// SPDX-License-Identifier: GPL-3.0-or-later

#define WEB_SERVER_INTERNALS 1
#include "static-threaded.h"

int web_client_timeout = DEFAULT_DISCONNECT_IDLE_WEB_CLIENTS_AFTER_SECONDS;
int web_client_first_request_timeout = DEFAULT_TIMEOUT_TO_RECEIVE_FIRST_WEB_REQUEST;
long web_client_streaming_rate_t = 0L;

// ----------------------------------------------------------------------------
// high level web clients connection management

static struct web_client *web_client_create_on_fd(int fd, const char *client_ip, const char *client_port, int port_acl) {
    struct web_client *w;

    w = web_client_get_from_cache_or_allocate();
    w->ifd = w->ofd = fd;

    strncpyz(w->client_ip, client_ip, sizeof(w->client_ip) - 1);
    strncpyz(w->client_port, client_port, sizeof(w->client_port) - 1);

    if(unlikely(!*w->client_ip))   strcpy(w->client_ip,   "-");
    if(unlikely(!*w->client_port)) strcpy(w->client_port, "-");
	w->port_acl = port_acl;

    web_client_initialize_connection(w);
    return(w);
}

// --------------------------------------------------------------------------------------
// the main socket listener - STATIC-THREADED

struct web_server_static_threaded_worker {
    netdata_thread_t thread;

    int id;
    int running;

    size_t max_sockets;

    volatile size_t connected;
    volatile size_t disconnected;
    volatile size_t receptions;
    volatile size_t sends;
    volatile size_t max_concurrent;

    volatile size_t files_read;
    volatile size_t file_reads;
};

static long long static_threaded_workers_count = 1;

static struct web_server_static_threaded_worker *static_workers_private_data = NULL;
static __thread struct web_server_static_threaded_worker *worker_private = NULL;

// ----------------------------------------------------------------------------

static inline int web_server_check_client_status(struct web_client *w) {
    if(unlikely(web_client_check_dead(w) || (!web_client_has_wait_receive(w) && !web_client_has_wait_send(w))))
        return -1;

    return 0;
}

// ----------------------------------------------------------------------------
// web server files

static void *web_server_file_add_callback(POLLINFO *pi, short int *events, void *data) {
    struct web_client *w = (struct web_client *)data;

    worker_private->files_read++;

    debug(D_WEB_CLIENT, "%llu: ADDED FILE READ ON FD %d", w->id, pi->fd);
    *events = POLLIN;
    pi->data = w;
    return w;
}

static void web_werver_file_del_callback(POLLINFO *pi) {
    struct web_client *w = (struct web_client *)pi->data;
    debug(D_WEB_CLIENT, "%llu: RELEASE FILE READ ON FD %d", w->id, pi->fd);

    w->pollinfo_filecopy_slot = 0;

    if(unlikely(!w->pollinfo_slot)) {
        debug(D_WEB_CLIENT, "%llu: CROSS WEB CLIENT CLEANUP (iFD %d, oFD %d)", w->id, pi->fd, w->ofd);
        web_client_release(w);
    }
}

static int web_server_file_read_callback(POLLINFO *pi, short int *events) {
    struct web_client *w = (struct web_client *)pi->data;

    // if there is no POLLINFO linked to this, it means the client disconnected
    // stop the file reading too
    if(unlikely(!w->pollinfo_slot)) {
        debug(D_WEB_CLIENT, "%llu: PREVENTED ATTEMPT TO READ FILE ON FD %d, ON CLOSED WEB CLIENT", w->id, pi->fd);
        return -1;
    }

    if(unlikely(w->mode != WEB_CLIENT_MODE_FILECOPY || w->ifd == w->ofd)) {
        debug(D_WEB_CLIENT, "%llu: PREVENTED ATTEMPT TO READ FILE ON FD %d, ON NON-FILECOPY WEB CLIENT", w->id, pi->fd);
        return -1;
    }

    debug(D_WEB_CLIENT, "%llu: READING FILE ON FD %d", w->id, pi->fd);

