/*************************************************************************/
/*  editor_file_system.cpp                                               */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/

#include "editor_file_system.h"

#include "core/io/resource_importer.h"
#include "core/io/resource_loader.h"
#include "core/io/resource_saver.h"
#include "core/os/file_access.h"
#include "core/os/os.h"
#include "core/project_settings.h"
#include "core/variant_parser.h"
#include "editor_node.h"
#include "editor_resource_preview.h"
#include "editor_settings.h"

EditorFileSystem *EditorFileSystem::singleton = NULL;
//the name is the version, to keep compatibility with different versions of Godot
#define CACHE_FILE_NAME "filesystem_cache6"

void EditorFileSystemDirectory::sort_files() {

	files.sort_custom<FileInfoSort>();
}

int EditorFileSystemDirectory::find_file_index(const String &p_file) const {

	for (int i = 0; i < files.size(); i++) {
		if (files[i]->file == p_file)
			return i;
	}
	return -1;
}
int EditorFileSystemDirectory::find_dir_index(const String &p_dir) const {

	for (int i = 0; i < subdirs.size(); i++) {
		if (subdirs[i]->name == p_dir)
			return i;
	}

	return -1;
}

void EditorFileSystemDirectory::force_update() {
	// We set modified_time to 0 to force `EditorFileSystem::_scan_fs_changes` to search changes in the directory
	modified_time = 0;
}

int EditorFileSystemDirectory::get_subdir_count() const {

	return subdirs.size();
}

EditorFileSystemDirectory *EditorFileSystemDirectory::get_subdir(int p_idx) {

	ERR_FAIL_INDEX_V(p_idx, subdirs.size(), NULL);
	return subdirs[p_idx];
}

int EditorFileSystemDirectory::get_file_count() const {

	return files.size();
}

String EditorFileSystemDirectory::get_file(int p_idx) const {

	ERR_FAIL_INDEX_V(p_idx, files.size(), "");

	return files[p_idx]->file;
}

String EditorFileSystemDirectory::get_path() const {

	String p;
	const EditorFileSystemDirectory *d = this;
	while (d->parent) {
		p = d->name.plus_file(p);
		d = d->parent;
	}

	return "res://" + p;
}

String EditorFileSystemDirectory::get_file_path(int p_idx) const {

	String file = get_file(p_idx);
	const EditorFileSystemDirectory *d = this;
	while (d->parent) {
		file = d->name.plus_file(file);
		d = d->parent;
	}

	return "res://" + file;
}

Vector<String> EditorFileSystemDirectory::get_file_deps(int p_idx) const {

	ERR_FAIL_INDEX_V(p_idx, files.size(), Vector<String>());
	return files[p_idx]->deps;
}

bool EditorFileSystemDirectory::get_file_import_is_valid(int p_idx) const {

	ERR_FAIL_INDEX_V(p_idx, files.size(), false);
	return files[p_idx]->import_valid;
}

String EditorFileSystemDirectory::get_file_script_class_name(int p_idx) const {
	return files[p_idx]->script_class_name;
}

String EditorFileSystemDirectory::get_file_script_class_extends(int p_idx) const {
	return files[p_idx]->script_class_extends;
}

String EditorFileSystemDirectory::get_file_script_class_icon_path(int p_idx) const {
	return files[p_idx]->script_class_icon_path;
}

StringName EditorFileSystemDirectory::get_file_type(int p_idx) const {

	ERR_FAIL_INDEX_V(p_idx, files.size(), "");
	return files[p_idx]->type;
}

String EditorFileSystemDirectory::get_name() {

	return name;
}

EditorFileSystemDirectory *EditorFileSystemDirectory::get_parent() {

	return parent;
}

void EditorFileSystemDirectory::_bind_methods() {

	ClassDB::bind_method(D_METHOD("get_subdir_count"), &EditorFileSystemDirectory::get_subdir_count);
	ClassDB::bind_method(D_METHOD("get_subdir", "idx"), &EditorFileSystemDirectory::get_subdir);
	ClassDB::bind_method(D_METHOD("get_file_count"), &EditorFileSystemDirectory::get_file_count);
	ClassDB::bind_method(D_METHOD("get_file", "idx"), &EditorFileSystemDirectory::get_file);
	ClassDB::bind_method(D_METHOD("get_file_path", "idx"), &EditorFileSystemDirectory::get_file_path);
	ClassDB::bind_method(D_METHOD("get_file_type", "idx"), &EditorFileSystemDirectory::get_file_type);
	ClassDB::bind_method(D_METHOD("get_file_script_class_name", "idx"), &EditorFileSystemDirectory::get_file_script_class_name);
	ClassDB::bind_method(D_METHOD("get_file_script_class_extends", "idx"), &EditorFileSystemDirectory::get_file_script_class_extends);
	ClassDB::bind_method(D_METHOD("get_file_import_is_valid", "idx"), &EditorFileSystemDirectory::get_file_import_is_valid);
	ClassDB::bind_method(D_METHOD("get_name"), &EditorFileSystemDirectory::get_name);
	ClassDB::bind_method(D_METHOD("get_path"), &EditorFileSystemDirectory::get_path);
	ClassDB::bind_method(D_METHOD("get_parent"), &EditorFileSystemDirectory::get_parent);
	ClassDB::bind_method(D_METHOD("find_file_index", "name"), &EditorFileSystemDirectory::find_file_index);
	ClassDB::bind_method(D_METHOD("find_dir_index", "name"), &EditorFileSystemDirectory::find_dir_index);
}

EditorFileSystemDirectory::EditorFileSystemDirectory() {

	modified_time = 0;
	parent = NULL;
	verified = false;
}

EditorFileSystemDirectory::~EditorFileSystemDirectory() {

	for (int i = 0; i < files.size(); i++) {

		memdelete(files[i]);
	}

	for (int i = 0; i < subdirs.size(); i++) {

		memdelete(subdirs[i]);
	}
}

void EditorFileSystem::_scan_filesystem() {

	ERR_FAIL_COND(!scanning || new_filesystem);

	//read .fscache
	String cpath;

	sources_changed.clear();
	file_cache.clear();

	String project = ProjectSettings::get_singleton()->get_resource_path();

	String fscache = EditorSettings::get_singleton()->get_project_settings_dir().plus_file(CACHE_FILE_NAME);
	FileAccess *f = FileAccess::open(fscache, FileAccess::READ);

	bool first = true;
	if (f) {
		//read the disk cache
		while (!f->eof_reached()) {

			String l = f->get_line().strip_edges();
			if (first) {
				if (first_scan) {
					// only use this on first scan, afterwards it gets ignored
					// this is so on first reimport we synchronize versions, then
					// we don't care until editor restart. This is for usability mainly so
					// your workflow is not killed after changing a setting by forceful reimporting
					// everything there is.
					filesystem_settings_version_for_import = l.strip_edges();
					if (filesystem_settings_version_for_import != ResourceFormatImporter::get_singleton()->get_import_settings_hash()) {
						revalidate_import_files = true;
					}
				}
				first = false;
				continue;
			}
			if (l == String())
				continue;

			if (l.begins_with("::")) {
				Vector<String> split = l.split("::");
				ERR_CONTINUE(split.size() != 3);
				String name = split[1];

				cpath = name;

			} else {
				Vector<String> split = l.split("::");
				ERR_CONTINUE(split.size() != 8);
				String name = split[0];
				String file;

				file = name;
				name = cpath.plus_file(name);

				FileCache fc;
				fc.type = split[1];
				fc.modification_time = split[2].to_int64();
				fc.import_modification_time = split[3].to_int64();
				fc.import_valid = split[4].to_int64() != 0;
				fc.import_group_file = split[5].strip_edges();
				fc.script_class_name = split[6].get_slice("<>", 0);
				fc.script_class_extends = split[6].get_slice("<>", 1);
				fc.script_class_icon_path = split[6].get_slice("<>", 2);

				String deps = split[7].strip_edges();
				if (deps.length()) {
					Vector<String> dp = deps.split("<>");
					for (int i = 0; i < dp.size(); i++) {
						String path = dp[i];
						fc.deps.push_back(path);
					}
				}

				file_cache[name] = fc;
			}
		}

		f->close();
		memdelete(f);
	}

	String update_cache = EditorSettings::get_singleton()->get_project_settings_dir().plus_file("filesystem_update4");

	if (FileAccess::exists(update_cache)) {
		{
			FileAccessRef f2 = FileAccess::open(update_cache, FileAccess::READ);
			String l = f2->get_line().strip_edges();
			while (l != String()) {

				file_cache.erase(l); //erase cache for this, so it gets updated
				l = f2->get_line().strip_edges();
			}
		}

