/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) NGINX, Inc.
 */

#include <nxt_main.h>


static void nxt_conn_write_timer_handler(nxt_task_t *task, void *obj,
    void *data);
static ssize_t nxt_conn_io_sendfile(nxt_task_t *task, nxt_sendbuf_t *sb);
static ssize_t nxt_sendfile(int fd, int s, off_t pos, size_t size);


void
nxt_conn_io_write(nxt_task_t *task, void *obj, void *data)
{
    ssize_t             ret;
    nxt_buf_t           *b;
    nxt_conn_t          *c;
    nxt_sendbuf_t       sb;
    nxt_event_engine_t  *engine;

    c = obj;

    nxt_debug(task, "conn write fd:%d er:%d bl:%d",
              c->socket.fd, c->socket.error, c->block_write);

    if (c->socket.error != 0 || c->block_write) {
        goto error;
    }

    if (!c->socket.write_ready || c->write == NULL) {
        return;
    }

    engine = task->thread->engine;

    c->socket.write_handler = nxt_conn_io_write;
    c->socket.error_handler = c->write_state->error_handler;

    b = c->write;

    sb.socket = c->socket.fd;
    sb.error = 0;
    sb.sent = 0;
    sb.size = 0;
    sb.buf = b;
#if (NXT_TLS)
    sb.tls = c->u.tls;
#endif
    sb.limit = 10 * 1024 * 1024;
    sb.ready = 1;
    sb.sync = 0;

    do {
        ret = c->io->sendbuf(task, &sb);

        c->socket.write_ready = sb.ready;
        c->socket.error = sb.error;

        if (ret < 0) {
            /* ret == NXT_AGAIN || ret == NXT_ERROR. */
            break;
        }

        sb.sent += ret;
        sb.limit -= ret;

        b = nxt_sendbuf_update(b, ret);

        if (b == NULL) {
            nxt_fd_event_block_write(engine, &c->socket);
            break;
        }

        sb.buf = b;

        if (!c->socket.write_ready) {
            ret = NXT_AGAIN;
            break;
        }

    } while (sb.limit != 0);

    nxt_debug(task, "event conn: %z sent:%O", ret, sb.sent);

    if (sb.sent != 0) {
        if (c->write_state->timer_autoreset) {
            nxt_timer_disable(engine, &c->write_timer);
        }
    }

    if (ret != NXT_ERROR) {

        if (sb.limit == 0) {
            /*
             * Postpone writing until next event poll to allow to
             * process other received events and to get new events.
             */
            c->write_timer.handler = nxt_conn_write_timer_handler;
            nxt_timer_add(engine, &c->write_timer, 0);

        } else if (ret == NXT_AGAIN) {
            /*
             * SSL libraries can require to toggle either write or read
             * event if renegotiation occurs during SSL write operation.
             * This case is handled on the c->io->send() level.  Timer
             * can be set here because it should be set only for write
             * direction.
             */
            nxt_conn_timer(engine, c, c->write_state, &c->write_timer);

            if (nxt_fd_event_is_disabled(c->socket.write)) {
                nxt_fd_event_enable_write(engine, &c->socket);
            }
        }
    }

    if (ret == 0 || sb.sent != 0) {
        /*
         * ret == 0 means a sync buffer was processed.
         * ret == NXT_ERROR is ignored here if some data was sent,
         * the error will be handled on the next nxt_conn_write() call.
         */
        c->sent += sb.sent;
        nxt_work_queue_add(c->write_work_queue, c->write_state->ready_handler,
                           task, c, data);
        return;
    }

    if (ret != NXT_ERROR) {
        return;
    }

    nxt_fd_event_block_write(engine, &c->socket);

error:

    nxt_work_queue_add(c->write_work_queue, c->write_state->error_handler,
                       task, c, data);
}


static void
nxt_conn_write_timer_handler(nxt_task_t *task, void *obj, void *data)
{
    nxt_conn_t   *c;
    nxt_timer_t  *timer;

    timer = obj;

    nxt_debug(task, "conn write timer");

    c = nxt_write_timer_conn(timer);
    c->delayed = 0;

    c->io->write(task, c, c->socket.data);
}


ssize_t
nxt_conn_io_sendbuf(nxt_task_t *task, nxt_sendbuf_t *sb)
{
    nxt_uint_t    niov;
    struct iovec  iov[NXT_IOBUF_MAX];

    niov = nxt_sendbuf_mem_coalesce0(task, sb, iov, NXT_IOBUF_MAX);

    if (niov == 0 && sb->sync) {
        return 0;
    }

    /*
     * XXX Temporary fix for <https://github.com/nginx/unit/issues/1125>
     */
    if (niov == 0 && sb->buf == NULL) {
        return 0;
    }

