package Threads

import java.util.*
import java.util.concurrent.locks.Lock
import java.util.concurrent.locks.ReentrantLock

fun main() {

    val deadlock = DeadlockOrnek()

    val t1 = Thread(Runnable { deadlock.thread1Fonk() })
    val t2 = Thread(Runnable { deadlock.thread2Fonk() })

    t1.start()
    t2.start()

    t1.join()
    t2.join()

    deadlock.threadOver()
}

class Hesap {
    var bakiye = 10000


    fun paraCek(miktar: Int) {
        bakiye -= miktar
    }

    fun paraYatir(miktar: Int) {
        bakiye += miktar
    }

    companion object {
        fun paraTransferi(h1: Hesap, h2: Hesap, miktar: Int) {
            h1.paraCek(miktar)
            h2.paraYatir(miktar)
        }
    }
}

class DeadlockOrnek {
    val h1 = Hesap()
    val h2 = Hesap()
    val rand = Random()

    val LOCK1 = ReentrantLock()
    val LOCK2 = ReentrantLock()

    fun thread1Fonk() {
        // LOCK1.lock() // ilk anahtarı t1 aldı
        // LOCK2.lock() // ikinci anahtarı t2 aldı ise deadlock oluşur (ikisi de birbirini bekler, ilerleyemez)

        lockCheck(LOCK1, LOCK2)

        for (i in 1..5000) {
            Hesap.paraTransferi(h1, h2, rand.nextInt(100))
        }

        LOCK1.unlock()
        LOCK2.unlock()
    }

    fun thread2Fonk() {
        // LOCK2.lock()
        // LOCK1.lock()

        lockCheck(LOCK2, LOCK1)

        for (i in 1..5000) {
            Hesap.paraTransferi(h2, h1, rand.nextInt(100))
        }

        LOCK2.unlock()
        LOCK1.unlock()
    }

    fun lockCheck(lock1: Lock, lock2: Lock) {
        var lock1EldeEdildi = false
        var lock2EldeEdildi = false

        while (true) {
            lock1EldeEdildi = lock1.tryLock()
            lock2EldeEdildi = lock2.tryLock()

            if (lock1EldeEdildi && lock2EldeEdildi)
                return

            if (lock1EldeEdildi)
                lock1.unlock()

            if (lock2EldeEdildi)
                lock2.unlock()
        }
    }

    fun threadOver() {
        println("H1 Bakiye: ${h1.bakiye}\nH2 Bakiye: ${h2.bakiye}\nToplam Bakiye: ${h1.bakiye + h2.bakiye}")
    }
}