		DirAccessRef d = DirAccess::create(DirAccess::ACCESS_FILESYSTEM);
		d->remove(update_cache); //bye bye update cache
	}

	EditorProgressBG scan_progress("efs", "ScanFS", 1000);

	ScanProgress sp;
	sp.low = 0;
	sp.hi = 1;
	sp.progress = &scan_progress;

	new_filesystem = memnew(EditorFileSystemDirectory);
	new_filesystem->parent = NULL;

	DirAccess *d = DirAccess::create(DirAccess::ACCESS_RESOURCES);
	d->change_dir("res://");
	_scan_new_dir(new_filesystem, d, sp);

	file_cache.clear(); //clear caches, no longer needed

	memdelete(d);

	if (!first_scan) {
		//on the first scan this is done from the main thread after re-importing
		_save_filesystem_cache();
	}

	scanning = false;
}

void EditorFileSystem::_save_filesystem_cache() {

	group_file_cache.clear();

	String fscache = EditorSettings::get_singleton()->get_project_settings_dir().plus_file(CACHE_FILE_NAME);

	FileAccess *f = FileAccess::open(fscache, FileAccess::WRITE);
	ERR_FAIL_COND_MSG(!f, "Cannot create file '" + fscache + "'. Check user write permissions.");

	f->store_line(filesystem_settings_version_for_import);
	_save_filesystem_cache(filesystem, f);
	f->close();
	memdelete(f);
}

void EditorFileSystem::_thread_func(void *_userdata) {

	EditorFileSystem *sd = (EditorFileSystem *)_userdata;
	sd->_scan_filesystem();
}

bool EditorFileSystem::_test_for_reimport(const String &p_path, bool p_only_imported_files) {

	if (!reimport_on_missing_imported_files && p_only_imported_files)
		return false;

	if (!FileAccess::exists(p_path + ".import")) {
		return true;
	}

	if (!ResourceFormatImporter::get_singleton()->are_import_settings_valid(p_path)) {
		//reimport settings are not valid, reimport
		return true;
	}

	Error err;
	FileAccess *f = FileAccess::open(p_path + ".import", FileAccess::READ, &err);

	if (!f) { //no import file, do reimport
		return true;
	}

	VariantParser::StreamFile stream;
	stream.f = f;

	String assign;
	Variant value;
	VariantParser::Tag next_tag;

	int lines = 0;
	String error_text;

	List<String> to_check;

	String importer_name;
	String source_file = "";
	String source_md5 = "";
	Vector<String> dest_files;
	String dest_md5 = "";

	while (true) {

		assign = Variant();
		next_tag.fields.clear();
		next_tag.name = String();

		err = VariantParser::parse_tag_assign_eof(&stream, lines, error_text, next_tag, assign, value, NULL, true);
		if (err == ERR_FILE_EOF) {
			break;
		} else if (err != OK) {
			ERR_PRINTS("ResourceFormatImporter::load - '" + p_path + ".import:" + itos(lines) + "' error '" + error_text + "'.");
			memdelete(f);
			return false; //parse error, try reimport manually (Avoid reimport loop on broken file)
		}

		if (assign != String()) {
			if (assign.begins_with("path")) {
				to_check.push_back(value);
			} else if (assign == "files") {
				Array fa = value;
				for (int i = 0; i < fa.size(); i++) {
					to_check.push_back(fa[i]);
				}
			} else if (assign == "importer") {
				importer_name = value;
			} else if (!p_only_imported_files) {
				if (assign == "source_file") {
					source_file = value;
				} else if (assign == "dest_files") {
					dest_files = value;
				}
			}

		} else if (next_tag.name != "remap" && next_tag.name != "deps") {
			break;
		}
	}

	memdelete(f);

	if (importer_name == "keep") {
		return false; //keep mode, do not reimport
	}

	// Read the md5's from a separate file (so the import parameters aren't dependent on the file version
	String base_path = ResourceFormatImporter::get_singleton()->get_import_base_path(p_path);
	FileAccess *md5s = FileAccess::open(base_path + ".md5", FileAccess::READ, &err);
	if (!md5s) { // No md5's stored for this resource
		return true;
	}

	VariantParser::StreamFile md5_stream;
	md5_stream.f = md5s;

	while (true) {
		assign = Variant();
		next_tag.fields.clear();
		next_tag.name = String();

		err = VariantParser::parse_tag_assign_eof(&md5_stream, lines, error_text, next_tag, assign, value, NULL, true);

		if (err == ERR_FILE_EOF) {
			break;
		} else if (err != OK) {
			ERR_PRINTS("ResourceFormatImporter::load - '" + p_path + ".import.md5:" + itos(lines) + "' error '" + error_text + "'.");
			memdelete(md5s);
			return false; // parse error
		}
		if (assign != String()) {
			if (!p_only_imported_files) {
				if (assign == "source_md5") {
					source_md5 = value;
				} else if (assign == "dest_md5") {
					dest_md5 = value;
				}
			}
		}
	}
	memdelete(md5s);

	//imported files are gone, reimport
	for (List<String>::Element *E = to_check.front(); E; E = E->next()) {
		if (!FileAccess::exists(E->get())) {
			return true;
		}
	}

	//check source md5 matching
	if (!p_only_imported_files) {

		if (source_file != String() && source_file != p_path) {
			return true; //file was moved, reimport
		}

		if (source_md5 == String()) {
			return true; //lacks md5, so just reimport
		}

		String md5 = FileAccess::get_md5(p_path);
		if (md5 != source_md5) {
			return true;
		}

		if (dest_files.size() && dest_md5 != String()) {
			md5 = FileAccess::get_multiple_md5(dest_files);
			if (md5 != dest_md5) {
				return true;
			}
		}
	}

	return false; //nothing changed
}

bool EditorFileSystem::_update_scan_actions() {

	sources_changed.clear();

	bool fs_changed = false;

	Vector<String> reimports;
	Vector<String> reloads;

	for (List<ItemAction>::Element *E = scan_actions.front(); E; E = E->next()) {

		ItemAction &ia = E->get();

		switch (ia.action) {
			case ItemAction::ACTION_NONE: {

			} break;
			case ItemAction::ACTION_DIR_ADD: {

				int idx = 0;
				for (int i = 0; i < ia.dir->subdirs.size(); i++) {

					if (ia.new_dir->name < ia.dir->subdirs[i]->name)
						break;
					idx++;
				}
				if (idx == ia.dir->subdirs.size()) {
					ia.dir->subdirs.push_back(ia.new_dir);
				} else {
					ia.dir->subdirs.insert(idx, ia.new_dir);
				}

				fs_changed = true;
			} break;
			case ItemAction::ACTION_DIR_REMOVE: {

				ERR_CONTINUE(!ia.dir->parent);
				ia.dir->parent->subdirs.erase(ia.dir);
				memdelete(ia.dir);
				fs_changed = true;
			} break;
			case ItemAction::ACTION_FILE_ADD: {

				int idx = 0;
				for (int i = 0; i < ia.dir->files.size(); i++) {

					if (ia.new_file->file < ia.dir->files[i]->file)
						break;
					idx++;
				}
				if (idx == ia.dir->files.size()) {
					ia.dir->files.push_back(ia.new_file);
				} else {
					ia.dir->files.insert(idx, ia.new_file);
				}

				fs_changed = true;

			} break;
			case ItemAction::ACTION_FILE_REMOVE: {

				int idx = ia.dir->find_file_index(ia.file);
				ERR_CONTINUE(idx == -1);
				_delete_internal_files(ia.dir->files[idx]->file);
				memdelete(ia.dir->files[idx]);
				ia.dir->files.remove(idx);

				fs_changed = true;

			} break;
			case ItemAction::ACTION_FILE_TEST_REIMPORT: {

				int idx = ia.dir->find_file_index(ia.file);
				ERR_CONTINUE(idx == -1);
				String full_path = ia.dir->get_file_path(idx);
				if (_test_for_reimport(full_path, false)) {
					//must reimport
					reimports.push_back(full_path);
					reimports.append_array(_get_dependencies(full_path));
				} else {
					//must not reimport, all was good
					//update modified times, to avoid reimport
					ia.dir->files[idx]->modified_time = FileAccess::get_modified_time(full_path);
					ia.dir->files[idx]->import_modified_time = FileAccess::get_modified_time(full_path + ".import");
				}

				fs_changed = true;
			} break;
			case ItemAction::ACTION_FILE_RELOAD: {

				int idx = ia.dir->find_file_index(ia.file);
				ERR_CONTINUE(idx == -1);
				String full_path = ia.dir->get_file_path(idx);

				reloads.push_back(full_path);

