// Copyright 2026 Versity Software
// This file is licensed under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

// C wrapper implementation for cuObjServer.
// Bridges extern "C" functions to the C++ cuObjServer class.

#include "cuobjserver_wrapper.h"
#include "cuobjserver.h"

#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <atomic>
#include <iostream>
#include <string>

// ---------------------------------------------------------------------------
// Session management — runtime symbol resolution
//
// libcuobjserver.so may export startRDMASession / closeRDMASession under one
// of two C++ mangled names depending on when the library was compiled:
//
//   Newer header layout (RDMAConnection base class):
//     _ZN14RDMAConnection16startRDMASessionEv
//     _ZN14RDMAConnection16closeRDMASessionEv
//
//   Older layout (method directly on cuObjServer):
//     _ZN11cuObjServer16startRDMASessionEv
//     _ZN11cuObjServer16closeRDMASessionEv
//
// We resolve lazily at first call so neither name needs to be present at
// link time, and the code works with both library generations.
// ---------------------------------------------------------------------------

typedef int  (*rdma_start_fn_t)(void *);
typedef void (*rdma_close_fn_t)(void *);

// Verbose wrapper logs are enabled when cuobj_server_set_telem_flags includes
// info/debug bits (configured by cuserver -debug).
static std::atomic<bool> g_verbose_logs{false};

static rdma_start_fn_t find_start_rdma_session() {
    void *proc = dlopen(nullptr, RTLD_LAZY);
    if (!proc) return nullptr;
    rdma_start_fn_t fn = reinterpret_cast<rdma_start_fn_t>(
        dlsym(proc, "_ZN14RDMAConnection16startRDMASessionEv"));
    if (!fn)
        fn = reinterpret_cast<rdma_start_fn_t>(
            dlsym(proc, "_ZN11cuObjServer16startRDMASessionEv"));
    dlclose(proc);
    return fn;
}

static rdma_close_fn_t find_close_rdma_session() {
    void *proc = dlopen(nullptr, RTLD_LAZY);
    if (!proc) return nullptr;
    rdma_close_fn_t fn = reinterpret_cast<rdma_close_fn_t>(
        dlsym(proc, "_ZN14RDMAConnection16closeRDMASessionEv"));
    if (!fn)
        fn = reinterpret_cast<rdma_close_fn_t>(
            dlsym(proc, "_ZN11cuObjServer16closeRDMASessionEv"));
    dlclose(proc);
    return fn;
}

extern "C" {

cuobj_server_t* cuobj_server_create(const char *ip, unsigned short port, unsigned proto) {
    try {
        auto *srv = new cuObjServer(ip, port, proto);
        return reinterpret_cast<cuobj_server_t*>(srv);
    } catch (...) {
        return nullptr;
    }
}

// Build a cuObjRDMATunable from the flat C struct, shared by
// cuobj_server_create_with_config and cuobj_server_init_rdma_config.
static cuObjRDMATunable tunables_from_c(const cuobj_rdma_tunables_t *t) {
    cuObjRDMATunable config;
    config.setNumDcis(t->num_dcis);
    config.setCqDepth(t->cq_depth);
    config.setDcKey(t->dc_key);
    config.setServiceLevel(t->service_level);
    config.setTimeout(t->timeout);
    config.setHopLimit(t->hop_limit);
    config.setPkeyIndex(t->pkey_index);
    config.setDelayInterval(t->delay_interval);
    config.setDelayMode(static_cast<cuObjDelayMode_t>(t->delay_mode));
    config.setRetryCount(t->retry_cnt);
    config.setQPResetOnFailure(t->qp_reset_on_failure != 0);
    config.setTrafficClass(t->traffic_class);
    config.setMaxRdAtomic(t->max_rd_atomic);
    return config;
}

cuobj_server_t* cuobj_server_create_with_config(const char *ip, unsigned short port,
                                                unsigned proto,
                                                const cuobj_rdma_tunables_t *t) {
    try {
        cuObjRDMATunable config = tunables_from_c(t);
        auto *srv = new cuObjServer(ip, port, proto, config);
        return reinterpret_cast<cuobj_server_t*>(srv);
    } catch (...) {
        return nullptr;
    }
}

void cuobj_server_destroy(cuobj_server_t *srv) {
    delete reinterpret_cast<cuObjServer*>(srv);
}