    worker_private->file_reads++;
    ssize_t ret = unlikely(web_client_read_file(w));

    if(likely(web_client_has_wait_send(w))) {
        POLLJOB *p = pi->p;                                        // our POLLJOB
        POLLINFO *wpi = pollinfo_from_slot(p, w->pollinfo_slot);  // POLLINFO of the client socket

        debug(D_WEB_CLIENT, "%llu: SIGNALING W TO SEND (iFD %d, oFD %d)", w->id, pi->fd, wpi->fd);
        p->fds[wpi->slot].events |= POLLOUT;
    }

    if(unlikely(ret <= 0 || w->ifd == w->ofd)) {
        debug(D_WEB_CLIENT, "%llu: DONE READING FILE ON FD %d", w->id, pi->fd);
        return -1;
    }

    *events = POLLIN;
    return 0;
}

static int web_server_file_write_callback(POLLINFO *pi, short int *events) {
    (void)pi;
    (void)events;

    error("Writing to web files is not supported!");

    return -1;
}

// ----------------------------------------------------------------------------
// web server clients

static void *web_server_add_callback(POLLINFO *pi, short int *events, void *data) {
    (void)data;

    worker_private->connected++;

    size_t concurrent = worker_private->connected - worker_private->disconnected;
    if(unlikely(concurrent > worker_private->max_concurrent))
        worker_private->max_concurrent = concurrent;

    *events = POLLIN;

    debug(D_WEB_CLIENT_ACCESS, "LISTENER on %d: new connection.", pi->fd);
    struct web_client *w = web_client_create_on_fd(pi->fd, pi->client_ip, pi->client_port, pi->port_acl);
    w->pollinfo_slot = pi->slot;

    if(unlikely(pi->socktype == AF_UNIX))
        web_client_set_unix(w);
    else
        web_client_set_tcp(w);

    debug(D_WEB_CLIENT, "%llu: ADDED CLIENT FD %d", w->id, pi->fd);
    return w;
}

// TCP client disconnected
static void web_server_del_callback(POLLINFO *pi) {
    worker_private->disconnected++;

    struct web_client *w = (struct web_client *)pi->data;

    w->pollinfo_slot = 0;
    if(unlikely(w->pollinfo_filecopy_slot)) {
        POLLINFO *fpi = pollinfo_from_slot(pi->p, w->pollinfo_filecopy_slot);  // POLLINFO of the client socket
        (void)fpi;

        debug(D_WEB_CLIENT, "%llu: THE CLIENT WILL BE FRED BY READING FILE JOB ON FD %d", w->id, fpi->fd);
    }
    else {
        if(web_client_flag_check(w, WEB_CLIENT_FLAG_DONT_CLOSE_SOCKET))
            pi->flags |= POLLINFO_FLAG_DONT_CLOSE;

        debug(D_WEB_CLIENT, "%llu: CLOSING CLIENT FD %d", w->id, pi->fd);
        web_client_release(w);
    }
}

static int web_server_rcv_callback(POLLINFO *pi, short int *events) {
    worker_private->receptions++;

    struct web_client *w = (struct web_client *)pi->data;
    int fd = pi->fd;

    if(unlikely(web_client_receive(w) < 0))
        return -1;

    debug(D_WEB_CLIENT, "%llu: processing received data on fd %d.", w->id, fd);
    web_client_process_request(w);

    if(unlikely(w->mode == WEB_CLIENT_MODE_FILECOPY)) {
        if(w->pollinfo_filecopy_slot == 0) {
            debug(D_WEB_CLIENT, "%llu: FILECOPY DETECTED ON FD %d", w->id, pi->fd);

            if (unlikely(w->ifd != -1 && w->ifd != w->ofd && w->ifd != fd)) {
                // add a new socket to poll_events, with the same
                debug(D_WEB_CLIENT, "%llu: CREATING FILECOPY SLOT ON FD %d", w->id, pi->fd);

