#include <stdio.h>
#define yes 1
#define no 0

void menu(int);
void ExChoice(char);
void PrintAssigned();
void PrintEmpty();
void AssignSeat();
void SetIDs();
void RemoveSeat();
void ReadData(FILE *);
void WriteData();

struct seat{
            char seatID[2];
            int assigned;
            char surname[20];
            char firstname[20];
            };

struct seat seats[12];

int main()
{
    FILE *seatassignments;
    if((seatassignments = fopen("seats.txt", "r"))==NULL){
                printf("No current data detected.\n\n");
                SetIDs();
                }
                else{ReadData(seatassignments);}


    menu(0);


    return 0;
}

void SetIDs(){
              int x=0,y=48;

              for(x=0;x<12;x++){
                                y++;
                                seats[x].seatID[0] = y;
                                seats[x].seatID[1] = 'a';
                                x++;
                                seats[x].seatID[0] = y;
                                seats[x].seatID[1] = 'b';
                                }
}

void ReadData(FILE *seatassignments){

     int i=0,size=0;

     for(i=0;i<12;i++){
                       fgets(seats[i].seatID, 3, seatassignments);
                       fscanf(seatassignments, "%d", &seats[i].assigned);
                       fgets(seats[i].surname, 21, seatassignments);
                       fgets(seats[i].firstname, 21, seatassignments);
                       if (seats[i].surname != NULL) {
                          size = (strlen(seats[i].surname) - 1);
                          if (seats[i].surname[size] == '\n') seats[i].surname[size] = '\0';
                          }
                       if (seats[i].firstname != NULL) {
                          size = (strlen(seats[i].firstname) - 1);
                          if (seats[i].firstname[size] == '\n') seats[i].firstname[size] = '\0';
                          }
     }

     if(fclose(seatassignments) != 0){
                                printf("Error Closing Data File");
                                }

}

void menu(int call){

     char choice;

     printf("Mersey Airlines Booking System\n");
     printf("**************************************************");
     printf("\n\na) Show assigned seats with passenger names\n");
     printf("b) Show list of empty seats\n");
     printf("c) Assign A customer to a seat\n");
     printf("d) Delete a seat assignment\n");

     if(call == 0){
                   printf("e) Quit\n");
                   }
                   else{printf("\n");}
     printf("**************************************************");
     printf("\n");
     fflush(stdin);
     printf("Enter choice:  ");
     choice = getchar();

     if(choice == 'e' && call == 1){
                                    printf("\n\nInvalid choice, menu feature not available at the present time\n\n");
                                    system("pause");
                                    menu(1);
                                    }
     ExChoice(choice);
     return;
}

void ExChoice(char choice){

     switch(choice){

     case 'a':PrintAssigned();
              break;
     case 'b':PrintEmpty();
              break;
     case 'c':AssignSeat();
              break;
     case 'd':RemoveSeat();
              break;
     case 'e':exit(1);
              break;
     default: printf("Incorrect menu choice\n");
              system("pause");
              system("cls");
              menu(0);
              break;
              }
}

void PrintAssigned(){

     int i=0;
     int AnyAssigned=no;

     printf("\nAssigned Seats:\n---------------\n\n");

     for(i=0;i<12;i++){
                       if(seats[i].assigned == yes)
                              {
                              printf("   Seat ID: %s\nFirst Name: %s\n Last Name: %s\n\n", seats[i].seatID,seats[i].firstname,seats[i].surname);
                              AnyAssigned = yes;
                              }
                       }
      if(AnyAssigned == no){
                     printf("\n\nThere are currently no assigned Seats\n\n");
                     }
      system("pause");
      system("cls");
      menu(1);

}

void PrintEmpty(){

     int i=0;
     int AnyEmpty = no;

     printf("\nEmpty Seats:\n-------------\n\n");

     for(i=0;i<12;i++){
                       if(seats[i].assigned == no)
                              {
                              printf("Seat ID: %s\n", seats[i].seatID);
                              AnyEmpty = yes;
                              }
                       }
       if(AnyEmpty == no){
                     printf("\n\nThere are currently no Empty Seats\n\n");
                     }

      system("pause");
      system("cls");
      menu(1);

}

void AssignSeat(){

     char TempSeatID[2];
     int i=0;

     printf("\nPlease enter the seat ID you wish to assign a passenger to \n(type M to return to menu):\n\n");
     scanf("%s",&TempSeatID);

     if(TempSeatID[0] == 'M'){
                   system("cls");
                   menu(1);
                   }

     for(i=0;i<12;i++){
                       if(seats[i].seatID[0] == TempSeatID[0] && seats[i].seatID[1] == TempSeatID[1])
                                          {
                                         printf("Seat Found\n\n");
                                         break;
                                          }
                       if(i==11){
                                 printf("\n\nSeat Not on Record\n\n");
                                 AssignSeat();
                                 }

     }

     if(seats[i].assigned == yes)
                          {
                           printf("\n\nSorry but this seat Number is already assigned, please make another choice\n\n");
                           AssignSeat();
                           }
     printf("Please Enter the customers Surname:  ");
     scanf("%s",&seats[i].surname);
     printf("\n\nPlease Enter the customers First Name:  ");
     scanf("%s",&seats[i].firstname);
     seats[i].assigned = yes;
     printf("\n\nThank you, Seat %s Assigned to %s %s\n\n", seats[i].seatID,seats[i].firstname,seats[i].surname);
     system("pause");
     system("cls");
     WriteData();
     menu(1);
}

void RemoveSeat(){

     char TempSeatID[2];
     int i=0;
     char sure;
     printf("Please Enter the Seat ID for which you wish to clear data:  ");
     scanf("%s",&TempSeatID);

   for(i=0;i<12;i++){
                       if(seats[i].seatID[0] == TempSeatID[0] && seats[i].seatID[1] == TempSeatID[1])
                                          {
                                         printf("Seat Found\n\n");
                                         break;
                                          }
                       if(i==11){
                                 printf("\n\nSeat Not on Record\n\n");
                                 RemoveSeat();
                                 }

     }
     if(seats[i].assigned == no){
                          printf("This seat is not currently assigned\n\n");
                          system("pause");
                          system("cls");
                          menu(1);
                          }
     printf("\n\nAre you sure you wish to remove the following data:\n\nSeat %s Assigned to %s %s\n\n", seats[i].seatID,seats[i].firstname,seats[i].surname);
     printf("Enter Y for yes and N for No:  ");
     fflush(stdin);
     scanf("%c",&sure);
     if(sure=='Y'){
                 seats[i].assigned = no;
                 printf("Seat Cleared, Thank you\n\n");
                 }
     system("pause");
     system("cls");
     WriteData();
     menu(1);

}

void WriteData(){

     int i=0;

     FILE *WriteSeatAssignments;
     if((WriteSeatAssignments = fopen("seats.txt", "w+"))==NULL)
             {
             printf("Error Creating Data File");
             menu(1);
             }

             for(i=0;i<12;i++)
                              {
                               fputs(seats[i].seatID,WriteSeatAssignments);
                               fprintf(WriteSeatAssignments, "%d", seats[i].assigned);
                               fputs(seats[i].surname,WriteSeatAssignments);
                               fprintf(WriteSeatAssignments,"\n");
                               fputs(seats[i].firstname,WriteSeatAssignments);
                               fprintf(WriteSeatAssignments,"\n");
                               }
              if(fclose(WriteSeatAssignments)!=0){
                                                  printf("Error closing File");
                                                  }

}