/*
 * Copyright (C) 2009 Julien BLACHE <jb@jblache.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <limits.h>
#include <errno.h>
#include <pthread.h>

#include <event.h>
#include <evhttp.h>

#include "daapd.h"
#include "err.h"
#include "conffile.h"
#include "httpd.h"


#define WEBFACE_ROOT "/usr/share/mt-daapd/admin-root/"

struct content_type_map {
  char *ext;
  char *ctype;
};


static struct content_type_map ext2ctype[] =
  {
    { ".html", "text/html; charset=utf-8" },
    { ".xml",  "text/xml; charset=utf-8" },
    { ".css",  "text/css; charset=utf-8" },
    { ".txt",  "text/plain; charset=utf-8" },
    { ".js",   "application/javascript; charset=utf-8" },
    { ".gif",  "image/gif" },
    { ".ico",  "image/x-ico" },
    { ".png",  "image/png" },
    { NULL, NULL }
  };

static int exit_pipe[2];
static int httpd_exit;
static struct event_base *evbase_httpd;
static struct event exitev;
static struct evhttp *evhttpd;
static pthread_t tid_httpd;


/* Thread: httpd */
static int
path_is_legal(char *path)
{
  return strncmp(WEBFACE_ROOT, path, strlen(WEBFACE_ROOT));
}

/* Thread: httpd */
static void
redirect_to_index(struct evhttp_request *req, char *uri)
{
  char buf[256];
  int slashed;
  int ret;

  slashed = (uri[strlen(uri) - 1] == '/');

  ret = snprintf(buf, sizeof(buf), "%s%sindex.html", uri, (slashed) ? "" : "/");
  if ((ret < 0) || (ret >= sizeof(buf)))
    {
      DPRINTF(E_LOG, L_HTTPD, "Redirection URL exceeds buffer length\n");

      evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");
      return;
    }

  evhttp_add_header(req->output_headers, "Location", buf);
  evhttp_send_reply(req, HTTP_MOVETEMP, "Moved", NULL);
}

/* Thread: httpd */
static void
serve_file(struct evhttp_request *req, char *uri)
{
  char *ext;
  char path[PATH_MAX];
  char *deref;
  char *ctype;
  struct evbuffer *evbuf;
  struct stat sb;
  int fd;
  int i;
  int ret;

  ret = snprintf(path, sizeof(path), "%s%s", WEBFACE_ROOT, uri + 1); /* skip starting '/' */
  if ((ret < 0) || (ret >= sizeof(path)))
    {
      DPRINTF(E_LOG, L_HTTPD, "Request exceeds PATH_MAX: %s\n", uri);

      evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");

      return;
    }

  ret = lstat(path, &sb);
  if (ret < 0)
    {
      DPRINTF(E_LOG, L_HTTPD, "Could not lstat() %s: %s\n", path, strerror(errno));

      evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");

      return;
    }

  if (S_ISDIR(sb.st_mode))
    {
      redirect_to_index(req, uri);

      return;
    }
  else if (S_ISLNK(sb.st_mode))
    {
      deref = realpath(path, NULL);
      if (!deref)
	{
	  DPRINTF(E_LOG, L_HTTPD, "Could not dereference %s: %s\n", path, strerror(errno));

	  evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");

	  return;
	}

      if (strlen(deref) + 1 > PATH_MAX)
	{
	  DPRINTF(E_LOG, L_HTTPD, "Dereferenced path exceeds PATH_MAX: %s\n", path);

	  evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");

	  free(deref);
	  return;
	}

      strcpy(path, deref);
      free(deref);

      ret = stat(path, &sb);
      if (ret < 0)
	{
	  DPRINTF(E_LOG, L_HTTPD, "Could not stat() %s: %s\n", path, strerror(errno));

	  evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");

	  return;
	}

      if (S_ISDIR(sb.st_mode))
	{
	  redirect_to_index(req, uri);

	  return;
	}
    }

  if (path_is_legal(path) != 0)
    {
      evhttp_send_error(req, 403, "Forbidden");

      return;
    }

  evbuf = evbuffer_new();
  if (!evbuf)
    {
      DPRINTF(E_LOG, L_HTTPD, "Could not create evbuffer\n");

      evhttp_send_error(req, HTTP_SERVUNAVAIL, "Internal error");
      return;
    }

  fd = open(path, O_RDONLY);
  if (fd < 0)
    {
      DPRINTF(E_LOG, L_HTTPD, "Could not open %s: %s\n", path, strerror(errno));

      evhttp_send_error(req, HTTP_NOTFOUND, "Not Found");
      return;
    }

  ret = evbuffer_read(evbuf, fd, sb.st_size);
  close(fd);
  if (ret < 0)
    {
      DPRINTF(E_LOG, L_HTTPD, "Could not read file into evbuffer\n");

