/*
 * Secure X Message Passing Library v2 implementation.
 * (sxmplv2) it superseed all versions before due to the:
 * - memory consumption
 * - new features such as pulse emitting
 * - performance optimization
 *
 * (c) Askele Group 2013-2015 <http://askele.com>
 * (c) Alexander Vdolainen 2013-2015,2016 <avdolainen@zoho.com>
 *
 * libsxmp is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * libsxmp is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.";
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <fcntl.h>

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/engine.h>

#include <tdata/usrtc.h>
#include <tdata/list.h>
#include <sexpr/sexp.h>

#include <sxmp/limits.h>
#include <sxmp/sxmp.h>

#include "internal.h"

static void __free_listentry(struct _stream_list_node *listentry);

static int __flag_check(int s_flag, int d_flag)
{
  int i;

  for(i = 1; i < 7; i++)
    if((d_flag & (1 << i)) && !(s_flag & (1 << i))) return 1;

  return 0;
}

static sxstream_t *__stream_open(sxlink_t *link, sxchnl_t *channel, const char *opt,
                                 struct sxstream_description *desc, int stid, int flags)
{
  char *msgbuf = NULL;
  size_t mlen = 0;
  sxstream_t *ss = NULL;
  sxmsg_t *msg = NULL;
  char *buf = NULL;
  sexp_t *sx, *isx;
  uint64_t sid = 0;
  int r = 0, idx;

  /* check flags */
  if(__flag_check(desc->flags, flags)) {
    errno = SXE_EPERM;
    goto __fini;
  }

  /* time to alloc all stuff */
  mlen = strlen(_SXSTREAMOPEN_CMD) + strlen(_SXSTREAMTYPE_PREFIX) + strlen(_SXSTREAMFLAGS_PREFIX);
  if(!opt)
    mlen += (_SXSTREAMOPEN_ADDMINLEN + sizeof(char));
  else mlen += (_SXSTREAMOPEN_ADDMAXLEN + sizeof(char)) + strlen(opt);

  if(!(msgbuf = malloc(mlen*sizeof(char)))) {
    errno = SXE_ENOMEM;
    goto __fini;
  }

  if(!opt)
    mlen = snprintf(msgbuf, mlen, "(%s (%s %d)(%s %d))", _SXSTREAMOPEN_CMD,
                    _SXSTREAMTYPE_PREFIX, stid, _SXSTREAMFLAGS_PREFIX, flags);
  else
    mlen = snprintf(msgbuf, mlen, "(%s (%s %d)(%s %d)(%s \"%s\"))", _SXSTREAMOPEN_CMD,
                    _SXSTREAMTYPE_PREFIX, stid, _SXSTREAMFLAGS_PREFIX, flags,
                    _SXSTREAMOPT_PREFIX, opt);

  r = sxmsg_send(channel, msgbuf, mlen + sizeof(char), &msg);
  if(r != SXE_RAPIDMSG) {
    errno = r;
    goto __fini;
  }

  /* time to get the special id, put it to the link and clean up all */
  buf = sxmsg_rapidbuf(msg);
  if(!(sx = parse_sexp(buf, strlen(buf)))) {
    errno = SXE_ENOMEM;
    sxmsg_clean(msg);
    goto __fini;
  } else  sxmsg_clean(msg);

  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(isx->ty == SEXP_LIST) r = SXE_BADPROTO;

    if(!idx && strcmp(isx->val, _SXSTREAMOPEN_CMD_R)) r = SXE_BADPROTO;
    if(idx && idx < 2) sid = strtoul(isx->val, NULL, 0);
    if(idx >= 2) r = SXE_BADPROTO;
  }

  destroy_sexp(sx);

  if(!r) {
    if(!(ss = malloc(sizeof(sxstream_t)))) {
      errno = SXE_ENOMEM;
      goto __fini;
    }

    memset(ss, 0, sizeof(sxstream_t));
    ss->flags = flags;
    ss->sid = sid;
    ss->link = link;
    ss->channel = channel;
  } else errno = r;

