/*
 * 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.
 */

// 导入所需的Android库和类
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类是用于与Google Tasks服务进行交互的客户端
public class GTaskClient {
    // 定义日志标签
    private static final String TAG = GTaskClient.class.getSimpleName();

    // 定义Google Tasks的URL
    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"; 

    // 单例模式，确保GTaskClient只有一个实例
    private static GTaskClient mInstance = null;

    // HTTP客户端，用于发送请求
    private DefaultHttpClient mHttpClient;

    // GET和POST请求的URL
    private String mGetUrl;
    private String mPostUrl;

    // 客户端版本号
    private long mClientVersion;

    // 登录状态
    private boolean mLoggedin;

    // 最后登录时间
    private long mLastLoginTime;

    // 操作ID
    private int mActionId;

    // 当前账户
    private Account mAccount;

    // 更新数组
    private JSONArray mUpdateArray;

    // 私有构造函数，防止外部直接创建实例
    private GTaskClient() {
        mHttpClient = null;
        mGetUrl = GTASK_GET_URL;
        mPostUrl = GTASK_POST_URL;
        mClientVersion = -1;
        mLoggedin = false;
        mLastLoginTime = 0;
        mActionId = 1;
        mAccount = null;
        mUpdateArray = null;
    }

    // 提供获取GTaskClient实例的方法，确保单例模式
    public static synchronized GTaskClient getInstance() {
        if (mInstance == null) {
            mInstance = new GTaskClient();
        }
        return mInstance;
    }

    // 登录方法，用于登录Google Tasks服务
    public boolean login(Activity activity) {
        // 如果登录间隔超过5分钟，则需要重新登录
        final long interval = 1000 * 60 * 5;
        if (mLastLoginTime + interval < System.currentTimeMillis()) {
            mLoggedin = false;
        }

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

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

        // 更新最后登录时间
        mLastLoginTime = System.currentTimeMillis();
        String authToken = loginGoogleAccount(activity, false);
        if (authToken == null) {
            Log.e(TAG, "login google account failed");
            return false;
        }

        // 如果账户不是gmail.com或googlemail.com，则需要使用自定义域名
        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;
            }
        }

        // 如果使用Google官方URL登录失败，则返回false
        if (!mLoggedin) {
            mGetUrl = GTASK_GET_URL;
            mPostUrl = GTASK_POST_URL;
            if (!tryToLoginGtask(activity, authToken)) {
                return false;
            }
        }

        // 登录成功，设置登录状态为true
        mLoggedin = true;
        return true;
    }

    // 登录Google账户的方法
    private String loginGoogleAccount(Activity activity, boolean invalidateToken) {
        String authToken;
        AccountManager accountManager = AccountManager.get(activity);
        Account[] accounts = accountManager.getAccountsByType("com.google");

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

        // 获取同步账户名称
        String accountName = NotesPreferenceActivity.getSyncAccountName(activity);
        Account account = null;
        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;
        }

        // 获取授权令牌
        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);
                loginGoogleAccount(activity, false);
            }
        } catch (Exception e) {
            Log.e(TAG, "get auth token failed");
            authToken = null;
        }

        return authToken;
    }

   // 尝试使用提供的授权令牌登录Google Tasks
private boolean tryToLoginGtask(Activity activity, String authToken) {
    // 首先尝试登录
    if (!loginGtask(authToken)) {
        // 如果登录失败，可能是授权令牌过期，因此使令牌失效并尝试重新获取
        authToken = loginGoogleAccount(activity, true);
        // 如果重新获取授权令牌失败，则记录错误并返回false
        if (authToken == null) {
            Log.e(TAG, "login google account failed");
            return false;
        }

        // 使用新的授权令牌再次尝试登录
        if (!loginGtask(authToken)) {
            Log.e(TAG, "login gtask failed");
            return false;
        }
    }
    // 登录成功，返回true
    return true;
}

// 使用授权令牌登录Google Tasks
private boolean loginGtask(String authToken) {
    // 设置连接超时和socket超时参数
    int timeoutConnection = 10000;
    int timeoutSocket = 15000;
    HttpParams httpParameters = new BasicHttpParams();
    HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
    HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
    // 创建HttpClient实例并设置超时参数
    mHttpClient = new DefaultHttpClient(httpParameters);
    BasicCookieStore localBasicCookieStore = new BasicCookieStore();
    mHttpClient.setCookieStore(localBasicCookieStore);
    // 设置HTTP协议参数，禁用Expect-Continue
    HttpProtocolParams.setUseExpectContinue(mHttpClient.getParams(), false);

    try {
        // 构造登录URL并发起GET请求
        String loginUrl = mGetUrl + "?auth=" + authToken;
        HttpGet httpGet = new HttpGet(loginUrl);
        HttpResponse response = mHttpClient.execute(httpGet);

        // 获取响应中的Cookie
        List<Cookie> cookies = mHttpClient.getCookieStore().getCookies();
        boolean hasAuthCookie = false;
        for (Cookie cookie : cookies) {
            // 检查是否存在名为"GTL"的授权Cookie
            if (cookie.getName().contains("GTL")) {
                hasAuthCookie = true;
            }
        }
        // 如果没有找到授权Cookie，则记录警告
        if (!hasAuthCookie) {
            Log.w(TAG, "it seems that there is no auth cookie");
        }

