/*
 *
 * Copyright 2015-2016, Google Inc.
 * All rights reserved.
 *
 * 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,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <grpc/support/port_platform.h>

#ifdef GPR_WINSOCK_SOCKET

#include "src/core/iomgr/sockaddr_win32.h"

#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/log_win32.h>
#include <grpc/support/slice_buffer.h>
#include <grpc/support/string_util.h>
#include <grpc/support/useful.h>

#include "src/core/iomgr/timer.h"
#include "src/core/iomgr/iocp_windows.h"
#include "src/core/iomgr/sockaddr.h"
#include "src/core/iomgr/sockaddr_utils.h"
#include "src/core/iomgr/socket_windows.h"
#include "src/core/iomgr/tcp_client.h"

static int set_non_block(SOCKET sock) {
  int status;
  unsigned long param = 1;
  DWORD ret;
  status =
      WSAIoctl(sock, FIONBIO, &param, sizeof(param), NULL, 0, &ret, NULL, NULL);
  return status == 0;
}

static int set_dualstack(SOCKET sock) {
  int status;
  unsigned long param = 0;
  status = setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, (const char *)&param,
                      sizeof(param));
  return status == 0;
}

int grpc_tcp_prepare_socket(SOCKET sock) {
  if (!set_non_block(sock)) return 0;
  if (!set_dualstack(sock)) return 0;
  return 1;
}

typedef struct grpc_tcp {
  /* This is our C++ class derivation emulation. */
  grpc_endpoint base;
  /* The one socket this endpoint is using. */
  grpc_winsocket *socket;
  /* Refcounting how many operations are in progress. */
  gpr_refcount refcount;

  grpc_closure on_read;
  grpc_closure on_write;

  grpc_closure *read_cb;
  grpc_closure *write_cb;
  gpr_slice read_slice;
  gpr_slice_buffer *write_slices;
  gpr_slice_buffer *read_slices;

  /* The IO Completion Port runs from another thread. We need some mechanism
     to protect ourselves when requesting a shutdown. */
  gpr_mu mu;
  int shutting_down;

  char *peer_string;
} grpc_tcp;

static void tcp_free(grpc_tcp *tcp) {
  grpc_winsocket_destroy(tcp->socket);
  gpr_mu_destroy(&tcp->mu);
  gpr_free(tcp->peer_string);
  gpr_free(tcp);
}

/*#define GRPC_TCP_REFCOUNT_DEBUG*/
#ifdef GRPC_TCP_REFCOUNT_DEBUG
#define TCP_UNREF(tcp, reason) tcp_unref((tcp), (reason), __FILE__, __LINE__)
#define TCP_REF(tcp, reason) tcp_ref((tcp), (reason), __FILE__, __LINE__)
static void tcp_unref(grpc_tcp *tcp, const char *reason, const char *file,
                      int line) {
  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "TCP unref %p : %s %d -> %d", tcp,
          reason, tcp->refcount.count, tcp->refcount.count - 1);
  if (gpr_unref(&tcp->refcount)) {
    tcp_free(tcp);
  }
}

static void tcp_ref(grpc_tcp *tcp, const char *reason, const char *file,
                    int line) {
  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "TCP   ref %p : %s %d -> %d", tcp,
          reason, tcp->refcount.count, tcp->refcount.count + 1);
  gpr_ref(&tcp->refcount);
}
#else
#define TCP_UNREF(tcp, reason) tcp_unref((tcp))
#define TCP_REF(tcp, reason) tcp_ref((tcp))
static void tcp_unref(grpc_tcp *tcp) {
  if (gpr_unref(&tcp->refcount)) {
    tcp_free(tcp);
  }
}

static void tcp_ref(grpc_tcp *tcp) { gpr_ref(&tcp->refcount); }
#endif

/* Asynchronous callback from the IOCP, or the background thread. */
static void on_read(grpc_exec_ctx *exec_ctx, void *tcpp, bool success) {
  grpc_tcp *tcp = tcpp;
  grpc_closure *cb = tcp->read_cb;
  grpc_winsocket *socket = tcp->socket;
  gpr_slice sub;
  grpc_winsocket_callback_info *info = &socket->read_info;

  if (success) {
    if (socket->read_info.wsa_error != 0 && !tcp->shutting_down) {
      if (socket->read_info.wsa_error != WSAECONNRESET) {
        char *utf8_message = gpr_format_message(info->wsa_error);
        gpr_log(GPR_ERROR, "ReadFile overlapped error: %s", utf8_message);
        gpr_free(utf8_message);
      }
      success = 0;
      gpr_slice_unref(tcp->read_slice);
    } else {
      if (info->bytes_transfered != 0 && !tcp->shutting_down) {
        sub = gpr_slice_sub_no_ref(tcp->read_slice, 0, info->bytes_transfered);
        gpr_slice_buffer_add(tcp->read_slices, sub);
        success = 1;
      } else {
        gpr_slice_unref(tcp->read_slice);
        success = 0;
      }
    }
  }

