/* ------- Booklist Program -----------------------------------
** Purpose: Illustrates simple file access using standard C.
**          Program inserts, updates, deletes, sorts/searches
**          book records. (elements: book code, title, author, status)
**          
** Copyright Notice: None. This code is intended for instructional
**                   purposes only. 
**
** ditallop@sprynet.com  5/2/93 
**
** ------------------------------------------------------------
*/
#include <stdio.h>
#include <string.h>
#include <conio.h>       
#define MAX_BOOKS 2000   /* number of books that can be stored in the library */

 struct book_rec         /* structure tag book_rec with 3 members */
 {
    char book_code[30];
    char title[30];
    char author[30];
    char status[30];
 };
 typedef struct book_rec BOOK;   /* defines a new type name BOOK as a synonym for type struct book_rec */

 /* function prototypes */
 void initialize_book_database(BOOK []);
 int menu(void);
 void add_a_book(BOOK bk_database[]);
 void delete_a_book( BOOK []);
 void update_a_book(BOOK []);
 void display_book_details(BOOK *);
 void Search_by_code(BOOK []);
 void Search_by_title(BOOK []);
 void summary_information(BOOK []);
 void all_books_sort(BOOK []);
 void all_on_loan_sort(BOOK []);
 void all_not_loan_sort(BOOK []);
 void bubble_sort(BOOK []);
 int sub_menu (void);
 void books_search(BOOK [],char*);

 /*
  function name  : main
  arguments      : none
  returns        : nothing
  purpose        : controls the overall program
 */

 void main()
 {
    BOOK book_database[MAX_BOOKS];
	int menu_choice;

	initialize_book_database(book_database);      /* clears library database */
    while(  (menu_choice = menu()) != 0 ){        /* main menu */
          bubble_sort(book_database);             /* sorts the books alphabetically by title */
		  switch ( menu_choice )
		        {
			       case 1 :
					       add_a_book(book_database);       /* adds a book to the database */
						   break;
                   case 2 :
						   delete_a_book(book_database);      /* removes a book from the database*/
						   break;
		           case 3 :
						   update_a_book(book_database);      /* changes book details */
						   break;
                   case 4 :
   				    	   Search_by_code(book_database);     /* search the database for a book by code */
		      			   break;
                   case 5 :
   				    	   Search_by_title(book_database);    /* search the database for a book by title */
		      			   break;
                   case 6 :
                           all_on_loan_sort(book_database);   /* search the database for all books on loan */
		      			   break;
                   case 7 :
						   summary_information(book_database); /* displays a summary information */
						   break;
                   default :
                           printf("\n INVALID CHOICE ENTERED");
                           break;
		        }
         }
 }

 /*
  function name  : initialize_book_database
  arguments      : book_dbase[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : clears the library database by storing an empty string for all
                   members of each structure
 */

 void initialize_book_database( BOOK book_dbase[] )
 {
    int i;

	for ( i = 0; i < MAX_BOOKS; i++ ){
	     strcpy( book_dbase[i].book_code , "");    /* set all the details of a book to empty strings */
         strcpy( book_dbase[i].title , "");
         strcpy( book_dbase[i].author , "");
         strcpy( book_dbase[i].status , "");
         }
 }

 /*
  function name  : menu
  arguments      : none
  returns        : choice - an integer value corresponding to the user choice
  purpose        : displays the main menu and gets the choice made
 */

 int menu(void)
 {
    int choice = 10;

    printf("\n       ************************************");
    printf("\n       WELCOME TO THE LIBRARY DATABASE MENU");
    printf("\n       ************************************");
	printf("\n\n 1. Add a Book\n");
	printf(" 2. Delete a Book\n");
	printf(" 3. update a Book\n");
    printf(" 4. Search a book by code\n");
	printf(" 5. Search a book by title\n");
    printf(" 6. Search a book by status(on loan or not)\n");
    printf(" 7. display summary\n");
	printf(" 0. Quit\n");
    printf("\n Enter choice(integer value 0 - 7):");
    scanf("%d",&choice);
    fflush(stdin);

    return choice;
 }

 /*
  function name  : add_a_book
  arguments      : bk_database[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : adds book details to the library database
 */

 void add_a_book(BOOK bk_database[])
 {
	int i = 0;
    char book_code[30],storage_string1[30],storage_string2[30];

    while ( strcmp( bk_database[i].book_code,"" )!= 0 && i < MAX_BOOKS )  /* check if there are empty spaces in the database */
	       i++;

	if ( i == MAX_BOOKS )
	    printf("\n Sorry, the database is full\n");
	else{
        printf("\n Please enter Book Code(Maximum 30 characters): ");
        gets( storage_string1);
        fflush(stdin);

        if( strcmp( storage_string1,"" ) == 0 )
             printf("\n INVALID ENTRY");
        else{
	         printf( "\n Please enter Book Title(Maximum 30 characters): ");
	         gets(storage_string2);
             fflush(stdin);
             if ( strcmp( storage_string2,"" ) == 0 )
                  printf("\n INVALID ENTRY");
             else{
                   strcpy(bk_database[i].book_code,storage_string1);
                   strcpy(bk_database[i].title,storage_string2);
	               printf( "\n Please enter Book Author(Maximum 30 characters): ");
	               gets(bk_database[i].author);
                   fflush(stdin);
                   strcpy(bk_database[i].status,"available");
                   fflush(stdin);
                   printf( "\n The book has been added to the library database");
                  }
           }
	   }
 }