    if (niov == 0 && nxt_buf_is_file(sb->buf)) {
        return nxt_conn_io_sendfile(task, sb);
    }

    return nxt_conn_io_writev(task, sb, iov, niov);
}


static ssize_t
nxt_conn_io_sendfile(nxt_task_t *task, nxt_sendbuf_t *sb)
{
    size_t     size;
    ssize_t    n;
    nxt_buf_t  *b;
    nxt_err_t  err;

    b = sb->buf;

    for ( ;; ) {
        size = b->file_end - b->file_pos;

        n = nxt_sendfile(b->file->fd, sb->socket, b->file_pos, size);

        err = (n == -1) ? nxt_errno : 0;

        nxt_debug(task, "sendfile(%FD, %d, @%O, %uz): %z",
                  b->file->fd, sb->socket, b->file_pos, size, n);

        if (n > 0) {
            if (n < (ssize_t) size) {
                sb->ready = 0;
            }

            return n;
        }

        if (nxt_slow_path(n == 0)) {
            nxt_alert(task, "sendfile() reported that file was truncated at %O",
                      b->file_pos);

            return NXT_ERROR;
        }

        /* n == -1 */

        switch (err) {

        case NXT_EAGAIN:
            sb->ready = 0;
            nxt_debug(task, "sendfile() %E", err);

            return NXT_AGAIN;

        case NXT_EINTR:
            nxt_debug(task, "sendfile() %E", err);
            continue;

        default:
            sb->error = err;
            nxt_log(task, nxt_socket_error_level(err),
                    "sendfile(%FD, %d, @%O, %uz) failed %E",
                    b->file->fd, sb->socket, b->file_pos, size, err);

            return NXT_ERROR;
        }
    }
}


static ssize_t
nxt_sendfile(int fd, int s, off_t pos, size_t size)
{
    ssize_t  res;

#if (NXT_HAVE_MACOSX_SENDFILE)

    off_t sent = size;

    int rc = sendfile(fd, s, pos, &sent, NULL, 0);

    res = (rc == 0 || sent > 0) ? sent : -1;

#elif (NXT_HAVE_FREEBSD_SENDFILE)

    off_t sent = 0;

    int rc = sendfile(fd, s, pos, size, NULL, &sent, 0);

    res = (rc == 0 || sent > 0) ? sent : -1;

#elif (NXT_HAVE_LINUX_SENDFILE)

    res = sendfile(s, fd, &pos, size);

#else

    int    err;
    void   *map;
    off_t  page_off;

    page_off = pos % nxt_pagesize;

    map = nxt_mem_mmap(NULL, size + page_off, PROT_READ, MAP_SHARED, fd,
                       pos - page_off);
    if (nxt_slow_path(map == MAP_FAILED)) {
        return -1;
    }

    res = write(s, nxt_pointer_to(map, page_off), size);

    /* Backup and restore errno to catch socket errors in the upper level. */
    err = errno;
    nxt_mem_munmap(map, size + page_off);
    errno = err;

#endif

    return res;
}


ssize_t
nxt_conn_io_writev(nxt_task_t *task, nxt_sendbuf_t *sb, struct iovec *iov,
    nxt_uint_t niov)
{
    ssize_t    n;
    nxt_err_t  err;

    if (niov == 1) {
        /* Disposal of surplus kernel iovec copy-in operation. */
        return nxt_conn_io_send(task, sb, iov[0].iov_base, iov[0].iov_len);
    }

    for ( ;; ) {
        n = writev(sb->socket, iov, niov);

        err = (n == -1) ? nxt_socket_errno : 0;

        nxt_debug(task, "writev(%d, %ui): %z", sb->socket, niov, n);

        if (n > 0) {
            return n;
        }

        /* n == -1 */

        switch (err) {

        case NXT_EAGAIN:
            sb->ready = 0;
            nxt_debug(task, "writev() %E", err);

            return NXT_AGAIN;

        case NXT_EINTR:
            nxt_debug(task, "writev() %E", err);
            continue;

        default:
            sb->error = err;
            nxt_log(task, nxt_socket_error_level(err),
                    "writev(%d, %ui) failed %E", sb->socket, niov, err);

            return NXT_ERROR;
        }
    }
}


ssize_t
nxt_conn_io_send(nxt_task_t *task, nxt_sendbuf_t *sb, void *buf, size_t size)
{
    ssize_t    n;
    nxt_err_t  err;

    for ( ;; ) {
        n = send(sb->socket, buf, size, 0);

