/*
 * This file is part of LibNSLayout
 * Licensed under the ISC License, http://opensource.org/licenses/ISC
 * Copyright 2015 Michael Drake <tlsa@netsurf-browser.org>
 */

/** \file src/dom/watcher.c
 * DOM mutation handling
 */

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "layout.h"
#include "dom/watcher.h"
#include "util/dom-str.h"
#include "util/util.h"

/**
 * Convert a dom node type to a string
 *
 * \param[in]  type		DOM node type
 * \return appropriate string.
 */
static const char *nsl__dom_node_type_to_string(dom_node_type type)
{
	const char *str[] = {
		"ELEMENT_NODE",
		"ATTRIBUTE_NODE",
		"TEXT_NODE",
		"CDATA_SECTION_NODE",
		"ENTITY_REFERENCE_NODE",
		"ENTITY_NODE",
		"PROCESSING_INSTRUCTION_NODE",
		"COMMENT_NODE",
		"DOCUMENT_NODE",
		"DOCUMENT_TYPE_NODE",
		"DOCUMENT_FRAGMENT_NODE",
		"NOTATION_NODE"
	};
	assert(DOM_NODE_TYPE_COUNT == 12);

	return str[type - 1];
}

/**
 * LibDOM event handler
 *
 * \param[in]  evt		The LibDOM event object
 * \param[in]  pw		Pointer to our nslayout_layout object
 */
static void nsl__dom_event_handler(struct dom_event *evt, void *pw)
{
	dom_event_target *node = NULL;
	dom_node_type node_type;
	dom_string *name = NULL;
	dom_string *type = NULL;
	dom_exception exc;

	UNUSED(pw);

	printf("  DOM Event: ");

	/* Ugly test to see what events come out */
	exc = dom_event_get_target(evt, &node);
	if ((exc != DOM_NO_ERR) || (node == NULL)) {
		printf("FAILED to get target node!\n");
		goto fail;
	}

	exc = dom_node_get_node_type(node, &node_type);
	if (exc != DOM_NO_ERR) {
		printf("FAILED to get target node type!\n");
		goto fail;
	}

	if (node_type == DOM_ELEMENT_NODE) {
		exc = dom_node_get_node_name(node, &name);
		if ((exc != DOM_NO_ERR) || (name == NULL)) {
			printf("FAILED to get target node name!\n");
			goto fail;
		}
	}

	exc = dom_event_get_type(evt, &type);
	if ((exc != DOM_NO_ERR) || (type == NULL)) {
		printf("FAILED to get event type!\n");
		goto fail;
	}

	if (node_type == DOM_ELEMENT_NODE) {
		printf("<%s> %s",
				dom_string_data(name),
				dom_string_data(type));
	} else {
		printf("%s %s",
				nsl__dom_node_type_to_string(node_type),
				dom_string_data(type));
	}

	/* TODO: Based on event type:
	 *         1. call to do (re)selection:
	 *              a. all nodes?
	 *              b. just this node?
	 *         2. call to update layout, if needed.
	 */

fail:
	if (type != NULL) dom_string_unref(type);
	if (name != NULL) dom_string_unref(name);
	if (node != NULL) dom_node_unref(node);

	printf("\n");
}

/* Exported function, documented in src/dom/event.h */
nslayout_error nsl_dom_watcher_add_for_layout(nslayout_layout *layout)
{
	nslayout_error err;
	dom_exception exc;

	/* TODO: LibDOM event listeners are really slow.  Need to find a better
	 *       way to get DOM change notifications.
	 */

	exc = dom_event_listener_create(layout->doc, nsl__dom_event_handler,
			layout, &layout->listener);
	if (exc != DOM_NO_ERR) {
		return NSL_DOM_ERR(exc);
	}
	exc = dom_event_target_add_event_listener(
			layout->doc, nsl_dom_str_node_inserted, 
			layout->listener, false);
	if (exc != DOM_NO_ERR) {
		err = NSL_DOM_ERR(exc);
		goto fail;
	}
	exc = dom_event_target_add_event_listener(
			layout->doc, nsl_dom_str_subtree_modified, 
			layout->listener, false);
	if (exc != DOM_NO_ERR) {
		(void) dom_event_target_remove_event_listener(
				layout->doc, nsl_dom_str_node_inserted,
				layout->listener, false);
		err = NSL_DOM_ERR(exc);
		goto fail;
	}

	return NSLAYOUT_OK;

fail:
	dom_event_listener_unref(layout->listener);
	layout->listener = NULL;

	return err;
}

/* Exported function, documented in src/dom/event.h */
nslayout_error nsl_dom_watcher_remove_for_layout(nslayout_layout *layout)
{
	dom_exception exc1, exc2;

	exc1 = dom_event_target_remove_event_listener(
			layout->doc, nsl_dom_str_node_inserted, 
			layout->listener, false);
	exc2 = dom_event_target_remove_event_listener(
			layout->doc, nsl_dom_str_subtree_modified, 
			layout->listener, false);

	if (exc1 != DOM_NO_ERR) {
		return NSL_DOM_ERR(exc1);
	}
	if (exc2 != DOM_NO_ERR) {
		return NSL_DOM_ERR(exc2);
	}

	dom_event_listener_unref(layout->listener);
	layout->listener = NULL;

	return NSLAYOUT_OK;
}