                POLLINFO *fpi = poll_add_fd(
                        pi->p
                        , w->ifd
                        , pi->port_acl
                        , 0
                        , POLLINFO_FLAG_CLIENT_SOCKET
                        , "FILENAME"
                        , ""
                        , web_server_file_add_callback
                        , web_werver_file_del_callback
                        , web_server_file_read_callback
                        , web_server_file_write_callback
                        , (void *) w
                );

                if(fpi)
                    w->pollinfo_filecopy_slot = fpi->slot;
                else {
                    error("Failed to add filecopy fd. Closing client.");
                    return -1;
                }
            }
        }
    }
    else {
        if(unlikely(w->ifd == fd && web_client_has_wait_receive(w)))
            *events |= POLLIN;
    }

    if(unlikely(w->ofd == fd && web_client_has_wait_send(w)))
        *events |= POLLOUT;

    return web_server_check_client_status(w);
}

static int web_server_snd_callback(POLLINFO *pi, short int *events) {
    worker_private->sends++;

    struct web_client *w = (struct web_client *)pi->data;
    int fd = pi->fd;

    debug(D_WEB_CLIENT, "%llu: sending data on fd %d.", w->id, fd);

    if(unlikely(web_client_send(w) < 0))
        return -1;

    if(unlikely(w->ifd == fd && web_client_has_wait_receive(w)))
        *events |= POLLIN;

    if(unlikely(w->ofd == fd && web_client_has_wait_send(w)))
        *events |= POLLOUT;

    return web_server_check_client_status(w);
}

static void web_server_tmr_callback(void *timer_data) {
    worker_private = (struct web_server_static_threaded_worker *)timer_data;

    static __thread RRDSET *st = NULL;
    static __thread RRDDIM *rd_user = NULL, *rd_system = NULL;

    if(unlikely(!st)) {
        char id[100 + 1];
        char title[100 + 1];

        snprintfz(id, 100, "web_thread%d_cpu", worker_private->id + 1);
        snprintfz(title, 100, "NetData web server thread No %d CPU usage", worker_private->id + 1);

        st = rrdset_create_localhost(
                "netdata"
                , id
                , NULL
                , "web"
                , "netdata.web_cpu"
                , title
                , "milliseconds/s"
                , "web"
                , "stats"
                , 132000 + worker_private->id
                , default_rrd_update_every
                , RRDSET_TYPE_STACKED
        );

        rd_user   = rrddim_add(st, "user", NULL, 1, 1000, RRD_ALGORITHM_INCREMENTAL);
        rd_system = rrddim_add(st, "system", NULL, 1, 1000, RRD_ALGORITHM_INCREMENTAL);
    }
    else
        rrdset_next(st);

    struct rusage rusage;
    getrusage(RUSAGE_THREAD, &rusage);
    rrddim_set_by_pointer(st, rd_user, rusage.ru_utime.tv_sec * 1000000ULL + rusage.ru_utime.tv_usec);
    rrddim_set_by_pointer(st, rd_system, rusage.ru_stime.tv_sec * 1000000ULL + rusage.ru_stime.tv_usec);
    rrdset_done(st);
}

// ----------------------------------------------------------------------------
// web server worker thread

static void socket_listen_main_static_threaded_worker_cleanup(void *ptr) {
    worker_private = (struct web_server_static_threaded_worker *)ptr;

    info("freeing local web clients cache...");
    web_client_cache_destroy();

    info("stopped after %zu connects, %zu disconnects (max concurrent %zu), %zu receptions and %zu sends",
            worker_private->connected,
            worker_private->disconnected,
            worker_private->max_concurrent,
            worker_private->receptions,
            worker_private->sends
    );

    worker_private->running = 0;
}

void *socket_listen_main_static_threaded_worker(void *ptr) {
    worker_private = (struct web_server_static_threaded_worker *)ptr;
    worker_private->running = 1;

    netdata_thread_cleanup_push(socket_listen_main_static_threaded_worker_cleanup, ptr);