      evhttp_send_error(req, HTTP_SERVUNAVAIL, "Internal error");
      return;
    }

  ctype = "application/octet-stream";
  ext = strrchr(path, '.');
  if (ext)
    {
      for (i = 0; ext2ctype[i].ext; i++)
	{
	  if (strcmp(ext, ext2ctype[i].ext) == 0)
	    {
	      ctype = ext2ctype[i].ctype;
	      break;
	    }
	}
    }

  evhttp_add_header(req->output_headers, "Content-Type", ctype);

  evhttp_send_reply(req, HTTP_OK, "OK", evbuf);

  evbuffer_free(evbuf);
}

/* Thread: httpd */
static void
webface_cb(struct evhttp_request *req, void *arg)
{
  const char *req_uri;
  char *uri;
  char *ptr;

  req_uri = evhttp_request_uri(req);
  if (!req_uri)
    {
      redirect_to_index(req, "/");

      return;
    }

  uri = strdup(req_uri);
  ptr = strchr(uri, '?');
  if (ptr)
    {
      DPRINTF(E_DBG, L_HTTPD, "Found query string\n");

      *ptr = '\0';
    }

  ptr = uri;
  uri = evhttp_decode_uri(uri);
  free(ptr);

  serve_file(req, uri);

  free(uri);
}

/* Thread: httpd */
static void *
httpd(void *arg)
{
  event_base_dispatch(evbase_httpd);

  if (!httpd_exit)
    DPRINTF(E_FATAL, L_HTTPD, "HTTPd event loop terminated ahead of time!\n");

  pthread_exit(NULL);
}

/* Thread: httpd */
static void
exit_cb(int fd, short event, void *arg)
{
  event_base_loopbreak(evbase_httpd);

  httpd_exit = 1;
}

/* Thread: main */
int
httpd_init(void)
{
  unsigned short port;
  int bindv6;
  int ret;

  httpd_exit = 0;

  ret = pipe2(exit_pipe, O_CLOEXEC);
  if (ret < 0)
    {
      DPRINTF(E_FATAL, L_HTTPD, "Could not create pipe: %s\n", strerror(errno));

      return -1;
    }

  evbase_httpd = event_base_new();
  if (!evbase_httpd)
    {
      DPRINTF(E_FATAL, L_HTTPD, "Could not create an event base\n");

      goto evbase_fail;
    }

  event_set(&exitev, exit_pipe[0], EV_READ, exit_cb, NULL);
  event_base_set(evbase_httpd, &exitev);
  event_add(&exitev, NULL);

  evhttpd = evhttp_new(evbase_httpd);
  if (!evhttpd)
    {
      DPRINTF(E_FATAL, L_HTTPD, "Could not create HTTP server\n");

      goto evhttp_fail;
    }

  port = cfg_getint(cfg_getnsec(cfg, "library", 0), "port") /* tmp */ + 1;

  /* evhttp doesn't support IPv6 yet, so this is expected to fail */
  bindv6 = evhttp_bind_socket(evhttpd, "::", port);
  if (bindv6 < 0)
    DPRINTF(E_INF, L_HTTPD, "Could not bind IN6ADDR_ANY:%d (that's OK)\n", port);

  ret = evhttp_bind_socket(evhttpd, "0.0.0.0", port);
  if (ret < 0)
    {
      if (bindv6 < 0)
	{
	  DPRINTF(E_FATAL, L_HTTPD, "Could not bind INADDR_ANY:%d\n", port);

	  goto bind_fail;
	}
    }

  evhttp_set_gencb(evhttpd, webface_cb, NULL);

  ret = pthread_create(&tid_httpd, NULL, httpd, NULL);
  if (ret != 0)
    {
      DPRINTF(E_FATAL, L_HTTPD, "Could not spawn HTTPd thread: %s\n", strerror(errno));

      goto thread_fail;
    }

  return 0;

 thread_fail:
 bind_fail:
  evhttp_free(evhttpd);
 evhttp_fail:
  event_base_free(evbase_httpd);
 evbase_fail:
  close(exit_pipe[0]);
  close(exit_pipe[1]);

  return -1;
}

/* Thread: main */
void
httpd_deinit(void)
{
  int dummy = 42;
  int ret;

  ret = write(exit_pipe[1], &dummy, sizeof(dummy));
  if (ret != sizeof(dummy))
    {
      DPRINTF(E_FATAL, L_HTTPD, "Could not write to exit fd: %s\n", strerror(errno));

      return;
    }

  ret = pthread_join(tid_httpd, NULL);
  if (ret != 0)
    {
      DPRINTF(E_FATAL, L_HTTPD, "Could not join HTTPd thread: %s\n", strerror(errno));

      return;
    }

  close(exit_pipe[0]);
  close(exit_pipe[1]);
  evhttp_free(evhttpd);
  event_base_free(evbase_httpd);
}