 __fini:
  if(msgbuf) free(msgbuf);

  return ss;
}

static struct sxstream_description *__get_stream_description(sxlink_t *link, int stid)
{
  usrtc_node_t *node = NULL;
  struct sxstream_description *s_desc = NULL;

  if(!link->remote_streams) return NULL;
  else node = usrtc_lookup(link->remote_streams, &stid);

  if(node) s_desc = (struct sxstream_description *)usrtc_node_getdata(node);

  return s_desc;
}

/*
 * NOTE: sxstream operations (except opening process i.e. few threads
 *       can open different streams) are NOT _thread-safe_, please
 *       care about that in your own application.
 */
sxstream_t *sxstream_open(sxlink_t *link, const char *opt, int stid, int flags)
{
  sxchnl_t *channel = NULL;
  struct sxstream_description *s_desc;
  sxstream_t *ss = NULL;
  int r = 0;

  if(!link) {
    r = SXE_FAILED;
    goto __fini;
  }
  if(!link->remote_streams) {
    r = SXE_NOSUCHSTREAMTYPE;
    goto __fini;
  }

  /* ok, let's a deal with channel */
  if(!(s_desc = __get_stream_description(link, stid))) {
    r = SXE_NOSUCHSTREAMTYPE;
    goto __fini;
  } else channel = sxchannel_open(link, s_desc->pcid);

  if(!channel) {
    r = errno;
    goto __fini;
  }

  flags |= SXE_O_OCHANNELED;
  ss = __stream_open(link, channel, opt, s_desc, stid, flags);

 __fini:
  errno = r;
  if(!ss && channel) sxchannel_close(channel);

  return ss;
}

sxstream_t *sxstream_openwch(sxlink_t *link, sxchnl_t *channel, const char *opt,
                             int stid, int flags)
{
  struct sxstream_description *s_desc = NULL;
  sxstream_t *ss = NULL;
  int r = 0;

  if(!link || !channel) {
    r = SXE_FAILED;
    goto __fini;
  }
  if(!link->remote_streams) {
    r = SXE_NOSUCHSTREAMTYPE;
    goto __fini;
  }

  /* get description */
  if(!(s_desc = __get_stream_description(link, stid))) {
    r = SXE_NOSUCHSTREAMTYPE;
    goto __fini;
  }

  ss = __stream_open(link, channel, opt, s_desc, stid, flags);

 __fini:
  errno = r;
  return ss;
}

int sxstream_close(sxstream_t *stream)
{
  sxmsg_t *msg = NULL;
  char *mbuf;
  list_node_t *iter, *s_iter;
  struct _stream_list_node *listentry;
  size_t mbuf_len = strlen(_SXSTREAMCLOSE_CMD) + _SXSTREAMCLOSE_ADDLEN;
  int r = 0;

  if(!stream) return SXE_FAILED;
  if(!stream->link || !stream->channel) return SXE_FAILED;
  if(!(mbuf = malloc(mbuf_len))) return SXE_ENOMEM;
  else mbuf_len = snprintf(mbuf, mbuf_len, "(%s %lu)", _SXSTREAMCLOSE_CMD, stream->sid);

  r = sxmsg_send(stream->channel, mbuf, mbuf_len + sizeof(char), &msg);
  if(r == SXE_RAPIDMSG)    sxmsg_clean(msg);

  if(r == SXE_SUCCESS) {
    /* TODO: free all caches, buffers etc */
    if(!(stream->flags & SXE_O_BINARY)) {
      if(!(stream->flags & SXE_O_NAMED) && stream->entries) {
        list_for_each_safe(stream->entries, iter, s_iter) {
          listentry = list_entry(iter, struct _stream_list_node, node);
          list_del(iter);
          __free_listentry(listentry);
        }
      }
    }
    if(stream->flags & SXE_O_OCHANNELED)
      r = sxchannel_close(stream->channel);

    free(stream);
  }

  free(mbuf);

  return r;
}

/* binary stream operations */
/*
 * NOTE: it will be done with with a copy paste,
 * there are todo - implement it with oilite style.
 */
size_t sxstream_bread(sxstream_t *stream, void *buf, size_t buf_len)
{
  return -1;
}

size_t sxstream_breadat(sxstream_t *stream, void *buf, size_t buf_len, off_t off)
{
  return -1;
}

size_t sxstream_bwriteat(sxstream_t *stream, const void *buf,
                         size_t buf_len, off_t off)
{
  return -1;
}

size_t sxstream_bsyncat(sxstream_t *stream, void *buf, size_t buf_len, off_t off)
{
  return -1;
}