            poll_events(&api_sockets
                        , web_server_add_callback
                        , web_server_del_callback
                        , web_server_rcv_callback
                        , web_server_snd_callback
                        , web_server_tmr_callback
                        , web_allow_connections_from
                        , NULL
                        , web_client_first_request_timeout
                        , web_client_timeout
                        , default_rrd_update_every * 1000 // timer_milliseconds
                        , ptr // timer_data
                        , worker_private->max_sockets
            );

    netdata_thread_cleanup_pop(1);
    return NULL;
}


// ----------------------------------------------------------------------------
// web server main thread - also becomes a worker

static void socket_listen_main_static_threaded_cleanup(void *ptr) {
    struct netdata_static_thread *static_thread = (struct netdata_static_thread *)ptr;
    static_thread->enabled = NETDATA_MAIN_THREAD_EXITING;

    int i, found = 0;
    usec_t max = 2 * USEC_PER_SEC, step = 50000;

    // we start from 1, - 0 is self
    for(i = 1; i < static_threaded_workers_count; i++) {
        if(static_workers_private_data[i].running) {
            found++;
            info("stopping worker %d", i + 1);
            netdata_thread_cancel(static_workers_private_data[i].thread);
        }
        else
            info("found stopped worker %d", i + 1);
    }

    while(found && max > 0) {
        max -= step;
        info("Waiting %d static web threads to finish...", found);
        sleep_usec(step);
        found = 0;

        // we start from 1, - 0 is self
        for(i = 1; i < static_threaded_workers_count; i++) {
            if (static_workers_private_data[i].running)
                found++;
        }
    }

    if(found)
        error("%d static web threads are taking too long to finish. Giving up.", found);

    info("closing all web server sockets...");
    listen_sockets_close(&api_sockets);

    info("all static web threads stopped.");
    static_thread->enabled = NETDATA_MAIN_THREAD_EXITED;
}

void *socket_listen_main_static_threaded(void *ptr) {
    netdata_thread_cleanup_push(socket_listen_main_static_threaded_cleanup, ptr);
            web_server_mode = WEB_SERVER_MODE_STATIC_THREADED;

            if(!api_sockets.opened)
                fatal("LISTENER: no listen sockets available.");

            // 6 threads is the optimal value
            // since 6 are the parallel connections browsers will do
            // so, if the machine has more CPUs, avoid using resources unnecessarily
            int def_thread_count = (processors > 6)?6:processors;

            if (!strcmp(config_get(CONFIG_SECTION_WEB, "mode", ""),"single-threaded")) {
                info("Running web server with one thread, because mode is single-threaded");
                config_set(CONFIG_SECTION_WEB, "mode", "static-threaded");
                def_thread_count = 1;
            }
            static_threaded_workers_count = config_get_number(CONFIG_SECTION_WEB, "web server threads", def_thread_count);

            if(static_threaded_workers_count < 1) static_threaded_workers_count = 1;

            size_t max_sockets = (size_t)config_get_number(CONFIG_SECTION_WEB, "web server max sockets", (long long int)(rlimit_nofile.rlim_cur / 2));

            static_workers_private_data = callocz((size_t)static_threaded_workers_count, sizeof(struct web_server_static_threaded_worker));

            web_server_is_multithreaded = (static_threaded_workers_count > 1);

            int i;
            for(i = 1; i < static_threaded_workers_count; i++) {
                static_workers_private_data[i].id = i;
                static_workers_private_data[i].max_sockets = max_sockets / static_threaded_workers_count;

                char tag[50 + 1];
                snprintfz(tag, 50, "WEB_SERVER[static%d]", i+1);

                info("starting worker %d", i+1);
                netdata_thread_create(&static_workers_private_data[i].thread, tag, NETDATA_THREAD_OPTION_DEFAULT, socket_listen_main_static_threaded_worker, (void *)&static_workers_private_data[i]);
            }

            // and the main one
            static_workers_private_data[0].max_sockets = max_sockets / static_threaded_workers_count;
            socket_listen_main_static_threaded_worker((void *)&static_workers_private_data[0]);

    netdata_thread_cleanup_pop(1);
    return NULL;
}