//
// !!! THIS IS A BUGGY CONCEPT/PROTOTYPE. USE AT YOUR OWN RISK !!!
//
// The following simple Webkit2GTK+ extension was hacked together
// in the sleepless night between 09th and 10th March 2018 (and later 
// refined) by:
//
// Michal Idziorek <m.i@gmx.at>.
//
// It regjsters a document_loaded_callback, where the DOM is manipulated,
// i.e: a <span> with a number added to every link encountered.
//
// The urls are extracted from the DOM and shared with the browsers 
// process over a system V memory segment. 
//
// As an example, this can be used to enable keyboardless navigation 
// in surf by simply typing in the number of the link. 
//
// TODO: Support multiple clients! See source for more TODOS!
//       THE biggest limitation by now is the lazily hardcoded:
//       key_t my_ftok = ftok("~/surf-webext-dom-shared-mem",'a');
//
// Last Update: 14th March 2018
// 
// Last Tested: with surf commit 81f0452bc6c2a110239fa303ad1e72f11c33dc94
//              from htps://git.suckless.org/surf
// 

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

#include <sys/ipc.h>
#include <sys/shm.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>

bool str_prefix(const char *str, const char *pre);

static int call=0;
static char *shared_buf;
WebKitDOMHTMLDocument *my_doc;

void
document_loaded_callback (WebKitWebPage *web_page,
                          GPtrArray     *elements,
                          GVariant      *user_data)
{

    my_doc = webkit_web_page_get_dom_document(web_page);
//    if(!WEBKIT_DOM_IS_HTML_DOCUMENT(my_doc))return;

//    GThread *t1 = g_thread_new ("show hints", show_hints, doc);
 //   g_thread_join(t1);
}

GThreadFunc
show_hints(WebKitDOMHTMLDocument *doc)
{

    // TODO: g_free where appropriate !!
    // TODO: allow focus on input boxes/forms 
    // TODO: Put this somehwere else? (but I dislike #defines)
    // share this info with surf itself! maybe surf can supply this along
    // the ftok path via the user_data GVariant.
    int MAX_LINKS=1024;
    int MAX_LINK_LENGTH=1024;
    int DEBUG=9;

    // get url
    char *url = webkit_dom_document_get_url (doc); 
    if(DEBUG>1) g_print("document_loaded (callback): %s\n", url);

    // tokenize url
    char *url_proto=strtok(url,"/");
    char *url_host=strtok(NULL,"/");
    if(DEBUG>2) g_print("proto: %s\n", url_proto);
    if(DEBUG>2) g_print("host: %s\n", url_host);

    // get html body
    WebKitDOMHTMLElement *body  = webkit_dom_document_get_body(doc);

    // get links (alt)
    WebKitDOMNodeList *links = webkit_dom_document_query_selector_all(doc,"a",NULL);
    gulong links_count		   = webkit_dom_node_list_get_length (links);
    g_print("extracted %i links\n",links_count);

    // get links 
    /*
    WebKitDOMHTMLCollection *links = webkit_dom_document_get_links(doc);
    gulong links_count		   = webkit_dom_html_collection_get_length (links);
    if(DEBUG>1) g_print("extracted %i links\n",links_count);
    */

    // iterate over links
    for(gulong i=0;i<links_count;i++)
    {
	char buf[MAX_LINK_LENGTH]; // TODO: dynamic!

	WebKitDOMHTMLElement * node = webkit_dom_node_list_item (links,i);

	// add hint for keyboard navigation
	
        //g_print("node address: %p\n", node);
	
	char *txt = webkit_dom_html_element_get_inner_html (node); 

	// TODO: style via stylesheet
	snprintf(buf,MAX_LINK_LENGTH, 
		"<span style='padding-right:5px;border-bottom:1px solid black;'>\
		<span style='font-size:13px;font-weight:bold;font-face:Arial;\
		      border:1px solid black;display:inline;color:white;\
		      background-color:#77b;padding:0 5px;margin:0;\
		      margin-right:5px;'>%i</span>%s</span>", i,txt);
        if(DEBUG>10) g_print("extracted link : %s\n",txt);

	webkit_dom_html_element_set_inner_html (node,buf,NULL);
	
	//sleep(1);
	// alternatively add hints at the end of the body
	// webkit_dom_element_insert_adjacent_html (body,"beforeend",buf,NULL);

	// TODO: this does not work for some sad reason. 
	// sadly, likely due to my misunderstanding.
	// node seems not to be a LinkElement at all :(
	//txt = webkit_dom_html_link_element_get_href (node); 
	// so we have to use this:
	txt = webkit_dom_element_get_attribute (node,"href");
	if(txt==NULL)continue;
	if(str_prefix(txt,"//"))     snprintf(buf,MAX_LINK_LENGTH,"%s%s",url_proto,txt);
	else if(str_prefix(txt,"/")) snprintf(buf,MAX_LINK_LENGTH,"%s//%s%s",url_proto,url_host,txt);
	else                         snprintf(buf,MAX_LINK_LENGTH,"%s",txt);
	
	if(i<MAX_LINKS) snprintf(&(shared_buf[MAX_LINK_LENGTH*i]),MAX_LINK_LENGTH,"%s\0",buf);
        if(DEBUG>10) g_print("extracted link : %s\n",buf);
    }
}

static gboolean mycallback(GIOChannel *ch, GIOCondition c, gpointer p)
{
    g_print("callback called\n");
    gchar *line;
    g_io_channel_read_line(ch, &line, NULL, NULL, NULL);
    g_print("read: %s\n",line);
    g_free(line);
    show_hints(my_doc);
    return true;

}
static void
page_created_callback (WebKitWebExtension *extension,
                       WebKitWebPage      *web_page,
                       GVariant           *user_data)
{
    g_signal_connect (web_page, "document-loaded", 
                      G_CALLBACK (document_loaded_callback), 
                      user_data);

    GMainContext *ctx = g_main_context_default();
    GIOChannel *io = g_io_channel_new_file("/home/miguel/temp/mypipe", "r+", NULL);
    GSource *watch = g_io_create_watch(io, G_IO_IN);
    g_source_attach(watch,ctx);
    g_source_set_callback(watch,(GSourceFunc)mycallback,NULL,NULL);

}

G_MODULE_EXPORT void
webkit_web_extension_initialize_with_user_data (WebKitWebExtension *extension,
					        GVariant           *user_data)
{
    g_print("Initalizing Miguel's Surfin' Quick Links WebKit2GTK+ Extension\n");
    g_print("Extension  PID: %d\n",getpid());
    gchar *str=g_variant_get_string(user_data,NULL);
    g_print("UI Process Data: %s\n",str);
//    g_free(str);
    g_signal_connect (extension, "page-created", 
                      G_CALLBACK (page_created_callback),
                      user_data );
    
}

//https://stackoverflow.com/questions/4770985/how-to-check-if-a-string-starts-with-another-string-in-c
bool str_prefix(const char *str, const char *pre)
{
    size_t lenpre = strlen(pre),
           lenstr = strlen(str);
    return lenstr < lenpre ? false : strncmp(pre, str, lenpre) == 0;
}