			} break;
		}
	}

	if (reimports.size()) {
		reimport_files(reimports);
	}

	if (first_scan) {
		//only on first scan this is valid and updated, then settings changed.
		revalidate_import_files = false;
		filesystem_settings_version_for_import = ResourceFormatImporter::get_singleton()->get_import_settings_hash();
		_save_filesystem_cache();
	}

	if (reloads.size()) {
		emit_signal("resources_reload", reloads);
	}
	scan_actions.clear();

	return fs_changed;
}

void EditorFileSystem::scan() {

	if (false /*&& bool(Globals::get_singleton()->get("debug/disable_scan"))*/)
		return;

	if (scanning || scanning_changes || thread.is_started())
		return;

	_update_extensions();

	abort_scan = false;
	if (!use_threads) {
		scanning = true;
		scan_total = 0;
		_scan_filesystem();
		if (filesystem)
			memdelete(filesystem);
		//file_type_cache.clear();
		filesystem = new_filesystem;
		new_filesystem = NULL;
		_update_scan_actions();
		scanning = false;
		emit_signal("filesystem_changed");
		emit_signal("sources_changed", sources_changed.size() > 0);
		_queue_update_script_classes();
		first_scan = false;
	} else {

		ERR_FAIL_COND(thread.is_started());
		set_process(true);
		Thread::Settings s;
		scanning = true;
		scan_total = 0;
		s.priority = Thread::PRIORITY_LOW;
		thread.start(_thread_func, this, s);
		//tree->hide();
		//progress->show();
	}
}

void EditorFileSystem::ScanProgress::update(int p_current, int p_total) const {

	float ratio = low + ((hi - low) / p_total) * p_current;
	progress->step(ratio * 1000);
	EditorFileSystem::singleton->scan_total = ratio;
}

EditorFileSystem::ScanProgress EditorFileSystem::ScanProgress::get_sub(int p_current, int p_total) const {

	ScanProgress sp = *this;
	float slice = (sp.hi - sp.low) / p_total;
	sp.low += slice * p_current;
	sp.hi = slice;
	return sp;
}

void EditorFileSystem::_scan_new_dir(EditorFileSystemDirectory *p_dir, DirAccess *da, const ScanProgress &p_progress) {

	List<String> dirs;
	List<String> files;

	String cd = da->get_current_dir();

	p_dir->modified_time = FileAccess::get_modified_time(cd);

	da->list_dir_begin();
	while (true) {

		String f = da->get_next();
		if (f == "")
			break;

		if (da->current_is_hidden())
			continue;

		if (da->current_is_dir()) {

			if (f.begins_with(".")) // Ignore special and . / ..
				continue;

			if (_should_skip_directory(cd.plus_file(f)))
				continue;

			dirs.push_back(f);

		} else {

			files.push_back(f);
		}
	}

	da->list_dir_end();

	dirs.sort_custom<NaturalNoCaseComparator>();
	files.sort_custom<NaturalNoCaseComparator>();

	int total = dirs.size() + files.size();
	int idx = 0;

	for (List<String>::Element *E = dirs.front(); E; E = E->next(), idx++) {

		if (da->change_dir(E->get()) == OK) {

			String d = da->get_current_dir();

			if (d == cd || !d.begins_with(cd)) {
				da->change_dir(cd); //avoid recursion
			} else {

				EditorFileSystemDirectory *efd = memnew(EditorFileSystemDirectory);

				efd->parent = p_dir;
				efd->name = E->get();

				_scan_new_dir(efd, da, p_progress.get_sub(idx, total));

				int idx2 = 0;
				for (int i = 0; i < p_dir->subdirs.size(); i++) {

					if (efd->name < p_dir->subdirs[i]->name)
						break;
					idx2++;
				}
				if (idx2 == p_dir->subdirs.size()) {
					p_dir->subdirs.push_back(efd);
				} else {
					p_dir->subdirs.insert(idx2, efd);
				}

				da->change_dir("..");
			}
		} else {
			ERR_PRINTS("Cannot go into subdir '" + E->get() + "'.");
		}

		p_progress.update(idx, total);
	}

	for (List<String>::Element *E = files.front(); E; E = E->next(), idx++) {

		String ext = E->get().get_extension().to_lower();
		if (!valid_extensions.has(ext)) {
			continue; //invalid
		}

		EditorFileSystemDirectory::FileInfo *fi = memnew(EditorFileSystemDirectory::FileInfo);
		fi->file = E->get();

		String path = cd.plus_file(fi->file);

		FileCache *fc = file_cache.getptr(path);
		uint64_t mt = FileAccess::get_modified_time(path);

		if (import_extensions.has(ext)) {

			//is imported
			uint64_t import_mt = 0;
			if (FileAccess::exists(path + ".import")) {
				import_mt = FileAccess::get_modified_time(path + ".import");
			}

			if (fc && fc->modification_time == mt && fc->import_modification_time == import_mt && !_test_for_reimport(path, true)) {

				fi->type = fc->type;
				fi->deps = fc->deps;
				fi->modified_time = fc->modification_time;
				fi->import_modified_time = fc->import_modification_time;

				fi->import_valid = fc->import_valid;
				fi->script_class_name = fc->script_class_name;
				fi->import_group_file = fc->import_group_file;
				fi->script_class_extends = fc->script_class_extends;
				fi->script_class_icon_path = fc->script_class_icon_path;

				if (revalidate_import_files && !ResourceFormatImporter::get_singleton()->are_import_settings_valid(path)) {
					ItemAction ia;
					ia.action = ItemAction::ACTION_FILE_TEST_REIMPORT;
					ia.dir = p_dir;
					ia.file = E->get();
					scan_actions.push_back(ia);
				}

				if (fc->type == String()) {
					fi->type = ResourceLoader::get_resource_type(path);
					fi->import_group_file = ResourceLoader::get_import_group_file(path);
					//there is also the chance that file type changed due to reimport, must probably check this somehow here (or kind of note it for next time in another file?)
					//note: I think this should not happen any longer..
				}

			} else {

				fi->type = ResourceFormatImporter::get_singleton()->get_resource_type(path);
				fi->import_group_file = ResourceFormatImporter::get_singleton()->get_import_group_file(path);
				fi->script_class_name = _get_global_script_class(fi->type, path, &fi->script_class_extends, &fi->script_class_icon_path);
				fi->modified_time = 0;
				fi->import_modified_time = 0;
				fi->import_valid = ResourceLoader::is_import_valid(path);

				ItemAction ia;
				ia.action = ItemAction::ACTION_FILE_TEST_REIMPORT;
				ia.dir = p_dir;
				ia.file = E->get();
				scan_actions.push_back(ia);
			}
		} else {

			if (fc && fc->modification_time == mt) {
				//not imported, so just update type if changed
				fi->type = fc->type;
				fi->modified_time = fc->modification_time;
				fi->deps = fc->deps;
				fi->import_modified_time = 0;
				fi->import_valid = true;
				fi->script_class_name = fc->script_class_name;
				fi->script_class_extends = fc->script_class_extends;
				fi->script_class_icon_path = fc->script_class_icon_path;
			} else {
				//new or modified time
				fi->type = ResourceLoader::get_resource_type(path);
				fi->script_class_name = _get_global_script_class(fi->type, path, &fi->script_class_extends, &fi->script_class_icon_path);
				fi->deps = _get_dependencies(path);
				fi->modified_time = mt;
				fi->import_modified_time = 0;
				fi->import_valid = true;
			}
		}

		p_dir->files.push_back(fi);
		p_progress.update(idx, total);
	}
}

void EditorFileSystem::_scan_fs_changes(EditorFileSystemDirectory *p_dir, const ScanProgress &p_progress) {

	uint64_t current_mtime = FileAccess::get_modified_time(p_dir->get_path());

	bool updated_dir = false;
	String cd = p_dir->get_path();

	if (current_mtime != p_dir->modified_time || using_fat32_or_exfat) {

		updated_dir = true;
		p_dir->modified_time = current_mtime;
		//ooooops, dir changed, see what's going on

		//first mark everything as veryfied

		for (int i = 0; i < p_dir->files.size(); i++) {

			p_dir->files[i]->verified = false;
		}

		for (int i = 0; i < p_dir->subdirs.size(); i++) {

			p_dir->get_subdir(i)->verified = false;
		}

		//then scan files and directories and check what's different

		DirAccessRef da = DirAccess::create(DirAccess::ACCESS_RESOURCES);