  tcp->read_cb = NULL;
  TCP_UNREF(tcp, "read");
  if (cb) {
    cb->cb(exec_ctx, cb->cb_arg, success);
  }
}

static void win_read(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                     gpr_slice_buffer *read_slices, grpc_closure *cb) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  grpc_winsocket *handle = tcp->socket;
  grpc_winsocket_callback_info *info = &handle->read_info;
  int status;
  DWORD bytes_read = 0;
  DWORD flags = 0;
  WSABUF buffer;

  if (tcp->shutting_down) {
    grpc_exec_ctx_enqueue(exec_ctx, cb, false, NULL);
    return;
  }

  tcp->read_cb = cb;
  tcp->read_slices = read_slices;
  gpr_slice_buffer_reset_and_unref(read_slices);

  tcp->read_slice = gpr_slice_malloc(8192);

  buffer.len = (ULONG)GPR_SLICE_LENGTH(
      tcp->read_slice);  // we know slice size fits in 32bit.
  buffer.buf = (char *)GPR_SLICE_START_PTR(tcp->read_slice);

  TCP_REF(tcp, "read");

  /* First let's try a synchronous, non-blocking read. */
  status =
      WSARecv(tcp->socket->socket, &buffer, 1, &bytes_read, &flags, NULL, NULL);
  info->wsa_error = status == 0 ? 0 : WSAGetLastError();

  /* Did we get data immediately ? Yay. */
  if (info->wsa_error != WSAEWOULDBLOCK) {
    info->bytes_transfered = bytes_read;
    grpc_exec_ctx_enqueue(exec_ctx, &tcp->on_read, true, NULL);
    return;
  }

  /* Otherwise, let's retry, by queuing a read. */
  memset(&tcp->socket->read_info.overlapped, 0, sizeof(OVERLAPPED));
  status = WSARecv(tcp->socket->socket, &buffer, 1, &bytes_read, &flags,
                   &info->overlapped, NULL);

  if (status != 0) {
    int wsa_error = WSAGetLastError();
    if (wsa_error != WSA_IO_PENDING) {
      info->wsa_error = wsa_error;
      grpc_exec_ctx_enqueue(exec_ctx, &tcp->on_read, false, NULL);
      return;
    }
  }

  grpc_socket_notify_on_read(exec_ctx, tcp->socket, &tcp->on_read);
}

/* Asynchronous callback from the IOCP, or the background thread. */
static void on_write(grpc_exec_ctx *exec_ctx, void *tcpp, bool success) {
  grpc_tcp *tcp = (grpc_tcp *)tcpp;
  grpc_winsocket *handle = tcp->socket;
  grpc_winsocket_callback_info *info = &handle->write_info;
  grpc_closure *cb;

  gpr_mu_lock(&tcp->mu);
  cb = tcp->write_cb;
  tcp->write_cb = NULL;
  gpr_mu_unlock(&tcp->mu);

  if (success) {
    if (info->wsa_error != 0) {
      if (info->wsa_error != WSAECONNRESET) {
        char *utf8_message = gpr_format_message(info->wsa_error);
        gpr_log(GPR_ERROR, "WSASend overlapped error: %s", utf8_message);
        gpr_free(utf8_message);
      }
      success = 0;
    } else {
      GPR_ASSERT(info->bytes_transfered == tcp->write_slices->length);
    }
  }

  TCP_UNREF(tcp, "write");
  cb->cb(exec_ctx, cb->cb_arg, success);
}

/* Initiates a write. */
static void win_write(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                      gpr_slice_buffer *slices, grpc_closure *cb) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  grpc_winsocket *socket = tcp->socket;
  grpc_winsocket_callback_info *info = &socket->write_info;
  unsigned i;
  DWORD bytes_sent;
  int status;
  WSABUF local_buffers[16];
  WSABUF *allocated = NULL;
  WSABUF *buffers = local_buffers;
  size_t len;

  if (tcp->shutting_down) {
    grpc_exec_ctx_enqueue(exec_ctx, cb, false, NULL);
    return;
  }

  tcp->write_cb = cb;
  tcp->write_slices = slices;
  GPR_ASSERT(tcp->write_slices->count <= UINT_MAX);
  if (tcp->write_slices->count > GPR_ARRAY_SIZE(local_buffers)) {
    buffers = (WSABUF *)gpr_malloc(sizeof(WSABUF) * tcp->write_slices->count);
    allocated = buffers;
  }

  for (i = 0; i < tcp->write_slices->count; i++) {
    len = GPR_SLICE_LENGTH(tcp->write_slices->slices[i]);
    GPR_ASSERT(len <= ULONG_MAX);
    buffers[i].len = (ULONG)len;
    buffers[i].buf = (char *)GPR_SLICE_START_PTR(tcp->write_slices->slices[i]);
  }

