/**
 * @file Heap.h
 */

#ifndef CGDS_HEAP_H
#define CGDS_HEAP_H

#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "cgds/types.h"
#include "cgds/Vector.h"
#include "cgds/safe_alloc.h"

/**
 * @brief Generic d-ary heap.
 */
typedef struct Heap {
	size_t dataSize; ///< Size of a heap item in bytes.
	OrderType hType; ///< Type of heap: max first (MAX_T) or min first (MIN_T).
	UInt arity; ///< Arity of the underlying tree.
	Vector* array; ///< Vector of ItemValue* (internal representation).
} Heap;

/**
 * @brief Return an allocated and initialized heap.
 */
Heap* _heap_new(
	size_t dataSize, ///< Size in bytes of a heap element.
	OrderType hType, ///< Type of heap: max first (MAX_T) or min first (MIN_T).
	UInt arity ///< Arity of the underlying tree.
);

/**
 * @brief Return an allocated and initialized heap.
 * @param type Type of a buffer item (int, char*, ...).
 * @param hType Type of heap: max first (MAX_T) or min first (MIN_T).
 * @param arity Arity of the underlying tree.
 * 
 * Usage: Heap* heap_new(<Type> type, OrderType hType, UInt arity)
 */
#define heap_new(type, hType, arity) \
	_heap_new(sizeof(type), hType, arity)

/**
 * @brief Copy constructor (works well if items do not have allocated sub-pointers).
 */
Heap* heap_copy(
	Heap* heap ///< "this" pointer.
);

/**
 * @brief Check if the heap is empty.
 */
Bool heap_empty(
	Heap* heap ///< "this" pointer.
);

/**
 * @brief Return the size of current heap.
 */
UInt heap_size(
	Heap* heap ///< "this" pointer.
);

/**
 * @brief "Bubble up" an item-value inserted somewhere in the tree in O(log(n)) operations.
 */
void _heap_bubble_up(
	Heap* heap, ///< "this" pointer.
	UInt startIndex ///< Index to bubble up.
);

/**
 * @brief "Bubble down" an item-value inserted somewhere in the tree in O(log(n)) operations.
 */
void _heap_bubble_down(
	Heap* heap, ///< "this" pointer.
	UInt startIndex ///< Index to bubble down.
);

/**
 * @brief Insert a pair (item,value) inside the heap.
 */
void _heap_insert(
	Heap* heap, ///< "this" pointer.
	void* item, ///< Pointer to an item of type as defined in the constructor.
	Real value ///< Value associated with the item.
);

/**
 * @brief Insert a pair (item,value) inside the heap.
 * @param heap "this" pointer.
 * @param item Item of type as defined in the constructor.
 * @param value Value associated with the item.
 * 
 * Usage: void heap_insert(Heap* heap, void item, Real value)
 */
#define heap_insert(heap, item, value) \
{ \
	typeof((item)) tmp = item; \
	_heap_insert(heap, &tmp, value); \
}

/**
 * @brief Change the value of an item at a given index.
 */
void _heap_modify(
	Heap* heap, ///< "this" pointer.
	UInt index, ///< Index of the item to modify.
	Real newValue ///< New value for the item.
);

/**
 * @brief Change the value of an item inside the heap.
 * @param heap "this" pointer.
 * @param item_ Item to modify.
 * @param newValue New value for the item.
 * @note If several similar items are present, only the first is affected.
 * 
 * Usage: void heap_modify(Heap* heap, void item_, Real newValue)
 * WARNING: does not work if items are not basic type nor pointers.
 */
#define heap_modify(heap, item_, newValue) \
{ \
    UInt index = 0; \
	typeof((item_)) item__ = item_; \
    for (; index<heap->array->size; index++) \
	{ \
		void* pItem = ((ItemValue*)(heap->array->datas[index]))->item; \
        if (*((typeof(&item__))pItem) == item__) break; \
    } \
	_heap_modify(heap, index, newValue); \
}

/**
 * @brief Remove an item-value at a given index.
 */
void _heap_remove(
	Heap* heap, ///< "this" pointer.
	UInt index  ///< Index of the item to remove.
);

/**
 * @brief Remove an item-value inside the heap.
 * @param heap "this" pointer.
 * @param item_ Item to remove.
 * @note If several similar items are present, only the first is deleted.
 * 
 * Usage: void heap_remove(Heap* heap, void item_)
 * WARNING: does not work if items are not basic type nor pointers.
 */
#define heap_remove(heap, item_) \
{ \
    UInt index = 0; \
	typeof((item_)) item__ = item_; \
    for (; index<heap->array->size; index++) \
	{ \
		void* pItem = ((ItemValue*)(heap->array->datas[index]))->item; \
        if (*((typeof(&item__))pItem) == item__) break; \
    } \
	_heap_remove(heap, index); \
}

/**
 * @brief Return what is at the beginning of the heap.
 */
ItemValue* heap_top_raw(
	Heap* heap ///< "this" pointer.
);

/**
 * @brief Return what is at the beginning of the heap.
 * @param heap "this" pointer.
 * @param item_ Item to be assigned.
 * 
 * Usage: void heap_top(Heap* heap, void item_)
 */
#define heap_top(heap, item_) \
{ \
	void* pItem = heap_top_raw(heap)->item; \
	item_ = *((typeof(&item_))pItem); \
}

/**
 * @brief Remove the top of the heap.
 */
void heap_pop(
	Heap* heap ///< "this" pointer.
);

/**
 * @brief Clear the entire heap.
 */
void heap_clear(
	Heap* heap ///< "this" pointer.
);

/**
 * @brief Destroy the heap: clear it, and free 'heap' pointer.
 */
void heap_destroy(
	Heap* heap ///< "this" pointer.
);

#endif