/*
 * NOTE: returning value for reading from entry streams
 *       shouldn't be managed, it's done by close operation.
 *       That means you should care about ridden values, since
 *       it might be freed on the next read operation.
 */
static struct _nn_stream_entry_node *__alloc_entry(const char *value)
{
  struct _nn_stream_entry_node *o = malloc(sizeof(struct _nn_stream_entry_node));

  if(!o) return NULL;
  if(!(o->value = strdup(value))) {
    free(o);
    return NULL;
  }

  list_init_node(&o->node);

  return o;
}

static void __free_entry(struct _nn_stream_entry_node *entry)
{
  free(entry->value);
  free(entry);

  return;
}

static struct _stream_list_node *__alloc_listentry(void)
{
  struct _stream_list_node *o = malloc(sizeof(struct _stream_list_node));

  if(!o) return NULL;
  if(!(o->list = malloc(sizeof(list_head_t)))) {
    free(o);
    return NULL;
  }

  list_init_head(o->list);
  list_init_node(&o->node);

  return o;
}

static void __free_listentry(struct _stream_list_node *listentry)
{
  struct _nn_stream_entry_node *entry;
  list_node_t *iter, *s_iter;

  list_for_each_safe(listentry->list, iter, s_iter) {
    entry = list_entry(iter, struct _nn_stream_entry_node, node);
    list_del(iter);
    __free_entry(entry);
  }

  free(listentry->list);
  free(listentry);

  return;
}

/* entry nonamed stream ops */
list_head_t *sxstream_read(sxstream_t *stream)
{
  sxmsg_t *msg;
  size_t mbuf_len;
  char *mbuf = NULL;
  list_node_t *cur = NULL, *iter, *s_iter;
  struct _stream_list_node *listentry = NULL;
  struct _nn_stream_entry_node *entry = NULL;
  sexp_t *sx, *isx, *iisx;
  int r = 0, idx, iidx;

  errno = SXE_FAILED;
  if(!stream) goto __fail;
  if(!stream->link || !stream->channel) goto __fail;

  if(stream->entries) {
    if(stream->cur == list_node_last(stream->entries)) {
      cur = stream->cur;
      stream->cur = NULL; /* we need to read from remote again on the next operation */
    } else if(stream->cur && stream->cur != list_node_last(stream->entries)) {
      cur = stream->cur;
      if(!list_node_next_isbound(cur))
        stream->cur = stream->cur->next;
      else stream->cur = NULL;
    } else       goto __read_seq;

  __success:
    if(cur) {
      errno = 0;
      listentry = list_entry(cur, struct _stream_list_node, node);
      return listentry->list;
    } else return NULL;
  }

 __read_seq:
  errno = SXE_ENOMEM;

  if(stream->entries) { /* ok, clean up all stuff */
    list_for_each_safe(stream->entries, iter, s_iter) {
      listentry = list_entry(iter, struct _stream_list_node, node);
      list_del(iter);
      __free_listentry(listentry);
    }
  } else { /* allocate it first time */
    if(!(stream->entries = malloc(sizeof(list_head_t)))) goto __fail;

    list_init_head(stream->entries);
  }

  /* prepare a message */
  mbuf_len = strlen(_SXSTREAMEREAD_CMD) + _SXSTREAMEREAD_ADDLEN;
  if(!(mbuf = malloc(mbuf_len))) goto __fail;

  mbuf_len = snprintf(mbuf, mbuf_len, "(%s)", _SXSTREAMEREAD_CMD);
  r = sxmsg_send(stream->channel, mbuf, mbuf_len, &msg);
  switch(r) {
  case SXE_RAPIDMSG: /* get our data */
    sx = parse_sexp(sxmsg_payload(msg), strlen(sxmsg_payload(msg)));
    sxmsg_clean(msg);

    if(!sx) {
    __badproto:
      if(sx) destroy_sexp(sx);
      errno = SXE_BADPROTO;
      goto __fail;
    }