		Error ret = da->change_dir(cd);
		ERR_FAIL_COND_MSG(ret != OK, "Cannot change to '" + cd + "' folder.");

		da->list_dir_begin();
		while (true) {

			String f = da->get_next();
			if (f == "")
				break;

			if (da->current_is_hidden())
				continue;

			if (da->current_is_dir()) {

				if (f.begins_with(".")) // Ignore special and . / ..
					continue;

				int idx = p_dir->find_dir_index(f);
				if (idx == -1) {

					if (_should_skip_directory(cd.plus_file(f)))
						continue;

					EditorFileSystemDirectory *efd = memnew(EditorFileSystemDirectory);

					efd->parent = p_dir;
					efd->name = f;
					DirAccess *d = DirAccess::create(DirAccess::ACCESS_RESOURCES);
					d->change_dir(cd.plus_file(f));
					_scan_new_dir(efd, d, p_progress.get_sub(1, 1));
					memdelete(d);

					ItemAction ia;
					ia.action = ItemAction::ACTION_DIR_ADD;
					ia.dir = p_dir;
					ia.file = f;
					ia.new_dir = efd;
					scan_actions.push_back(ia);
				} else {
					p_dir->subdirs[idx]->verified = true;
				}

			} else {
				String ext = f.get_extension().to_lower();
				if (!valid_extensions.has(ext))
					continue; //invalid

				int idx = p_dir->find_file_index(f);

				if (idx == -1) {
					//never seen this file, add actition to add it
					EditorFileSystemDirectory::FileInfo *fi = memnew(EditorFileSystemDirectory::FileInfo);
					fi->file = f;

					String path = cd.plus_file(fi->file);
					fi->modified_time = FileAccess::get_modified_time(path);
					fi->import_modified_time = 0;
					fi->type = ResourceLoader::get_resource_type(path);
					fi->script_class_name = _get_global_script_class(fi->type, path, &fi->script_class_extends, &fi->script_class_icon_path);
					fi->import_valid = ResourceLoader::is_import_valid(path);
					fi->import_group_file = ResourceLoader::get_import_group_file(path);

					{
						ItemAction ia;
						ia.action = ItemAction::ACTION_FILE_ADD;
						ia.dir = p_dir;
						ia.file = f;
						ia.new_file = fi;
						scan_actions.push_back(ia);
					}

					if (import_extensions.has(ext)) {
						//if it can be imported, and it was added, it needs to be reimported
						ItemAction ia;
						ia.action = ItemAction::ACTION_FILE_TEST_REIMPORT;
						ia.dir = p_dir;
						ia.file = f;
						scan_actions.push_back(ia);
					}

				} else {
					p_dir->files[idx]->verified = true;
				}
			}
		}

		da->list_dir_end();
	}

	for (int i = 0; i < p_dir->files.size(); i++) {

		if (updated_dir && !p_dir->files[i]->verified) {
			//this file was removed, add action to remove it
			ItemAction ia;
			ia.action = ItemAction::ACTION_FILE_REMOVE;
			ia.dir = p_dir;
			ia.file = p_dir->files[i]->file;
			scan_actions.push_back(ia);
			continue;
		}

		String path = cd.plus_file(p_dir->files[i]->file);

		if (import_extensions.has(p_dir->files[i]->file.get_extension().to_lower())) {
			//check here if file must be imported or not

			uint64_t mt = FileAccess::get_modified_time(path);

			bool reimport = false;

			if (mt != p_dir->files[i]->modified_time) {
				reimport = true; //it was modified, must be reimported.
			} else if (!FileAccess::exists(path + ".import")) {
				reimport = true; //no .import file, obviously reimport
			} else {

				uint64_t import_mt = FileAccess::get_modified_time(path + ".import");
				if (import_mt != p_dir->files[i]->import_modified_time) {
					reimport = true;
				} else if (_test_for_reimport(path, true)) {
					reimport = true;
				}
			}

			if (reimport) {

				ItemAction ia;
				ia.action = ItemAction::ACTION_FILE_TEST_REIMPORT;
				ia.dir = p_dir;
				ia.file = p_dir->files[i]->file;
				scan_actions.push_back(ia);
			}
		} else if (ResourceCache::has(path)) { //test for potential reload

			uint64_t mt = FileAccess::get_modified_time(path);

			if (mt != p_dir->files[i]->modified_time) {

				p_dir->files[i]->modified_time = mt; //save new time, but test for reload

				ItemAction ia;
				ia.action = ItemAction::ACTION_FILE_RELOAD;
				ia.dir = p_dir;
				ia.file = p_dir->files[i]->file;
				scan_actions.push_back(ia);
			}
		}
	}

	for (int i = 0; i < p_dir->subdirs.size(); i++) {

		if (updated_dir && !p_dir->subdirs[i]->verified) {
			//this directory was removed, add action to remove it
			ItemAction ia;
			ia.action = ItemAction::ACTION_DIR_REMOVE;
			ia.dir = p_dir->subdirs[i];
			scan_actions.push_back(ia);
			continue;
		}
		_scan_fs_changes(p_dir->get_subdir(i), p_progress);
	}
}

void EditorFileSystem::_delete_internal_files(String p_file) {
	if (FileAccess::exists(p_file + ".import")) {
		List<String> paths;
		ResourceFormatImporter::get_singleton()->get_internal_resource_path_list(p_file, &paths);
		DirAccess *da = DirAccess::create(DirAccess::ACCESS_RESOURCES);
		for (List<String>::Element *E = paths.front(); E; E = E->next()) {
			da->remove(E->get());
		}
		da->remove(p_file + ".import");
		memdelete(da);
	}
}

void EditorFileSystem::_thread_func_sources(void *_userdata) {

	EditorFileSystem *efs = (EditorFileSystem *)_userdata;
	if (efs->filesystem) {
		EditorProgressBG pr("sources", TTR("ScanSources"), 1000);
		ScanProgress sp;
		sp.progress = &pr;
		sp.hi = 1;
		sp.low = 0;
		efs->_scan_fs_changes(efs->filesystem, sp);
	}
	efs->scanning_changes_done = true;
}

void EditorFileSystem::get_changed_sources(List<String> *r_changed) {

	*r_changed = sources_changed;
}

void EditorFileSystem::scan_changes() {

	if (first_scan || // Prevent a premature changes scan from inhibiting the first full scan
			scanning || scanning_changes || thread.is_started()) {
		scan_changes_pending = true;
		set_process(true);
		return;
	}

	_update_extensions();
	sources_changed.clear();
	scanning_changes = true;
	scanning_changes_done = false;

	abort_scan = false;

	if (!use_threads) {
		if (filesystem) {
			EditorProgressBG pr("sources", TTR("ScanSources"), 1000);
			ScanProgress sp;
			sp.progress = &pr;
			sp.hi = 1;
			sp.low = 0;
			scan_total = 0;
			_scan_fs_changes(filesystem, sp);
			if (_update_scan_actions())
				emit_signal("filesystem_changed");
		}
		scanning_changes = false;
		scanning_changes_done = true;
		emit_signal("sources_changed", sources_changed.size() > 0);
	} else {

		ERR_FAIL_COND(thread_sources.is_started());
		set_process(true);
		scan_total = 0;
		Thread::Settings s;
		s.priority = Thread::PRIORITY_LOW;
		thread_sources.start(_thread_func_sources, this, s);
	}
}

void EditorFileSystem::_notification(int p_what) {

	switch (p_what) {

		case NOTIFICATION_ENTER_TREE: {

			call_deferred("scan"); //this should happen after every editor node entered the tree

		} break;
		case NOTIFICATION_EXIT_TREE: {
			Thread &active_thread = thread.is_started() ? thread : thread_sources;
			if (use_threads && active_thread.is_started()) {
				//abort thread if in progress
				abort_scan = true;
				while (scanning) {
					OS::get_singleton()->delay_usec(1000);
				}
				active_thread.wait_to_finish();
				WARN_PRINT("Scan thread aborted...");
				set_process(false);
			}

			if (filesystem)
				memdelete(filesystem);
			if (new_filesystem)
				memdelete(new_filesystem);
			filesystem = NULL;
			new_filesystem = NULL;

