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

typedef struct _Node { // 12+ bytes
    int value;          // 4 bytes
    struct _Node* next; // 8 bytes
} Node;

#define log_int(n) printf("%s == %d\n", #n, n)

void print_list(const Node* head) {
    // good code quality: using a for loop
    for (const Node* node = head; node != NULL; node = node->next) {
        printf("[%d]->", node->value);
    }
    printf("NULL\n");
}

void destroy_list(Node* head) {
    Node* node = head;
    while (node != NULL) {
        Node* next = node->next;
        free(node);
        node = next;
    }
}

// append and remove_front effectively makes this a queue
void append(Node** a_head, Node** a_tail, int value) {
    Node* new_node = malloc(sizeof(*new_node));
    *new_node = (Node) { .next = NULL, .value = value };

    if (*a_head == NULL) {
        // from size 0 to size 1
        *a_head = new_node;
    } else {
        // from size N to size N+1
        (*a_tail)->next = new_node;
    }
    *a_tail = new_node;
}

Node* remove_front(Node** a_head, Node** a_tail) {
    Node* node = *a_head;
    if (node == NULL) {
        return NULL;
    }
    *a_head = node->next;
    if (*a_head == NULL) {
        *a_tail = NULL;
    }
    node->next = NULL;
    return node;
}

int get_size_of_list(const Node* head) {
    int size = 0;
    for (const Node* node = head; node != NULL; node = node->next) {
        size += 1;
    }
    return size;
}

int main(int argc, char* argv[]) {
    Node* head = NULL;
    Node* tail = NULL;
    print_list(head);

    append(&head, &tail, 1);
    print_list(head);

    append(&head, &tail, 2);
    print_list(head);

    append(&head, &tail, 3);
    print_list(head);
    print_list(head->next);

    append(&head, &tail, 343);
    append(&head, &tail, 34);
    append(&head, &tail, 6654);
    append(&head, &tail, 545);
    append(&head, &tail, 934);
    append(&head, &tail, 49);
    print_list(head);
    log_int(get_size_of_list(head));
    log_int(get_size_of_list(head->next));

    Node* node = remove_front(&head, &tail);
    print_list(head);
    print_list(node);
    destroy_list(node);

    node = remove_front(&head, &tail);
    print_list(head);
    print_list(node);
    destroy_list(node);

    append(&head, &tail, 1234);
    print_list(head);

    node = remove_front(&head, &tail);
    print_list(head);
    print_list(node);
    destroy_list(node);

    destroy_list(head);

    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */