/*
 * This file Copyright (C) Mnemosyne LLC
 *
 * This file is licensed by the GPL version 2. Works owned by the
 * Transmission project are granted a special exemption to clause 2 (b)
 * so that the bulk of its code can remain under the MIT license.
 * This exemption does not extend to derived works not owned by
 * the Transmission project.
 *
 * $Id$
 */

#include <glib/gstdio.h> /* g_remove () */
#include <gtk/gtk.h>

#include <libtransmission/transmission.h>
#include <libtransmission/web.h> /* tr_webRun () */

#include "favicon.h"
#include "util.h" /* gtr_get_host_from_url () */

#define IMAGE_TYPES 4
static const char * image_types[IMAGE_TYPES] = { "ico", "png", "gif", "jpg" };

struct favicon_data
{
    tr_session * session;
    GFunc func;
    gpointer data;
    char * host;
    char * contents;
    size_t len;
    int type;
};

static char*
get_url (const char * host, int image_type)
{
    return g_strdup_printf ("http://%s/favicon.%s", host, image_types[image_type]);
}

static char*
favicon_get_cache_dir (void)
{
    static char * dir = NULL;

    if (dir == NULL)
    {
        dir = g_build_filename (g_get_user_cache_dir (),
                                "transmission",
                                "favicons",
                                NULL);
        g_mkdir_with_parents (dir, 0777);
    }

    return dir;
}

static char*
favicon_get_cache_filename (const char * host)
{
    return g_build_filename (favicon_get_cache_dir (), host, NULL);
}

static void
favicon_save_to_cache (const char * host, const void * data, size_t len)
{
    char * filename = favicon_get_cache_filename (host);
    g_file_set_contents (filename, data, len, NULL);
    g_free (filename);
}

static GdkPixbuf*
favicon_load_from_cache (const char * host)
{
    char * filename = favicon_get_cache_filename (host);
    GdkPixbuf * pixbuf = gdk_pixbuf_new_from_file_at_size (filename, 16, 16, NULL);
    if (pixbuf == NULL) /* bad file */
        g_remove (filename);
    g_free (filename);
    return pixbuf;
}

static void favicon_web_done_cb (tr_session*, bool, bool, long, const void*, size_t, void*);

static gboolean
favicon_web_done_idle_cb (gpointer vfav)
{
    GdkPixbuf * pixbuf = NULL;
    gboolean finished = FALSE;
    struct favicon_data * fav = vfav;

    if (fav->len > 0) /* we got something... try to make a pixbuf from it */
    {
        favicon_save_to_cache (fav->host, fav->contents, fav->len);
        pixbuf = favicon_load_from_cache (fav->host);
        finished = pixbuf != NULL;
    }

    if (!finished) /* no pixbuf yet... */
    {
        if (++fav->type == IMAGE_TYPES) /* failure */
        {
            finished = TRUE;
        }
        else /* keep trying */
        {
            char * url = get_url (fav->host, fav->type);

            g_free (fav->contents);
            fav->contents = NULL;
            fav->len = 0;

            tr_webRun (fav->session, url, NULL, NULL, favicon_web_done_cb, fav);
            g_free (url);
        }
    }

    if (finished)
    {
        fav->func (pixbuf, fav->data);
        g_free (fav->host);
        g_free (fav->contents);
        g_free (fav);
    }

    return FALSE;
}

static void
favicon_web_done_cb (tr_session    * session UNUSED,
                     bool            did_connect UNUSED,
                     bool            did_timeout UNUSED,
                     long            code UNUSED,
                     const void    * data,
                     size_t          len,
                     void          * vfav)
{
    struct favicon_data * fav = vfav;
    fav->contents = g_memdup (data, len);
    fav->len = len;

    gdk_threads_add_idle (favicon_web_done_idle_cb, fav);
}

void
gtr_get_favicon (tr_session  * session,
                 const char  * host,
                 GFunc         pixbuf_ready_func,
                 gpointer      pixbuf_ready_func_data)
{
    GdkPixbuf * pixbuf = favicon_load_from_cache (host);

    if (pixbuf != NULL)
    {
        pixbuf_ready_func (pixbuf, pixbuf_ready_func_data);
    }
    else
    {
        struct favicon_data * data;
        char * url = get_url (host, 0);

        data = g_new (struct favicon_data, 1);
        data->session = session;
        data->func = pixbuf_ready_func;
        data->data = pixbuf_ready_func_data;
        data->host = g_strdup (host);
        data->type = 0;

        tr_webRun (session, url, NULL, NULL, favicon_web_done_cb, data);
        g_free (url);
    }
}

void
gtr_get_favicon_from_url (tr_session  * session,
                          const char  * url,
                          GFunc         pixbuf_ready_func,
                          gpointer      pixbuf_ready_func_data)
{
    char host[1024];
    gtr_get_host_from_url (host, sizeof (host), url);
    gtr_get_favicon (session, host, pixbuf_ready_func, pixbuf_ready_func_data);
}