		} break;
		case NOTIFICATION_PROCESS: {

			if (use_threads) {

				if (scanning_changes) {

					if (scanning_changes_done) {

						scanning_changes = false;

						set_process(false);

						thread_sources.wait_to_finish();
						if (_update_scan_actions())
							emit_signal("filesystem_changed");
						emit_signal("sources_changed", sources_changed.size() > 0);
						_queue_update_script_classes();
						first_scan = false;
					}
				} else if (!scanning) {

					set_process(false);

					if (filesystem)
						memdelete(filesystem);
					filesystem = new_filesystem;
					new_filesystem = NULL;
					thread.wait_to_finish();
					_update_scan_actions();
					emit_signal("filesystem_changed");
					emit_signal("sources_changed", sources_changed.size() > 0);
					_queue_update_script_classes();
					first_scan = false;
				}

				if (!is_processing() && scan_changes_pending) {
					scan_changes_pending = false;
					scan_changes();
				}
			}
		} break;
	}
}

bool EditorFileSystem::is_scanning() const {

	return scanning || scanning_changes;
}
float EditorFileSystem::get_scanning_progress() const {

	return scan_total;
}

EditorFileSystemDirectory *EditorFileSystem::get_filesystem() {

	return filesystem;
}

void EditorFileSystem::_save_filesystem_cache(EditorFileSystemDirectory *p_dir, FileAccess *p_file) {

	if (!p_dir)
		return; //none
	p_file->store_line("::" + p_dir->get_path() + "::" + String::num(p_dir->modified_time));

	for (int i = 0; i < p_dir->files.size(); i++) {

		if (p_dir->files[i]->import_group_file != String()) {
			group_file_cache.insert(p_dir->files[i]->import_group_file);
		}
		String s = p_dir->files[i]->file + "::" + p_dir->files[i]->type + "::" + itos(p_dir->files[i]->modified_time) + "::" + itos(p_dir->files[i]->import_modified_time) + "::" + itos(p_dir->files[i]->import_valid) + "::" + p_dir->files[i]->import_group_file + "::" + p_dir->files[i]->script_class_name + "<>" + p_dir->files[i]->script_class_extends + "<>" + p_dir->files[i]->script_class_icon_path;
		s += "::";
		for (int j = 0; j < p_dir->files[i]->deps.size(); j++) {

			if (j > 0)
				s += "<>";
			s += p_dir->files[i]->deps[j];
		}

		p_file->store_line(s);
	}

	for (int i = 0; i < p_dir->subdirs.size(); i++) {

		_save_filesystem_cache(p_dir->subdirs[i], p_file);
	}
}

bool EditorFileSystem::_find_file(const String &p_file, EditorFileSystemDirectory **r_d, int &r_file_pos) const {
	//todo make faster

	if (!filesystem || scanning)
		return false;

	String f = ProjectSettings::get_singleton()->localize_path(p_file);

	if (!f.begins_with("res://"))
		return false;
	f = f.substr(6, f.length());
	f = f.replace("\\", "/");

	Vector<String> path = f.split("/");

	if (path.size() == 0)
		return false;
	String file = path[path.size() - 1];
	path.resize(path.size() - 1);

	EditorFileSystemDirectory *fs = filesystem;

	for (int i = 0; i < path.size(); i++) {

		if (path[i].begins_with("."))
			return false;

		int idx = -1;
		for (int j = 0; j < fs->get_subdir_count(); j++) {

			if (fs->get_subdir(j)->get_name() == path[i]) {
				idx = j;
				break;
			}
		}

		if (idx == -1) {
			//does not exist, create i guess?
			EditorFileSystemDirectory *efsd = memnew(EditorFileSystemDirectory);

			efsd->name = path[i];
			efsd->parent = fs;

			int idx2 = 0;
			for (int j = 0; j < fs->get_subdir_count(); j++) {

				if (efsd->name < fs->get_subdir(j)->get_name())
					break;
				idx2++;
			}

			if (idx2 == fs->get_subdir_count())
				fs->subdirs.push_back(efsd);
			else
				fs->subdirs.insert(idx2, efsd);
			fs = efsd;
		} else {

			fs = fs->get_subdir(idx);
		}
	}

	int cpos = -1;
	for (int i = 0; i < fs->files.size(); i++) {

		if (fs->files[i]->file == file) {
			cpos = i;
			break;
		}
	}

	r_file_pos = cpos;
	*r_d = fs;

	return cpos != -1;
}

String EditorFileSystem::get_file_type(const String &p_file) const {

	EditorFileSystemDirectory *fs = NULL;
	int cpos = -1;

	if (!_find_file(p_file, &fs, cpos)) {

		return "";
	}

	return fs->files[cpos]->type;
}

EditorFileSystemDirectory *EditorFileSystem::find_file(const String &p_file, int *r_index) const {

	if (!filesystem || scanning)
		return NULL;

	EditorFileSystemDirectory *fs = NULL;
	int cpos = -1;
	if (!_find_file(p_file, &fs, cpos)) {

		return NULL;
	}

	if (r_index)
		*r_index = cpos;

	return fs;
}

EditorFileSystemDirectory *EditorFileSystem::get_filesystem_path(const String &p_path) {

	if (!filesystem || scanning)
		return NULL;

	String f = ProjectSettings::get_singleton()->localize_path(p_path);

	if (!f.begins_with("res://"))
		return NULL;

	f = f.substr(6, f.length());
	f = f.replace("\\", "/");
	if (f == String())
		return filesystem;

	if (f.ends_with("/"))
		f = f.substr(0, f.length() - 1);

	Vector<String> path = f.split("/");

	if (path.size() == 0)
		return NULL;

	EditorFileSystemDirectory *fs = filesystem;

	for (int i = 0; i < path.size(); i++) {

		int idx = -1;
		for (int j = 0; j < fs->get_subdir_count(); j++) {

			if (fs->get_subdir(j)->get_name() == path[i]) {
				idx = j;
				break;
			}
		}

		if (idx == -1) {
			return NULL;
		} else {

			fs = fs->get_subdir(idx);
		}
	}

	return fs;
}

void EditorFileSystem::_save_late_updated_files() {
	//files that already existed, and were modified, need re-scanning for dependencies upon project restart. This is done via saving this special file
	String fscache = EditorSettings::get_singleton()->get_project_settings_dir().plus_file("filesystem_update4");
	FileAccessRef f = FileAccess::open(fscache, FileAccess::WRITE);
	ERR_FAIL_COND_MSG(!f, "Cannot create file '" + fscache + "'. Check user write permissions.");
	for (Set<String>::Element *E = late_update_files.front(); E; E = E->next()) {
		f->store_line(E->get());
	}
}

Vector<String> EditorFileSystem::_get_dependencies(const String &p_path) {

	List<String> deps;
	ResourceLoader::get_dependencies(p_path, &deps);

	Vector<String> ret;
	for (List<String>::Element *E = deps.front(); E; E = E->next()) {
		ret.push_back(E->get());
	}

	return ret;
}

String EditorFileSystem::_get_global_script_class(const String &p_type, const String &p_path, String *r_extends, String *r_icon_path) const {

	for (int i = 0; i < ScriptServer::get_language_count(); i++) {
		if (ScriptServer::get_language(i)->handles_global_class_type(p_type)) {
			String global_name;
			String extends;
			String icon_path;

			global_name = ScriptServer::get_language(i)->get_global_class_name(p_path, &extends, &icon_path);
			*r_extends = extends;
			*r_icon_path = icon_path;
			return global_name;
		}
	}
	*r_extends = String();
	*r_icon_path = String();
	return String();
}

void EditorFileSystem::_scan_script_classes(EditorFileSystemDirectory *p_dir) {
	int filecount = p_dir->files.size();
	const EditorFileSystemDirectory::FileInfo *const *files = p_dir->files.ptr();
	for (int i = 0; i < filecount; i++) {
		if (files[i]->script_class_name == String()) {
			continue;
		}

		String lang;
		for (int j = 0; j < ScriptServer::get_language_count(); j++) {
			if (ScriptServer::get_language(j)->handles_global_class_type(files[i]->type)) {
				lang = ScriptServer::get_language(j)->get_name();
			}
		}
		ScriptServer::add_global_class(files[i]->script_class_name, files[i]->script_class_extends, lang, p_dir->get_file_path(i));
		EditorNode::get_editor_data().script_class_set_icon_path(files[i]->script_class_name, files[i]->script_class_icon_path);
		EditorNode::get_editor_data().script_class_set_name(files[i]->file, files[i]->script_class_name);
	}
	for (int i = 0; i < p_dir->get_subdir_count(); i++) {
		_scan_script_classes(p_dir->get_subdir(i));
	}
}

void EditorFileSystem::update_script_classes() {

	if (!update_script_classes_queued.is_set())
		return;

	update_script_classes_queued.clear();
	ScriptServer::global_classes_clear();
	if (get_filesystem()) {
		_scan_script_classes(get_filesystem());
	}

