game_of_chance.c

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <time.h>
#include <stdlib.h>
#include "hacking.h"

#define DATAFILE "/var/chance.data" // File to store user data

// Custom user struct to store information about users
struct user {
   int uid;
   int credits;
   int highscore;
   char name[100];
   int (*current_game) ();
};

// function prototypes
int get_player_data();
void register_new_player();
void update_player_data();
void show_highscore();
void jackpot();
void input_name();
void print_cards(char *, char *, int);
int take_wager(int, int);
void play_the_game();
int pick_a_number();
int dealer_no_match();
int find_the_ace();
void fatal(char *);

// Global variables
struct user player;      // Player struct

int main() {
   int choice, last_game;

   srand(time(0)); // Seed the randomizer with the current time.
   
   if(get_player_data() == -1) // Try to read player data from file.
      register_new_player();    // If there is no data, register a new player.
   
   while(choice != 7) {
      printf("-=[ Game of Chance Menu ]=-\n");
      printf("1 - Play the Pick a Number game\n");
      printf("2 - Play the No Match Dealer game\n");
      printf("3 - Play the Find the Ace game\n");
      printf("4 - View current high score\n");
      printf("5 - Change your user name\n");
      printf("6 - Reset your account at 100 credits\n");
      printf("7 - Quit\n");
      printf("[Name: %s]\n", player.name);
      printf("[You have %u credits] ->  ", player.credits);
      scanf("%d", &choice);

      if((choice < 1) || (choice > 7))
         printf("\n[!!] The number %d is an invalid selection.\n\n", choice);
      else if (choice < 4) {  // Othewise, choice was a game of some sort.
            if(choice != last_game) { // If the function ptr isn't set
               if(choice == 1)        // then point it at the selected game 
                  player.current_game = pick_a_number;   
               else if(choice == 2)                     
                  player.current_game = dealer_no_match;
               else
                  player.current_game = find_the_ace;
               last_game = choice;   // and set last_game.
            }
            play_the_game();   // Play the game.
         }
      else if (choice == 4)
         show_highscore();
      else if (choice == 5) {
         printf("\nChange user name\n");
         printf("Enter your new name: ");
         input_name();
         printf("Your name has been changed.\n\n");
      }
      else if (choice == 6) {
         printf("\nYour account has been reset with 100 credits.\n\n");
         player.credits = 100;
      }
   }
   update_player_data();
   printf("\nThanks for playing! Bye.\n");
}

// This function reads the player data for the current uid
// from the file. It returns -1 if it is unable to find player
// data for the current uid.
int get_player_data() { 
   int fd, uid, read_bytes;
   struct user entry;

   uid = getuid();

   fd = open(DATAFILE, O_RDONLY);
   if(fd == -1) // Can't open the file, maybe it doesn't exist
      return -1; 
   read_bytes = read(fd, &entry, sizeof(struct user)); // Read the first chunk.
   while(entry.uid != uid && read_bytes > 0) {  // Loop until proper uid is found.
      read_bytes = read(fd, &entry, sizeof(struct user)); // Keep reading.
   }
   close(fd); // close the file
   if(read_bytes  < sizeof(struct user)) // This means that the end of file was reached.
      return -1;
   else
      player = entry; // Copy the read entry into the player struct.
   return 1; // Return a success.
}

// This is the new user registration function.
// It will create a new player account and append it to the file
void register_new_player()  { 
   int fd;

   printf("-=-={ New Player Registration }=-=-\n");
   printf("Enter your name: ");
   input_name();

   player.uid = getuid();
   player.highscore = player.credits = 100;

   fd = open(DATAFILE, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR);
   if(fd == -1)
      fatal("in register_new_player() while opening file");
   write(fd, &player, sizeof(struct user));
   close(fd);

   printf("\nWelcome to the Game of Chance %s.\n", player.name);
   printf("You have been given %u credits.\n", player.credits);
}

// This function writes the current player data to the file.
// It is used primarily for updating the credits after games.
void update_player_data() {
   int fd, i, read_uid;
   char burned_byte;

   fd = open(DATAFILE, O_RDWR);
   if(fd == -1) // If open fails here, something is really wrong.
      fatal("in update_player_data() while opening file");
   read(fd, &read_uid, 4);       // Read the uid from the first struct.
   while(read_uid != player.uid) {  // Loop until correct uid is found.
      for(i=0; i < sizeof(struct user) - 4; i++)  // Read through the
         read(fd, &burned_byte, 1);            // rest of that struct.
      read(fd, &read_uid, 4);     // Read the uid from the next struct. 
   }
   write(fd, &(player.credits), 4);   // Update credits.
   write(fd, &(player.highscore), 4); // Update highscore.
   write(fd, &(player.name), 100);    // Update name.
   close(fd);
}

