/* fun_with_lists.c
 * Authors: Pete Broadwell
 *          Josh Vickery
 * This program serves as the front-end interactive interface to the
 * list manipulation library. It allows the user to read a list from
 * a file and then perform a wide variety of operations on that list.
 * Attempting to run these operations before a list has been loaded
 * results in error messages
 */

#include "ll_defs.h"

int main(int argc, char *argv[]) {

  llist *clist=NULL; /* pointer to the current list */
  char c;
  int quit=0;
  char filename[256];
  FILE *fd;
  int count;

  printf("\nWelcome to Josh and Pete's list manipulator!\n");

  while (quit==0) {
    /* print the main menu */
    printf("\nOperations:\n");
    printf("r Read a list from a file\n");
    printf("w Write the current list to a file\n");
    printf("p Print the current list to the screen\n");
    printf("s Sort the current list using quicksort\n");
    printf("a Advance the cursor in the list\n");
    printf("b Back up the cursor in the list\n"); 
    printf("d Delete the current element in the list\n");
    printf("f Move the cursor to the front of the list\n");
    printf("e Move the cursor to the end of the list\n");
    printf("c Count the number of nodes on the list\n");
    printf("q Quit Josh and Pete's list manipulator\n\n");
    printf("What would you like to do? ");

    scanf("%c", &c);
    /* I'm not sure why this is necessary, but otherwise it reads the
     * newline as a new character. */
    while(c == '\n')
      scanf("%c", &c);
    switch(c) {
    case 'r':
      /* read a list from the given file and return a pointer to the list */
      printf("Name of file: ");
      scanf("%s", filename);
      /* if a list is currently in use, deallocate that list */
      if (clist != NULL){
        printf("\nDELETING CURRENT LIST.\n");
        delete_l(clist);
      }
      /* read the new list from the file */
      clist=(llist *)readfile(filename);
      printf("\nLIST CREATED.\n"); 
      break;
    case 'w':
      /* write the list to the given file */
      printf("Name of file: ");
      scanf("%s", filename);
      fd=fopen(filename, "w");
      if (fd == NULL) {
        printf("Unacceptable filename.\n");
        break;
      }
      writefile(fd, clist);
      printf("\nFILE CREATED.\n"); 
      fclose(fd);
      break;
    case 'p':
      /* print the current list to the screen (stdout) */
      printf("\n");
      printf("LIST CONTENTS:\n");
      writefile(stdout, clist);
      break;
    case 's':
      /* sort the list */
      clist=(llist *)quicksort(clist);
      printf("\nLIST SORTED.\n");
      break;
    case 'a':
      /* advance the cursor one element, if possible */
      if (clist==NULL){
        printf("List is currently empty. Nothing done.\n");
        break;
      }
      printf("\nADVANCING CURSOR\n");
      clist->current=(node *)advance_cursor(clist);
      break;
    case 'b':
      /* move the cursor backwards one element, if possible */
      if (clist==NULL){
        printf("List is currently empty. Nothing done.\n");
        break;
      }
      printf("\nBACKING UP CURSOR\n");
      clist->current=(node *)backup_cursor(clist);
      break;
    case 'd':
      /* delete the current element from the list and reset the cursor */
      if (clist==NULL){
        printf("List is currently empty. Nothing changed.\n");
        break;
      }
      delete_element(clist);
      printf("\nELEMENT DELETED.\n");
      clist->current=(node *)tofront(clist);
      printf("Cursor reset to front of list.\n");
      break;
    case 'f':
      /* move the cursor to the front of the list */
      if (clist==NULL){
        printf("List is currently empty. Nothing done.\n");
        break;
      }
      clist->current=(node *)tofront(clist);
      printf("\nCURSOR IS AT FRONT OF LIST.\n");
      break;
    case 'e':
      /* move the cursor to the end of the list */
      if (clist==NULL){
        printf("List is currently empty. Nothing done.\n");
        break;
      }
      clist->current=(node *)toend(clist);
      printf("\nCURSOR IS AT END OF LIST.\n");
      break;
    case 'c':
      count=count_nodes(clist);
      printf("\nTHE LIST HAS %d ELEMENTS.\n", count);
      printf("Cursor reset to front of list.\n");
      break;
    case 'q':
      /* prepare to exit */
      quit=1;
      break;
    default:
      break;
    }

  }

  printf("\nThank you for using Josh and Pete's list manipulator!\n");

}