/*
 * 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;
//导入Android账户相关类
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;
//导入自定义数据结构和工具类
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;
// 导入Apache HttpClient相关类
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;
// JSON处理类
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
// Java IO相关类
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;


public class GTaskClient {
  // 日志标签
    private static final String TAG = GTaskClient.class.getSimpleName();
  // Google Tasks API地址
    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;
  // HTTP客户端和相关配置
    private DefaultHttpClient mHttpClient;// HTTP客户端实例

    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
    private GTaskClient() {
        mHttpClient = null;
        mGetUrl = GTASK_GET_URL;
        mPostUrl = GTASK_POST_URL;
        mClientVersion = -1;
        mLoggedin = false;
        mLastLoginTime = 0;
        mActionId = 1;
        mAccount = null;
        mUpdateArray = null;
    }
    // 获取单例实例
    public static synchronized GTaskClient getInstance() {
        if (mInstance == null) {
            mInstance = new GTaskClient();
        }
        return mInstance;
    }

    public boolean login(Activity activity) {
        // we suppose that the cookie would expire after 5 minutes
        // then we need to re-login
      // 检查登录有效期（5分钟）
        final long interval = 1000 * 60 * 5;
        if (mLastLoginTime + interval < System.currentTimeMillis()) {
            mLoggedin = false; 
       // 超时需重新登录
        }

        // need to re-login after account switch
      // 检查账户是否变更
        if (mLoggedin
                && !TextUtils.equals(getSyncAccount().name, NotesPreferenceActivity
                        .getSyncAccountName(activity))) {
            mLoggedin = false;
        }

        if (mLoggedin) {
            Log.d(TAG, "already logged in");
            return true;
        }
// 更新最后登录时间
        mLastLoginTime = System.currentTimeMillis();
// 获取Google账户授权令牌
        String authToken = loginGoogleAccount(activity, false);
        if (authToken == null) {
            Log.e(TAG, "login google account failed");
            return false;
        }
 // 处理自定义域名账户
// login with custom domain if necessary
        if (!(mAccount.name.toLowerCase().endsWith("gmail.com") || mAccount.name.toLowerCase()
                .endsWith("googlemail.com"))) {
// 构建自定义URL路径
            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";
 // 尝试登录自定义域名
            if (tryToLoginGtask(activity, authToken)) {
                mLoggedin = true;
            }
        }

        // try to login with google official url
        if (!mLoggedin) {
            mGetUrl = GTASK_GET_URL;
            mPostUrl = GTASK_POST_URL;
            if (!tryToLoginGtask(activity, authToken)) {
                return false;
            }
        }

        mLoggedin = true;
        return true;
    }

    private String loginGoogleAccount(Activity activity, boolean invalidateToken) {
        String authToken;
// 账户管理器操作
        AccountManager accountManager = AccountManager.get(activity);
        Account[] accounts = accountManager.getAccountsByType("com.google");
// 无可用账户检查
        if (accounts.length == 0) {
            Log.e(TAG, "there is no available google account");
            return null;
        }
// 获取配置中的同步账户
        String accountName = NotesPreferenceActivity.getSyncAccountName(activity);
        Account account = null;
// 遍历匹配账户名称
        for (Account a : accounts) {
            if (a.name.equals(accountName)) {
                account = a;
                break;
            }
        }
        if (account != null) {
          // 设置当前账户
            mAccount = account;
        } else {
            Log.e(TAG, "unable to get an account with the same name in the settings");
            return null;
        }

        // get the token now
        AccountManagerFuture<Bundle> accountManagerFuture = accountManager.getAuthToken(account,
                "goanna_mobile", null, activity, null, null);
// 获取授权令牌
        try {
            Bundle authTokenBundle = accountManagerFuture.getResult();
            authToken = authTokenBundle.getString(AccountManager.KEY_AUTHTOKEN);
// 需要失效旧令牌时重新获取 
          if (invalidateToken) {
                accountManager.invalidateAuthToken("com.google", authToken);
                loginGoogleAccount(activity, false);
            }
        } catch (Exception e) {
            Log.e(TAG, "get auth token failed");
            authToken = null;
        }