        err = (n == -1) ? nxt_socket_errno : 0;

        nxt_debug(task, "send(%d, %p, %uz): %z", sb->socket, buf, size, n);

        if (n > 0) {
            return n;
        }

        /* n == -1 */

        switch (err) {

        case NXT_EAGAIN:
            sb->ready = 0;
            nxt_debug(task, "send() %E", err);

            return NXT_AGAIN;

        case NXT_EINTR:
            nxt_debug(task, "send() %E", err);
            continue;

        default:
            sb->error = err;
            nxt_log(task, nxt_socket_error_level(err),
                    "send(%d, %p, %uz) failed %E", sb->socket, buf, size, err);

            return NXT_ERROR;
        }
    }
}


/* Obsolete interfaces. */

size_t
nxt_event_conn_write_limit(nxt_conn_t *c)
{
    ssize_t                 limit, correction;
    nxt_event_write_rate_t  *rate;

    rate = c->rate;

    if (rate == NULL) {
        return c->max_chunk;
    }

    limit = rate->limit;
    correction = limit - (size_t) rate->average;

    nxt_debug(c->socket.task, "event conn correction:%z average:%0.3f",
              correction, rate->average);

    limit += correction;

    if (limit <= 0) {
        return 0;
    }

    if (rate->limit_after != 0) {
        limit += rate->limit_after;
        limit = nxt_min((size_t) limit, rate->max_limit);
    }

    return nxt_min((size_t) limit, c->max_chunk);
}


nxt_bool_t
nxt_event_conn_write_delayed(nxt_event_engine_t *engine, nxt_conn_t *c,
    size_t sent)
{
    return 0;
}


ssize_t
nxt_event_conn_io_sendbuf(nxt_conn_t *c, nxt_buf_t *b, size_t limit)
{
    nxt_uint_t              niob;
    struct iovec            iob[NXT_IOBUF_MAX];
    nxt_sendbuf_coalesce_t  sb;

    sb.buf = b;
    sb.iobuf = iob;
    sb.nmax = NXT_IOBUF_MAX;
    sb.sync = 0;
    sb.size = 0;
    sb.limit = limit;

    niob = nxt_sendbuf_mem_coalesce(c->socket.task, &sb);

    if (niob == 0 && sb.sync) {
        return 0;
    }

    return nxt_event_conn_io_writev(c, iob, niob);
}


ssize_t
nxt_event_conn_io_writev(nxt_conn_t *c, nxt_iobuf_t *iob, nxt_uint_t niob)
{
    ssize_t    n;
    nxt_err_t  err;

    if (niob == 1) {
        /* Disposal of surplus kernel iovec copy-in operation. */
        return nxt_event_conn_io_send(c, iob->iov_base, iob->iov_len);
    }

    for ( ;; ) {
        n = writev(c->socket.fd, iob, niob);

        err = (n == -1) ? nxt_socket_errno : 0;

        nxt_debug(c->socket.task, "writev(%d, %ui): %z", c->socket.fd, niob, n);

        if (n > 0) {
            return n;
        }

        /* n == -1 */

        switch (err) {

        case NXT_EAGAIN:
            nxt_debug(c->socket.task, "writev() %E", err);
            c->socket.write_ready = 0;
            return NXT_AGAIN;

        case NXT_EINTR:
            nxt_debug(c->socket.task, "writev() %E", err);
            continue;

        default:
            c->socket.error = err;
            nxt_log(c->socket.task, nxt_socket_error_level(err),
                    "writev(%d, %ui) failed %E", c->socket.fd, niob, err);
            return NXT_ERROR;
        }
    }
}


ssize_t
nxt_event_conn_io_send(nxt_conn_t *c, void *buf, size_t size)
{
    ssize_t    n;
    nxt_err_t  err;

    for ( ;; ) {
        n = send(c->socket.fd, buf, size, 0);

        err = (n == -1) ? nxt_socket_errno : 0;

        nxt_debug(c->socket.task, "send(%d, %p, %uz): %z",
                  c->socket.fd, buf, size, n);

        if (n > 0) {
            return n;
        }

        /* n == -1 */

        switch (err) {

        case NXT_EAGAIN:
            nxt_debug(c->socket.task, "send() %E", err);
            c->socket.write_ready = 0;
            return NXT_AGAIN;

        case NXT_EINTR:
            nxt_debug(c->socket.task, "send() %E", err);
            continue;

        default:
            c->socket.error = err;
            nxt_log(c->socket.task, nxt_socket_error_level(err),
                    "send(%d, %p, %uz) failed %E",
                    c->socket.fd, buf, size, err);
            return NXT_ERROR;
        }
    }
}