// This function will display the current high score and
// the name of the person who set that high score.
void show_highscore() {
   unsigned int top_score = 0;
   char top_name[100];
   struct user entry;
   int fd;

   printf("\n====================| HIGH SCORE |====================\n");
   fd = open(DATAFILE, O_RDONLY);
   if(fd == -1)
      fatal("in show_highscore() while opening file");
   while(read(fd, &entry, sizeof(struct user)) > 0) { // Loop until end of file.
      if(entry.highscore > top_score) {   // If there is a higher score,
            top_score = entry.highscore;  // set top_score to that score
            strcpy(top_name, entry.name); // and top_name to that username.
         }
   }
   close(fd);
   if(top_score > player.highscore)
      printf("%s has the high score of %u\n", top_name, top_score);
   else
      printf("You currently have the high score of %u credits!\n", player.highscore);
   printf("======================================================\n\n");
}

// This function simply awards the jackpot for the Pick a Number game
void jackpot() {
   printf("*+*+*+*+*+* JACKPOT *+*+*+*+*+*\n");
   printf("You have won the jackpot of 100 credits!\n");
   player.credits += 100;
}

// This function is used to input the player name, since 
// scanf("%s", &whatever) will stop input at the first space.
void input_name() {
   char *name_ptr, input_char='\n';
   while(input_char == '\n')    // Flush any leftover 
      scanf("%c", &input_char); // newline chars.
   
   name_ptr = (char *) &(player.name); // name_ptr = player name's address
   while(input_char != '\n') {  // Loop until newline.
      *name_ptr = input_char;   // Put the input char into name field.
      scanf("%c", &input_char); // Get the next char.
      name_ptr++;               // Increment the name pointer.
   }
   *name_ptr = 0;  // Terminate the string.
}

// This function prints the 3 cards for the Find the Ace game.
// It expects a message to display, a pointer to the cards array,
// and the card the user has picked as input. If the user_pick is
// -1, then the selection numbers are displayed.
void print_cards(char *message, char *cards, int user_pick) {
   int i;

   printf("\n\t*** %s ***\n", message);
   printf("      \t._.\t._.\t._.\n");
   printf("Cards:\t|%c|\t|%c|\t|%c|\n\t", cards[0], cards[1], cards[2]);
   if(user_pick == -1)
      printf(" 1 \t 2 \t 3\n");
   else {
      for(i=0; i < user_pick; i++)
         printf("\t");
      printf(" ^-- your pick\n");
   }
}

// This function inputs wagers for both the No Match Dealer and
// Find the Ace games. It expects the available credits and the
// previous wager as arguments. The previous_wager is only important
// for the second wager in the Find the Ace game. The function
// returns -1 if the wager is too big or too little, and it returns
// the wager amount otherwise.
int take_wager(int available_credits, int previous_wager) {
   int wager, total_wager;

   printf("How many of your %d credits would you like to wager?  ", available_credits);
   scanf("%d", &wager);
   if(wager < 1) {   // Make sure the wager is greater than 0.
      printf("Nice try, but you must wager a positive number!\n");
      return -1;
   }
   total_wager = previous_wager + wager;
   if(total_wager > available_credits) {  // Confirm available credits
      printf("Your total wager of %d is more than you have!\n", total_wager);
      printf("You only have %d available credits, try again.\n", available_credits);
      return -1;
   }
   return wager;
}

// This function contains a loop to allow the current game to be
// played again. It also writes the new credit totals to file
// after each game is played.
void play_the_game() { 
   int play_again = 1;
   int (*game) ();
   char selection;

   while(play_again) {
      printf("\n[DEBUG] current_game pointer @ 0x%08x\n", player.current_game);
      if(player.current_game() != -1) { // If the game plays without error and
         if(player.credits > player.highscore)  // a new high score is set,
            player.highscore = player.credits;  // update the highscore.
         printf("\nYou now have %u credits\n", player.credits);
         update_player_data(); // Write the new credit total to file.
         printf("Would you like to play again? (y/n)  ");
         selection = '\n';
         while(selection == '\n')   // Flush any extra newlines.
            scanf("%c", &selection);
         if(selection == 'n')
            play_again = 0;
      }
      else  // This means the game returned an error,
         play_again = 0; // so return to main menu.
   }
}

// This function is the Pick a Number game.
// It returns -1 if the player doesn't have enough credits.
int pick_a_number() { 
   int pick, winning_number;

   printf("\n####### Pick a Number ######\n");
   printf("This game costs 10 credits to play. Simply pick a number\n");
   printf("between 1 and 20, and if you pick the winning number, you\n");
   printf("will win the jackpot of 100 credits!\n\n");
   winning_number = (rand() % 20) + 1; // Pick a number between 1 and 20.
   if(player.credits < 10) {
      printf("You only have %d credits. That's not enough to play!\n\n", player.credits);
      return -1;  // Not enough credits to play 
   }
   player.credits -= 10; // Deduct 10 credits
   printf("10 credits have been deducted from your account.\n");
   printf("Pick a number between 1 and 20: ");
   scanf("%d", &pick);

   printf("The winning number is %d\n", winning_number);
   if(pick == winning_number)
      jackpot();
   else
      printf("Sorry, you didn't win.\n");
   return 0;
}

