modelverse/core/core_algorithm.alc

include "modelling.alh"
include "library.alh"
include "primitives.alh"
include "constructors.alh"
include "object_operations.alh"
include "mini_modify.alh"
include "model_management.alh"
include "ramify.alh"
include "conformance_scd.alh"
include "transform.alh"
include "metamodels.alh"

Element core = ?

String core_location = "models/CoreFormalism"
String core_model_location = "core"

String function JSON_print(model : Element):
	String result
	Element keys_m
	String v_m
	String type
	String attr_key
	Element attr_keys

	result = "["
	keys_m = dict_keys(model["model"])

	while (read_nr_out(keys_m) > 0):
		v_m = set_pop(keys_m)
		type = read_type(model["metamodel"], read_type(model, v_m))

		if (bool_or(type == "Class", type == "Association")):
			result = result + "{"
			result = (((result + "\"id\": \"") + v_m) + "\"") + ","
			result = (((result + "\"type\": \"") + read_type(model, v_m)) + "\"") + ","
			if (type == "Association"):
				result = ((result + "\"__source\": \"") + reverseKeyLookup(model["model"], read_edge_src(model["model"][v_m]))) + "\","
				result = ((result + "\"__target\": \"") + reverseKeyLookup(model["model"], read_edge_dst(model["model"][v_m]))) + "\","

			// Has attributes
			attr_keys = dict_keys(getAttributeList(model, v_m))
			while (0 < read_nr_out(attr_keys)):
				attr_key = set_pop(attr_keys)
				result = ((((result + "\"") + attr_key) + "\": ") + cast_v2s(read_attribute(model, v_m, attr_key))) + ","

			result = result + "}"

			if (read_nr_out(keys_m) > 0):
				result = result + ","
	result = result + "]"

	return result!

Void function main():
	// Initialize the Core Formalism
	String core_model
	String core_formalism_model
	String scd_model
	Element al_model
	String admin_group
	String admin_user
	String nobody_group
	String instance_of
	String core_formalism
	Element scd
	Element al
	Element pm
	Element tracability
	String pm_model
	String tracability_model
	String coreM_model_location 
	String pm_location
	String scd_location
	String al_location
	String tracability_location

	coreM_model_location = "models/core"
	pm_location = "models/ProcessModel"
	scd_location = "models/SimpleClassDiagrams"
	al_location = "models/ActionLanguage"
	tracability_location = "models/Tracability"

	scd = import_node(scd_location)
	al = import_node(al_location)
	pm = import_node(pm_location)
	tracability = import_node(tracability_location)

	// Create the Model itself and make public
	core_formalism = import_node(core_location)
	core = instantiate_model(core_formalism)
	export_node(core_model_location, core)
	export_node(coreM_model_location, core["model"])

	// Switch all new users to the user_function
	// This accesses the bootstrap level, so do not change this unless you know what you are doing
	Element root
	Element prev
	root = read_root()
	root = root["__hierarchy"]["__IP"]
	while (value_neq(root, !call)):
		prev = root
		root = root["next"]
	dict_delete(prev, "next")
	dict_add(prev, "next", user_function["body"])

	// Create admin group
	admin_group = instantiate_node(core, "Group", "")
	instantiate_attribute(core, admin_group, "name", "admin")

	// Create nobody group
	nobody_group = instantiate_node(core, "Group", "")
	instantiate_attribute(core, nobody_group, "name", "nobody")

	// Create admin user
	admin_user = instantiate_node(core, "User", "")
	output("Desired username for admin user?")
	instantiate_attribute(core, admin_user, "name", input())
	instantiate_attribute(core, admin_user, "admin", True)

	String password

	while (True):
		output("Desired password for admin user?")
		password = hash(input())

		output("Please repeat the password")
		if (password == hash(input())):
			output("Passwords match!")
			instantiate_attribute(core, admin_user, "password", password)
			break!
		else:
			output("Not the same password, please try again!")

