/* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 *  Copyright © 2014 Igalia S.L.
 *
 *  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, 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, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"
#include "ephy-web-overview.h"

#include <string.h>

#define WEBKIT_DOM_USE_UNSTABLE_API
#include <webkitdom/WebKitDOMElementUnstable.h>
#include <webkitdom/WebKitDOMDOMTokenList.h>

struct _EphyWebOverview {
  GObject parent_instance;

  WebKitWebPage *web_page;
  EphyWebOverviewModel *model;
  GList *items;

  GHashTable *delayed_thumbnail_changes;
};

G_DEFINE_TYPE (EphyWebOverview, ephy_web_overview, G_TYPE_OBJECT)

enum {
  PROP_0,
  PROP_WEB_PAGE,
  PROP_MODEL,
  LAST_PROP
};

static GParamSpec *obj_properties[LAST_PROP];

typedef struct {
  char *url;

  WebKitDOMElement *anchor;
  WebKitDOMElement *thumbnail;
  WebKitDOMElement *title;
} OverviewItem;

static OverviewItem *
overview_item_new (WebKitDOMElement *anchor)
{
  OverviewItem *item;
  WebKitDOMNodeList *nodes;
  int i, n_nodes;

  item = g_slice_new0 (OverviewItem);
  item->anchor = g_object_ref (anchor);
  item->url = webkit_dom_element_get_attribute (anchor, "href");

  nodes = webkit_dom_node_get_child_nodes (WEBKIT_DOM_NODE (anchor));
  n_nodes = webkit_dom_node_list_get_length (nodes);
  for (i = 0; i < n_nodes; i++) {
    WebKitDOMNode *node = webkit_dom_node_list_item (nodes, i);
    WebKitDOMElement *element;
    char *tag;

    if (!WEBKIT_DOM_IS_ELEMENT (node))
      continue;

    element = WEBKIT_DOM_ELEMENT (node);
    tag = webkit_dom_element_get_tag_name (element);
    if (g_strcmp0 (tag, "SPAN") == 0) {
      char *class;

      class = webkit_dom_element_get_class_name (element);
      if (g_strcmp0 (class, "overview-thumbnail") == 0)
        item->thumbnail = g_object_ref (element);
      else if (g_strcmp0 (class, "overview-title") == 0)
        item->title = g_object_ref (element);

      g_free (class);
    }

    g_free (tag);
  }
  g_object_unref (nodes);

  return item;
}

static void
overview_item_free (OverviewItem *item)
{
  g_free (item->url);
  g_clear_object (&item->anchor);
  g_clear_object (&item->thumbnail);
  g_clear_object (&item->title);

  g_slice_free (OverviewItem, item);
}

static void
update_thumbnail_element_style (WebKitDOMElement *thumbnail,
                                const char       *path)
{
  char *style;

  style = g_strdup_printf ("background: url(file://%s) no-repeat;", path);
  webkit_dom_element_set_attribute (thumbnail, "style", style, NULL);
  g_free (style);
}

static gboolean
apply_delayed_thumbnail_change (gpointer key,
                                gpointer value,
                                gpointer user_data)
{
  EphyWebOverview *overview = EPHY_WEB_OVERVIEW (user_data);
  const char *url = key;
  const char *path = value;
  GList *l;

  for (l = overview->items; l; l = g_list_next (l)) {
    OverviewItem *item = (OverviewItem *)l->data;

    if (g_strcmp0 (item->url, url) == 0) {
      update_thumbnail_element_style (item->thumbnail, path);
      return TRUE;
    }
  }

  return FALSE;
}

static void
ephy_web_overview_model_thumbnail_changed (EphyWebOverviewModel *model,
                                           const char           *url,
                                           const char           *path,
                                           EphyWebOverview      *overview)
{
  GList *l;
  for (l = overview->items; l; l = g_list_next (l)) {
    OverviewItem *item = (OverviewItem *)l->data;

    if (g_strcmp0 (item->url, url) == 0) {
      update_thumbnail_element_style (item->thumbnail, path);
      return;
    }
  }

  if (!overview->delayed_thumbnail_changes) {
    overview->delayed_thumbnail_changes = g_hash_table_new_full (g_str_hash,
                                                                 g_str_equal,
                                                                 g_free,
                                                                 g_free);
  }

