/*
  $Id$

  Copyright (c) 2006 Joshua Elsasser. All rights reserved.
   
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:
   
   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
   2. 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.
   
  THIS SOFTWARE IS PROVIDED BY AUTHOR 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 <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>

#include <glib.h>

#include "io.h"
#include "util.h"

#define IO_BLOCKSIZE            (1024)

struct iosource {
  GSource source;
  GPollFD infd;
  GPollFD outfd;
  ioidfunc_t sent;
  iodatafunc_t received;
  ionewfunc_t accepted;
  iofunc_t closed;
  void *cbdata;
  char *inbuf;
  unsigned int inused;
  unsigned int inmax;
  GList *outbufs;
  unsigned int lastid;
};

struct iooutbuf {
  char *data;
  unsigned int len;
  unsigned int off;
  unsigned int id;
};

static gboolean
nonblock(int fd);
static struct iosource *
newsource(void);
static void
freeoutbuf(struct iooutbuf *buf);
static gboolean
io_prepare(GSource *source, gint *timeout_);
static gboolean
io_check(GSource *source);
static gboolean
io_dispatch(GSource *source, GSourceFunc callback, gpointer gdata);
static void
io_finalize(GSource *source);
static void
io_accept(struct iosource *io);
static void
io_read(struct iosource *io);
static void
io_write(struct iosource *io);
static void
io_disconnect(struct iosource *io, int err);

static GSourceFuncs sourcefuncs = {
  io_prepare,
  io_check,
  io_dispatch,
  io_finalize,
  NULL,
  NULL
};

GSource *
io_new(int fd, ioidfunc_t sent, iodatafunc_t received,
       iofunc_t closed, void *cbdata) {
  struct iosource *io;

  if(!nonblock(fd))
    return NULL;

  io = newsource();
  io->sent = sent;
  io->received = received;
  io->closed = closed;
  io->cbdata = cbdata;
  io->infd.fd = fd;
  io->infd.events = G_IO_IN | G_IO_HUP | G_IO_ERR;
  io->infd.revents = 0;
  io->outfd.fd = fd;
  io->outfd.events = G_IO_OUT | G_IO_ERR;
  io->outfd.revents = 0;

  g_source_add_poll((GSource*)io, &io->infd);
  g_source_attach((GSource*)io, NULL);

  return (GSource*)io;
}

GSource *
io_new_listening(int fd, socklen_t len, ionewfunc_t accepted,
                 iofunc_t closed, void *cbdata) {
  struct iosource *io;

  g_assert(NULL != accepted);

  if(!nonblock(fd))
    return NULL;

  io = newsource();
  io->accepted = accepted;
  io->closed = closed;
  io->cbdata = cbdata;
  io->infd.fd = fd;
  io->infd.events = G_IO_IN | G_IO_ERR;
  io->infd.revents = 0;
  io->inbuf = g_new(char, len);
  io->inmax = len;

  g_source_add_poll((GSource*)io, &io->infd);
  g_source_attach((GSource*)io, NULL);

  return (GSource*)io;
}

static gboolean
nonblock(int fd) {
  int flags;

  if(0 > (flags = fcntl(fd, F_GETFL)) ||
     0 > fcntl(fd, F_SETFL, flags | O_NONBLOCK))
    return FALSE;

  return TRUE;
}

static struct iosource *
newsource(void) {
  GSource *source = g_source_new(&sourcefuncs, sizeof(struct iosource));
  struct iosource *io = (struct iosource*)source;

  io->sent = NULL;
  io->received = NULL;
  io->accepted = NULL;
  io->closed = NULL;
  io->cbdata = NULL;
  bzero(&io->infd, sizeof(io->infd));
  io->infd.fd = -1;
  bzero(&io->outfd, sizeof(io->outfd));
  io->outfd.fd = -1;
  io->inbuf = NULL;
  io->inused = 0;
  io->inmax = 0;
  io->outbufs = NULL;
  io->lastid = 0;

  return io;
}

unsigned int
io_send(GSource *source, const char *data, unsigned int len) {
  char *new = g_new(char, len);

  memcpy(new, data, len);

  return io_send_keepdata(source, new, len);
}

unsigned int
io_send_keepdata(GSource *source, char *data, unsigned int len) {
  struct iosource *io = (struct iosource*)source;
  struct iooutbuf *buf = g_new(struct iooutbuf, 1);

  buf->data = data;
  buf->len = len;
  buf->off = 0;
  io->lastid++;
  buf->id = io->lastid;

  if(NULL != io->outbufs)
    io->outbufs = g_list_append(io->outbufs, buf);
  else {
    io->outbufs = g_list_append(io->outbufs, buf);
    g_source_add_poll(source, &io->outfd);
  }