    SEXP_ITERATE_LIST(sx, isx, idx) {
      if(isx->ty != SEXP_LIST)         goto __badproto;

      /* allocate list entry and add it */
      if(!(listentry = __alloc_listentry())) {
      __enomem:
        errno = SXE_ENOMEM;
        destroy_sexp(sx);
        goto __fail;
      } else list_add2tail(stream->entries, &listentry->node);

      SEXP_ITERATE_LIST(isx, iisx, iidx) {
        if(isx->ty == SEXP_LIST) goto __badproto;
        if(!(entry = __alloc_entry((const char *)iisx->val))) goto __enomem;
        else list_add2tail(listentry->list, &entry->node);
      }
    }

    /* ok let's see what we got */
    if(idx) {
      stream->cur = list_node_first(stream->entries);
      cur = stream->cur;

      /* point to the next one if exists */
      if(!list_node_next_isbound(cur)) stream->cur = stream->cur->next;
      else stream->cur = NULL;
    } else {
      errno = SXE_NILREPLY;
      stream->cur = NULL;
      cur = NULL;
    }

    destroy_sexp(sx);
    break;
  case SXE_EOS: /* stream is over */
    errno = SXE_EOS;
    cur = NULL;
    break;
  default:
    errno = r;
    goto __fail;
    break;
  }

  free(mbuf);

  goto __success;

 __fail:
  if(mbuf) free(mbuf);
  return NULL;
}

/* entry named stream ops */
list_head_t *sxstream_readnamed(sxstream_t *stream)
{
  return NULL;
}

/* builtin functions for streams */
static struct sxstream_opened *__alloc_stream(sxlink_t *link)
{
  int idx;
  struct sxstream_opened *stream;

  pthread_mutex_lock(&link->idx_streams_lock);
  idx = idx_allocate(&link->idx_streams);
  pthread_mutex_unlock(&link->idx_streams_lock);
  if(idx == IDX_INVAL) return NULL;
  else stream = link->streams[idx];

  if(!link->streams[idx] && !(stream = malloc(sizeof(struct sxstream_opened)))) {
  __inval:
    pthread_mutex_lock(&link->idx_streams_lock);
    idx_free(&link->idx_streams, idx);
    pthread_mutex_unlock(&link->idx_streams_lock);

    return NULL;
  } else if(link->streams[idx]) goto __inval;

  memset(stream, 0, sizeof(struct sxstream_opened));
  stream->sto_id = idx;
  link->streams[idx] = stream;

  return stream;
}

static void __free_stream(sxlink_t *link, struct sxstream_opened *stream)
{
  pthread_mutex_lock(&link->idx_streams_lock);
  idx_free(&link->idx_streams, stream->sto_id);
  link->streams[stream->sto_id] = NULL;
  pthread_mutex_unlock(&link->idx_streams_lock);

  free(stream);

  return;
}

int _builtin_stream_open(void *m, sexp_t *sx)
{
  sxmsg_t *msg = (sxmsg_t *)m;
  sxchnl_t *channel = msg->pch;
  sxlink_t *link = NULL;
  sxhub_t *hub;
  sexp_t *isx, *iisx;
  char *rbuf = NULL, *opt = NULL, *s_opt = NULL;
  usrtc_node_t *node;
  struct sxstream_description *s_desc;
  struct sxstream_opened *strea;
  size_t rbuf_len;
  int chan_type, idx, r = SXE_FAILED;
  int flags = 0, des_type, iidx;

  if(!channel) goto __fail;
  link = channel->link;
  chan_type = channel->type_id;

  if(!link || !channel->rpc_list) goto __fail; /* paranoid test */

  /* parse incoming builtin function */
  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(!idx && isx->ty == SEXP_LIST) {
    __badproto:
      r = SXE_BADPROTO;
      goto __fail;
    } else if(idx && isx->ty != SEXP_LIST) goto __badproto;