  /* We got the thumbnail change request before document-loaded. Save the
   * request, else we will wind up with an overview showing placeholder icons.
   * This isn't needed for title and URL changes because EphyAboutHandler is
   * sure to have those right when creating the overview HTML. But thumbnail
   * changes can arrive delayed if the snapshot service does not have the right
   * snapshot on demand.
   */
  g_hash_table_insert (overview->delayed_thumbnail_changes, g_strdup (url), g_strdup (path));
}

static void
ephy_web_overview_model_title_changed (EphyWebOverviewModel *model,
                                       const char           *url,
                                       const char           *title,
                                       EphyWebOverview      *overview)
{
  GList *l;

  for (l = overview->items; l; l = g_list_next (l)) {
    OverviewItem *item = (OverviewItem *)l->data;

    if (g_strcmp0 (item->url, url) != 0)
      continue;

    webkit_dom_element_set_attribute (item->anchor, "title", title, NULL);
    webkit_dom_node_set_text_content (WEBKIT_DOM_NODE (item->title), title, NULL);
  }
}

static void
ephy_web_overview_update_thumbnail_in_model_from_element (EphyWebOverview  *overview,
                                                          const char       *url,
                                                          WebKitDOMElement *thumbnail)
{
  WebKitDOMCSSStyleDeclaration *style;
  char *background;
  char *thumbnail_path;

  style = webkit_dom_element_get_style (thumbnail);
  if (webkit_dom_css_style_declaration_is_property_implicit (style, "background")) {
    g_object_unref (style);
    return;
  }

  background = webkit_dom_css_style_declaration_get_property_value (style, "background");
  if (!background) {
    g_object_unref (style);
    return;
  }

  thumbnail_path = g_strrstr (background, "file://");
  if (thumbnail_path) {
    char *p;

    thumbnail_path += strlen ("file://");
    p = g_strrstr (thumbnail_path, ")");
    if (p) {
      thumbnail_path = g_strndup (thumbnail_path, strlen (thumbnail_path) - strlen (p));
      g_signal_handlers_block_by_func (overview->model, G_CALLBACK (ephy_web_overview_model_thumbnail_changed), overview);
      ephy_web_overview_model_set_url_thumbnail (overview->model, url, thumbnail_path);
      g_signal_handlers_unblock_by_func (overview->model, G_CALLBACK (ephy_web_overview_model_thumbnail_changed), overview);
      g_free (thumbnail_path);
    }
  } else {
    const char *path;

    /* Check whether the model was updated while the overview was loading */
    path = ephy_web_overview_model_get_url_thumbnail (overview->model, url);
    if (path)
      update_thumbnail_element_style (thumbnail, path);
  }
  g_free (background);
  g_object_unref (style);
}

static void
ephy_web_overview_document_loaded (WebKitWebPage   *web_page,
                                   EphyWebOverview *overview)
{
  WebKitDOMDocument *document;
  WebKitDOMNodeList *nodes;
  int i, n_nodes;

  document = webkit_web_page_get_dom_document (web_page);
  nodes = webkit_dom_document_get_elements_by_tag_name (document, "a");
  n_nodes = webkit_dom_node_list_get_length (nodes);
  for (i = 0; i < n_nodes; i++) {
    WebKitDOMElement *element = WEBKIT_DOM_ELEMENT (webkit_dom_node_list_item (nodes, i));
    char *class;

    class = webkit_dom_element_get_class_name (element);
    if (g_strcmp0 (class, "overview-item") == 0) {
      OverviewItem *item = overview_item_new (element);

      /* URLs and titles are always sent from the UI process, but thumbnails don't,
       * so update the model with the thumbnail of there's one.
       */
      ephy_web_overview_update_thumbnail_in_model_from_element (overview, item->url, item->thumbnail);

      overview->items = g_list_prepend (overview->items, item);
    }
    g_free (class);
  }
  g_object_unref (nodes);
  overview->items = g_list_reverse (overview->items);

  if (overview->delayed_thumbnail_changes) {
    g_hash_table_foreach_remove (overview->delayed_thumbnail_changes,
                                 apply_delayed_thumbnail_change,
                                 overview);
    g_clear_pointer (&overview->delayed_thumbnail_changes, g_hash_table_unref);
  }
}

static void
ephy_web_overview_model_urls_changed (EphyWebOverviewModel *model,
                                      EphyWebOverview      *overview)
{
  GList *urls;
  GList *l;
  GList *items;
  OverviewItem *item;
  WebKitDOMDocument *document;

  urls = ephy_web_overview_model_get_urls (model);
  document = webkit_web_page_get_dom_document (overview->web_page);

  if (document && !overview->items) {
    /* We were loaded from page cache. The items already exist in the DOM. */
    ephy_web_overview_document_loaded (overview->web_page, overview);
  }

  items = overview->items;
  for (l = urls; l; l = g_list_next (l)) {
    EphyWebOverviewModelItem *url = (EphyWebOverviewModelItem *)l->data;
    const char *thumbnail_path;

    thumbnail_path = ephy_web_overview_model_get_url_thumbnail (model, url->url);