	ScriptServer::save_global_classes();
	EditorNode::get_editor_data().script_class_save_icon_paths();

	// Rescan custom loaders and savers.
	// Doing the following here because the `filesystem_changed` signal fires multiple times and isn't always followed by script classes update.
	// So I thought it's better to do this when script classes really get updated
	ResourceLoader::remove_custom_loaders();
	ResourceLoader::add_custom_loaders();
	ResourceSaver::remove_custom_savers();
	ResourceSaver::add_custom_savers();
}

void EditorFileSystem::_queue_update_script_classes() {
	if (update_script_classes_queued.is_set()) {
		return;
	}

	update_script_classes_queued.set();
	call_deferred("update_script_classes");
}

void EditorFileSystem::update_file(const String &p_file) {

	EditorFileSystemDirectory *fs = NULL;
	int cpos = -1;

	if (!_find_file(p_file, &fs, cpos)) {

		if (!fs)
			return;
	}

	if (!FileAccess::exists(p_file)) {
		//was removed
		_delete_internal_files(p_file);
		if (cpos != -1) { // Might've never been part of the editor file system (*.* files deleted in Open dialog).
			memdelete(fs->files[cpos]);
			fs->files.remove(cpos);
		}

		call_deferred("emit_signal", "filesystem_changed"); //update later
		_queue_update_script_classes();
		return;
	}

	String type = ResourceLoader::get_resource_type(p_file);

	if (cpos == -1) {
		// The file did not exist, it was added.

		late_added_files.insert(p_file); // Remember that it was added. This mean it will be scanned and imported on editor restart.
		int idx = 0;
		String file_name = p_file.get_file();

		for (int i = 0; i < fs->files.size(); i++) {
			if (file_name < fs->files[i]->file) {
				break;
			}
			idx++;
		}

		EditorFileSystemDirectory::FileInfo *fi = memnew(EditorFileSystemDirectory::FileInfo);
		fi->file = file_name;
		fi->import_modified_time = 0;
		fi->import_valid = ResourceLoader::is_import_valid(p_file);

		if (idx == fs->files.size()) {
			fs->files.push_back(fi);
		} else {

			fs->files.insert(idx, fi);
		}
		cpos = idx;
	} else {

		//the file exists and it was updated, and was not added in this step.
		//this means we must force upon next restart to scan it again, to get proper type and dependencies
		late_update_files.insert(p_file);
		_save_late_updated_files(); //files need to be updated in the re-scan
	}

	fs->files[cpos]->type = type;
	fs->files[cpos]->script_class_name = _get_global_script_class(type, p_file, &fs->files[cpos]->script_class_extends, &fs->files[cpos]->script_class_icon_path);
	fs->files[cpos]->import_group_file = ResourceLoader::get_import_group_file(p_file);
	fs->files[cpos]->modified_time = FileAccess::get_modified_time(p_file);
	fs->files[cpos]->deps = _get_dependencies(p_file);
	fs->files[cpos]->import_valid = ResourceLoader::is_import_valid(p_file);

	// Update preview
	EditorResourcePreview::get_singleton()->check_for_invalidation(p_file);

	call_deferred("emit_signal", "filesystem_changed"); //update later
	_queue_update_script_classes();
}

Error EditorFileSystem::_reimport_group(const String &p_group_file, const Vector<String> &p_files) {

	String importer_name;

	Map<String, Map<StringName, Variant> > source_file_options;
	Map<String, String> base_paths;
	for (int i = 0; i < p_files.size(); i++) {

		Ref<ConfigFile> config;
		config.instance();
		Error err = config->load(p_files[i] + ".import");
		ERR_CONTINUE(err != OK);
		ERR_CONTINUE(!config->has_section_key("remap", "importer"));
		String file_importer_name = config->get_value("remap", "importer");
		ERR_CONTINUE(file_importer_name == String());

		if (importer_name != String() && importer_name != file_importer_name) {
			print_line("one importer '" + importer_name + "' the other '" + file_importer_name + "'.");
			EditorNode::get_singleton()->show_warning(vformat(TTR("There are multiple importers for different types pointing to file %s, import aborted"), p_group_file));
			ERR_FAIL_V(ERR_FILE_CORRUPT);
		}

		source_file_options[p_files[i]] = Map<StringName, Variant>();
		importer_name = file_importer_name;

		if (importer_name == "keep") {
			continue; //do nothing
		}

		Ref<ResourceImporter> importer = ResourceFormatImporter::get_singleton()->get_importer_by_name(importer_name);
		ERR_FAIL_COND_V(!importer.is_valid(), ERR_FILE_CORRUPT);
		List<ResourceImporter::ImportOption> options;
		importer->get_import_options(&options);
		//set default values
		for (List<ResourceImporter::ImportOption>::Element *E = options.front(); E; E = E->next()) {

			source_file_options[p_files[i]][E->get().option.name] = E->get().default_value;
		}

		if (config->has_section("params")) {
			List<String> sk;
			config->get_section_keys("params", &sk);
			for (List<String>::Element *E = sk.front(); E; E = E->next()) {
				String param = E->get();
				Variant value = config->get_value("params", param);
				//override with whathever is in file
				source_file_options[p_files[i]][param] = value;
			}
		}

		base_paths[p_files[i]] = ResourceFormatImporter::get_singleton()->get_import_base_path(p_files[i]);
	}

	if (importer_name == "keep") {
		return OK; // (do nothing)
	}

	ERR_FAIL_COND_V(importer_name == String(), ERR_UNCONFIGURED);

	Ref<ResourceImporter> importer = ResourceFormatImporter::get_singleton()->get_importer_by_name(importer_name);

	Error err = importer->import_group_file(p_group_file, source_file_options, base_paths);

	//all went well, overwrite config files with proper remaps and md5s
	for (Map<String, Map<StringName, Variant> >::Element *E = source_file_options.front(); E; E = E->next()) {

		const String &file = E->key();
		String base_path = ResourceFormatImporter::get_singleton()->get_import_base_path(file);
		FileAccessRef f = FileAccess::open(file + ".import", FileAccess::WRITE);
		ERR_FAIL_COND_V_MSG(!f, ERR_FILE_CANT_OPEN, "Cannot open import file '" + file + ".import'.");

		//write manually, as order matters ([remap] has to go first for performance).
		f->store_line("[remap]");
		f->store_line("");
		f->store_line("importer=\"" + importer->get_importer_name() + "\"");
		if (importer->get_resource_type() != "") {
			f->store_line("type=\"" + importer->get_resource_type() + "\"");
		}

		Vector<String> dest_paths;

		if (err == OK) {
			String path = base_path + "." + importer->get_save_extension();
			f->store_line("path=\"" + path + "\"");
			dest_paths.push_back(path);
		}

		f->store_line("group_file=" + Variant(p_group_file).get_construct_string());

		if (err == OK) {
			f->store_line("valid=true");
		} else {
			f->store_line("valid=false");
		}
		f->store_line("[deps]\n");

		f->store_line("");

		f->store_line("source_file=" + Variant(file).get_construct_string());
		if (dest_paths.size()) {
			Array dp;
			for (int i = 0; i < dest_paths.size(); i++) {
				dp.push_back(dest_paths[i]);
			}
			f->store_line("dest_files=" + Variant(dp).get_construct_string() + "\n");
		}
		f->store_line("[params]");
		f->store_line("");

		//store options in provided order, to avoid file changing. Order is also important because first match is accepted first.

