#include "common.h"

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

char chrToUpper(char chr) {
  if (chr >= 'a' && chr <= 'z')
    return chr - 32;
  return chr;
}

LinkedList *linkedList_init(void *value) {
  LinkedList *node = (LinkedList *)malloc(sizeof(LinkedList));
  node->value = value;
  node->next = NULL;
  node->prev = NULL;
  return node;
}

LinkedList *linkedList_getAt(LinkedList *head, const uint index) {
  uint current_index = 0;
  LinkedList *current_node = head;
  while (current_index++ != index) {
    if (current_node->next == NULL) {
      printf("[ERROR]: Linked List out of bounds.\n");
      return NULL;
    }
    current_node = current_node->next;
  }
  return current_node;
}

bool linkedList_insertAt(LinkedList *head, void *value, const uint index) {
  LinkedList *current_node = linkedList_getAt(head, index);
  if (current_node == NULL)
    return false;
  LinkedList *node = linkedList_init(value);
  // Set node's next neighbor to current node's next neighbor.
  node->next = current_node->next;
  // The previous neighbor of the newly created node is the current node.
  node->prev = current_node;
  // The new neightbor of current node is the newly created node.
  current_node->next = node;

  // Set the previous neighbor of node's next neighbor to node.
  if (node->next != NULL) {
    node->next->prev = node;
  }

  return true;
}

bool linkedList_removeAt(LinkedList **head, const uint index) {
  LinkedList *current_node = linkedList_getAt(*head, index);
  if (current_node == NULL)
    return false;

  LinkedList *prev = current_node->prev;
  LinkedList *next = current_node->next;
  if (prev != NULL)
    prev->next = next;
  if (next != NULL)
    next->prev = prev;
  if (index == 0)
    *head = next;
  free(current_node);
  return true;
}

void linkedList_print(LinkedList *head, void (*callback)(void *)) {
  LinkedList *current_node = head;
  while (current_node != NULL) {
    callback(current_node->value);
    printf("->");
    current_node = current_node->next;
  }
  printf("NULL\n");
}