEW_ID));

        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("create task: handing jsonobject failed");
        }
    }

    /**
      创建一个新的任务列表
      @param tasklist 要创建的任务列表对象
      @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public void createTaskList(TaskList tasklist) throws NetworkFailureException {
        commitUpdate();
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();

            // 添加创建任务列表的操作到操作列表
            actionList.put(tasklist.getCreateAction(getActionId()));
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            // 设置客户端版本号
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            //发送 POST 请求
            JSONObject jsResponse = postRequest(jsPost);
            JSONObject jsResult = (JSONObject) jsResponse.getJSONArray(
                    GTaskStringUtils.GTASK_JSON_RESULTS).get(0);
            // 设置任务列表的 Google ID
            tasklist.setGid(jsResult.getString(GTaskStringUtils.GTASK_JSON_NEW_ID));

        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("create tasklist: handing jsonobject failed");
        }
    }

    /**
      提交更新操作
      @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public void commitUpdate() throws NetworkFailureException {
        if (mUpdateArray != null) {
            try {
                JSONObject jsPost = new JSONObject();

                //  添加更新操作列表到请求对象
                jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, mUpdateArray);

                // 设置客户端版本号
                jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

                // 发送 POST 请求
                postRequest(jsPost);
                mUpdateArray = null;
            } catch (JSONException e) {
                Log.e(TAG, e.toString());
                e.printStackTrace();
                throw new ActionFailureException("commit update: handing jsonobject failed");
            }
        }
    }

    /**
     * 添加一个更新节点到更新数组中
     * @param node 要更新的节点对象
     * @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public void addUpdateNode(Node node) throws NetworkFailureException {
        if (node != null) {
            //如果更新数组中的操作数量超过 10 个，先提交更新操作
            if (mUpdateArray != null && mUpdateArray.length() > 10) {
                commitUpdate();
            }

            if (mUpdateArray == null)
                mUpdateArray = new JSONArray();
            // 将节点的更新操作添加到更新数组中
            mUpdateArray.put(node.getUpdateAction(getActionId()));
        }
    }

    /**
     * 移动一个任务到另一个任务列表中
     * @param task     要移动的任务对象
     * @param preParent 任务原来所在的任务列表
     * @param curParent 任务要移动到的任务列表
     * @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public void moveTask(Task task, TaskList preParent, TaskList curParent)
            throws NetworkFailureException {
        commitUpdate();
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();
            JSONObject action = new JSONObject();

            // 设置操作类型为移动任务
            action.put(GTaskStringUtils.GTASK_JSON_ACTION_TYPE,
                    GTaskStringUtils.GTASK_JSON_ACTION_TYPE_MOVE);
            action.put(GTaskStringUtils.GTASK_JSON_ACTION_ID, getActionId());
            action.put(GTaskStringUtils.GTASK_JSON_ID, task.getGid());
            if (preParent == curParent && task.getPriorSibling() != null) {
                // 如果在同一个任务列表中移动且不是第一个任务，设置前置兄弟任务的 ID
                action.put(GTaskStringUtils.GTASK_JSON_PRIOR_SIBLING_ID, task.getPriorSibling());
            }
            action.put(GTaskStringUtils.GTASK_JSON_SOURCE_LIST, preParent.getGid());
            action.put(GTaskStringUtils.GTASK_JSON_DEST_PARENT, curParent.getGid());
            if (preParent != curParent) {
                // 如果在不同的任务列表中移动，设置目标任务列表的 Google ID
                action.put(GTaskStringUtils.GTASK_JSON_DEST_LIST, curParent.getGid());
            }
            actionList.put(action);
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            // 设置客户端版本号
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            postRequest(jsPost);

        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("move task: handing jsonobject failed");
        }
    }

    /**
     * 删除一个节点（任务或任务列表）
     * @param node 要删除的节点对象
     * @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public void deleteNode(Node node) throws NetworkFailureException {
        commitUpdate();
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();

            // 标记节点为已删除
            node.setDeleted(true);
            // 添加节点的更新操作到操作列表
            actionList.put(node.getUpdateAction(getActionId()));
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            // 设置客户端版本号
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            postRequest(jsPost);
            //清空更新数组
            mUpdateArray = null;
        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("delete node: handing jsonobject failed");
        }
    }

    /**
     * 获取所有任务列表
     * @return 包含所有任务列表信息的 JSON 数组
     * @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public JSONArray getTaskLists() throws NetworkFailureException {
        if (!mLoggedin) {
            Log.e(TAG, "please login first");
            throw new ActionFailureException("not logged in");
        }

        try {
            HttpGet httpGet = new HttpGet(mGetUrl);
            HttpResponse response = null;
            response = mHttpClient.execute(httpGet);

            //获取响应内容
            String resString = getResponseContent(response.getEntity());
            String jsBegin = "_setup(";
            String jsEnd = ")}</script>";
            int begin = resString.indexOf(jsBegin);
            int end = resString.lastIndexOf(jsEnd);
            String jsString = null;
            if (begin != -1 && end != -1 && begin < end) {
                jsString = resString.substring(begin + jsBegin.length(), end);
            }
            JSONObject js = new JSONObject(jsString);
            // 从响应中提取任务列表信息
            return js.getJSONObject("t").getJSONArray(GTaskStringUtils.GTASK_JSON_LISTS);
        } catch (ClientProtocolException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new NetworkFailureException("gettasklists: httpget failed");
        } catch (IOException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new NetworkFailureException("gettasklists: httpget failed");
        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("get task lists: handing jasonobject failed");
        }
    }

    /**
     * 获取指定任务列表中的所有任务
     * @param listGid 任务列表的 Google ID
     * @return 包含指定任务列表中所有任务信息的 JSON 数组
     * @throws NetworkFailureException 网络请求失败时抛出的异常
     */
    public JSONArray getTaskList(String listGid) throws NetworkFailureException {
        commitUpdate();
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();
            JSONObject action = new JSONObject();

            // 设置操作类型为获取所有任务
            action.put(GTaskStringUtils.GTASK_JSON_ACTION_TYPE,
                    GTaskStringUtils.GTASK_JSON_ACTION_TYPE_GETALL);
            action.put(GTaskStringUtils.GTASK_JSON_ACTION_ID, getActionId());
            action.put(GTaskStringUtils.GTASK_JSON_LIST_ID, listGid);
            action.put(GTaskStringUtils.GTASK_JSON_GET_DELETED, false);
            actionList.put(action);
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            //设置客户端版本号
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            JSONObject jsResponse = postRequest(jsPost);
            return jsResponse.getJSONArray(GTaskStringUtils.GTASK_JSON_TASKS);
        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("get task list: handing jsonobject failed");
        }
    }

    /**
      获取当前同步的 Google 账户
      @return 当前同步的 Google 账户对象
     */
    public Account getSyncAccount() {
        return mAccount;
    }

//    重置更新数组
    public void resetUpdateArray() {
        mUpdateArray = null;
    }
}