        return authToken;
    }

    private boolean tryToLoginGtask(Activity activity, String authToken) {
// 首次登录尝试
        if (!loginGtask(authToken)) {
            // maybe the auth token is out of date, now let's invalidate the
            // token and try again
            authToken = loginGoogleAccount(activity, true);
            if (authToken == null) {
                Log.e(TAG, "login google account failed");
                return false;
            }
// 使用新令牌再次尝试登录
            if (!loginGtask(authToken)) {
                Log.e(TAG, "login gtask failed");
                return false;
            }
        }
        return true;
    }

    private boolean loginGtask(String authToken) {
// 设置HTTP连接参数
        int timeoutConnection = 10000;
        int timeoutSocket = 15000;
        HttpParams httpParameters = new BasicHttpParams();
        HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
        HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
// 初始化HTTP客户端
      mHttpClient = new DefaultHttpClient(httpParameters);
        BasicCookieStore localBasicCookieStore = new BasicCookieStore();
        mHttpClient.setCookieStore(localBasicCookieStore);
        HttpProtocolParams.setUseExpectContinue(mHttpClient.getParams(), false);

        // login gtask
        try {
// 构建带认证令牌的登录URL
            String loginUrl = mGetUrl + "?auth=" + authToken;
            HttpGet httpGet = new HttpGet(loginUrl);
            HttpResponse response = null;
            response = mHttpClient.execute(httpGet);

            // get the cookie now
            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");
            }

            // get the client version
// 解析响应内容获取客户端版本
            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) {
            // simply catch all exceptions
            Log.e(TAG, "httpget gtask_url failed");
            return false;
        }

        return true;
    }

    private int getActionId() {
        return mActionId++;
    }

    private HttpPost createHttpPost() {
        HttpPost httpPost = new HttpPost(mPostUrl);
// 设置请求头信息
        httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
        httpPost.setHeader("AT", "1");
        return httpPost;
    }

    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();
// 处理压缩内容
        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);
        }
// 读取响应内容
        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();
        }
    }

    private JSONObject postRequest(JSONObject js) throws NetworkFailureException {
// 登录状态检查
      if (!mLoggedin) {
            Log.e(TAG, "please login first");
            throw new ActionFailureException("not logged in");
        }

        HttpPost httpPost = createHttpPost();
        try {
// 构建POST参数
            LinkedList<BasicNameValuePair> list = new LinkedList<BasicNameValuePair>();
            list.add(new BasicNameValuePair("r", js.toString()));
            UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, "UTF-8");
            httpPost.setEntity(entity);
// 执行请求并处理响应
            // execute the post
            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");
        }
    }

    public void createTask(Task task) throws NetworkFailureException {
        commitUpdate();
// 提交暂存的更新
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();
// 构建创建动作
            // action_list
            actionList.put(task.getCreateAction(getActionId()));
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);
// 添加客户端版本
            // client_version
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);
// 发送请求并处理响应
            // post
            JSONObject jsResponse = postRequest(jsPost);
            JSONObject jsResult = (JSONObject) jsResponse.getJSONArray(
                    GTaskStringUtils.GTASK_JSON_RESULTS).get(0);
            task.setGid(jsResult.getString(GTaskStringUtils.GTASK_JSON_NEW_ID));
// 设置服务器生成ID
        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("create task: handing jsonobject failed");
        }
    }

    public void createTaskList(TaskList tasklist) throws NetworkFailureException {
        commitUpdate();// 提交暂存的更新
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();
 // 构建创建动作
            // action_list
            actionList.put(tasklist.getCreateAction(getActionId()));
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);
// 添加客户端版本
            // client version
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);
// 发送请求并处理响应
            // post
            JSONObject jsResponse = postRequest(jsPost);
            JSONObject jsResult = (JSONObject) jsResponse.getJSONArray(
                    GTaskStringUtils.GTASK_JSON_RESULTS).get(0);
            tasklist.setGid(jsResult.getString(GTaskStringUtils.GTASK_JSON_NEW_ID));// 设置服务器生成ID

