#ifndef INCLUDED_C_INDEXMINPQ_H
#define INCLUDED_C_INDEXMINPQ_H

#ifndef INCLUDED_C_TYPES_H
#include <c_Types.h>
#endif /*INCLUDED_C_TYPES_H*/

/* ------------------------------------------------------------------------------------------------------------------ */
/*  */


typedef struct {
    void* keys;             // Flat array storing user's complex items (indexed by external ID)
    c_size_t element_size;  // Size of each element in bytes
    c_size_t max_items;     // Maximum external ID capacity (0 to max_items - 1)
    c_size_t size;          // Current active element count inside the heap
    
    long long* pq;          // Heap array: map heap position -> external ID
    long long* qp;          // Inverted index array: map external ID -> heap position (-1 if not in heap)
    
    int (*compar)(const void*, const void*); // Custom comparison rule pointer
} c_IndexMinPQ_t;

/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

c_err_t c_IndexMinPQ_Init(c_IndexMinPQ_t* pq_inst, c_size_t max_items, c_size_t element_size,
                          int (*compar)(const void*, const void*));

void c_IndexMinPQ_Destroy(c_IndexMinPQ_t* pq_inst);

c_bool_t c_IndexMinPQ_Contains(c_IndexMinPQ_t* pq_inst, c_size_t ext_id);

c_err_t c_IndexMinPQ_Push(c_IndexMinPQ_t* pq_inst, c_size_t ext_id, const void* element);

c_err_t c_IndexMinPQ_Pop(c_IndexMinPQ_t* pq_inst, c_size_t* out_ext_id, void* out_element_buffer) ;

c_err_t c_IndexMinPQ_ChangeKey(c_IndexMinPQ_t* pq_inst, c_size_t ext_id, const void* new_element);

void* c_IndexMinPQ_Peek(c_IndexMinPQ_t* pq_inst, c_size_t* out_ext_id);

#endif /*INCLUDED_C_INDEXMINPQ_H*/