using System;
using System.Collections.Generic;
using System.Text;
using Npgsql;
using System.Data;
using System.Threading;

namespace SafeMobileLib
{
    public class DBmanager
    {
                    
        public NpgsqlConnection cn;
        private string p_server;
        private string p_dbname;
        private string p_user;
        private string p_password;
        private string p_port;
        String MyConString = "";
        public static int countConn = 0;

        public DBmanager(string p_server, string p_dbname, string p_user, string p_password, string p_port)
        {
            this.p_server = p_server;
            this.p_dbname = p_dbname;
            this.p_user = p_user;
            this.p_password = p_password;
            this.p_port = p_port;
            MyConString = getConnectionString();
        }

        public void InitConnection()
        {
            
            cn = new NpgsqlConnection();
            cn.ConnectionString = getConnectionString(); 

            try
            {
                cn.Open();
                
                Interlocked.Increment(ref countConn);   //countConn = countConn + 1;

                Utils.WriteLine($"Open a new connection. Active connections : {countConn}", ConsoleColor.DarkGreen);
                if (countConn > 280)
                    Utils.WriteLine($"Max limit of active connections is abount to be reached: {countConn}/300", ConsoleColor.Red);
            }
            catch (Exception o)
            {
                if (cn != null)
                {
                    cn.Close();
                }
                if (o.ToString().Contains("The connection pool has been exhausted"))
                {
                    NpgsqlConnection.ClearAllPools();
                    countConn = 0;
                }
            }
        }

        
        public sqlResponse RunCommand(string command)
        {
            
            sqlResponse toReturn = sqlResponse.done;

            try
            {
                using (NpgsqlConnection connection = new NpgsqlConnection())
                {

                    connection.ConnectionString = getConnectionString();
                    connection.Open();


                    using (NpgsqlCommand cmd = new NpgsqlCommand(command, connection))
                    {
                        cmd.ExecuteNonQuery();
                    }
                }
            }
            catch (Exception ee)
            {
                Console.WriteLine(ee.Message + " " + ee.StackTrace + " " + ee.Source, ConsoleColor.Red);
                toReturn = sqlResponse.SQLerror;
            }
            
            return toReturn;
        }

        public int GetInt32Result(string command)
        {
            string result = GetStringResult(command);
            if (result == string.Empty)
                return -1;

            return Int32.Parse(result);
        }


        public string GetStringResult(string command)
        {
            string result = string.Empty;

            try
            {
                using (NpgsqlConnection connection = new NpgsqlConnection())
                {

                    connection.ConnectionString = getConnectionString();
                    connection.Open();


                    using (NpgsqlCommand cmd = new NpgsqlCommand(command, connection))
                    {
                        using (NpgsqlDataReader reader = cmd.ExecuteReader())
                        {
                            reader.Read();
                            result = reader.GetValue(0).ToString();
                        }
                    }
                }

            }
            catch (Exception ee)
            {
                if(!ee.ToString().Contains("No row is available"))
                    Console.WriteLine(ee.ToString(), ConsoleColor.Red);
            }
            
            return result;
        }

        public int CommandTimeout = 60;


        public String getConnectionString()
        {
            return String.Format("Server={0};Port={1};" +
                    "User Id={2};Password={3};Database={4};Pooling=true;MinPoolSize=30;MaxPoolSize=300;Timeout=15;CommandTimeout={5};",
                        p_server, p_port, p_user, p_password, p_dbname, CommandTimeout);
            
        }

        public void InitConnectionHistoryReport()
        {
            
            cn = new NpgsqlConnection();
            cn.ConnectionString = getConnectionString();
            try
            {
                if (cn != null && cn.State == System.Data.ConnectionState.Closed)
                    cn.Open();
            }
            catch (Exception o)
            {
                if (cn != null)
                {
                    cn.Close();
                }
                throw new ArgumentException(o.Message.ToString());
            }
        }
        
        public void CloseConnection()
        {
            try
            {
                if (cn != null)
                {
                    cn.Close();

                    Interlocked.Decrement(ref countConn);     //countConn = countConn - 1;
                    if (countConn > 280)
                    {
                        Utils.WriteLine("CLOSED : " + countConn, ConsoleColor.Blue);
                        NpgsqlConnection.ClearAllPools();
                        countConn = 0;
                    }
                }

                
            }
            catch(Exception ex)
            {
                Utils.WriteLine(ex.ToString(), ConsoleColor.Magenta);
            }
            
        }
        
    }

    public enum sqlResponse
    {
        done,
        SQLerror,
        noUpdate
    }
}