// This program demonstrates what happens when you have a linked list inside
// a struct and how to access the different elements (like in your assignment).

//Sasha Vassar Week09 Lecture 15

#include <stdio.h>
#include <stdlib.h>

struct list {
    struct number *numbers;
    struct letter *letters;
};

struct number {
    int data;
    struct number *next_number;    
};

struct letter {
    char letter;
    struct letter *next_letter;    
};

//Function prototypes for some of the functions that we will create
struct list *create_list();
struct number *create_number (int data);
int add_number(struct list *list_start, int data); 
void print_numbers(struct list *list_start);

// You can see if you can create the bottom two of these functions as practice
struct letter *create_letter (char letter);
int add_letter(struct list *list_start, char letter);


int main (void) {
    //TODO: We need to create our list structure to house everything first 
    struct list *list_start = create_list();
  
    //Add some numbers to out list
    add_number(list_start, 1);
    add_number(list_start, 2);
    add_number(list_start, 3);
   
    //Print the list
    print_numbers(list_start);
      
    return 0;
}

//Function to create the list 
struct list *create_list(){
    //TODO: Allocate space to the list
    struct list *new_list = malloc(sizeof(struct list));
    //TODO: Initialise the new list
    new_list->numbers = NULL;
    new_list->letters = NULL;
    
    return new_list;
}


//Function that creates a new number (node)
struct number *create_number (int number) {
    //Allocate some memory for a new node
    struct number *new_number = malloc(sizeof(struct number));
    //TODO: Initialise the new node    
    new_number->data = number;
    new_number->next_number = NULL;
       
    return new_number;
}

//Function to add a number to the list 
int add_number(struct list *list_start, int number){
    //Make the number node that you will be adding in
    struct number *new_number = create_number(number);
    //TODO: Create a current pointer to keep track of where we are in the list
    //and set it to the head of the numbers list (since we are adding a number)
    struct number *current = list_start->numbers;
    //TODO: Boundary case: What if there are no other items in the list? 
    //We will make the new number the head of the list
    if (current == NULL){
        list_start->numbers = new_number;
        return 0;
    }
    
    //TODO: Otherwise, insert at the end of the list
    while (current->next_number != NULL) {
        current = current->next_number;
    }
    //I am standing at the last node/on the last node
    current->next_number = new_number;
    new_number->next_number = NULL;
    
    return 0;
}

//Function to print the numbers
void print_numbers(struct list *list_start) {
    //TODO: Create a current pointer and set it to the start of the numbers
    //list (so the head)
    struct number *current = list_start->numbers;
    while (current != NULL) {
        printf("%d -> ", current->data);
        current = current->next_number;
    }
    printf("X\n");
}