/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 */

#include "uv.h"

#include "uv-common.h"

#ifdef _WIN32

#include "win/internal.h"

#include "win/handle-inl.h"

#define uv__make_close_pending(h) uv__want_endgame((h)->loop, (h))

#else

#include "unix/internal.h"

#endif

#include <assert.h>

#include <stdlib.h>

#include <string.h>

struct poll_ctx {

  uv_fs_poll_t* parent_handle;

  int busy_polling;

  unsigned int interval;

  uint64_t start_time;

  uv_loop_t* loop;

  uv_fs_poll_cb poll_cb;

  uv_timer_t timer_handle;

  uv_fs_t fs_req; /* TODO(bnoordhuis) mark fs_req internal */

  uv_stat_t statbuf;

  struct poll_ctx* previous; /* context from previous start()..stop() period */

  char path[1]; /* variable length */

};

static int statbuf_eq(const uv_stat_t* a, const uv_stat_t* b);

static void poll_cb(uv_fs_t* req);

static void timer_cb(uv_timer_t* timer);

static void timer_close_cb(uv_handle_t* handle);

static uv_stat_t zero_statbuf;

int uv_fs_poll_init(uv_loop_t* loop, uv_fs_poll_t* handle) {

  uv__handle_init(loop, (uv_handle_t*)handle, UV_FS_POLL);

  handle->poll_ctx = NULL;

  return 0;

}

int uv_fs_poll_start(uv_fs_poll_t* handle,

                     uv_fs_poll_cb cb,

                     const char* path,

                     unsigned int interval) {

  struct poll_ctx* ctx;

  uv_loop_t* loop;

  size_t len;

  int err;

  if (uv_is_active((uv_handle_t*)handle))

    return 0;

  loop = handle->loop;

  len = strlen(path);

  ctx = uv__calloc(1, sizeof(*ctx) + len);

  if (ctx == NULL)

    return UV_ENOMEM;

  ctx->loop = loop;

  ctx->poll_cb = cb;

  ctx->interval = interval ? interval : 1;

  ctx->start_time = uv_now(loop);

  ctx->parent_handle = handle;

  memcpy(ctx->path, path, len + 1);

  err = uv_timer_init(loop, &ctx->timer_handle);

  if (err < 0)

    goto error;

  ctx->timer_handle.flags |= UV_HANDLE_INTERNAL;

  uv__handle_unref(&ctx->timer_handle);

  err = uv_fs_stat(loop, &ctx->fs_req, ctx->path, poll_cb);

  if (err < 0)

    goto error;

  if (handle->poll_ctx != NULL)

    ctx->previous = handle->poll_ctx;

  handle->poll_ctx = ctx;

  uv__handle_start(handle);

  return 0;

error:

  uv__free(ctx);

  return err;

}

int uv_fs_poll_stop(uv_fs_poll_t* handle) {

  struct poll_ctx* ctx;

  if (!uv_is_active((uv_handle_t*)handle))

    return 0;

  ctx = handle->poll_ctx;

  assert(ctx != NULL);

  assert(ctx->parent_handle == handle);

  /* Close the timer if it's active. If it's inactive, there's a stat request

   * in progress and poll_cb will take care of the cleanup.

   */

  if (uv_is_active((uv_handle_t*)&ctx->timer_handle))

    uv_close((uv_handle_t*)&ctx->timer_handle, timer_close_cb);

  uv__handle_stop(handle);

  return 0;

}

int uv_fs_poll_getpath(uv_fs_poll_t* handle, char* buffer, size_t* size) {

  struct poll_ctx* ctx;

  size_t required_len;

  if (!uv_is_active((uv_handle_t*)handle)) {

    *size = 0;

    return UV_EINVAL;

  }

  ctx = handle->poll_ctx;

  assert(ctx != NULL);

  required_len = strlen(ctx->path);

  if (required_len >= *size) {

    *size = required_len + 1;

    return UV_ENOBUFS;

  }

  memcpy(buffer, ctx->path, required_len);

  *size = required_len;

  buffer[required_len] = '\0';

  return 0;

}

void uv__fs_poll_close(uv_fs_poll_t* handle) {

  uv_fs_poll_stop(handle);

  if (handle->poll_ctx == NULL)

    uv__make_close_pending((uv_handle_t*)handle);