	// Create link between admin user and group
	instantiate_link(core, "ownedBy", "", admin_group, admin_user)
	instantiate_link(core, "belongsTo", "", admin_user, admin_group)

	// Add the SimpleClassDiagrams formalism already
	scd_model = instantiate_node(core, "Model", "")
	instantiate_attribute(core, scd_model, "name", "SimpleClassDiagrams")
	instantiate_attribute(core, scd_model, "location", scd_location + "/model")
	instantiate_attribute(core, scd_model, "permissions", "221")
	instance_of = instantiate_link(core, "instanceOf", "", scd_model, scd_model)
	instantiate_attribute(core, instance_of, "type_mapping", scd["type_mapping"])

	// Make necessary links for the formalism to the owners
	instantiate_link(core, "group", "", scd_model, admin_group)
	instantiate_link(core, "owner", "", scd_model, admin_user)

	// Add the Tracability formalism
	tracability_model = instantiate_node(core, "Model", "")
	instantiate_attribute(core, tracability_model, "name", "Tracability")
	instantiate_attribute(core, tracability_model, "location", tracability_location + "/model")
	instantiate_attribute(core, tracability_model, "permissions", "221")
	instance_of = instantiate_link(core, "instanceOf", "", tracability_model, scd_model)
	instantiate_attribute(core, instance_of, "type_mapping", tracability["type_mapping"])

	// Add the user/group links
	instantiate_link(core, "group", "", tracability_model, admin_group)
	instantiate_link(core, "owner", "", tracability_model, admin_user)

	// Add the Process Model formalism
	pm_model = instantiate_node(core, "Model", "")
	instantiate_attribute(core, pm_model, "name", "ProcessModel")
	instantiate_attribute(core, pm_model, "location", pm_location + "/model")
	instantiate_attribute(core, pm_model, "permissions", "221")
	instance_of = instantiate_link(core, "instanceOf", "", pm_model, scd_model)
	instantiate_attribute(core, instance_of, "type_mapping", pm["type_mapping"])

	// Make necessary links for the formalism to the owners
	instantiate_link(core, "group", "", pm_model, admin_group)
	instantiate_link(core, "owner", "", pm_model, admin_user)

	// Add the Action Language formalism
	al_model = instantiate_node(core, "Model", "")
	instantiate_attribute(core, al_model, "name", "ActionLanguage")
	instantiate_attribute(core, al_model, "location", al_location + "/model")
	instantiate_attribute(core, al_model, "permissions", "221")
	instance_of = instantiate_link(core, "instanceOf", "", al_model, scd_model)
	instantiate_attribute(core, instance_of, "type_mapping", al["type_mapping"])

	// Make necessary links for the formalism to the owners
	instantiate_link(core, "group", "", al_model, admin_group)
	instantiate_link(core, "owner", "", al_model, admin_user)

	// Add the Manual Operation formalism
	Element manual
	String manual_model
	manual = instantiate_model(scd)
	manual_model = instantiate_node(core, "Model", "")
	export_node("models/ManualOperation", manual)
	instantiate_attribute(core, manual_model, "name", "ManualOperation")
	instantiate_attribute(core, manual_model, "location", "models/ManualOperation/model")
	instantiate_attribute(core, manual_model, "permissions", "221")
	instance_of = instantiate_link(core, "instanceOf", "", manual_model, scd_model)
	instantiate_attribute(core, instance_of, "type_mapping", create_node())

	// Make necessary links for the formalism to the owners
	instantiate_link(core, "group", "", manual_model, admin_group)
	instantiate_link(core, "owner", "", manual_model, admin_user)

	// Add the core formalism already
	core_formalism_model = instantiate_node(core, "Model", "")
	instantiate_attribute(core, core_formalism_model, "name", "CoreFormalism")
	instantiate_attribute(core, core_formalism_model, "location", core_location + "/model")
	instantiate_attribute(core, core_formalism_model, "permissions", "221")
	instance_of = instantiate_link(core, "instanceOf", "", core_formalism_model, scd_model)
	instantiate_attribute(core, instance_of, "type_mapping", core_formalism["type_mapping"])

	// Make necessary links for the formalism to the owners
	instantiate_link(core, "group", "", core_formalism_model, admin_group)
	instantiate_link(core, "owner", "", core_formalism_model, admin_user)

	// Add the core model
	core_model = instantiate_node(core, "Model", "")
	instantiate_attribute(core, core_model, "name", "core")
	instantiate_attribute(core, core_model, "location", coreM_model_location)
	instantiate_attribute(core, core_model, "permissions", "200")
	instance_of = instantiate_link(core, "instanceOf", "", core_model, core_formalism_model)
	instantiate_attribute(core, instance_of, "type_mapping", core["type_mapping"])

	// Make necessary links for the formalism to the owners
	instantiate_link(core, "group", "", core_model, admin_group)
	instantiate_link(core, "owner", "", core_model, admin_user)

	// Call this for ourselves as well
	log("MvC is ready!")
	user_function_skip_init(admin_user)

	// Done, so finish up
	// Admin user will have been deleted by the user_function as usual
	// Note that if there are no admin users left, it will be very difficult to manage, as nobody will have admin permissions!
	return !

