/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */

#include "test/core/util/reconnect_server.h"

#include <grpc/grpc.h>
#include <grpc/support/alloc.h>
#include <grpc/support/host_port.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <grpc/support/time.h>
#include <string.h>
#include "src/core/iomgr/endpoint.h"
#include "src/core/iomgr/sockaddr.h"
#include "src/core/iomgr/tcp_server.h"
#include "test/core/util/port.h"

static void
pretty_print_backoffs (reconnect_server * server)
{
  gpr_timespec diff;
  int i = 1;
  double expected_backoff = 1000.0, backoff;
  timestamp_list *head = server->head;
  gpr_log (GPR_INFO, "reconnect server: new connection");
  for (head = server->head; head && head->next; head = head->next, i++)
    {
      diff = gpr_time_sub (head->next->timestamp, head->timestamp);
      backoff = gpr_time_to_millis (diff);
      gpr_log (GPR_INFO, "retry %2d:backoff %6.2fs,expected backoff %6.2fs, jitter %4.2f%%", i, backoff / 1000.0, expected_backoff / 1000.0, (backoff - expected_backoff) * 100.0 / expected_backoff);
      expected_backoff *= 1.6;
      if (expected_backoff > 120 * 1000)
	{
	  expected_backoff = 120 * 1000;
	}
    }
}

static void
on_connect (grpc_exec_ctx * exec_ctx, void *arg, grpc_endpoint * tcp)
{
  char *peer;
  char *last_colon;
  reconnect_server *server = (reconnect_server *) arg;
  gpr_timespec now = gpr_now (GPR_CLOCK_REALTIME);
  timestamp_list *new_tail;
  peer = grpc_endpoint_get_peer (tcp);
  grpc_endpoint_shutdown (exec_ctx, tcp);
  grpc_endpoint_destroy (exec_ctx, tcp);
  if (peer)
    {
      last_colon = strrchr (peer, ':');
      if (server->peer == NULL)
	{
	  server->peer = peer;
	}
      else
	{
	  if (last_colon == NULL)
	    {
	      gpr_log (GPR_ERROR, "peer does not contain a ':'");
	    }
	  else if (strncmp (server->peer, peer, (size_t) (last_colon - peer)) != 0)
	    {
	      gpr_log (GPR_ERROR, "mismatched peer! %s vs %s", server->peer, peer);
	    }
	  gpr_free (peer);
	}
    }
  new_tail = gpr_malloc (sizeof (timestamp_list));
  new_tail->timestamp = now;
  new_tail->next = NULL;
  if (server->tail == NULL)
    {
      server->head = new_tail;
      server->tail = new_tail;
    }
  else
    {
      server->tail->next = new_tail;
      server->tail = new_tail;
    }
  pretty_print_backoffs (server);
}

void
reconnect_server_init (reconnect_server * server)
{
  grpc_init ();
  server->tcp_server = NULL;
  grpc_pollset_init (&server->pollset);
  server->pollsets[0] = &server->pollset;
  server->head = NULL;
  server->tail = NULL;
  server->peer = NULL;
}

void
reconnect_server_start (reconnect_server * server, int port)
{
  struct sockaddr_in addr;
  int port_added;
  grpc_closure_list closure_list = GRPC_CLOSURE_LIST_INIT;

  addr.sin_family = AF_INET;
  addr.sin_port = htons ((gpr_uint16) port);
  memset (&addr.sin_addr, 0, sizeof (addr.sin_addr));

  server->tcp_server = grpc_tcp_server_create ();
  port_added = grpc_tcp_server_add_port (server->tcp_server, &addr, sizeof (addr));
  GPR_ASSERT (port_added == port);

  grpc_tcp_server_start (server->tcp_server, server->pollsets, 1, on_connect, server, &closure_list);
  gpr_log (GPR_INFO, "reconnect tcp server listening on 0.0.0.0:%d", port);

  grpc_exec_ctx_finish (&exec_ctx);
}

void
reconnect_server_poll (reconnect_server * server, int seconds)
{
  grpc_pollset_worker worker;
  gpr_timespec deadline = gpr_time_add (gpr_now (GPR_CLOCK_MONOTONIC),
					gpr_time_from_seconds (seconds, GPR_TIMESPAN));
  grpc_closure_list closure_list = GRPC_CLOSURE_LIST_INIT;
  gpr_mu_lock (GRPC_POLLSET_MU (&server->pollset));
  grpc_pollset_work (&server->pollset, &worker, gpr_now (GPR_CLOCK_MONOTONIC), deadline, &closure_list);
  gpr_mu_unlock (GRPC_POLLSET_MU (&server->pollset));
  grpc_exec_ctx_finish (&exec_ctx);
}

void
reconnect_server_clear_timestamps (reconnect_server * server)
{
  timestamp_list *new_head = server->head;
  while (server->head)
    {
      new_head = server->head->next;
      gpr_free (server->head);
      server->head = new_head;
    }
  server->tail = NULL;
  gpr_free (server->peer);
  server->peer = NULL;
}

static void
do_nothing (grpc_exec_ctx * exec_ctx, void *ignored, int success)
{
}

void
reconnect_server_destroy (reconnect_server * server)
{
  grpc_closure_list closure_list = GRPC_CLOSURE_LIST_INIT;
  grpc_closure do_nothing_closure[2];
  grpc_closure_init (&do_nothing_closure[0], do_nothing, NULL);
  grpc_closure_init (&do_nothing_closure[1], do_nothing, NULL);
  grpc_tcp_server_destroy (server->tcp_server, &do_nothing_closure[0], &closure_list);
  reconnect_server_clear_timestamps (server);
  grpc_pollset_shutdown (&server->pollset, &do_nothing_closure[1], &closure_list);
  grpc_exec_ctx_finish (&exec_ctx);
  grpc_pollset_destroy (&server->pollset);
  grpc_shutdown ();
}