    if(isx->ty == SEXP_LIST) {
      SEXP_ITERATE_LIST(isx, iisx, iidx) {
        if(iisx->ty == SEXP_LIST) goto __badproto;
        switch(iidx) {
        case 0:
          opt = iisx->val;

          if(*opt != ':') goto __badproto;
          break;
        case 1:
          if(!strcmp(opt, _SXSTREAMTYPE_PREFIX)) des_type = atoi(iisx->val);
          else if(!strcmp(opt, _SXSTREAMFLAGS_PREFIX)) flags = atoi(iisx->val);
          else if(!strcmp(opt, _SXSTREAMOPT_PREFIX)) s_opt = iisx->val;
          else goto __badproto;
          break;
        default: goto __badproto; break;
        }
      }
    } else goto __badproto;
  }

  /* check availability */
  hub = link->ssys;
  if(!hub->streams) {
  __nostream:
    r = SXE_NOSUCHSTREAMTYPE;
    goto __fail;
  }
  if(!(node = usrtc_lookup(hub->streams, &des_type))) goto __nostream;
  else s_desc = (struct sxstream_description *)usrtc_node_getdata(node);

  if(s_desc->pcid != chan_type) { /* check permission by channel */
  __eperm:
    r = SXE_EPERM;
    goto __fail;
  }
  if(__flag_check(s_desc->flags, flags)) goto __eperm; /* by flags */

  /* create a new remote side channel */
  if(!(strea = __alloc_stream(link))) {
    r = SXE_ENOMEM;
    goto __fail;
  }

  /* rbuf length */
  rbuf_len = _SXSTREAMCLOSE_ADDLEN + strlen(_SXSTREAMOPEN_CMD_R);

  /* set stream details */
  strea->desc = s_desc;
  strea->flags = flags;
  strea->pin_channelid = channel->cid;

  r = s_desc->ops->s_open(link, strea, s_opt);
  if(r != SXE_SUCCESS) {
    /* deallocate stream */
    __free_stream(link, strea);
    goto __fail;
  }
  rbuf = sxmsg_rapidbuf(msg);
  rbuf_len = snprintf(rbuf, rbuf_len, "(%s %lu)", _SXSTREAMOPEN_CMD_R,
                      strea->sto_id);

  return sxmsg_rreply(msg, rbuf_len + sizeof(char));

 __fail:

  return sxmsg_return(msg, r);
}

int _builtin_stream_close(void *m, sexp_t *sx)
{
  sxmsg_t *msg = (sxmsg_t *)m;
  sxchnl_t *channel = msg->pch;
  sxlink_t *link = NULL;
  struct sxstream_opened *stream = NULL;
  sexp_t *isx;
  uint64_t sid = 0;
  int r = SXE_FAILED, idx;

  if(!channel) goto __fini;
  link = channel->link;

  if(!link || !channel->rpc_list) goto __fini; /* paranoid test */

  /* parse input */
  SEXP_ITERATE_LIST(sx, isx, idx) {
    if(isx->ty == SEXP_LIST) {
    __badproto:
      r = SXE_BADPROTO;
      goto __fini;
    }
    switch(idx) {
    case 0: r = SXE_BADPROTO; break;
    case 1: sid = strtoul(isx->val, NULL, 0); r = SXE_SUCCESS; break;
    default: goto __badproto; break;
    }
  }
  if(r != SXE_SUCCESS) goto __fini;

  /* get this */
  stream = link->streams[(int)sid];
  if(stream) {
    if(stream->pin_channelid == channel->cid) {
      r = SXE_SUCCESS;
      r = stream->desc->ops->s_close(stream);
    } else r = SXE_EPERM;
  } else r = SXE_NOSUCHSTREAMTYPE;

 __fini:
  return sxmsg_return(msg, r);
}

int _builtin_stream_eread(void *m, sexp_t *sx)
{
  sxmsg_t *msg = (sxmsg_t *)m;

  return sxmsg_return(msg, SXE_FAILED);
}