#include <assert.h>

#include "osi/include/allocator.h"
#include "osi/include/list.h"
#include "osi/include/osi.h"

struct list_node_t {
  struct list_node_t *next;
  void *data;
};

typedef struct list_t {
  list_node_t *head;
  list_node_t *tail;
  size_t length;
  list_free_cb free_cb;
  const allocator_t *allocator;
} list_t;

static list_node_t *list_free_node_(list_t *list, list_node_t *node);

// Hidden constructor, only to be used by the hash map for the allocation tracker.
// Behaves the same as |list_new|, except you get to specify the allocator.
list_t *list_new_internal(list_free_cb callback, const allocator_t *zeroed_allocator) {
  list_t *list = (list_t *)zeroed_allocator->alloc(sizeof(list_t));
  if (!list)
    return NULL;

  list->free_cb = callback;
  list->allocator = zeroed_allocator;
  return list;
}

list_t *list_new(list_free_cb callback) {
  return list_new_internal(callback, &allocator_calloc);
}

void list_free(list_t *list) {
  if (!list)
    return;

  list_clear(list);
  list->allocator->free(list);
}

bool list_is_empty(const list_t *list) {
  assert(list != NULL);
  return (list->length == 0);
}

bool list_contains(const list_t *list, const void *data) {
  assert(list != NULL);
  assert(data != NULL);

  for (const list_node_t *node = list_begin(list); node != list_end(list); node = list_next(node)) {
    if (list_node(node) == data)
      return true;
  }

  return false;
}

size_t list_length(const list_t *list) {
  assert(list != NULL);
  return list->length;
}

void *list_front(const list_t *list) {
  assert(list != NULL);
  assert(!list_is_empty(list));

  return list->head->data;
}

void *list_back(const list_t *list) {
  assert(list != NULL);
  assert(!list_is_empty(list));

  return list->tail->data;
}

list_node_t *list_back_node(const list_t *list) {
  assert(list != NULL);
  assert(!list_is_empty(list));

  return list->tail;
}

bool list_insert_after(list_t *list, list_node_t *prev_node, void *data) {
  assert(list != NULL);
  assert(prev_node != NULL);
  assert(data != NULL);

  list_node_t *node = (list_node_t *)list->allocator->alloc(sizeof(list_node_t));
  if (!node)
    return false;

  node->next = prev_node->next;
  node->data = data;
  prev_node->next = node;
  if (list->tail == prev_node)
    list->tail = node;
  ++list->length;
  return true;
}

bool list_prepend(list_t *list, void *data) {
  assert(list != NULL);
  assert(data != NULL);

  list_node_t *node = (list_node_t *)list->allocator->alloc(sizeof(list_node_t));
  if (!node)
    return false;
  node->next = list->head;
  node->data = data;
  list->head = node;
  if (list->tail == NULL)
    list->tail = list->head;
  ++list->length;
  return true;
}

bool list_append(list_t *list, void *data) {
  assert(list != NULL);
  assert(data != NULL);

  list_node_t *node = (list_node_t *)list->allocator->alloc(sizeof(list_node_t));
  if (!node)
    return false;
  node->next = NULL;
  node->data = data;
  if (list->tail == NULL) {
    list->head = node;
    list->tail = node;
  } else {
    list->tail->next = node;
    list->tail = node;
  }
  ++list->length;
  return true;
}

bool list_remove(list_t *list, void *data) {
  assert(list != NULL);
  assert(data != NULL);

  if (list_is_empty(list))
    return false;

  if (list->head->data == data) {
    list_node_t *next = list_free_node_(list, list->head);
    if (list->tail == list->head)
      list->tail = next;
    list->head = next;
    return true;
  }

  for (list_node_t *prev = list->head, *node = list->head->next; node; prev = node, node = node->next)
    if (node->data == data) {
      prev->next = list_free_node_(list, node);
      if (list->tail == node)
        list->tail = prev;
      return true;
    }

  return false;
}

void list_clear(list_t *list) {
  assert(list != NULL);
  for (list_node_t *node = list->head; node; )
    node = list_free_node_(list, node);
  list->head = NULL;
  list->tail = NULL;
  list->length = 0;
}

list_node_t *list_foreach(const list_t *list, list_iter_cb callback, void *context) {
  assert(list != NULL);
  assert(callback != NULL);

  for (list_node_t *node = list->head; node; ) {
    list_node_t *next = node->next;
    if (!callback(node->data, context))
      return node;
    node = next;
  }
  return NULL;
}

// Iterates through the entire |list| and calls |callback| for each data element.
// Passes the caller provided data along with node
// If the list is empty, |callback| will never be called. It is safe to mutate the
// list inside the callback. If an element is added before the node being visited,
// there will be no callback for the newly-inserted node. Neither |list| nor
// |callback| may be NULL.
void list_foreach_ext(const list_t *list, list_iter_cb_ext callback, void *cb_data) {
  assert(list != NULL);
  assert(callback != NULL);
  if (list)
    for (list_node_t *node = list->head; node; ) {
      list_node_t *next = node->next;
      callback(node->data, cb_data);
      node = next;
    }
}

list_node_t *list_begin(const list_t *list) {
  assert(list != NULL);
  return list->head;
}

list_node_t *list_end(UNUSED_ATTR const list_t *list) {
  assert(list != NULL);
  return NULL;
}

list_node_t *list_next(const list_node_t *node) {
  assert(node != NULL);
  return node->next;
}

void *list_node(const list_node_t *node) {
  assert(node != NULL);
  return node->data;
}

static list_node_t *list_free_node_(list_t *list, list_node_t *node) {
  assert(list != NULL);
  assert(node != NULL);

  list_node_t *next = node->next;

  if (list->free_cb)
    list->free_cb(node->data);
  list->allocator->free(node);
  --list->length;

  return next;
}
