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#ifndef AO_PAIR_LIST_API_H
#define AO_PAIR_LIST_API_H

#include <stddef.h>
#include <stdint.h>

#include "../macros.h"
#include "../types/cuest_types.h"
#include "../types/cuest_parameter_types.h"
#include "../types/workspace_api.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @brief Build an AO pair list structure.
 * @ingroup Basis
 *
 * Constructs a sparse or dense pair list for efficient evaluation of integrals over AOs.
 * All input pointers and buffers must be valid and not NULL.
 * The number of atoms and xyz array length must match.
 * Workspace buffers must be preallocated as returned by \c cuestAOPairListCreateWorkspaceQuery.
 *
 * The cuestAOBasis_t basis handle used to construct the cuestAOPairList_t pair list handle
 * is not needed for the pair list handle to be valid. However, in practice, use of the pair list
 * will also require the cuestAOBasis_t basis handle and it should not be destroyed after creating
 * the pair list.
 *
 * @param[in]  handle              cuEST handle. Must not be NULL.
 * @param[in]  basis               AO basis set handle (object describing basis for the atoms). Must not be NULL.
 * @param[in]  numAtoms            Number of atoms in molecule or fragment. Must be greater than zero.
 * @param[in]  xyz                 Array of atomic Cartesian coordinates (length \c numAtoms * 3) on the CPU. Ordering of elements is row-major: \f$ [x_0, y_0, z_0, ...] \f$ . Must not be NULL.
 * @param[in]  thresholdPQ         Sparsity threshold for pair sieve (e.g., 1e-10). Must be non-negative.
 * @param[in]  parameters          AO pair list parameters structure. Must not be NULL.
 * @param[in]  persistentWorkspace Pointer to persistent workspace (preallocated). Must not be NULL.
 * @param[in]  temporaryWorkspace  Pointer to temporary workspace (preallocated). Must not be NULL.
 * @param[out] outPairList         Output pointer for AO pair list handle. Must not be NULL.
 *
 * @return
 *   - \c CUEST_STATUS_SUCCESS on success;
 *   - \c CUEST_STATUS_INVALID_HANDLE if the cuEST handle is NULL;
 *   - \c CUEST_STATUS_NULL_POINTER if any pointer is NULL;
 *   - \c CUEST_STATUS_INVALID_TYPE if opaque handles are not the correct type;
 *   - \c CUEST_STATUS_INVALID_ARGUMENT if \c numAtoms == 0 or \c thresholdPQ is negative;
 *   - \c CUEST_STATUS_EXCEPTION or \c CUEST_STATUS_UNKNOWN_ERROR on error.
 */
CUEST_API
cuestStatus_t cuestAOPairListCreate(
    cuestHandle_t handle,
    const cuestAOBasis_t basis,
    uint64_t numAtoms,
    const double* xyz,
    double thresholdPQ,
    const cuestAOPairListParameters_t parameters, 
    cuestWorkspace_t* persistentWorkspace,
    cuestWorkspace_t* temporaryWorkspace,
    cuestAOPairList_t* outPairList);

/**
 * @brief Query workspace requirements for AO pair list construction.
 * @ingroup Basis
 *
 * Simulates memory usage to determine sizes of persistent and temporary buffers.
 * All buffer and parameter pointers must be valid.
 *
 * @param[in]  handle                             cuEST handle. Must not be NULL.
 * @param[in]  basis                              AO basis set handle (object describing basis for the atoms); must not be NULL.
 * @param[in]  numAtoms                           Number of atoms. Must be greater than zero.
 * @param[in]  xyz                                Array of atomic Cartesian coordinates (length \c numAtoms * 3) on the CPU. Ordering of elements is \f$ [x_0, y_0, z_0, ...] \f$. Must not be NULL.
 * @param[in]  thresholdPQ                        Sparsity threshold for pair sieve (e.g., 1e-10). Must be non-negative.
 * @param[in]  parameters                         AO pair list parameters structure. Must not be NULL.
 * @param[out] persistentWorkspaceDescriptor      Output workspace descriptor for persistent buffer sizing. Must not be NULL.
 * @param[out] temporaryWorkspaceDescriptor       Output workspace descriptor for temporary buffer sizing. Must not be NULL.
 * @param      outPairList                        Output pointer for AO pair list handle. May be NULL.
 *
 * @return
 *   - \c CUEST_STATUS_SUCCESS on success;
 *   - \c CUEST_STATUS_INVALID_HANDLE if the cuEST handle is NULL;
 *   - \c CUEST_STATUS_NULL_POINTER if any required pointer is NULL;
 *   - \c CUEST_STATUS_INVALID_TYPE if opaque handles are not the correct type;
 *   - \c CUEST_STATUS_INVALID_ARGUMENT if \c numAtoms == 0 or \c thresholdPQ is negative;
 *   - \c CUEST_STATUS_EXCEPTION or \c CUEST_STATUS_UNKNOWN_ERROR otherwise.
 */
CUEST_API
cuestStatus_t cuestAOPairListCreateWorkspaceQuery(
    cuestHandle_t handle,
    const cuestAOBasis_t basis,
    uint64_t numAtoms,
    const double* xyz,
    double thresholdPQ,
    const cuestAOPairListParameters_t parameters, 
    cuestWorkspaceDescriptor_t* persistentWorkspaceDescriptor,
    cuestWorkspaceDescriptor_t* temporaryWorkspaceDescriptor,
    cuestAOPairList_t* outPairList);

/**
 * @brief Destroy/free an AO pair list object and its resources.
 * @ingroup Basis
 *
 * The AO pair list handle and associated resources must not be used after this call.
 *
 * @param[in] pairList AO pair list handle to destroy. Must not be NULL.
 *
 * @return
 *   - \c CUEST_STATUS_SUCCESS on success;
 *   - \c CUEST_STATUS_NULL_POINTER if pairList is NULL;
 *   - \c CUEST_STATUS_INVALID_TYPE if the cuEST AOPairList handle is not of type \c cuestAOPairList_t;
 *   - \c CUEST_STATUS_EXCEPTION or \c CUEST_STATUS_UNKNOWN_ERROR on error.
 */
CUEST_API
cuestStatus_t cuestAOPairListDestroy(
    cuestAOPairList_t pairList);


#ifdef __cplusplus
}
#endif

#endif /* AO_PAIR_LIST_API_H */