// This is the No Match Dealer game.
// It returns -1 if the player has 0 credits.
int dealer_no_match() { 
   int i, j, numbers[16], wager = -1, match = -1;

   printf("\n::::::: No Match Dealer :::::::\n");
   printf("In this game, you can wager up to all of your credits.\n");
   printf("The dealer will deal out 16 random numbers between 0 and 99.\n");
   printf("If there are no matches among them, you double your money!\n\n");
  
   if(player.credits == 0) {
      printf("You don't have any credits to wager!\n\n");
      return -1;
   }
   while(wager == -1)
      wager = take_wager(player.credits, 0);

   printf("\t\t::: Dealing out 16 random numbers :::\n");
   for(i=0; i < 16; i++) {
      numbers[i] = rand() % 100; // pick a number 0 to 99
      printf("%2d\t", numbers[i]);
      if(i%8 == 7)  // Print a line break every 8 numbers.
         printf("\n");
   }
   for(i=0; i < 15; i++) {  // Loop looking for matches
      j = i + 1;
      while(j < 16) {
         if(numbers[i] == numbers[j])
            match = numbers[i];
         j++;
      }
   }
   if(match != -1) {
      printf("The dealer matched the number %d!\n", match);
      printf("You lose %d credits.\n", wager);
      player.credits -= wager;
   } else {
      printf("There were no matches! You win %d credits!\n", wager);
      player.credits += wager;
   }
   return 0;
}

// This is the Find the Ace game.
// It returns -1 if the player has 0 credits.
int find_the_ace() {
   int i, ace, total_wager;
   int invalid_choice, pick = -1, wager_one = -1, wager_two = -1;
   char choice_two, cards[3] = {'X', 'X', 'X'};

   ace = rand()%3; // Place the ace randomly.

   printf("******* Find the Ace *******\n");
   printf("In this game, you can wager up to all of your credits.\n");
   printf("Three cards will be dealt out, two queens and one ace.\n");
   printf("If you find the ace, you will win your wager.\n");
   printf("After choosing a card, one of the queens will be revealed.\n");
   printf("At this point, you may either select a different card or\n");
   printf("increase your wager.\n\n");

   if(player.credits == 0) {
      printf("You don't have any credits to wager!\n\n");
      return -1;
   }
   
   while(wager_one == -1) // Loop until valid wager is made.
      wager_one = take_wager(player.credits, 0);

   print_cards("Dealing cards", cards, -1);
   pick = -1;
   while((pick < 1) || (pick > 3)) { // Loop until valid pick is made.
      printf("Select a card: 1, 2, or 3  ");
      scanf("%d", &pick);
   }
   pick--; // Adjust the pick since card numbering starts at 0.
   i=0;
   while(i == ace || i == pick) // Keep looping until 
      i++;                      // we find a valid queen to reveal.
   cards[i] = 'Q';
   print_cards("Revealing a queen", cards, pick);
   invalid_choice = 1;
   while(invalid_choice) {   // Loop until valid choice is made.
      printf("Would you like to:\n[c]hange your pick\tor\t[i]ncrease your wager?\n");
      printf("Select c or i:  ");
      choice_two = '\n';
      while(choice_two == '\n') // Flush extra newlines.
         scanf("%c", &choice_two);
      if(choice_two == 'i') {   // Increase wager.
            invalid_choice=0;   // This is a valid choice.
            while(wager_two == -1)  // Loop until valid second wager is made.
               wager_two = take_wager(player.credits, wager_one);
         }
      if(choice_two == 'c') {    // Change pick.
         i = invalid_choice = 0; // Valid choice
         while(i == pick || cards[i] == 'Q') // Loop until the other card
            i++;// is found,
         pick = i;// and then swap pick.
         printf("Your card pick has been changed to card %d\n", pick+1);
      }
   }

   for(i=0; i < 3; i++) {  // Reveal all of the cards.
      if(ace == i)
         cards[i] = 'A';
      else
         cards[i] = 'Q';
   }
   print_cards("End result", cards, pick);
   
   if(pick == ace) {  // handle win
      printf("You have won %d credits from your first wager\n", wager_one);
      player.credits += wager_one;
      if(wager_two != -1) {
         printf("and an additional %d credits from your second wager!\n", wager_two);
         player.credits += wager_two;
      }
   } else { // handle loss
      printf("You have lost %d credits from your first wager\n", wager_one);
      player.credits -= wager_one;
      if(wager_two != -1) {
         printf("and an additional %d credits from your second wager!\n", wager_two);
         player.credits -= wager_two;
      }
   }
   return 0;
}