 /*
  function name  : delete_a_book
  arguments      : book_dtb[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : deleates book details from the library database
 */

 void delete_a_book( BOOK book_dtb[])
 {
    int i = 0;
    char storage_string[30];

    printf("\n Please enter book code(Maximum 30 characters): ");
    gets(storage_string);
    if( strcmp( storage_string,"" ) == 0 )
          printf("\n INVALID ENTRY");
    else{
          while ( strcmp( book_dtb[i].book_code,storage_string)!= 0 && i < MAX_BOOKS )  /* look for the entered book code */
	             i++;

          if ( i == MAX_BOOKS )
	             printf("\n Sorry, the book is not in the database\n");
          else{
                 strcpy( book_dtb[i].book_code , "");
                 strcpy( book_dtb[i].title , "");
                 strcpy( book_dtb[i].author , "");
                 strcpy( book_dtb[i].status , "");
                 printf("\n The book has been deleted from the Database");
              }
       }
 }

 /*
  function name  : update_a_book
  arguments      : book_dtbase[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : changes the status of a book in the library database
 */

 void update_a_book(BOOK book_dtbase[])
 {
    int i = 0;
    char storage_string1[30],storage_string2[30];

    printf("\n Please enter book code(Maximum 30 characters): ");
    gets(storage_string1);

    if( strcmp( storage_string1,"" ) == 0 )
         printf("\n INVALID ENTRY");
    else{

         while ( strcmp( book_dtbase[i].book_code,storage_string1)!= 0 && i < MAX_BOOKS )
	           i++;

         if ( i == MAX_BOOKS )
	           printf("\n Sorry, the the book is not in the database\n");
         else{
               printf("\n The book you have chosen is:");
               display_book_details( &book_dtbase[i]);
               printf("\n Please enter new Book Code(Maximum 30 characters): ");
               gets( storage_string1);
               fflush(stdin);

              if( strcmp( storage_string1,"" ) == 0 )
                  printf("\n INVALID ENTRY");
              else{
	              printf( "\n Please enter new Book Title(Maximum 30 characters): ");
	              gets(storage_string2);
                  fflush(stdin);
                  if ( strcmp( storage_string2,"" ) == 0 )
                       printf("\n INVALID ENTRY");
                  else{
                       strcpy(book_dtbase[i].book_code,storage_string1);
                       strcpy(book_dtbase[i].title,storage_string2);
	                   printf( "\n Please enter new Book Author(Maximum 30 characters): ");
	                   gets(book_dtbase[i].author);
                       fflush(stdin);
                       do{
	                       printf( "\n Enter new Status (available or on loan): ");
                           gets(book_dtbase[i].status);
                           fflush(stdin);
                         }
                       while (strcmp(book_dtbase[i].status,"available") != 0 && strcmp(book_dtbase[i].status,"on loan") != 0);
                       printf( "\n The book has been updated");
                     }
                 }
              }
       }
 }

 /*
  function name  : display_book_details
  arguments      : ptr - pointer to a structure which stores the book details
  returns        : nothing
  purpose        : displays details of a specific book
 */

 void display_book_details(BOOK *ptr)
 {
    printf("\n book title : ");
    puts ( ptr->title);
    printf(" book code  : ");
    puts ( ptr->book_code);
    printf(" book author: ");
    puts ( ptr->author);
    printf(" book status: ");
    puts ( ptr->status);
    printf("\n");
 }

 /*
  function name  : Search_by_code
  arguments      : book_base[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : searches the library database for information on a book
                   identified by a unique book code
 */

 void Search_by_code(BOOK book_base[])
 {
    char code[25];
    int i = 0;

    printf("\n Please enter book code: ");
    gets(code);

    if( strcmp( code,"" ) == 0 )
         printf("\n INVALID ENTRY");
    else{

         while( strcmp(book_base[i].book_code,code) != 0 && i <MAX_BOOKS )
              i++;

         if (i == MAX_BOOKS)
              printf("\n The Book is not in the database");
         else{
              printf("\n The book you have chosen is:");
              display_book_details( &book_base[i]);
            }
        }
 }

 /*
  function name  : Search_by_title
  arguments      : bk_dbase[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : searches the library database for information identified by
                   its title
 */

 void Search_by_title(BOOK bk_dbase[])
 {
    char title[25];
    int i = 0;

    printf("\n Please enter book title(Maximum 30 characters): ");
    gets(title);

    if( strcmp( title,"" ) == 0 )
         printf("\n INVALID ENTRY");
    else{

         while( strcmp(bk_dbase[i].title,title) != 0 && i <MAX_BOOKS )
               i++;
         if (i == MAX_BOOKS)
               printf("\n The Book is not in the database");
         else{
               printf("\n The book you have chosen is:");
               display_book_details( &bk_dbase[i]);
             }
        }
 }

