infog/extension.c

#define _GNU_SOURCE

#include <stddef.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include <glib.h>
#include <gtk/gtk.h>
#include <webkit2/webkit-web-extension.h>

#include "common.h"
#include "infopath.h"

void
vmsg (char *fmt, va_list v)
{
  vprintf (fmt, v);
}

int debug_level = 1;

void
debug (WebKitWebPage *web_page, int level, char *fmt, ...)
{
  if (level > debug_level)
    return;

  va_list v;
  va_start (v, fmt);

  printf ("PAGE[%lu]: ", webkit_web_page_get_id (web_page));
  vmsg (fmt, v);
  va_end (v);
}

void
send_js_message (WebKitWebPage *web_page, char *message)
{
  WebKitFrame *frame = webkit_web_page_get_main_frame (web_page);
  if (!frame)
    return;
  JSCContext *jsc = webkit_frame_get_js_context (frame);
  if (!jsc)
    return;

  JSCValue *js_string = jsc_value_new_string (jsc, message);
  jsc_context_set_value (jsc, "texinfoMsgString", js_string);

  JSCValue *jscValue = jsc_context_evaluate (jsc,
    "window.webkit.messageHandlers.channel.postMessage(texinfoMsgString);",
    -1);
}


static char *current_manual;

int
load_manual (WebKitWebPage *web_page, char *manual)
{
  current_manual = manual;

  /* Inform the main process the manual has changed so that it can
     load the TOC and indices. */
  g_print ("LOAD MANUAL %s\n", manual);
  GString *s1 = g_string_new (NULL);
  g_string_append (s1, "new-manual\n");
  g_string_append (s1, manual);

  send_js_message (web_page, s1->str);

  g_string_free (s1, TRUE);
  
  return 1;
}

gboolean
request_callback (WebKitWebPage     *web_page,
		  WebKitURIRequest  *request,
		  WebKitURIResponse *redirected_response,
		  gpointer           user_data)
{
  const char *uri = webkit_uri_request_get_uri (request);

  debug (web_page, 1, "Intercepting link <%s>\n", uri);

  /* Clear flags on WebKitWebPage object.  These flags are checked after
     the page is actually loaded.  We can't use global variables for this
     because multiple WebKitWebViews may share them. */
  g_object_set_data (G_OBJECT(web_page), "top-node",
                     GINT_TO_POINTER(0));
  g_object_set_data (G_OBJECT(web_page), "send-index",
                     GINT_TO_POINTER(0));

  const char *p = strchr (uri, '?');
  if (p)
    {
      char *new_uri = strdup (uri);
      new_uri[p - uri] = 0;
      webkit_uri_request_set_uri (request, new_uri);
      debug (web_page, 1, "new_uri %s\n", new_uri);
      free (new_uri);

      p++;
      debug (web_page, 1, "request type %s\n", p);
      if (!strcmp (p, "send-index"))
        {
          g_object_set_data (G_OBJECT(web_page), "send-index",
                             GINT_TO_POINTER(1));
        }
      else if (!strcmp (p, "top-node"))
        {
          g_object_set_data (G_OBJECT(web_page), "top-node",
                             GINT_TO_POINTER(1));
        }
      
      return FALSE;
    }

  /* Web links to other Texinfo manuals are rewritten to have the "private"
     URI scheme.  Any relative links like "../MANUAL/NODE.html"
     are absolute paths beginning "file:/" by the time this function
     is called. */
  if (!memcmp (uri, "private:", 8))
    {
      char *manual, *node;
      parse_external_url (uri, &manual, &node);
      if (!manual || !node)
        {
          /* Possibly a *.css file or malformed link. */
          debug (web_page, 1, "COULDNT PARSE URL\n");
          free (manual); free (node);
          return FALSE;
        }

      debug (web_page, 1, "finding manual and node %s:%s\n", manual, node);

      if (!current_manual || strcmp(manual, current_manual) != 0)
        {
          load_manual (web_page, manual);
        }

      /* Ask main process to load node for us.  */
      GString *s = g_string_new (NULL);
      g_string_append (s, "new-node\n");
      g_string_append (s, node);
      send_js_message (web_page, s->str);
      g_string_free (s, TRUE);

      return TRUE; /* Cancel load request */
    }
  else if (!memcmp (uri, "file:", 5))
    {
      /* Load file for real. */
      char *manual, *node;
      parse_external_url (uri, &manual, &node);
      if (!manual || !node)
        {
          /* Possibly a *.css file or malformed link. */
          free (manual); free (node);
          return FALSE;
        }

      debug (web_page, 1, "finding manual and node %s:%s\n", manual, node);

      if (!current_manual || strcmp(manual, current_manual) != 0)
        {
          load_manual (web_page, manual);
        }