  /* First, let's try a synchronous, non-blocking write. */
  status = WSASend(socket->socket, buffers, (DWORD)tcp->write_slices->count,
                   &bytes_sent, 0, NULL, NULL);
  info->wsa_error = status == 0 ? 0 : WSAGetLastError();

  /* We would kind of expect to get a WSAEWOULDBLOCK here, especially on a busy
     connection that has its send queue filled up. But if we don't, then we can
     avoid doing an async write operation at all. */
  if (info->wsa_error != WSAEWOULDBLOCK) {
    bool ok = false;
    if (status == 0) {
      ok = true;
      GPR_ASSERT(bytes_sent == tcp->write_slices->length);
    } else {
      if (socket->read_info.wsa_error != WSAECONNRESET) {
        char *utf8_message = gpr_format_message(info->wsa_error);
        gpr_log(GPR_ERROR, "WSASend error: %s", utf8_message);
        gpr_free(utf8_message);
      }
    }
    if (allocated) gpr_free(allocated);
    grpc_exec_ctx_enqueue(exec_ctx, cb, ok, NULL);
    return;
  }

  TCP_REF(tcp, "write");

  /* If we got a WSAEWOULDBLOCK earlier, then we need to re-do the same
     operation, this time asynchronously. */
  memset(&socket->write_info.overlapped, 0, sizeof(OVERLAPPED));
  status = WSASend(socket->socket, buffers, (DWORD)tcp->write_slices->count,
                   &bytes_sent, 0, &socket->write_info.overlapped, NULL);
  if (allocated) gpr_free(allocated);

  if (status != 0) {
    int wsa_error = WSAGetLastError();
    if (wsa_error != WSA_IO_PENDING) {
      TCP_UNREF(tcp, "write");
      grpc_exec_ctx_enqueue(exec_ctx, cb, false, NULL);
      return;
    }
  }

  /* As all is now setup, we can now ask for the IOCP notification. It may
     trigger the callback immediately however, but no matter. */
  grpc_socket_notify_on_write(exec_ctx, socket, &tcp->on_write);
}

static void win_add_to_pollset(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                               grpc_pollset *ps) {
  grpc_tcp *tcp;
  (void)ps;
  tcp = (grpc_tcp *)ep;
  grpc_iocp_add_socket(tcp->socket);
}

static void win_add_to_pollset_set(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep,
                                   grpc_pollset_set *pss) {
  grpc_tcp *tcp;
  (void)pss;
  tcp = (grpc_tcp *)ep;
  grpc_iocp_add_socket(tcp->socket);
}

/* Initiates a shutdown of the TCP endpoint. This will queue abort callbacks
   for the potential read and write operations. It is up to the caller to
   guarantee this isn't called in parallel to a read or write request, so
   we're not going to protect against these. However the IO Completion Port
   callback will happen from another thread, so we need to protect against
   concurrent access of the data structure in that regard. */
static void win_shutdown(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  gpr_mu_lock(&tcp->mu);
  /* At that point, what may happen is that we're already inside the IOCP
     callback. See the comments in on_read and on_write. */
  tcp->shutting_down = 1;
  grpc_winsocket_shutdown(tcp->socket);
  gpr_mu_unlock(&tcp->mu);
}

static void win_destroy(grpc_exec_ctx *exec_ctx, grpc_endpoint *ep) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  TCP_UNREF(tcp, "destroy");
}

static char *win_get_peer(grpc_endpoint *ep) {
  grpc_tcp *tcp = (grpc_tcp *)ep;
  return gpr_strdup(tcp->peer_string);
}

static grpc_endpoint_vtable vtable = {win_read, win_write, win_add_to_pollset,
                                      win_add_to_pollset_set, win_shutdown,
                                      win_destroy, win_get_peer};

grpc_endpoint *grpc_tcp_create(grpc_winsocket *socket, char *peer_string) {
  grpc_tcp *tcp = (grpc_tcp *)gpr_malloc(sizeof(grpc_tcp));
  memset(tcp, 0, sizeof(grpc_tcp));
  tcp->base.vtable = &vtable;
  tcp->socket = socket;
  gpr_mu_init(&tcp->mu);
  gpr_ref_init(&tcp->refcount, 1);
  grpc_closure_init(&tcp->on_read, on_read, tcp);
  grpc_closure_init(&tcp->on_write, on_write, tcp);
  tcp->peer_string = gpr_strdup(peer_string);
  return &tcp->base;
}

#endif /* GPR_WINSOCK_SOCKET */