#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>

#include <uv.h>

static uv_tcp_t serversock;
static uv_timer_t stats;
static int connection_count = 0;

static void on_timer(uv_timer_t *timer) {
  printf("%d connections\n", connection_count);
}

static void alloc_buffer(uv_handle_t *handle, size_t suggested_size, uv_buf_t *buf) {
  buf->base = calloc(1, suggested_size);
  buf->len = suggested_size;
}

static void on_write_complete(uv_write_t *req, int status) {
  /* we could check status here, but we don't care; just free, and be done */
  free(req->data);
  free(req);
}

static void on_timer_closed(uv_handle_t *timer) {
  printf("Exiting after timer shutdown.\n");
  uv_stop(timer->loop);
}

static void on_serversock_closed(uv_handle_t *serversock) {
  printf("Shutting down statistics timer after server socket shutdown.\n");
  uv_timer_stop(&stats);
  uv_close((uv_handle_t *) &stats, on_timer_closed);
}

static void on_conn_closed(uv_handle_t *conn) {
  connection_count--;
  if (connection_count == 0) {
    printf("Shutting down server socket on zero connection count.\n");
    uv_close((uv_handle_t *) &serversock, on_serversock_closed);
  }
  free(conn);
}

static void on_input(uv_stream_t *conn, ssize_t nread, uv_buf_t const *buf) {
  if (nread < 0) {
    /* here we could check uv_last_error(conn->loop).code to see whether it's UV_EOF or not */
    /* but we don't care; just close, and be done */
    uv_close((uv_handle_t *) conn, on_conn_closed);
    if (buf->base != NULL) {
      free(buf->base);
    }
  } else {
    /* we just echo what came in. */
    uv_write_t *req = calloc(1, sizeof(uv_write_t));
    uv_buf_t outbuf = { .base = buf->base, .len = nread };
    req->data = buf->base;
    uv_write(req, conn, &outbuf, 1, on_write_complete);
  }
}

static void on_connection(uv_stream_t *serversock, int status) {
  uv_tcp_t *conn;

  if (status == -1) {
    /* error? */
    return;
  }

  conn = calloc(1, sizeof(uv_tcp_t));
  uv_tcp_init(serversock->loop, conn);
  if (uv_accept(serversock, (uv_stream_t *) conn) == 0) {
    connection_count++;
    uv_read_start((uv_stream_t *) conn, alloc_buffer, on_input);
  } else {
    uv_close((uv_handle_t *) conn, NULL);
  }
}

static int const PORTNUMBER = 5999;

int main(int argc, char const *argv[]) {
  uv_loop_t uv;
  struct sockaddr_in bind_addr;

  printf("uvserver; libuv version %s\n", uv_version_string());

  if (argc > 1) {
    return 0;
  }

  uv_loop_init(&uv);

  printf("Accepting connections on port %d.\n", PORTNUMBER);
  uv_tcp_init(&uv, &serversock);
  uv_ip4_addr("0.0.0.0", PORTNUMBER, &bind_addr);
  uv_tcp_bind(&serversock, (struct sockaddr const *) &bind_addr, 0);
  uv_listen((uv_stream_t *) &serversock, 4, on_connection);

  uv_timer_init(&uv, &stats);
  uv_timer_start(&stats, on_timer, 2000, 2000);

  uv_run(&uv, UV_RUN_DEFAULT);

  uv_loop_close(&uv);
  return 0;
}