 /*
  function name  : summary_information
  arguments      : bk_data_base[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : main calling function to display a summary of information
                   on all books sorted alphabetically by title available,
                   currently on loan and all not on loan.
 */

 void summary_information(BOOK bk_data_base[])
 {
    void(*array_of_3ptr_to_func[3])(BOOK[]) ={all_books_sort,all_on_loan_sort,all_not_loan_sort};
    int choice;

    while(  (choice = sub_menu()) != 3 ){
	      switch ( choice ){

			     case 0:case 1:case 2:
                                    (*array_of_3ptr_to_func[choice])(bk_data_base);
                                    break;
                 default :
                                    printf("\n INVALID CHOICE");
                                    break;
		         }
        }
 }

 /*
  function name  : all_books_sort
  arguments      : book[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : display all books sorted alphabetically by title
 */

 void all_books_sort(BOOK book[])
 {
    int i =0,check = 0 ;

    while ( strcmp( book[i].book_code,"")== 0 && i < MAX_BOOKS )
	       i++;

    if ( i == MAX_BOOKS )
	       printf("\n Sorry, the database is empty\n");
    else{
           printf("\n all books sorted alphabetically by title are:");

           for(i = 0; i < MAX_BOOKS; i++)
               if (strcmp( book[i].book_code,"")!= 0){
                   display_book_details( &book[i]);
                   system("PAUSE");
                   }
        }
 }

 /*
  function name  : all_on_loan_sort
  arguments      : books_database[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : display all books on loan sorted alphabetically by title
 */

 void all_on_loan_sort(BOOK books_database[])
 {
    char status_string[30];

    strcpy(status_string,"on loan");
    books_search(books_database,status_string);
 }

 /*
  function name  : all_not_loan_sort
  arguments      : books_dbase[] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : display all books that are not on loan sorted alphabetically by title
 */

 void all_not_loan_sort(BOOK books_dbase[])
 {
    char status_string[30];

    strcpy(status_string,"available");
    books_search(books_dbase,status_string);
 }

 /*
  function name  : bubble_sort
  arguments      : books_dbs [] -pointer to an array of structures which stores all books
  returns        : nothing
  purpose        : sorts the entire library database alphabetically by title
 */

 void bubble_sort(BOOK books_dbs[])
 {
    void swap(BOOK*,BOOK*);     /* function prototype for swap declared here because it it the only function used by bubble_sort */
    int pass,j;

    for (pass = 0; pass < MAX_BOOKS - 1; pass++)
         for (j = 0; j < MAX_BOOKS - 1; j++)
              if( strcmp(books_dbs[j].title,books_dbs[j+1].title)> 0)
                  swap(&(books_dbs[j]),&(books_dbs[j+1]));
 }

 /*
  function name  : swap
  arguments      : element1_ptr - pointer to a structure that store details of a book
                   element2_ptr - pointer to a structure that store details of a book
  returns        : nothing
  purpose        : function used by bubble_sort to swap the addresses of two books
 */

 void swap(BOOK *element1_ptr,BOOK *element2_ptr)
 {
    BOOK temp;      /* temporary structure to hold values being swapped */

    temp = *element1_ptr;
    *element1_ptr = *element2_ptr;
    *element2_ptr = temp;
 }

 /*
  function name  : sub_menu
  arguments      : none
  returns        : choice - an integer value corresponding to the user choice
  purpose        : displays a menu of summary information to the user and reads
                   the choice made
 */

 int sub_menu (void)
 {
    int choice = 4;

    printf("\n **************************");
    printf("\n Alphabetical sort by title");
    printf("\n **************************");
    printf("\n Enter 0 to display all books");
    printf("\n Enter 1 to display all books on loan");
    printf("\n Enter 2 to display all books not on loan");
    printf("\n Enter 3 to return to main menu: ");
    scanf ("%d",&choice);
    fflush(stdin);

    return choice;
 }

 /*
  function name  : books_search
  arguments      : books_databs[] -pointer to an array of structures which stores all books
                   status_strng - pointer to a string that stores the book status
  returns        : nothing
  purpose        : utility function used to search for a book identified by
                   its status i.e on loan or available
 */

 void books_search(BOOK books_databs[],char*status_strng)
 {
    int i,check = 0 ;

    for(i = 0; i < MAX_BOOKS; i++)
        if (strcmp(books_databs[i].status,status_strng) == 0 )
            check ++;

    if (check == 0){
        printf("\n The search did not find any book ");
        puts(status_strng);
        }
    else{
        printf("\n books sorted alphabetically by title :");
        puts(status_strng);
        for(i = 0; i < MAX_BOOKS; i++)
          if (strcmp(books_databs[i].status,status_strng) == 0 ){
              display_book_details( &books_databs[i]);
              system("PAUSE");
             }
       }
 }