#include <sys/socket.h>
#include <sys/epoll.h>
#include <sys/poll.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>

#include "osd.h"

osd_t::osd_t(blockstore_config_t & config, blockstore_t *bs, ring_loop_t *ringloop)
{
    bind_address = config["bind_address"];
    if (bind_address == "")
        bind_address = "0.0.0.0";
    bind_port = strtoull(config["bind_port"].c_str(), NULL, 10);
    if (!bind_port || bind_port > 65535)
        bind_port = 11203;

    this->config = config;
    this->bs = bs;
    this->ringloop = ringloop;

    listen_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (listen_fd < 0)
    {
        throw std::runtime_error(std::string("socket: ") + strerror(errno));
    }
    int enable = 1;
    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable));

    sockaddr_in addr;
    int r;
    if ((r = inet_pton(AF_INET, bind_address.c_str(), &addr.sin_addr)) != 1)
    {
        close(listen_fd);
        throw std::runtime_error("bind address "+bind_address+(r == 0 ? " is not valid" : ": no ipv4 support"));
    }
    addr.sin_family = AF_INET;
    addr.sin_port = htons(bind_port);

    if (bind(listen_fd, (sockaddr*)&addr, sizeof(addr)) < 0)
    {
        close(listen_fd);
        throw std::runtime_error(std::string("bind: ") + strerror(errno));
    }

    if (listen(listen_fd, listen_backlog) < 0)
    {
        close(listen_fd);
        throw std::runtime_error(std::string("listen: ") + strerror(errno));
    }

    fcntl(listen_fd, F_SETFL, fcntl(listen_fd, F_GETFL, 0) | O_NONBLOCK);

    epoll_fd = epoll_create(1);
    if (epoll_fd < 0)
    {
        close(listen_fd);
        throw std::runtime_error(std::string("epoll_create: ") + strerror(errno));
    }

    epoll_event ev;
    ev.data.fd = listen_fd;
    ev.events = EPOLLIN;
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, listen_fd, &ev) < 0)
    {
        close(listen_fd);
        close(epoll_fd);
        throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
    }

    consumer.loop = [this]() { loop(); };
    ringloop->register_consumer(consumer);
}

osd_t::~osd_t()
{
    ringloop->unregister_consumer(consumer);
    close(epoll_fd);
    close(listen_fd);
}

osd_op_t::~osd_op_t()
{
    if (buf)
    {
        // Note: reusing osd_op_t WILL currently lead to memory leaks
        // So we don't reuse it, but free it every time
        if (op_type == OSD_OP_IN &&
            op.hdr.opcode == OSD_OP_SHOW_CONFIG)
        {
            std::string *str = (std::string*)buf;
            delete str;
        }
        else
            free(buf);
    }
}

bool osd_t::shutdown()
{
    stopping = true;
    if (inflight_ops > 0)
    {
        return false;
    }
    return bs->is_safe_to_stop();
}

void osd_t::loop()
{
    if (wait_state == 0)
    {
        io_uring_sqe *sqe = ringloop->get_sqe();
        if (!sqe)
        {
            wait_state = 0;
            return;
        }
        ring_data_t *data = ((ring_data_t*)sqe->user_data);
        my_uring_prep_poll_add(sqe, epoll_fd, POLLIN);
        data->callback = [&](ring_data_t *data)
        {
            if (data->res < 0)
            {
                throw std::runtime_error(std::string("epoll failed: ") + strerror(-data->res));
            }
            handle_epoll_events();
        };
        wait_state = 1;
    }
    else if (wait_state == 2)
    {
        handle_epoll_events();
    }
    send_replies();
    read_requests();
    ringloop->submit();
}

void osd_t::connect_peer(unsigned osd_num, char *peer_host, int peer_port, std::function<void(int)> callback)
{
    struct sockaddr_in addr;
    int r;
    if ((r = inet_pton(AF_INET, peer_host, &addr.sin_addr)) != 1)
    {
        callback(-EINVAL);
        return;
    }
    addr.sin_family = AF_INET;
    addr.sin_port = htons(peer_port ? peer_port : 11203);
    int peer_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (peer_fd < 0)
    {
        callback(-errno);
        return;
    }
    fcntl(peer_fd, F_SETFL, fcntl(peer_fd, F_GETFL, 0) | O_NONBLOCK);
    r = connect(peer_fd, (sockaddr*)&addr, sizeof(addr));
    if (r < 0 && r != EINPROGRESS)
    {
        close(peer_fd);
        callback(-errno);
        return;
    }
    clients[peer_fd] = (osd_client_t){
        .peer_addr = addr,
        .peer_port = peer_port,
        .peer_fd = peer_fd,
        .peer_state = PEER_CONNECTING,
        .connect_callback = callback,
        .osd_num = osd_num,
    };
    osd_peer_fds[osd_num] = peer_fd;
    // Add FD to epoll (EPOLLOUT for tracking connect() result)
    epoll_event ev;
    ev.data.fd = peer_fd;
    ev.events = EPOLLOUT | EPOLLIN | EPOLLRDHUP;
    if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, peer_fd, &ev) < 0)
    {
        throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
    }
}

void osd_t::handle_connect_result(int peer_fd)
{
    auto & cl = clients[peer_fd];
    std::function<void(int)> callback = cl.connect_callback;
    int result = 0;
    socklen_t result_len = sizeof(result);
    if (getsockopt(peer_fd, SOL_SOCKET, SO_ERROR, &result, &result_len) < 0)
    {
        result = errno;
    }
    if (result != 0)
    {
        stop_client(peer_fd);
        callback(-result);
        return;
    }
    int one = 1;
    setsockopt(peer_fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
    // Disable EPOLLOUT on this fd
    cl.connect_callback = NULL;
    cl.peer_state = PEER_CONNECTED;
    epoll_event ev;
    ev.data.fd = peer_fd;
    ev.events = EPOLLIN | EPOLLRDHUP;
    if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, peer_fd, &ev) < 0)
    {
        throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
    }
    callback(peer_fd);
}

