#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include "log_macros.h"

typedef struct _Node {   // always called Node or ▒Node in ECE 26400
    int value;           // usually called 'value'                //  4 bytes¹ for int
    struct _Node* next;  // address of the next node in the list  //  8 bytes¹ for ▒▒▒▒▒*
} Node;                  // Think of .next as your link to the next node.
// ¹ Disclaimer:  On our platform; sizes on other platforms may vary.

void append(int value, Node** a_head, Node** a_tail) {
    // Allocate space on the heap sufficient to store one new Node.
    Node* new_tail = malloc(sizeof(*new_tail));

    // Initialize the .value field to 'value' and the .next field to NULL.
    // new_tail -> value = value;  // same as (*new_tail).value = value … but please use <-
    // new_tail -> next  = NULL;   // same as (*new_tail).next  = next  … but please use <-

    // Better syntax:  "COMPOUND LITERAL"

    if(*a_head == NULL) {  // If list is empty
        *a_head = new_tail;  // store the address of the new tail at address a_head.
    }
    else {
        (*a_tail) -> next = new_tail;  // append to end of list
    }

    *a_tail = new_tail;
}

void print_list(Node* head) {
    for(Node* curr = head; curr != NULL; curr = curr -> next) {
        log_int(curr -> value);
    }
}

// YOU CANNOT ACCESS MEMORY AFTER IT HAS BEEN FREED.

void destroy_list(Node** a_head, Node** a_tail) {

    while(*a_head != NULL) {
        // Save the new head
        Node* new_head = (*a_head) -> next;

        // Free the old head
        free(*a_head);
        
        // Set 'head' to the address of new head
        *a_head = new_head;
    }

    *a_tail = NULL;
    
    // NOTE: *a_head and *a_tail will be NULL at the end so we can't accidentally access.
}

int main(int argc, char* argv[]) {
    // size==0  - empty list
    Node* head = NULL;   // first node in the list is always called 'head'
    Node* tail = NULL;   // last  node in the list is always called 'tail'
    append(10, &head, &tail);
    append(11, &head, &tail);
    append(12, &head, &tail);

    print_list(head);

    // [ 10 | → ] → [ 11 | → ] → NULL
    
    destroy_list(&head, &tail);
    
    return EXIT_SUCCESS;
}
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