  return io->lastid;
}

static void
freeoutbuf(struct iooutbuf *buf) {
  if(NULL != buf->data)
    g_free(buf->data);
  g_free(buf);
}

static gboolean
io_prepare(GSource *source SHUTUP, gint *timeout_) {
  *timeout_ = -1;
  return FALSE;
}

static gboolean
io_check(GSource *source) {
  struct iosource *io = (struct iosource*)source;

  if(io->infd.revents)
    return TRUE;
  if(NULL != io->outbufs && io->outfd.revents)
    return TRUE;
  else
    return FALSE;
}

static gboolean
io_dispatch(GSource *source, GSourceFunc callback SHUTUP,
            gpointer gdata SHUTUP) {
  struct iosource *io = (struct iosource*)source;

  if(io->infd.revents & (G_IO_ERR | G_IO_HUP) ||
     io->outfd.revents & G_IO_ERR)
    io_disconnect(io, 0 /* XXX how do I get errors here? */ );
  else if(io->infd.revents & G_IO_IN)
    (NULL == io->accepted ? io_read : io_accept)(io);
  else if(io->outfd.revents & G_IO_OUT)
    io_write(io);
  else
    return FALSE;

  return TRUE;
}


static void
io_finalize(GSource *source SHUTUP) {
  struct iosource *io = (struct iosource*)source;

  if(NULL != io->outbufs) {
    g_list_foreach(io->outbufs, (GFunc)freeoutbuf, NULL);
    g_list_free(io->outbufs);
  }

  if(NULL != io->inbuf)
    g_free(io->inbuf);
}

static void
io_biggify(char **buf, unsigned int used, unsigned int *max) {
  if(used + IO_BLOCKSIZE > *max) {
    *max += IO_BLOCKSIZE;
    *buf = g_renew(char, *buf, *max);
  }
}

static void
io_accept(struct iosource *io) {
  int fd;
  socklen_t len;

  if(0 > (fd = accept(io->infd.fd, (struct sockaddr*)io->inbuf, &len))) {
    if(EAGAIN == errno || ECONNABORTED == errno || EWOULDBLOCK == errno)
      return;
    io_disconnect(io, errno);
  }

  io->accepted((GSource*)io, fd, (struct sockaddr*)io->inbuf, len, io->cbdata);
}

static void
io_read(struct iosource *io) {
  ssize_t res = 0;
  gboolean newdata = FALSE;
  unsigned int used;
  int err = 0;

  g_source_ref((GSource*)io);

  do {
    if(!newdata && 0 < res)
      newdata = TRUE;
    io->inused += res;
    io_biggify(&io->inbuf, io->inused, &io->inmax);
    errno = 0;
    res = read(io->infd.fd, io->inbuf + io->inused, io->inmax - io->inused);
    if(0 > res)
      err = errno;
  } while(0 < res);

  if(NULL == io->received)
    io->inused = 0;
  else if(newdata) {
    used = io->received((GSource*)io, io->inbuf, io->inused, io->cbdata);
    if(used > io->inused)
      used = io->inused;
    if(0 < used) {
      if(used < io->inused)
        memmove(io->inbuf, io->inbuf + used, io->inused - used);
      io->inused -= used;
    }
  }

  if(0 != err && EAGAIN != err)
    io_disconnect(io, err);
  else if(0 == res)
    io_disconnect(io, 0);
  g_source_unref((GSource*)io);
}

static void
io_write(struct iosource *io) {
  struct iooutbuf *buf;
  ssize_t res = 1;
  int err = 0;

  g_source_ref((GSource*)io);

  while(NULL != io->outbufs && 0 == err) {
    buf = io->outbufs->data;
    while(buf->off < buf->len && 0 < res) {
      errno = 0;
      res = write(io->outfd.fd, buf->data + buf->off, buf->len - buf->off);
      if(0 > res)
        err = errno;
      else
        buf->off += res;
    }

    if(buf->off >= buf->len) {
      io->outbufs = g_list_remove(io->outbufs, buf);
      if(NULL == io->outbufs)
        g_source_remove_poll((GSource*)io, &io->outfd);
      if(NULL != io->sent)
        io->sent((GSource*)io, buf->id, io->cbdata);
      freeoutbuf(buf);
    }
  }

  if(0 != err && EAGAIN != err)
    io_disconnect(io, err);

  g_source_unref((GSource*)io);
}

static void
io_disconnect(struct iosource *io, int err) {
  if(NULL != io->closed) {
    errno = err;
    io->closed((GSource*)io, io->cbdata);
  }

  if(NULL != io->outbufs)
    g_source_remove_poll((GSource*)io, &io->outfd);

  g_source_remove_poll((GSource*)io, &io->infd);
  g_source_remove(g_source_get_id((GSource*)io));
  g_source_unref((GSource*)io);
}