int osd_t::handle_epoll_events()
{
    epoll_event events[MAX_EPOLL_EVENTS];
    int nfds = epoll_wait(epoll_fd, events, MAX_EPOLL_EVENTS, 0);
    for (int i = 0; i < nfds; i++)
    {
        if (events[i].data.fd == listen_fd)
        {
            // Accept new connections
            sockaddr_in addr;
            socklen_t peer_addr_size = sizeof(addr);
            int peer_fd;
            while ((peer_fd = accept(listen_fd, (sockaddr*)&addr, &peer_addr_size)) >= 0)
            {
                char peer_str[256];
                printf("osd: new client %d: connection from %s port %d\n", peer_fd, inet_ntop(AF_INET, &addr.sin_addr, peer_str, 256), ntohs(addr.sin_port));
                fcntl(peer_fd, F_SETFL, fcntl(listen_fd, F_GETFL, 0) | O_NONBLOCK);
                int one = 1;
                setsockopt(peer_fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
                clients[peer_fd] = {
                    .peer_addr = addr,
                    .peer_port = ntohs(addr.sin_port),
                    .peer_fd = peer_fd,
                    .peer_state = PEER_CONNECTED,
                };
                // Add FD to epoll
                epoll_event ev;
                ev.data.fd = peer_fd;
                ev.events = EPOLLIN | EPOLLRDHUP;
                if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, peer_fd, &ev) < 0)
                {
                    throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
                }
                // Try to accept next connection
                peer_addr_size = sizeof(addr);
            }
            if (peer_fd == -1 && errno != EAGAIN)
            {
                throw std::runtime_error(std::string("accept: ") + strerror(errno));
            }
        }
        else
        {
            auto & cl = clients[events[i].data.fd];
            if (events[i].events & EPOLLRDHUP)
            {
                // Stop client
                printf("osd: client %d disconnected\n", cl.peer_fd);
                stop_client(cl.peer_fd);
            }
            else if (cl.peer_state == PEER_CONNECTING)
            {
                if (events[i].events & EPOLLOUT)
                {
                    handle_connect_result(cl.peer_fd);
                }
            }
            else if (!cl.read_ready)
            {
                // Mark client as ready (i.e. some data is available)
                cl.read_ready = true;
                if (!cl.reading)
                {
                    read_ready_clients.push_back(cl.peer_fd);
                    ringloop->wakeup();
                }
            }
        }
    }
    wait_state = nfds == MAX_EPOLL_EVENTS ? 2 : 0;
    return nfds;
}

void osd_t::stop_client(int peer_fd)
{
    if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, peer_fd, NULL) < 0)
    {
        throw std::runtime_error(std::string("epoll_ctl: ") + strerror(errno));
    }
    auto it = clients.find(peer_fd);
    if (it->second.osd_num)
    {
        osd_peer_fds.erase(it->second.osd_num);
    }
    for (auto rit = read_ready_clients.begin(); rit != read_ready_clients.end(); rit++)
    {
        if (*rit == peer_fd)
        {
            read_ready_clients.erase(rit);
            break;
        }
    }
    for (auto wit = write_ready_clients.begin(); wit != write_ready_clients.end(); wit++)
    {
        if (*wit == peer_fd)
        {
            write_ready_clients.erase(wit);
            break;
        }
    }
    clients.erase(it);
    close(peer_fd);
}

void osd_t::exec_op(osd_op_t *cur_op)
{
    if (stopping)
    {
        // Throw operation away
        delete cur_op;
        return;
    }
    inflight_ops++;
    if (cur_op->op.hdr.magic != SECONDARY_OSD_OP_MAGIC ||
        cur_op->op.hdr.opcode < OSD_OP_MIN || cur_op->op.hdr.opcode > OSD_OP_MAX ||
        (cur_op->op.hdr.opcode == OSD_OP_SECONDARY_READ || cur_op->op.hdr.opcode == OSD_OP_SECONDARY_WRITE ||
        cur_op->op.hdr.opcode == OSD_OP_READ || cur_op->op.hdr.opcode == OSD_OP_WRITE) &&
        (cur_op->op.sec_rw.len > OSD_RW_MAX || cur_op->op.sec_rw.len % OSD_RW_ALIGN || cur_op->op.sec_rw.offset % OSD_RW_ALIGN))
    {
        // Bad command
        cur_op->bs_op.retval = -EINVAL;
        secondary_op_callback(cur_op);
        return;
    }
    if (cur_op->op.hdr.opcode == OSD_OP_TEST_SYNC_STAB_ALL)
    {
        exec_sync_stab_all(cur_op);
    }
    else if (cur_op->op.hdr.opcode == OSD_OP_SHOW_CONFIG)
    {
        exec_show_config(cur_op);
    }
    else if (cur_op->op.hdr.opcode == OSD_OP_READ)
    {
        // Primary OSD also works with individual stripes, but they're twice the size of the blockstore's stripe
        // - convert offset & len to stripe number
        // - fail operation if offset & len span multiple stripes
        // - calc stripe hash and determine PG
        // - check if this is our PG
        // - redirect or fail operation if not
        // - determine whether we need to read A and B or just A or just B or A + parity or B + parity
        //   and determine read ranges for both objects
        // - send read requests
        // - reconstruct result
    }
    else
    {
        exec_secondary(cur_op);
    }
}