#include "postgres.h"
#include "fmgr.h"
#include "access/htup_details.h"
#include "funcapi.h"
#include "storage/lwlock.h"
#include "storage/shmem.h"
#include "utils/builtins.h"

PG_MODULE_MAGIC;

PG_FUNCTION_INFO_V1(pg_lock_hash_info);

typedef struct {
    int bucket_idx;
    char hash_type;
    int directory;
    int entries;
    int free_slots;
} LockHashEntry;

Datum
pg_lock_hash_info(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    LockHashEntry *entries;

    if (SRF_IS_FIRSTCALL())
    {
        TupleDesc tupdesc;
        MemoryContext oldcontext;

        funcctx = SRF_FIRSTCALL_INIT();
        oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

        tupdesc = CreateTemplateTupleDesc(5);
        TupleDescInitEntry(tupdesc, (AttrNumber) 1, "hash_type", TEXTOID, -1, 0);
        TupleDescInitEntry(tupdesc, (AttrNumber) 2, "directory", INT4OID, -1, 0);
        TupleDescInitEntry(tupdesc, (AttrNumber) 3, "bucket_hash", INT4OID, -1, 0);
        TupleDescInitEntry(tupdesc, (AttrNumber) 4, "entries", INT4OID, -1, 0);
        TupleDescInitEntry(tupdesc, (AttrNumber) 5, "free_slots", INT4OID, -1, 0);
        funcctx->tuple_desc = BlessTupleDesc(tupdesc);

        /* Allocate space for results (this should fetch real data) */
        entries = palloc(sizeof(LockHashEntry) * 10); /* Placeholder for real count */
        funcctx->user_fctx = entries;
        MemoryContextSwitchTo(oldcontext);
    }

    funcctx = SRF_PERCALL_SETUP();
    entries = (LockHashEntry *) funcctx->user_fctx;

    /* Placeholder loop to return mock data */
    if (funcctx->call_cntr < 10)
    {
        Datum values[5];
        bool nulls[5] = {false, false, false, false, false};
        HeapTuple tuple;

        values[0] = CharGetDatum(funcctx->call_cntr % 2 == 0 ? 'l' : 'p');
        values[1] = Int32GetDatum(funcctx->call_cntr / 5);
        values[2] = Int32GetDatum(funcctx->call_cntr);
        values[3] = Int32GetDatum(5);  /* Fake number of entries */
        values[4] = Int32GetDatum(10); /* Fake number of free slots */

        tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
        SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
    }
    else
    {
        SRF_RETURN_DONE(funcctx);
    }
}