//
//  DBManager.swift
//  Pazar-Backend
//
//  Created by Bilgehan IŞIKLI on 19/01/2018.
//

import PerfectMySQL
import Foundation
import PerfectThread
#if os(Linux)
import Glibc
#else
import Darwin
#endif

class DBManager {

    struct MySQLPoolItem {
        let mysql = MySQL()
        let lock = Threading.Lock()
        func connect()->Bool{
            return mysql.connect(host: Prefs.dbhost, user: Prefs.dbuser, password: Prefs.dbpass, db: Prefs.schema)
        }
    }

    var pool: [MySQLPoolItem] = []

    static let shared = DBManager()

    func preparePool() {

        var connectionCount = Prefs.connectionPoolCount

        while connectionCount > 0 {

            let item = MySQLPoolItem()
            _ = item.mysql.setOption(.MYSQL_SET_CHARSET_NAME, "utf8")
            let connected = item.connect()
            guard connected else {
                // verify we connected successfully
                print(item.mysql.errorMessage())
                return
            }
            print("Database connection \((connectionCount)) success");
            pool.append(item)
            connectionCount -= 1
        }

    }

    func getAvailableConnection() -> MySQLPoolItem {

        var item : MySQLPoolItem? = nil;

        while item == nil {
            item = tryAvailableConnection()
            if(item == nil){
                sleep(1)
            }
        }

        return item!
    }

    private func tryAvailableConnection() -> MySQLPoolItem? {

        for item in pool {

            if(item.lock.tryLock()){

                if(!item.mysql.ping()){
                    if(item.mysql.connect()){
                        return item
                    }
                }else{
                    return item
                }

            }

        }

        return nil

    }

    func runSync(query: String) -> ((result:Bool,items:MySQL.Results?)) {

        let poolItem = getAvailableConnection()

        defer {
            poolItem.lock.unlock()
        }

        let querySuccess = poolItem.mysql.query(statement: query)

        return (querySuccess,poolItem.mysql.storeResults())

    }




}