#ifndef LSUP_KEYSET_H
#define LSUP_KEYSET_H

#include "core.h"

typedef enum LSUP_KSFlag {
    LSUP_KS_CHECK_CAP = 1 << 0,
    LSUP_KS_CHECK_DUP = 1 << 1
} LSUP_KSFlag;

typedef struct keyset {
    LSUP_TripleKey  *data;
    size_t          capacity;
    size_t          cur;
    size_t          free_i;
    float           expand_ratio;
} LSUP_Keyset;


int LSUP_keyset_init(LSUP_Keyset *ks, size_t capacity, float expand_ratio);

LSUP_Keyset *LSUP_keyset_new(size_t capacity, float expand_ratio);


/**
 * Move cursor to a non-empty position.
 */
inline bool LSUP_keyset_seek(LSUP_Keyset* ks, size_t idx)
{
    if (idx >= ks->free_i) return false;

    ks->cur = idx;

    return true;
}


inline size_t LSUP_keyset_size(LSUP_Keyset* ks)
{
    return(ks->free_i);
}


inline size_t LSUP_keyset_tell(LSUP_Keyset* ks)
{
    return(ks->cur);
}


inline const LSUP_TripleKey *LSUP_keyset_peek(LSUP_Keyset *ks) {
    return (const LSUP_TripleKey *)(ks->data + ks->cur);
}


inline bool LSUP_keyset_contains(
        const LSUP_Keyset *ks, const LSUP_TripleKey *val) {

    for (size_t i = 0; i < ks->free_i; i++) {
        // scan from the least to the most probable to match.
        if (
                (*val)[2] == ks->data[i][2] &&
                (*val)[0] == ks->data[i][0] &&
                (*val)[1] == ks->data[i][1]) {
            return true;
        }
    }

    return false;
}


inline bool LSUP_keyset_next(LSUP_Keyset *ks)
{
    if (ks->free_i > 0 && ks->cur < ks->free_i - 1) {
        ks->cur ++;
        return true;
    }
    return false;
}

/**
 * Resize the keyset capacity.
 *
 * Size cannot be smaller than `free_i`. Therefore, specifying a size of 0 will
 * always compact the keyset to the current occupied space.
 */
int LSUP_keyset_resize(LSUP_Keyset *ks, size_t new_size);

/**
 * Add a single key.
 */
int LSUP_keyset_add(
        LSUP_Keyset *ks, const LSUP_TripleKey *val, LSUP_KSFlag flags);

int LSUP_keyset_remove(LSUP_Keyset *ks, const LSUP_TripleKey *val);

int LSUP_keyset_copy(const LSUP_Keyset *src, LSUP_Keyset *dest);

int LSUP_keyset_sparse_copy(LSUP_Keyset *src, LSUP_Keyset *dest);

int LSUP_keyset_lookup(
        LSUP_Keyset *ks, LSUP_Keyset *res,
        const LSUP_Key sk, const LSUP_Key pk, const LSUP_Key ok);

/**
 * Set-theoretical union (ks1 ∪ ks2).
 *
 * The resulting Keyset is initialized beforehand and is not compacted.
 */
int LSUP_keyset_join(LSUP_Keyset *ks1, LSUP_Keyset *ks2, LSUP_Keyset *res);

/**
 * Set-theoretical complement (ks1 \ ks2).
 *
 * The resulting Keyset is initialized beforehand and is not compacted.
 */
int LSUP_keyset_subtract(LSUP_Keyset *ks1, LSUP_Keyset *ks2, LSUP_Keyset *res);

/**
 * Set-theoretical intersection (ks1 ∩ ks2).
 *
 * The resulting Keyset is initialized beforehand and is not compacted.
 */
int LSUP_keyset_intersect(LSUP_Keyset *ks1, LSUP_Keyset *ks2, LSUP_Keyset *res);

/**
 * Disjunctive union (XOR) (ks1 ⊕ ks2).
 *
 * The resulting Keyset is initialized beforehand and is not compacted.
 */
int LSUP_keyset_xor(LSUP_Keyset *ks1, LSUP_Keyset *ks2, LSUP_Keyset *res);


void LSUP_keyset_done(LSUP_Keyset *ks);

void LSUP_keyset_free(LSUP_Keyset *ks);

#endif