}

static void timer_cb(uv_timer_t* timer) {

  struct poll_ctx* ctx;

  ctx = container_of(timer, struct poll_ctx, timer_handle);

  assert(ctx->parent_handle != NULL);

  assert(ctx->parent_handle->poll_ctx == ctx);

  ctx->start_time = uv_now(ctx->loop);

  if (uv_fs_stat(ctx->loop, &ctx->fs_req, ctx->path, poll_cb))

    abort();

}

static void poll_cb(uv_fs_t* req) {

  uv_stat_t* statbuf;

  struct poll_ctx* ctx;

  uint64_t interval;

  uv_fs_poll_t* handle;

  ctx = container_of(req, struct poll_ctx, fs_req);

  handle = ctx->parent_handle;

  if (!uv_is_active((uv_handle_t*)handle) || uv__is_closing(handle))

    goto out;

  if (req->result != 0) {

    if (ctx->busy_polling != req->result) {

      ctx->poll_cb(ctx->parent_handle,

                   req->result,

                   &ctx->statbuf,

                   &zero_statbuf);

      ctx->busy_polling = req->result;

    }

    goto out;

  }

  statbuf = &req->statbuf;

  if (ctx->busy_polling != 0)

    if (ctx->busy_polling < 0 || !statbuf_eq(&ctx->statbuf, statbuf))

      ctx->poll_cb(ctx->parent_handle, 0, &ctx->statbuf, statbuf);

  ctx->statbuf = *statbuf;

  ctx->busy_polling = 1;

out:

  uv_fs_req_cleanup(req);

  if (!uv_is_active((uv_handle_t*)handle) || uv__is_closing(handle)) {

    uv_close((uv_handle_t*)&ctx->timer_handle, timer_close_cb);

    return;

  }

  /* Reschedule timer, subtract the delay from doing the stat(). */

  interval = ctx->interval;

  interval -= (uv_now(ctx->loop) - ctx->start_time) % interval;

  if (uv_timer_start(&ctx->timer_handle, timer_cb, interval, 0))

    abort();

}

static void timer_close_cb(uv_handle_t* timer) {

  struct poll_ctx* ctx;

  struct poll_ctx* it;

  struct poll_ctx* last;

  uv_fs_poll_t* handle;

  ctx = container_of(timer, struct poll_ctx, timer_handle);

  handle = ctx->parent_handle;

  if (ctx == handle->poll_ctx) {

    handle->poll_ctx = ctx->previous;

    if (handle->poll_ctx == NULL && uv__is_closing(handle))

      uv__make_close_pending((uv_handle_t*)handle);

  } else {

    for (last = handle->poll_ctx, it = last->previous;

         it != ctx;

         last = it, it = it->previous) {

      assert(last->previous != NULL);

    }

    last->previous = ctx->previous;

  }

  uv__free(ctx);

}

static int statbuf_eq(const uv_stat_t* a, const uv_stat_t* b) {

  return a->st_ctim.tv_nsec == b->st_ctim.tv_nsec

      && a->st_mtim.tv_nsec == b->st_mtim.tv_nsec

      && a->st_birthtim.tv_nsec == b->st_birthtim.tv_nsec

      && a->st_ctim.tv_sec == b->st_ctim.tv_sec

      && a->st_mtim.tv_sec == b->st_mtim.tv_sec

      && a->st_birthtim.tv_sec == b->st_birthtim.tv_sec

      && a->st_size == b->st_size

      && a->st_mode == b->st_mode

      && a->st_uid == b->st_uid

      && a->st_gid == b->st_gid

      && a->st_ino == b->st_ino

      && a->st_dev == b->st_dev

      && a->st_flags == b->st_flags

      && a->st_gen == b->st_gen;

}

#if defined(_WIN32)

#include "win/internal.h"

#include "win/handle-inl.h"

void uv__fs_poll_endgame(uv_loop_t* loop, uv_fs_poll_t* handle) {

  assert(handle->flags & UV_HANDLE_CLOSING);

  assert(!(handle->flags & UV_HANDLE_CLOSED));

  uv__handle_close(handle);

}

#endif /* _WIN32 */