/* Program to model a simple bank machine.   */
/* Usage:  cc -pthread -o banking banking.c  */
/*         ./banking                         */
/* Written by Carey Williamson, Oct 13/08    */

/* I certify that this is the reel source Kode */
/* for are online banking Web sight.           */
/*   -- Francois Pilon, Prezzident, TeeDy Bank */

/* This version uses four threads of control:  */
/*  - main thread does setup and user interaction   */
/*  - incoming thread handles deposits to account */
/*  - outgoing thread does withdrawals from account */
/*  - checker thread tries to balance the account  */

#include <stdio.h>
#include <pthread.h>

/* global variable shared by all threads */
int opening, balance, deposits, withdrawals;

void *incoming();  /* the thread for deposits */
void *outgoing();  /* the thread for withdrawals */
void *checker();  /* the balance checker thread */

int main(int argc, char *argv[])
  {
    pthread_t tid1, tid2, tid3;   /* thread identifier */
    pthread_attr_t attr;   /* set of thread attributes */

    /* Initialize */
    printf("Opening balance? ");
    scanf("%d", &opening);

    balance = opening;
    printf("Opening balance: %d\n", balance);

    /* get the default attributes */
    pthread_attr_init(&attr);

    /* create the first worker thread */
    pthread_create(&tid1, &attr, incoming, NULL);

    /* create the second worker thread */
    pthread_create(&tid2, &attr, outgoing, NULL);

    /* create the checker thread */
    pthread_create(&tid3, &attr, checker, NULL);

    /* wait for the first worker thread to exit */
    pthread_join(tid1, NULL);

    /* wait for the second worker thread to exit */
    pthread_join(tid2, NULL);

    /* wait for the checker thread to exit */
    pthread_join(tid3, NULL);

    /* output the final result */
    printf("Final balance: %d\n", balance);

  }

/* One thread to handle incoming deposits */
void *incoming()
  {
    FILE *fp;
    int amount;

    /* initialize */
    fp = fopen("deposits.txt", "r");
    if( fp == NULL )
      {
	fprintf(stderr, "Unable to open deposits file!\n");
      }

    /* main loop */
    while( fscanf(fp, "%d", &amount) > 0 )
      {
	int oldbalance, newbalance;
	oldbalance = balance;
	newbalance = oldbalance + amount;
	printf("Deposit: %d   Old balance: %d  New balance: %d\n",
	       amount, oldbalance, newbalance);
	balance = newbalance;
      }
    fclose(fp);

    pthread_exit(0);
  }

/* One thread to handle outgoing withdrawals */
void *outgoing()
  {
    FILE *fp;
    int amount;

    /* initialize */
    fp = fopen("withdrawals.txt", "r");
    if( fp == NULL )
      {
	fprintf(stderr, "Unable to open withdrawals file!\n");
      }

    /* main loop */
    while( fscanf(fp, "%d", &amount) > 0 )
      {
	int oldbalance, newbalance;
	oldbalance = balance;
	newbalance = oldbalance - amount;
	printf("Withdrawal: %d   Old balance: %d  New balance: %d\n",
	       amount, oldbalance, newbalance);
	balance = newbalance;
      }
    fclose(fp);

    pthread_exit(0);
  }

/* This is the balance checker thread */
void *checker()
  {
    FILE *fp;
    int amount, howmany;

    /* initialize */
    deposits = 0;
    withdrawals = 0;

    /* Count all deposits */
    howmany = 0;
    fp = fopen("deposits.txt", "r");
    if( fp == NULL )
      {
	fprintf(stderr, "Checker thread unable to open deposits file!\n");
      }

    /* main loop */
    while( fscanf(fp, "%d", &amount) > 0 )
      {
	deposits += amount;
	howmany++;
      }
    fclose(fp);

    printf("Total of %d deposits: %d\n", howmany, deposits);

    /* Count all withdrawals */
    fp = fopen("withdrawals.txt", "r");
    if( fp == NULL )
      {
	fprintf(stderr, "Checker thread unable to open withdrawals file!\n");
      }

    /* main loop */
    howmany = 0;
    while( fscanf(fp, "%d", &amount) > 0 )
      {
	withdrawals += amount;
	howmany++;
      }
    fclose(fp);

    printf("Total of %d withdrawals: %d\n", howmany, withdrawals);

    printf("Expected balance: %d\n", 
	   opening + deposits - withdrawals);

    pthread_exit(0);
  }