        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("create tasklist: handing jsonobject failed");
        }
    }
// 提交暂存的更新操作（批量执行队列中的更新）
    public void commitUpdate() throws NetworkFailureException {
        if (mUpdateArray != null) {
            try {
                JSONObject jsPost = new JSONObject();
 // 设置操作列表字段（直接使用暂存的更新数组）
                // action_list
                jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, mUpdateArray);
 // 添加客户端版本号
                // client_version
                jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

                postRequest(jsPost);// 发送批量更新请求
                mUpdateArray = null;// 清空更新队列
            } catch (JSONException e) {
                Log.e(TAG, e.toString());
                e.printStackTrace();
                throw new ActionFailureException("commit update: handing jsonobject failed");
            }
        }
    }
// 向更新队列添加单个操作（自动处理批量限制）
    public void addUpdateNode(Node node) throws NetworkFailureException {
        if (node != null) {
            // too many update items may result in an error
            // set max to 10 items
// 限制更新队列最大长度为10（超过则先提交当前队列）
            if (mUpdateArray != null && mUpdateArray.length() > 10) {
                commitUpdate();// 提交当前队列// 初始化更新队列
            }

            if (mUpdateArray == null)// 初始化更新队列
                mUpdateArray = new JSONArray();
 // 添加节点的更新操作（调用Node对象生成操作JSON）
            mUpdateArray.put(node.getUpdateAction(getActionId()));
        }
    }
// 移动任务到新位置（支持任务列表间移动和任务排序）
    public void moveTask(Task task, TaskList preParent, TaskList curParent)
            throws NetworkFailureException {
        commitUpdate();// 先提交之前暂存的更新
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();
            JSONObject action = new JSONObject();// 创建移动操作JSON对象
// 设置操作类型为移动
            // action_list
            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());
// 如果在同一任务列表内移动且非第一个任务，设置前置兄弟ID（用于排序）
            if (preParent == curParent && task.getPriorSibling() != null) {
                // put prioring_sibing_id only if moving within the tasklist and
                // it is not the first one
                action.put(GTaskStringUtils.GTASK_JSON_PRIOR_SIBLING_ID, task.getPriorSibling());
            }
// 设置源任务列表ID和目标父级ID（目标任务列表ID）
            action.put(GTaskStringUtils.GTASK_JSON_SOURCE_LIST, preParent.getGid());
            action.put(GTaskStringUtils.GTASK_JSON_DEST_PARENT, curParent.getGid());
// 如果跨任务列表移动，额外设置目标列表ID
          if (preParent != curParent) {
                // put the dest_list only if moving between tasklists
                action.put(GTaskStringUtils.GTASK_JSON_DEST_LIST, curParent.getGid());
            }
            actionList.put(action); // 添加操作到列表
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            // client_version
          // 添加客户端版本号
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            postRequest(jsPost);// 发送移动请求

        } catch (JSONException e) {
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new ActionFailureException("move task: handing jsonobject failed");
        }
    }
// 删除任务或任务列表（标记为删除并提交更新）
    public void deleteNode(Node node) throws NetworkFailureException {
        commitUpdate();// 先提交之前暂存的更新
        try {
            JSONObject jsPost = new JSONObject();
            JSONArray actionList = new JSONArray();
// 标记节点为已删除
            // action_list
            node.setDeleted(true);
          // 添加删除操作
            actionList.put(node.getUpdateAction(getActionId()));
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);
          // 添加客户端版本号
            // client_version
            jsPost.put(GTaskStringUtils.GTASK_JSON_CLIENT_VERSION, mClientVersion);

            postRequest(jsPost);
            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（从Google Tasks获取根任务列表数据）
    public JSONArray getTaskLists() throws NetworkFailureException {
        if (!mLoggedin) {// 未登录检查
            Log.e(TAG, "please login first");
            throw new ActionFailureException("not logged in");
        }

        try {
            HttpGet httpGet = new HttpGet(mGetUrl);// 创建GET请求
            HttpResponse response = null;
            response = mHttpClient.execute(httpGet);
// 解析响应内容
            // get the task list
            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);
// 提取任务列表数据
            return js.getJSONObject("t").getJSONArray(GTaskStringUtils.GTASK_JSON_LISTS);
        } catch (ClientProtocolException e) {
// HTTP协议异常
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new NetworkFailureException("gettasklists: httpget failed");
        } catch (IOException e) {
 // IO异常
            Log.e(TAG, e.toString());
            e.printStackTrace();
            throw new NetworkFailureException("gettasklists: httpget failed");
        } catch (JSONException e) {
// JSON解析异常
            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任务（支持获取未删除任务）
    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_list
            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);// 添加操作到列表
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

            // client_version
            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");
        }
    }
// 获取当前同步账户对象
    public Account getSyncAccount() {
        return mAccount;
    }
// 重置更新队列（清空待提交的操作）
    public void resetUpdateArray() {
        mUpdateArray = null;
    }
}