int cuobj_server_start_session(cuobj_server_t *srv) {
    static rdma_start_fn_t fn = find_start_rdma_session();
    if (!fn) {
        // Symbol not exported — library calls startRDMASession() internally
        // from the cuObjServer constructor. Verify the session actually came
        // up instead of unconditionally reporting success.
        auto *s = reinterpret_cast<cuObjServer*>(srv);
        return s->isConnected() ? 0 : -1;
    }
    int rc = fn(reinterpret_cast<void *>(srv));
    if (rc != 0)
        fprintf(stderr, "cuobjwrapper: startRDMASession returned %d\n", rc);
    return rc;
}

void cuobj_server_close_session(cuobj_server_t *srv) {
    static rdma_close_fn_t fn = find_close_rdma_session();
    if (!fn) {
        // Symbol not exported — session cleanup handled by destructor.
        return;
    }
    fn(reinterpret_cast<void *>(srv));
}

int cuobj_server_is_connected(cuobj_server_t *srv) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    return s->isConnected() ? 1 : 0;
}

void* cuobj_server_alloc_host_buffer(cuobj_server_t *srv, size_t size) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    return s->allocHostBuffer(size);
}

void cuobj_server_free_host_buffer(void *ptr) {
    free(ptr);
}

cuobj_rdma_buffer_t* cuobj_server_register_buffer(cuobj_server_t *srv, void *ptr, size_t size) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    return s->registerBuffer(ptr, size);
}

void cuobj_server_deregister_buffer(cuobj_server_t *srv, cuobj_rdma_buffer_t *buf) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    s->deRegisterBuffer(buf);
}

uint16_t cuobj_server_allocate_channel(cuobj_server_t *srv) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    return s->allocateChannelId();
}

void cuobj_server_free_channel(cuobj_server_t *srv, uint16_t channel_id) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    s->freeChannelId(channel_id);
}

ssize_t cuobj_server_handle_get(cuobj_server_t *srv,
                                const char *key,
                                cuobj_rdma_buffer_t *local_buf,
                                uint64_t remote_buf_start,
                                size_t size,
                                const char *rdma_descr,
                                uint16_t channel) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    std::string k(key);
    std::string descr(rdma_descr);
    ibv_wc_status wc_status = IBV_WC_SUCCESS;
    ssize_t rc = s->handleGetObject(k, local_buf, remote_buf_start, size, descr,
                                    channel, 0, &wc_status);
    if (rc < 0 && g_verbose_logs.load()) {
        fprintf(stderr,
                "cuobjwrapper: handleGetObject rc=%zd channel=%u wc_status=%d\n",
                rc, static_cast<unsigned>(channel), static_cast<int>(wc_status));
    }
    return rc;
}

ssize_t cuobj_server_handle_put(cuobj_server_t *srv,
                                const char *key,
                                cuobj_rdma_buffer_t *local_buf,
                                uint64_t remote_buf_start,
                                size_t size,
                                const char *rdma_descr,
                                uint16_t channel) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    std::string k(key);
    std::string descr(rdma_descr);
    ibv_wc_status wc_status = IBV_WC_SUCCESS;
    ssize_t rc = s->handlePutObject(k, local_buf, remote_buf_start, size, descr,
                                    channel, 0, &wc_status);
    if (rc < 0 && g_verbose_logs.load()) {
        fprintf(stderr,
                "cuobjwrapper: handlePutObject rc=%zd channel=%u wc_status=%d\n",
                rc, static_cast<unsigned>(channel), static_cast<int>(wc_status));
    }
    return rc;
}

void cuobj_server_setup_telemetry(int use_otel) {
    cuObjServer::setupTelemetry(use_otel != 0, &std::cout);
}

void cuobj_server_shutdown_telemetry(void) {
    cuObjServer::shutdownTelemetry();
}

void cuobj_server_set_telem_flags(unsigned flags) {
    g_verbose_logs.store((flags & 0x0003u) != 0u);
    cuObjServer::setTelemFlags(flags);
}

int cuobj_server_init_rdma_config(cuobj_server_t *srv, const cuobj_rdma_tunables_t *t) {
    auto *s = reinterpret_cast<cuObjServer*>(srv);
    try {
        s->initRDMAConfigParams(tunables_from_c(t));
        return 0;
    } catch (...) {
        return -1;
    }
}

} // extern "C"