        // 从响应内容中提取客户端版本号
        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) {
            // 提取JavaScript代码中的客户端版本信息
            jsString = resString.substring(begin + jsBegin.length(), end);
        }
        JSONObject js = new JSONObject(jsString);
        mClientVersion = js.getLong("v");
    } catch (JSONException e) {
        // 如果JSON解析失败，则记录错误并返回false
        Log.e(TAG, e.toString());
        e.printStackTrace();
        return false;
    } catch (Exception e) {
        // 捕获所有其他异常，并记录错误，返回false
        Log.e(TAG, "httpget gtask_url failed");
        return false;
    }

    // 登录成功，返回true
    return true;
}

// 获取下一个操作ID，用于标识请求
private int getActionId() {
    return mActionId++;
}

// 创建一个HttpPost请求对象，设置必要的头部信息
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HttpEntity中获取响应内容的方法。
 * @param entity HttpEntity对象，包含响应数据。
 * @return 响应内容的字符串表示。
 * @throws IOException 如果读取输入流时发生I/O错误。
 */
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();
    // 根据内容编码类型，包装输入流
    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();

        // 读取响应内容直到结束
        while (true) {
            String buff = br.readLine();
            if (buff == null) {
                return sb.toString();
            }
            sb = sb.append(buff);
        }
    } finally {
        // 确保输入流被关闭
        input.close();
    }
}

/**
 * 发送POST请求并返回响应的JSONObject。
 * @param js 包含请求数据的JSONObject。
 * @return 响应内容的JSONObject。
 * @throws NetworkFailureException 如果网络请求失败。
 */
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 {
        // 构造请求参数
        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");
    }
}

/**
 * 创建新任务的方法。
 * @param task 要创建的任务对象。
 * @throws NetworkFailureException 如果网络请求失败。
 */
public void createTask(Task task) throws NetworkFailureException {
    commitUpdate();
    try {
        JSONObject jsPost = new JSONObject();
        JSONArray actionList = new JSONArray();

        // 构造创建任务的行动列表
        actionList.put(task.getCreateAction(getActionId()));
        jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

        // 设置客户端版本
        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);
        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");
    }
}

/**
 * 创建新任务列表的方法。
 * @param tasklist 要创建的任务列表对象。
 * @throws NetworkFailureException 如果网络请求失败。
 */
public void createTaskList(TaskList tasklist) throws NetworkFailureException {
    commitUpdate();
    try {
        JSONObject jsPost = new JSONObject();
        JSONArray actionList = new JSONArray();

        // 构造创建任务列表的行动列表
        actionList.put(tasklist.getCreateAction(getActionId()));
        jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

        // 设置客户端版本
        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);
        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");
    }
}

  /**
 * 提交更新到服务器。
 * 如果有待更新的节点，将它们打包成一个JSON对象并发送到服务器。
 * @throws NetworkFailureException 如果网络请求失败。
 */
public void commitUpdate() throws NetworkFailureException {
    if (mUpdateArray != null) {
        try {
            JSONObject jsPost = new JSONObject();

            // 将待更新的节点数组添加到JSON对象中
            jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, mUpdateArray);

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

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

/**
 * 向更新数组中添加一个新的更新节点。
 * 如果更新数组已满（超过10个项目），则先提交当前的更新数组。
 * @param node 要添加的更新节点。
 * @throws NetworkFailureException 如果网络请求失败。
 */
public void addUpdateNode(Node node) throws NetworkFailureException {
    if (node != null) {
        // 如果更新数组已满，则先提交更新
        if (mUpdateArray != null && mUpdateArray.length() > 10) {
            commitUpdate();
        }

        // 如果更新数组为空，则创建一个新的JSONArray
        if (mUpdateArray == null)
            mUpdateArray = new JSONArray();
        // 将节点的更新动作添加到更新数组中
        mUpdateArray.put(node.getUpdateAction(getActionId()));
    }
}

/**
 * 移动任务到不同的任务列表。
 * @param task 要移动的任务。
 * @param preParent 任务原来所在的任务列表。
 * @param curParent 任务移动到的新任务列表。
 * @throws NetworkFailureException 如果网络请求失败。
 */
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();

        // 构造移动任务的动作
        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());
        // 如果任务在同一个任务列表内移动，并且不是第一个任务，则添加前一个兄弟任务的ID
        if (preParent == curParent && task.getPriorSibling() != null) {
            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());
        // 如果任务移动到不同的任务列表，则添加目标任务列表的ID
        if (preParent != curParent) {
            action.put(GTaskStringUtils.GTASK_JSON_DEST_LIST, curParent.getGid());
        }
        actionList.put(action);
        jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

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

        // 发送POST请求
        postRequest(jsPost);

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

/**
 * 删除节点。
 * @param node 要删除的节点。
 * @throws NetworkFailureException 如果网络请求失败。
 */
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);
        // 构造删除节点的动作
        actionList.put(node.getUpdateAction(getActionId()));
        jsPost.put(GTaskStringUtils.GTASK_JSON_ACTION_LIST, actionList);

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

        // 发送POST请求
        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 任务列表的JSONArray。
 * @throws NetworkFailureException 如果网络请求失败。
 */
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 = mHttpClient.execute(httpGet);

        // 提取响应内容中的JavaScript代码，并解析出任务列表
        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);
        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");
    }
}

/**
 * 获取指定任务列表下的所有任务。
 * @param listGid 任务列表的ID。
 * @return 任务的JSONArray。
 * @throws NetworkFailureException 如果网络请求失败。
 */
public JSONArray getTaskList(String listGid) throws NetworkFailureException {
    commitUpdate();
    try {
        JSONObject jsPost = new JSONObject();
        JSONArray actionList = new JSONArray();
        JSONObject action = new JSONObject();

        // 构造获取任务的动作
        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);

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

        // 发送POST请求
        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");
    }
}

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

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