      /* Update sidebar */
      GString *s = g_string_new (NULL);
      g_string_append (s, "inform-new-node\n");
      g_string_append (s, node);
      send_js_message (web_page, s->str);
      g_string_free (s, TRUE);
    }
  
  return FALSE;
}

/* Given the main index.html Top node in the document, find the nodes 
   containing indices. */
void
find_indices (WebKitWebPage *web_page,
              WebKitDOMHTMLCollection *links, gulong num_links)
{
  debug (web_page, 1, "looking for indices\n");

  gulong i = 0;
  GString *s = g_string_new (NULL);

  g_string_assign (s, "index-nodes\n");

  for (; i < num_links; i++)
    {
      WebKitDOMNode *node
        = webkit_dom_html_collection_item (links, i);
      if (!node)
        {
          debug (web_page, 1, "No node\n");
          return;
        }

      WebKitDOMElement *element;
      if (WEBKIT_DOM_IS_ELEMENT(node))
        {
          element = WEBKIT_DOM_ELEMENT(node);
        }
      else
        {
          /* When would this happen? */
          debug (web_page, 1, "Not an DOM element\n");
          continue;
        }

      gchar *href = webkit_dom_element_get_attribute (element, "href");


      char *rel = webkit_dom_element_get_attribute (element, "rel");
      char *id = webkit_dom_element_get_attribute (element, "id");

      /* Look for links to index nodes in top node by checking the "rel" 
         attribute.  Only use links in the table of contents to avoid
         loading the same index more than once. */
      if (href
          && id && !strncmp (id, "toc-", 4)
          && rel && !strcmp(rel, "index"))
        {
          debug (web_page, 1, "index node at |%s|\n", href);
          g_string_append (s, href);
          g_string_append (s, "\n");
        }
      free (rel); free (id);
    }

  send_js_message (web_page, s->str);
  g_string_free (s, TRUE);
}

void
send_index (WebKitWebPage *web_page,
            WebKitDOMHTMLCollection *links, gulong num_links)
{
  debug (web_page, 1, "trying to send index\n");

  gulong i = 0;
  GString *s = g_string_new (NULL);

  g_string_append (s, "index\n");

  for (; i < num_links; i++)
    {
      WebKitDOMNode *node
        = webkit_dom_html_collection_item (links, i);
      if (!node)
        {
          debug (web_page, 1, "No node\n");
          return;
        }

      WebKitDOMElement *element;
      if (WEBKIT_DOM_IS_ELEMENT(node))
        {
          element = WEBKIT_DOM_ELEMENT(node);
        }
      else
        {
          /* When would this happen? */
          debug (web_page, 1, "Not an DOM element\n");
          continue;
        }

      gchar *href = webkit_dom_element_get_attribute (element, "href");
      if (href && strstr (href, "#index-"))
        {
          g_string_append (s, webkit_dom_node_get_text_content (node));
          g_string_append (s, "\n");
          g_string_append (s, href);
          g_string_append (s, "\n");
        }
    }

  /* Mark end of index. */
  g_string_append (s, "\n");
  g_string_append (s, "\n");

  send_js_message (web_page, s->str);

  g_string_free (s, TRUE);

  debug (web_page, 1, "index sent\n");
}

void
build_toc_string (GString *toc, WebKitDOMElement *elt)
{
  char *s, *s2, *s3;
  WebKitDOMElement *e, *e1;
  int first = 1;

  e = webkit_dom_element_get_first_element_child (elt);
  while (e)
    {
      s = webkit_dom_element_get_tag_name (e);
      if (!strcmp (s, "LI") || !strcmp (s, "li"))
        {
          e1 = webkit_dom_element_get_first_element_child (e);
          e = webkit_dom_element_get_next_element_sibling (e);

          s2 = webkit_dom_element_get_tag_name (e1);
          if (!strcmp (s2, "a") || !strcmp (s2, "A"))
            {
              s3 = webkit_dom_element_get_inner_html (e1);
              g_string_append (toc, s3);
              g_string_append (toc, "\n");

              s3 = webkit_dom_element_get_attribute (e1, "href");
              if (first)
                {
                  first = 0;
                  g_string_append (toc, "+");
                }
              if (!e)
                {
                  g_string_append (toc, "-");
                }
              g_string_append (toc, s3);
              g_string_append (toc, "\n");
            }

          e1 = webkit_dom_element_get_next_element_sibling (e1);
          if (e1)
            {
              s2 = webkit_dom_element_get_tag_name (e1);
              if (!strcmp (s2, "UL") || !strcmp (s2, "ul"))
                {
                  build_toc_string (toc, e1);
                }
            }
        }
      else
        break;
    }
}

void
send_toc (WebKitWebPage *web_page, WebKitDOMDocument *dom_document)
{
  GString *toc;

