/*
 * greddit - a very simple GLib-friendly reddit client
 * Copyright (c) 2009 Thomas Thurman
 * thomas@thurman.org.uk
 * 
 * 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 be able to view the GNU General Public License at 
 * http://www.gnu.org/copyleft/gpl.html ; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

#include <json-glib/json-glib.h>
#include <string.h>
#include <glib.h>
#include <curl/curl.h>

#include "greddit.h"

#define REDDIT_FRONT_PAGE_IN_JSON "http://www.reddit.com/.json"

/**
 * Comparison function for sorting GRedditPost objects by
 * score.
 */
static int
greddit_post_compare (gconstpointer a,
		      gconstpointer b)
{
  GRedditPost* grpa = (GRedditPost*) a;
  GRedditPost* grpb = (GRedditPost*) b;

  if (grpa->score == grpb->score)
    return 0;
  else if (grpa->score < grpb->score)
    return 1;
  else
    return -1;
}

typedef struct
{
  size_t size;
  char *content;
} GRedditIncomingData;

static size_t
greddit_eat_data (void *buffer, size_t size, size_t nmemb, void *targetp)
{
  GRedditIncomingData *target = (GRedditIncomingData*) targetp;

  target->content = g_realloc (target->content,
			       target->size + size*nmemb);

  g_memmove (target->content + target->size,
	     buffer,
	     size*nmemb);

  target->size += size*nmemb;

  return size*nmemb;
}

GSList *
greddit_get_posts (void)
{
  JsonParser *parser = json_parser_new ();
  GSList *result = NULL;
  GList *posts, *cursor;
  CURL *curl = curl_easy_init ();
  GRedditIncomingData json;

  json.size = 0;
  json.content = NULL;

  /* set curl_easy_setopt (curl, CURLOPT_VERBOSE, 1); for debugging here */
  curl_easy_setopt (curl, CURLOPT_URL, REDDIT_FRONT_PAGE_IN_JSON);
  curl_easy_setopt (curl, CURLOPT_WRITEFUNCTION, greddit_eat_data);
  curl_easy_setopt (curl, CURLOPT_WRITEDATA, &json);

  if (curl_easy_perform (curl) != CURLE_OK)
    {
      fprintf (stderr, "Warning: curl error\n");
      return NULL;
    }

  if (json.content==NULL)
    {
      fprintf (stderr, "Warning: empty document\n");
      return NULL;
    }

  if (!json_parser_load_from_data (parser,
				   json.content,
				   -1,
				   NULL))
    {
      fprintf (stderr, "Warning: malformed JSON:\n%s\n",
	       json.content);
      g_free (json.content);
      return NULL;
    }

  g_free (json.content);

  posts = json_array_get_elements
    (json_node_get_array
     (json_object_get_member
      (json_node_get_object
       (json_object_get_member
	(json_node_get_object
	 (json_parser_get_root (parser)),
	 "data")
	),
       "children")
      )
     );

  for (cursor=posts; cursor; cursor=cursor->next)
    {
      JsonNode *wrapper = (JsonNode *) cursor->data;
      JsonObject *post =
	json_node_get_object (json_object_get_member (json_node_get_object (wrapper), "data"));
      GRedditPost *p = g_new(GRedditPost, 1);

      p->id = g_strdup (json_node_get_string (json_object_get_member (post, "id")));
      p->url = g_strdup (json_node_get_string (json_object_get_member (post, "url"))); 
      p->title = g_strdup (json_node_get_string (json_object_get_member (post, "title")));
      p->author = g_strdup (json_node_get_string (json_object_get_member (post, "author")));
      p->subreddit = g_strdup (json_node_get_string (json_object_get_member (post, "subreddit")));
      p->score = json_node_get_int (json_object_get_member (post, "score"));

      result = g_slist_insert_sorted (result, p, greddit_post_compare);
    }

  g_list_free (posts);
  g_object_unref (parser);

  curl_easy_cleanup (curl);

  return result;
}

void
greddit_free_posts (GSList *posts)
{
  GSList *cursor;

  for (cursor=posts; cursor; cursor=cursor->next)
    {
      GRedditPost *grp = (GRedditPost*) cursor->data;

      g_free (grp->id);
      g_free (grp->url);
      g_free (grp->title);
      g_free (grp->author);
      g_free (grp->subreddit);
    }

  g_slist_free (posts);
}

/* eof greddit.c */