// Special thanks to https://bytesbeneath.com/p/dynamic-arrays-in-c
#include "dyn_arr.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define ARRAY_GROWTH_MULTIPLIER 1.3
#define ARRAY_SHRINK_TRIGGER 2

void *dyn_arr_init(size_t item_size, size_t capacity) {
  void *dyna_ptr = NULL;
  size_t size = item_size * capacity + sizeof(dyna_header);
  dyna_header *header = malloc(size);

  if (header) {
    header->item_size = item_size;
    header->capacity = capacity;
    header->length = 0;
    dyna_ptr = header + 1;
  }

  return dyna_ptr;
}

void *dyna_ensure_capacity(void *array, int64_t item_count) {
  size_t item_size = dyna_item_size(array);
  dyna_header *header = dyna_get_header(array);
  size_t minimum_capacity = header->length + item_count;
  size_t maximum_capacity =
      (header->length + item_count) * ARRAY_SHRINK_TRIGGER;

  // Return if capacity is in acceptable range.
  if (header->capacity > minimum_capacity &&
      header->capacity < maximum_capacity) {
    return header + 1;
  }

  size_t new_capacity = minimum_capacity * ARRAY_GROWTH_MULTIPLIER;

  // Return if the array is valid and so small it's not worth reallocating
  if (header->capacity > minimum_capacity &&
      new_capacity <= ARRAY_INITIAL_CAPACITY) {
    return header + 1;
  }

  size_t new_size = sizeof(dyna_header) + new_capacity * item_size;
  header = realloc(header, new_size);
  header->capacity = new_capacity;
  return header + 1;
}

void dyna_deinit(void *array) {
  free(dyna_get_header(array));
  array = NULL;
}

bool dyna_empty(void *array) {
  if (dyna_length(array) == 0) {
    return true;
  }
  return false;
}