using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using MongoDB.Bson;
using MongoDB.Driver;

namespace MES_MonitoringService.Common
{
    /// <summary>
    /// Mongodb操作类
    /// </summary>
    public class MongodbHandler
    {
        /*默认MongoDB参数*/
        /*-------------------------------------------------------------------------------------*/

        public static string MongodbServiceName = Common.ConfigFileHandler.GetAppConfig("MongodbServiceName");
        private static string MongodbDefaultUrl = Common.ConfigFileHandler.GetAppConfig("MongodbURL");
        private static string MongodbDefaultDBName = Common.ConfigFileHandler.GetAppConfig("MongodbName");

        // 定义一个静态变量来保存类的实例
        private static MongodbHandler uniqueInstance;
        //定义一个标识确保线程同步 
        private static readonly object locker = new object();


        /*构造函数*/
        /*-------------------------------------------------------------------------------------*/

        /// <summary>
        /// mongo连接客户端
        /// </summary>
        public static MongoClient mc_MongoClient = null;

        /// <summary>
        /// mongo数据库
        /// </summary>
        public IMongoDatabase mc_MongoDatabase = null;


        /*构造函数*/
        /*-------------------------------------------------------------------------------------*/

        /// <summary>
        /// 定义私有构造函数，使外界不能创建该类实例
        /// </summary>
        private MongodbHandler()
        {
            if (!Common.CommonFunction.ServiceRunning(MongodbServiceName))
            {
                throw new Exception("Mongodb 服务未安装或未运行，无法连接至Mongodb");
            }

            //client
            mc_MongoClient = new MongoClient(MongodbDefaultUrl);
            //database
            mc_MongoDatabase = mc_MongoClient.GetDatabase(MongodbDefaultDBName);
        }

        /// <summary>
        /// 定义公有方法提供一个全局访问点,同时你也可以定义公有属性来提供全局访问点
        /// </summary>
        /// <returns></returns>
        public static MongodbHandler GetInstance()
        {
            // 当第一个线程运行到这里时，此时会对locker对象 "加锁"，
            // 当第二个线程运行该方法时，首先检测到locker对象为"加锁"状态，该线程就会挂起等待第一个线程解锁
            // lock语句运行完之后（即线程运行完之后）会对该对象"解锁"
            // 双重锁定只需要一句判断就可以了
            if (uniqueInstance == null)
            {
                lock (locker)
                {
                    // 如果类的实例不存在则创建，否则直接返回
                    if (uniqueInstance == null)
                    {
                        uniqueInstance = new MongodbHandler();
                    }
                }
            }
            return uniqueInstance;
        }




        /// <summary>
        /// 获取数据集
        /// </summary>
        /// <param name="collectionName"></param>
        /// <returns></returns>
        public IMongoCollection<BsonDocument> GetCollection(string collectionName)
        {
            return mc_MongoDatabase.GetCollection<BsonDocument>(collectionName);
        }


        /*操作数据*/
        /*-------------------------------------------------------------------------------------*/

        /// <summary>
        /// 数据集插入一条数据
        /// </summary>
        /// <param name="collection"></param>
        /// <param name="newDocument"></param>
        public void InsertOne(IMongoCollection<BsonDocument> collection, BsonDocument newDocument)
        {
            collection.InsertOne(newDocument);
        }

        /// <summary>
        /// 找到所有
        /// </summary>
        /// <param name="collection"></param>
        /// <returns></returns>
        public MongoDB.Driver.Linq.IMongoQueryable FindAll(IMongoCollection<BsonDocument> collection)
        {
            return collection.AsQueryable<BsonDocument>();
        }

        /// <summary>
        /// 找到一条
        /// </summary>
        /// <param name="collection"></param>
        /// <param name="filter"></param>
        /// <returns></returns>
        public IFindFluent<BsonDocument,BsonDocument> Find(IMongoCollection<BsonDocument> collection, FilterDefinition<BsonDocument> filter)
        {            
            return collection.Find(filter);
        }

        /// <summary>
        /// 找到并更新
        /// </summary>
        /// <param name="collection"></param>
        /// <param name="filter"></param>
        /// <param name="update"></param>
        /// <returns></returns>
        public BsonDocument FindOneAndUpdate(IMongoCollection<BsonDocument> collection, FilterDefinition<BsonDocument> filter,UpdateDefinition<BsonDocument> update)
        {
            return collection.FindOneAndUpdate(filter, update);
        }

        /// <summary>
        /// 找到并删除
        /// </summary>
        /// <param name="collection"></param>
        /// <param name="filter"></param>
        /// <returns></returns>
        public BsonDocument FindOneAndDelete(IMongoCollection<BsonDocument> collection, FilterDefinition<BsonDocument> filter)
        {
            return collection.FindOneAndDelete(filter);
        }
    }
}