    if (items) {
      WebKitDOMDOMTokenList *class_list;

      item = (OverviewItem *)items->data;

      g_free (item->url);
      item->url = g_strdup (url->url);

      class_list = webkit_dom_element_get_class_list (item->anchor);
      if (class_list && webkit_dom_dom_token_list_contains (class_list, "overview-removed"))
        webkit_dom_dom_token_list_remove (class_list, NULL, "overview-removed", NULL);

      webkit_dom_element_set_attribute (item->anchor, "href", url->url, NULL);
      webkit_dom_element_set_attribute (item->anchor, "title", url->title, NULL);
      webkit_dom_node_set_text_content (WEBKIT_DOM_NODE (item->title), url->title, NULL);

      if (thumbnail_path) {
        char *style;

        style = g_strdup_printf ("background: url(file://%s) no-repeat;", thumbnail_path);
        webkit_dom_element_set_attribute (item->thumbnail, "style", style, NULL);
        g_free (style);
      } else {
        webkit_dom_element_remove_attribute (item->thumbnail, "style");
      }
      g_clear_object (&class_list);
    }

    items = g_list_next (items);
  }

  while (items) {
    WebKitDOMNode *anchor;
    GList *next = items->next;

    item = (OverviewItem *)items->data;

    anchor = WEBKIT_DOM_NODE (item->anchor);
    webkit_dom_node_remove_child (webkit_dom_node_get_parent_node (anchor), anchor, NULL);

    overview_item_free (item);
    overview->items = g_list_delete_link (overview->items, items);

    items = next;
  }
}

static void
ephy_web_overview_set_property (GObject      *object,
                                guint         prop_id,
                                const GValue *value,
                                GParamSpec   *pspec)
{
  EphyWebOverview *overview = EPHY_WEB_OVERVIEW (object);

  switch (prop_id) {
    case PROP_WEB_PAGE:
      overview->web_page = g_value_get_object (value);
      break;
    case PROP_MODEL:
      overview->model = g_value_get_object (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
ephy_web_overview_dispose (GObject *object)
{
  EphyWebOverview *overview = EPHY_WEB_OVERVIEW (object);

  if (overview->items) {
    g_list_free_full (overview->items, (GDestroyNotify)overview_item_free);
    overview->items = NULL;
  }

  g_clear_pointer (&overview->delayed_thumbnail_changes, g_hash_table_unref);

  G_OBJECT_CLASS (ephy_web_overview_parent_class)->dispose (object);
}

static void
ephy_web_overview_constructed (GObject *object)
{
  EphyWebOverview *overview = EPHY_WEB_OVERVIEW (object);

  G_OBJECT_CLASS (ephy_web_overview_parent_class)->constructed (object);

  g_signal_connect_object (overview->web_page, "document-loaded",
                           G_CALLBACK (ephy_web_overview_document_loaded),
                           overview, 0);

  g_signal_connect_object (overview->model, "urls-changed",
                           G_CALLBACK (ephy_web_overview_model_urls_changed),
                           overview, 0);
  g_signal_connect_object (overview->model, "thumbnail-changed",
                           G_CALLBACK (ephy_web_overview_model_thumbnail_changed),
                           overview, 0);
  g_signal_connect_object (overview->model, "title-changed",
                           G_CALLBACK (ephy_web_overview_model_title_changed),
                           overview, 0);
}

static void
ephy_web_overview_class_init (EphyWebOverviewClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  object_class->dispose = ephy_web_overview_dispose;
  object_class->constructed = ephy_web_overview_constructed;
  object_class->set_property = ephy_web_overview_set_property;

  obj_properties[PROP_WEB_PAGE] =
    g_param_spec_object ("web-page",
                         "WebPage",
                         "The overview WebPage",
                         WEBKIT_TYPE_WEB_PAGE,
                         G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS);

  obj_properties[PROP_MODEL] =
    g_param_spec_object ("model",
                         "Model",
                         "The overview model",
                         EPHY_TYPE_WEB_OVERVIEW_MODEL,
                         G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS);

  g_object_class_install_properties (object_class, LAST_PROP, obj_properties);
}

static void
ephy_web_overview_init (EphyWebOverview *overview)
{
}

EphyWebOverview *
ephy_web_overview_new (WebKitWebPage        *web_page,
                       EphyWebOverviewModel *model)
{
  g_return_val_if_fail (WEBKIT_IS_WEB_PAGE (web_page), NULL);
  g_return_val_if_fail (EPHY_IS_WEB_OVERVIEW_MODEL (model), NULL);

  return g_object_new (EPHY_TYPE_WEB_OVERVIEW,
                       "web-page", web_page,
                       "model", model,
                       NULL);
}