		List<ResourceImporter::ImportOption> options;
		importer->get_import_options(&options);
		//set default values
		for (List<ResourceImporter::ImportOption>::Element *F = options.front(); F; F = F->next()) {

			String base = F->get().option.name;
			Variant v = F->get().default_value;
			if (source_file_options[file].has(base)) {
				v = source_file_options[file][base];
			}
			String value;
			VariantWriter::write_to_string(v, value);
			f->store_line(base + "=" + value);
		}

		f->close();

		// Store the md5's of the various files. These are stored separately so that the .import files can be version controlled.
		FileAccessRef md5s = FileAccess::open(base_path + ".md5", FileAccess::WRITE);
		ERR_FAIL_COND_V_MSG(!md5s, ERR_FILE_CANT_OPEN, "Cannot open MD5 file '" + base_path + ".md5'.");

		md5s->store_line("source_md5=\"" + FileAccess::get_md5(file) + "\"");
		if (dest_paths.size()) {
			md5s->store_line("dest_md5=\"" + FileAccess::get_multiple_md5(dest_paths) + "\"\n");
		}
		md5s->close();

		EditorFileSystemDirectory *fs = NULL;
		int cpos = -1;
		bool found = _find_file(file, &fs, cpos);
		ERR_FAIL_COND_V_MSG(!found, ERR_UNCONFIGURED, "Can't find file '" + file + "'.");

		//update modified times, to avoid reimport
		fs->files[cpos]->modified_time = FileAccess::get_modified_time(file);
		fs->files[cpos]->import_modified_time = FileAccess::get_modified_time(file + ".import");
		fs->files[cpos]->deps = _get_dependencies(file);
		fs->files[cpos]->type = importer->get_resource_type();
		fs->files[cpos]->import_valid = err == OK;

		//if file is currently up, maybe the source it was loaded from changed, so import math must be updated for it
		//to reload properly
		if (ResourceCache::has(file)) {

			Resource *r = ResourceCache::get(file);

			if (r->get_import_path() != String()) {

				String dst_path = ResourceFormatImporter::get_singleton()->get_internal_resource_path(file);
				r->set_import_path(dst_path);
				r->set_import_last_modified_time(0);
			}
		}

		EditorResourcePreview::get_singleton()->check_for_invalidation(file);
	}

	return err;
}

void EditorFileSystem::_reimport_file(const String &p_file) {

	EditorFileSystemDirectory *fs = NULL;
	int cpos = -1;
	bool found = _find_file(p_file, &fs, cpos);
	ERR_FAIL_COND_MSG(!found, "Can't find file '" + p_file + "'.");

	//try to obtain existing params

	Map<StringName, Variant> params;
	String importer_name;

	if (FileAccess::exists(p_file + ".import")) {
		//use existing
		Ref<ConfigFile> cf;
		cf.instance();
		Error err = cf->load(p_file + ".import");
		if (err == OK) {
			if (cf->has_section("params")) {
				List<String> sk;
				cf->get_section_keys("params", &sk);
				for (List<String>::Element *E = sk.front(); E; E = E->next()) {
					params[E->get()] = cf->get_value("params", E->get());
				}
			}
			if (cf->has_section("remap")) {
				importer_name = cf->get_value("remap", "importer");
			}
		}

	} else {
		late_added_files.insert(p_file); //imported files do not call update_file(), but just in case..
		params["nodes/use_legacy_names"] = false;
	}

	if (importer_name == "keep") {
		//keep files, do nothing.
		fs->files[cpos]->modified_time = FileAccess::get_modified_time(p_file);
		fs->files[cpos]->import_modified_time = FileAccess::get_modified_time(p_file + ".import");
		fs->files[cpos]->deps.clear();
		fs->files[cpos]->type = "";
		fs->files[cpos]->import_valid = false;
		EditorResourcePreview::get_singleton()->check_for_invalidation(p_file);
		return;
	}
	Ref<ResourceImporter> importer;
	bool load_default = false;
	//find the importer
	if (importer_name != "") {
		importer = ResourceFormatImporter::get_singleton()->get_importer_by_name(importer_name);
	}

	if (importer.is_null()) {
		//not found by name, find by extension
		importer = ResourceFormatImporter::get_singleton()->get_importer_by_extension(p_file.get_extension());
		load_default = true;
		if (importer.is_null()) {
			ERR_PRINT("BUG: File queued for import, but can't be imported!");
			ERR_FAIL();
		}
	}

	//mix with default params, in case a parameter is missing

	List<ResourceImporter::ImportOption> opts;
	importer->get_import_options(&opts);
	for (List<ResourceImporter::ImportOption>::Element *E = opts.front(); E; E = E->next()) {
		if (!params.has(E->get().option.name)) { //this one is not present
			params[E->get().option.name] = E->get().default_value;
		}
	}

	if (load_default && ProjectSettings::get_singleton()->has_setting("importer_defaults/" + importer->get_importer_name())) {
		//use defaults if exist
		Dictionary d = ProjectSettings::get_singleton()->get("importer_defaults/" + importer->get_importer_name());
		List<Variant> v;
		d.get_key_list(&v);

		for (List<Variant>::Element *E = v.front(); E; E = E->next()) {
			params[E->get()] = d[E->get()];
		}
	}

	//finally, perform import!!
	String base_path = ResourceFormatImporter::get_singleton()->get_import_base_path(p_file);

	List<String> import_variants;
	List<String> gen_files;
	Variant metadata;
	Error err = importer->import(p_file, base_path, params, &import_variants, &gen_files, &metadata);

	if (err != OK) {
		ERR_PRINTS("Error importing '" + p_file + "'.");
	}

	//as import is complete, save the .import file

	FileAccess *f = FileAccess::open(p_file + ".import", FileAccess::WRITE);
	ERR_FAIL_COND_MSG(!f, "Cannot open file from path '" + p_file + ".import'.");

	//write manually, as order matters ([remap] has to go first for performance).
	f->store_line("[remap]");
	f->store_line("");
	f->store_line("importer=\"" + importer->get_importer_name() + "\"");
	if (importer->get_resource_type() != "") {
		f->store_line("type=\"" + importer->get_resource_type() + "\"");
	}

	Vector<String> dest_paths;

	if (err == OK) {

		if (importer->get_save_extension() == "") {
			//no path
		} else if (import_variants.size()) {
			//import with variants
			for (List<String>::Element *E = import_variants.front(); E; E = E->next()) {

				String path = base_path.c_escape() + "." + E->get() + "." + importer->get_save_extension();

				f->store_line("path." + E->get() + "=\"" + path + "\"");
				dest_paths.push_back(path);
			}
		} else {
			String path = base_path + "." + importer->get_save_extension();
			f->store_line("path=\"" + path + "\"");
			dest_paths.push_back(path);
		}

	} else {

		f->store_line("valid=false");
	}

	if (metadata != Variant()) {
		f->store_line("metadata=" + metadata.get_construct_string());
	}

	f->store_line("");

	f->store_line("[deps]\n");

	if (gen_files.size()) {
		Array genf;
		for (List<String>::Element *E = gen_files.front(); E; E = E->next()) {
			genf.push_back(E->get());
			dest_paths.push_back(E->get());
		}

		String value;
		VariantWriter::write_to_string(genf, value);
		f->store_line("files=" + value);
		f->store_line("");
	}

	f->store_line("source_file=" + Variant(p_file).get_construct_string());

	if (dest_paths.size()) {
		Array dp;
		for (int i = 0; i < dest_paths.size(); i++) {
			dp.push_back(dest_paths[i]);
		}
		f->store_line("dest_files=" + Variant(dp).get_construct_string() + "\n");
	}

	f->store_line("[params]");
	f->store_line("");

	//store options in provided order, to avoid file changing. Order is also important because first match is accepted first.

	for (List<ResourceImporter::ImportOption>::Element *E = opts.front(); E; E = E->next()) {

		String base = E->get().option.name;
		String value;
		VariantWriter::write_to_string(params[base], value);
		f->store_line(base + "=" + value);
	}

	f->close();
	memdelete(f);

	// Store the md5's of the various files. These are stored separately so that the .import files can be version controlled.
	FileAccess *md5s = FileAccess::open(base_path + ".md5", FileAccess::WRITE);
	ERR_FAIL_COND_MSG(!md5s, "Cannot open MD5 file '" + base_path + ".md5'.");

	md5s->store_line("source_md5=\"" + FileAccess::get_md5(p_file) + "\"");
	if (dest_paths.size()) {
		md5s->store_line("dest_md5=\"" + FileAccess::get_multiple_md5(dest_paths) + "\"\n");
	}
	md5s->close();
	memdelete(md5s);

	//update modified times, to avoid reimport
	fs->files[cpos]->modified_time = FileAccess::get_modified_time(p_file);
	fs->files[cpos]->import_modified_time = FileAccess::get_modified_time(p_file + ".import");
	fs->files[cpos]->deps = _get_dependencies(p_file);
	fs->files[cpos]->type = importer->get_resource_type();
	fs->files[cpos]->import_valid = ResourceLoader::is_import_valid(p_file);

	//if file is currently up, maybe the source it was loaded from changed, so import math must be updated for it
	//to reload properly
	if (ResourceCache::has(p_file)) {

		Resource *r = ResourceCache::get(p_file);

		if (r->get_import_path() != String()) {

			String dst_path = ResourceFormatImporter::get_singleton()->get_internal_resource_path(p_file);
			r->set_import_path(dst_path);
			r->set_import_last_modified_time(0);
		}
	}