  WebKitDOMElement *toc_elt = webkit_dom_document_query_selector
                            (dom_document, "div.contents ul", NULL);
  if (!toc_elt)
    return;

  toc = g_string_new (NULL);

  g_string_append (toc, "toc\n");
  build_toc_string (toc, toc_elt);

  send_js_message (web_page, toc->str);
  g_string_free (toc, TRUE);
}

void
send_pointer (WebKitWebPage *web_page,
              WebKitDOMElement *link_elt,
              const char *rel, const char *current_uri)
{
  char *link = 0;
  char *href = webkit_dom_element_get_attribute (link_elt, "href");

  if (current_uri)
    {
      const char *p = current_uri;
      const char *q;

      /* Set p to after the last '/'. */
      while ((q = strchr (p, '/')))
        {
          q++;
          p = q;
        }
      if (p != current_uri)
        {
          link = malloc ((p - current_uri)
                              + strlen (href) + 1);
          memcpy (link, current_uri, p - current_uri);
          strcpy (link + (p - current_uri), href);

          char *message;
          asprintf (&message, "%s\n%s\n", rel, link);
          send_js_message (web_page, message);

          free (message);
        }
    }
  g_free (href);
  free (link);
}

/* Use variadic macro to allow for commas in argument */
#define QUOTE(...) #__VA_ARGS__

/* Rewrite URLs to other Texinfo manuals to private scheme. */
const char *INJECTED_JAVASCRIPT = QUOTE(
  var x = document.querySelectorAll("a[data-manual]");
  for (var i = 0; i < x.length; i++) {
    var manual = x[i].attributes["data-manual"].value;
    if (x[i].protocol == "https:" || x[i].protocol == "http:") {
      var node = x[i].pathname.split('/').pop();
      x[i].href = 'private:/' + manual + '/' + node;
    }
  };
);


static void
inject_javascript (WebKitWebPage *web_page)
{
  WebKitFrame *frame = webkit_web_page_get_main_frame (web_page);
  if (!frame)
    return;
  JSCContext *jsc = webkit_frame_get_js_context (frame);
  if (!jsc)
    return;
  JSCValue *result = jsc_context_evaluate (jsc, INJECTED_JAVASCRIPT, -1);
}


void
document_loaded_callback (WebKitWebPage *web_page,
                          gpointer       user_data)
{
  debug (web_page, 1, "Page loaded\n");

  WebKitDOMDocument *dom_document
    = webkit_web_page_get_dom_document (web_page);

  if (!dom_document)
    {
      debug (web_page, 1, "No DOM document\n");
      return;
    }

  gint send_index_p
    = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(web_page), "send-index"));
  gint top_node_p
    = GPOINTER_TO_INT(g_object_get_data(G_OBJECT(web_page), "top-node"));

  WebKitDOMHTMLCollection *links =
    webkit_dom_document_get_links (dom_document);
  gulong num_links = webkit_dom_html_collection_get_length (links);

  if (send_index_p)
    {
      send_index (web_page, links, num_links);
      return;
    }

  if (top_node_p)
    {
      send_toc (web_page, dom_document);
      find_indices (web_page, links, num_links);
      return;
    }

  inject_javascript (web_page);

  WebKitDOMElement *link_elt;

  const char *current_uri = webkit_web_page_get_uri (web_page);

  link_elt = webkit_dom_document_query_selector
    (dom_document, "a[rel=\"up\"]", NULL);
  if (link_elt)
    send_pointer (web_page, link_elt, "up", current_uri);
  
  link_elt = webkit_dom_document_query_selector
    (dom_document, "a[rel=\"next\"]", NULL);
  if (link_elt)
    send_pointer (web_page, link_elt, "next", current_uri);

  link_elt = webkit_dom_document_query_selector
    (dom_document, "a[rel=\"prev\"]", NULL);
  if (link_elt)
    send_pointer (web_page, link_elt, "prev", current_uri);
}


static void
web_page_created_callback (WebKitWebExtension *extension,
                           WebKitWebPage      *web_page,
                           gpointer            user_data)
{
    debug (web_page, 1, "Page %d created for %s\n",
             webkit_web_page_get_id (web_page),
             webkit_web_page_get_uri (web_page));

    g_signal_connect (web_page, "document-loaded", 
                      G_CALLBACK (document_loaded_callback), 
                      NULL);

    g_signal_connect_object (web_page, "send-request", 
                      G_CALLBACK (request_callback), 
                      NULL, 0);
}

G_MODULE_EXPORT void
webkit_web_extension_initialize_with_user_data (WebKitWebExtension *extension,
                                                GVariant *user_data)
{
  g_signal_connect (extension, "page-created", 
                    G_CALLBACK (web_page_created_callback), 
                    NULL);
}