Seat Booking Program

#include <ctype.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

// IMPORTANT VARIABLES
const int MAX_COLUMNS = 12;
const int MAX_ROWS = 6;

// FUNCTION DECLARATIONS
bool check_empty_seat(int row, int column, bool (*seats)[MAX_COLUMNS]);
bool check_seat(int row, int column, bool (*seats)[MAX_COLUMNS]);
bool is_empty(bool (*seats)[MAX_COLUMNS]);
bool is_full(bool (*seats)[MAX_COLUMNS]);
int get_column(char *seat);
int get_row(char *seat);
void color_green();
void color_red();
void remove_newline(char *seat);
void show_seats(bool seats[MAX_ROWS][MAX_COLUMNS]);

// DRIVER CODE
int main() {

  bool seat_state[MAX_ROWS][MAX_COLUMNS];
  bool given_seat_status = false;
  bool main_loop = true;
  int row, column;
  char response[8];
  char choice; int num;

  // Initialize all seat's state to FALSE
  for(int i = 0; i < MAX_ROWS; i++) {
    for(int j = 0; j < MAX_COLUMNS; j++) {
      seat_state[i][j] = false;
    }
  }

  // MAIN LOOP
  while(main_loop) {
    system("clear");
    show_seats(seat_state);

    printf("\n");
    printf("\033[1;37m");


    printf("+-----+CUSTOM BOOKING SYSTEM+-----+\n\n");
    printf("[1] Fill-up Seats\n");
    printf("[2] Free-up Seats\n");
    printf("[0] Exit\n");
    printf(">>> ");
    scanf("%c", &choice);
    getchar();

    if(choice < '0' || choice > '9') {
      num = -1;
    } else {
      num = choice - '0';
    }

    switch (num) {
    case 0:
      main_loop = false;
      break;
    case 1:
      printf("\n+---------+FILL-UP SEATS+---------+\n");
      if(is_full(seat_state)) {
        printf("All seats are filled!!\n");
        printf("Press enter to continue...");
        getchar();
        break;
      }
      printf("Type \"EXIT\" to exit...\n");
      printf("Enter seat number: ");
      fgets(response, 8, stdin);
      remove_newline(response);
      if(strcmp(response, "EXIT") == 0) {
        main_loop = false;
        break;
      } else if(strlen(response) < 3 || strlen(response) > 3) {
        printf("Invalid seat number!!\n");
        printf("Press enter to continue...");
        getchar();
        continue;
      }
      row = get_row(response);
      column = get_column(response);
      if(row == -1 || column == -1) {
        printf("Invalid seat number!!\n");
      } else {
        given_seat_status = check_seat(row, column, seat_state);
        if(!given_seat_status) {
          printf("Given seat was already taken!!\n");
        } else {
          printf("Seat #%s successfully booked!!\n", response);
        }
      }
      printf("Press enter to continue...");
      getchar();
      break;
    case 2:
      printf("\n+---------+FREE-UP SEATS+---------+\n");
      if(is_empty(seat_state)) {
        printf("All seats are empty!!\n");
        printf("Press enter to continue...");
        getchar();
        break;
      }
      printf("Type \"EXIT\" to exit...\n");
      printf("Enter seat number: ");
      fgets(response, 8, stdin);
      remove_newline(response);
      if(strcmp(response, "EXIT") == 0) {
        main_loop = false;
        break;
      } else if(strlen(response) < 3 || strlen(response) > 3) {
        printf("Invalid seat number!!\n");
        printf("Press enter to continue...");
        getchar();
        continue;
      }
      row = get_row(response);
      column = get_column(response);
      if(row == -1 || column == -1) {
        printf("Invalid seat number!!\n");
      } else {
        given_seat_status = check_empty_seat(row, column, seat_state);
        if(!given_seat_status) {
          printf("Given seat was already empty!!\n");
        } else {
          printf("Seat #%s successfully freed!!\n", response);
        }
      }
      printf("Press enter to continue...");
      getchar();
      break;
    default:
      printf("Invalid choice!!\n");
      printf("Press enter to continue..");
      getchar();
      break;
    }
  }

  printf("\n+-----+CUSTOM BOOKING SYSTEM+-----+\n");
  return 0;

}

// FUNCTION DEFINITIONS
int get_column(char* seat) {
  // DEFINITION: Returns the integer-equivalent of the column part of the given seat

  // If the row part not a number, return -1
  if(seat[1] < '0' || seat[1] > '9') {
    return -1;
  } else if(seat[2] < '0' || seat[2] > '9') {
    return -1;
  }

  // Get the integer-equivalent of the column part of the given seat
  int res = (((seat[1] - '0') * 10) + (seat[2] - '0')) - 1;

  // If the integer-equivalent is greater than the maximum columns, we change "res" to -1
  if(res > MAX_COLUMNS - 1) {
    res = -1;
  }

  return res;
}

int get_row(char* seat) {
  // DEFINITION: Returns the integer-equivalent of the row part of the given seat

  // If the row part is not an alphabet, return -1;
  if(!isalpha(seat[0])) {
    return -1;
  }

  // Get the integer-equivalent of the row part of the given seat
  int res = toupper(seat[0]) - 'A';

  // If the integer-equivalent is greater than the maximum rows, we change "res" to -1
  if(res > MAX_ROWS - 1) {
    res = -1;
  }

  return res;
}

bool is_empty(bool (*seats)[MAX_COLUMNS]) {
  // DEFINITION: Returns true if all seats are empty
  for(int i = 0; i < MAX_ROWS; i++) {
    for(int j = 0; j < MAX_COLUMNS; j++) {
      if(seats[i][j]) {
        return false;
      }
    }
  }
  return true;
}

bool is_full(bool (*seats)[MAX_COLUMNS]) {
  // DEFINITION: Returns true if all seats are full
  for(int i = 0; i < MAX_ROWS; i++) {
    for(int j = 0; j < MAX_COLUMNS; j++) {
      if(!seats[i][j]) {
        return false;
      }
    }
  }
  return true;
}

bool check_empty_seat(int row, int column, bool(*seats)[MAX_COLUMNS]) {
  // DEFINITION: Checks if given seat is not empty, frees it, and returns true after freeing seat
  if(!seats[row][column]) {
    return false;
  }
  seats[row][column] = false;
  return true;
}

bool check_seat(int row, int column, bool (*seats)[MAX_COLUMNS]) {
  // DEFINITION: Checks if given seat is empty, fills it, and returns true after filling seat
  if(seats[row][column]) {
    return false;
  }
  seats[row][column] = true;
  return true;
}

void color_green() {
  // DEFINITION: Changes the text color to green
  printf("\033[1;32m");
}

void color_red() {
  // DEFINITION: Changes the text color to red
  printf("\033[1;31m");
}

void show_seats(bool seats[MAX_ROWS][MAX_COLUMNS]) {
  //DEFINITION: Shows all seat and their current booking status by colors
  for(int i = 0; i < MAX_ROWS; i++) {
    for(int j = 0; j < MAX_COLUMNS; j++) {
      if(seats[i][j]) {
        color_red();
      } else {
        color_green();
      }
      printf("%c", 'A' + i);
      if(j < 9) {
        printf("0%d  ", j + 1);
      } else {
        printf("%d  ", j + 1);
      }
    }
    printf("\n");
  }
}

void remove_newline(char *seat) {
  // DEFINITION: Removes the newline character from fgets function
  int i = 0;
  int len = strlen(seat);
  while(i < len) {
    if(seat[i] == '\n') {
      seat[i] = '\0';
      return;
    }
    i++;
  }
}