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

// To add:
// Support for A-Z && a-z  - FIXED
// Insert function: insert node only if alphabet letters - fix: main() will not enter values unless it's a letter
// Double pointer instead of return values
// Make insert() shorter

typedef struct Node
{
    char data;
    struct Node* next;
} node;

node *create_node(char data)
{
    node* temp = (node*)malloc(sizeof(node));

    temp->data = data;
    temp->next = NULL;

    return temp;
}

char lower(char c)
{
    if (c >= 'A' && c <= 'Z')
    {
        return c + 32;
    }

    else if (c >= 'a' && c <= 'z')
    {
        return c;
    }
}

node *insert(node* head, node *newnode)
{
    // d->e->a->b ---- INPUT
    // a->b->d->e ---- SORTED
    // Insert(c)
    // a->b->c->d->e ---- NEW SORTED

    node* temp = head;

    if (head == NULL) // head empty
    {
        head = newnode;
        head->next = NULL;
        return head;
    }

    if (head->next == NULL) // 1 item in list
    {
        if (head->data <= newnode->data)
        {
            newnode->next = NULL;
            head->next = newnode;
            return head;
        }

        else if (newnode->data <= head->data)
        {
            newnode->next = head;
            head = newnode;
            return head;
        }
    }

    if (head != NULL && (newnode->data <= head->data))
    {
        newnode->next = head;
        head = newnode;
        return head;
    }

    while (temp != NULL) // normal
    {
        if (temp->next == NULL) // Last item
        {
            newnode->next = NULL;
            temp->next = newnode;
            return head;
        }

        else // Not last item
        {
            if (lower(temp->data) <= lower(newnode->data) && lower(newnode->data) <= lower(temp->next->data)) // b<c<d
            {
                newnode->next = temp->next;
                temp->next = newnode;
                return head;
            }

            else
                temp = temp->next;
        }
    }

    return head;
}

void print_list(node* head)
{
    node* temp = head;

    while (temp != NULL)
    {
        printf("%c->", temp->data);
        temp = temp->next;
    }
}

node* func()
{
    node* head = NULL;

    char input;
    node *input_node;

    printf("Insert only a-z letters. Insert any other character to stop.\n");
    printf("Please enter a value: ");
    scanf("%c", &input);
    rewind(stdin);

    while ((input >= 'a' && input <= 'z') || (input >= 'A' && input <= 'Z'))
    {
        input_node = create_node(input);
        head = insert(head, input_node);

        printf("Please enter a value: ");
        scanf("%c", &input);
        rewind(stdin);
    }

    return head;
}


node* reverse(node *head)
{

}

int main()
{
    node* head = NULL;

    head = func();

    print_list(head);

    return 0;
}