	EditorResourcePreview::get_singleton()->check_for_invalidation(p_file);
}

void EditorFileSystem::_find_group_files(EditorFileSystemDirectory *efd, Map<String, Vector<String> > &group_files, Set<String> &groups_to_reimport) {

	int fc = efd->files.size();
	const EditorFileSystemDirectory::FileInfo *const *files = efd->files.ptr();
	for (int i = 0; i < fc; i++) {
		if (groups_to_reimport.has(files[i]->import_group_file)) {
			if (!group_files.has(files[i]->import_group_file)) {
				group_files[files[i]->import_group_file] = Vector<String>();
			}
			group_files[files[i]->import_group_file].push_back(efd->get_file_path(i));
		}
	}

	for (int i = 0; i < efd->get_subdir_count(); i++) {
		_find_group_files(efd->get_subdir(i), group_files, groups_to_reimport);
	}
}

void EditorFileSystem::reimport_files(const Vector<String> &p_files) {

	{ //check that .import folder exists
		DirAccess *da = DirAccess::open("res://");
		if (da->change_dir(".import") != OK) {
			Error err = da->make_dir(".import");
			if (err) {
				memdelete(da);
				ERR_FAIL_MSG("Failed to create 'res://.import' folder.");
			}
		}
		memdelete(da);
	}

	importing = true;
	EditorProgress pr("reimport", TTR("(Re)Importing Assets"), p_files.size());

	Vector<ImportFile> files;
	Set<String> groups_to_reimport;

	for (int i = 0; i < p_files.size(); i++) {

		String group_file = ResourceFormatImporter::get_singleton()->get_import_group_file(p_files[i]);

		if (group_file_cache.has(p_files[i])) {
			//maybe the file itself is a group!
			groups_to_reimport.insert(p_files[i]);
			//groups do not belong to grups
			group_file = String();
		} else if (group_file != String()) {
			//it's a group file, add group to import and skip this file
			groups_to_reimport.insert(group_file);
		} else {
			//it's a regular file
			ImportFile ifile;
			ifile.path = p_files[i];
			ifile.order = ResourceFormatImporter::get_singleton()->get_import_order(p_files[i]);
			files.push_back(ifile);
		}

		//group may have changed, so also update group reference
		EditorFileSystemDirectory *fs = NULL;
		int cpos = -1;
		if (_find_file(p_files[i], &fs, cpos)) {

			fs->files.write[cpos]->import_group_file = group_file;
		}
	}

	files.sort();

	for (int i = 0; i < files.size(); i++) {
		pr.step(files[i].path.get_file(), i);
		_reimport_file(files[i].path);
	}

	//reimport groups

	if (groups_to_reimport.size()) {
		Map<String, Vector<String> > group_files;
		_find_group_files(filesystem, group_files, groups_to_reimport);
		for (Map<String, Vector<String> >::Element *E = group_files.front(); E; E = E->next()) {

			Error err = _reimport_group(E->key(), E->get());
			if (err == OK) {
				_reimport_file(E->key());
			}
		}
	}

	_save_filesystem_cache();
	importing = false;
	if (!is_scanning()) {
		emit_signal("filesystem_changed");
	}

	emit_signal("resources_reimported", p_files);
}

Error EditorFileSystem::_resource_import(const String &p_path) {

	Vector<String> files;
	files.push_back(p_path);

	singleton->update_file(p_path);
	singleton->reimport_files(files);

	return OK;
}

bool EditorFileSystem::_should_skip_directory(const String &p_path) {
	if (FileAccess::exists(p_path.plus_file("project.godot"))) // skip if another project inside this
		return true;

	if (FileAccess::exists(p_path.plus_file(".gdignore"))) // skip if a `.gdignore` file is inside this
		return true;

	return false;
}

bool EditorFileSystem::is_group_file(const String &p_path) const {
	return group_file_cache.has(p_path);
}

void EditorFileSystem::_move_group_files(EditorFileSystemDirectory *efd, const String &p_group_file, const String &p_new_location) {

	int fc = efd->files.size();
	EditorFileSystemDirectory::FileInfo *const *files = efd->files.ptrw();
	for (int i = 0; i < fc; i++) {

		if (files[i]->import_group_file == p_group_file) {

			files[i]->import_group_file = p_new_location;

			Ref<ConfigFile> config;
			config.instance();
			String path = efd->get_file_path(i) + ".import";
			Error err = config->load(path);
			if (err != OK) {
				continue;
			}
			if (config->has_section_key("remap", "group_file")) {

				config->set_value("remap", "group_file", p_new_location);
			}

			List<String> sk;
			config->get_section_keys("params", &sk);
			for (List<String>::Element *E = sk.front(); E; E = E->next()) {
				//not very clean, but should work
				String param = E->get();
				String value = config->get_value("params", param);
				if (value == p_group_file) {
					config->set_value("params", param, p_new_location);
				}
			}

			config->save(path);
		}
	}

	for (int i = 0; i < efd->get_subdir_count(); i++) {
		_move_group_files(efd->get_subdir(i), p_group_file, p_new_location);
	}
}

void EditorFileSystem::move_group_file(const String &p_path, const String &p_new_path) {

	if (get_filesystem()) {
		_move_group_files(get_filesystem(), p_path, p_new_path);
		if (group_file_cache.has(p_path)) {
			group_file_cache.erase(p_path);
			group_file_cache.insert(p_new_path);
		}
	}
}

void EditorFileSystem::_bind_methods() {

	ClassDB::bind_method(D_METHOD("get_filesystem"), &EditorFileSystem::get_filesystem);
	ClassDB::bind_method(D_METHOD("is_scanning"), &EditorFileSystem::is_scanning);
	ClassDB::bind_method(D_METHOD("get_scanning_progress"), &EditorFileSystem::get_scanning_progress);
	ClassDB::bind_method(D_METHOD("scan"), &EditorFileSystem::scan);
	ClassDB::bind_method(D_METHOD("scan_sources"), &EditorFileSystem::scan_changes);
	ClassDB::bind_method(D_METHOD("update_file", "path"), &EditorFileSystem::update_file);
	ClassDB::bind_method(D_METHOD("get_filesystem_path", "path"), &EditorFileSystem::get_filesystem_path);
	ClassDB::bind_method(D_METHOD("get_file_type", "path"), &EditorFileSystem::get_file_type);
	ClassDB::bind_method(D_METHOD("update_script_classes"), &EditorFileSystem::update_script_classes);

	ADD_SIGNAL(MethodInfo("filesystem_changed"));
	ADD_SIGNAL(MethodInfo("sources_changed", PropertyInfo(Variant::BOOL, "exist")));
	ADD_SIGNAL(MethodInfo("resources_reimported", PropertyInfo(Variant::POOL_STRING_ARRAY, "resources")));
	ADD_SIGNAL(MethodInfo("resources_reload", PropertyInfo(Variant::POOL_STRING_ARRAY, "resources")));
}

void EditorFileSystem::_update_extensions() {

	valid_extensions.clear();
	import_extensions.clear();

	List<String> extensionsl;
	ResourceLoader::get_recognized_extensions_for_type("", &extensionsl);
	for (List<String>::Element *E = extensionsl.front(); E; E = E->next()) {

		valid_extensions.insert(E->get());
	}

	extensionsl.clear();
	ResourceFormatImporter::get_singleton()->get_recognized_extensions(&extensionsl);
	for (List<String>::Element *E = extensionsl.front(); E; E = E->next()) {

		import_extensions.insert(E->get());
	}
}

EditorFileSystem::EditorFileSystem() {

	ResourceLoader::import = _resource_import;
	reimport_on_missing_imported_files = GLOBAL_DEF("editor/reimport_missing_imported_files", true);

	singleton = this;
	filesystem = memnew(EditorFileSystemDirectory); //like, empty
	filesystem->parent = NULL;

	scanning = false;
	importing = false;
	use_threads = true;
	new_filesystem = NULL;

	abort_scan = false;
	scanning_changes = false;
	scanning_changes_done = false;

	DirAccess *da = DirAccess::create(DirAccess::ACCESS_RESOURCES);
	if (da->change_dir("res://.import") != OK) {
		da->make_dir("res://.import");
	}
	// This should probably also work on Unix and use the string it returns for FAT32 or exFAT
	using_fat32_or_exfat = (da->get_filesystem_type() == "FAT32" || da->get_filesystem_type() == "exFAT");
	memdelete(da);

	scan_total = 0;
	update_script_classes_queued.clear();
	first_scan = true;
	scan_changes_pending = false;
	revalidate_import_files = false;
}

EditorFileSystem::~EditorFileSystem() {
}