String function get_instanceOf_link(model_id : String):
	Element all_links
	String choice

	all_links = allOutgoingAssociationInstances(core, model_id, "instanceOf")

	if (read_nr_out(all_links) > 1):
		log("WARNING: multiple instanceOf relations were detected for this model; picking one at random!")
	elif (read_nr_out(all_links) == 0):
		log("ERROR: untyped model!")
	
	choice = set_pop(allOutgoingAssociationInstances(core, model_id, "instanceOf"))

	return choice!

Element function get_full_model(model_id : String):
	Element m
	Element all_links
	String choice

	choice = get_instanceOf_link(model_id)

	m = create_node()
	dict_add(m, "model", import_node(read_attribute(core, model_id, "location")))
	dict_add(m, "type_mapping", read_attribute(core, choice, "type_mapping"))

	if (readAssociationDestination(core, choice) == model_id):
		// Found the meta-circular level, so we can stop!
		dict_add(m, "metamodel", m)
	else:
		dict_add(m, "metamodel", get_full_model(readAssociationDestination(core, choice)))
		
	return m!

Integer function get_relation_to_model(user_id : String, model_id : String):
	if (set_in(allAssociationDestinations(core, model_id, "owner"), user_id)):
		// We are the owner
		return 0!
	else:
		String group_id
		group_id = set_pop(allAssociationDestinations(core, model_id, "group"))
		if (set_in(allAssociationDestinations(core, user_id, "belongsTo"), group_id)):
			// We are in the owning group
			return 1!
		else:
			// We are not related whatsoever
			return 2!

Boolean function is_admin(user_id : String):
	if (read_attribute(core, user_id, "admin")):
		return True!
	else:
		return False!
	
Boolean function allow_read(user_id : String, model_id : String):
	if (is_admin(user_id)):
		// Is admin, so always allow
		return True!
	else:
		// Check permissions
		String permission
		permission = string_get(read_attribute(core, model_id, "permissions"), get_relation_to_model(user_id, model_id))
		if (bool_or(permission == "1", permission == "2")):
			return True!
		else:
			return False!

Boolean function allow_write(user_id : String, model_id : String):
	if (is_admin(user_id)):
		// Is admin, so always allow
		return True!
	else:
		// Check permissions
		String permission
		permission = string_get(read_attribute(core, model_id, "permissions"), get_relation_to_model(user_id, model_id))
		if (permission == "2"):
			return True!
		else:
			return False!

Boolean function allow_change_metadata(user_id : String, model_id : String):
	if (is_admin(user_id)):
		// Is admin, so always allow
		return True!
	else:
		if (get_relation_to_model(user_id, model_id) == 0):
			// Only owner can chmod
			return True!
		else:
			return False!

Boolean function allow_group_modify(user_id : String, group_id : String):
	if (is_admin(user_id)):
		// Is admin, so always allow
		return True!
	else:
		if (read_nr_out(set_overlap(allIncomingAssociationInstances(core, user_id, "owner"), allOutgoingAssociationInstances(core, group_id, "owner"))) > 0):
			// We are an owner
			return True!
		else:
			return False!

Boolean function check_login(user_id : String):
	String password
	String stored_password

	stored_password = read_attribute(core, user_id, "password")

	output("Password for existing user?")
	password = hash(input())

	return password == stored_password!

Element function extract_ftg(user_id : String):
	// Extract your personal FTG, showing only the readable models that can be opened
	// This function does the actual projection of transformations

	// TODO: Only keep transformations satisfying some properties!

	return create_node()!

Element function user_function():
	String username
	String user_id
	String password

	// Load in all global variables, as this code is hotloaded!
	Element root
	root = read_root()
	root = root["__hierarchy"]["objects"]
	exec(root["bootstrap/modelling.alc"]["initializers"])
	exec(root["bootstrap/library.alc"]["initializers"])
	exec(root["bootstrap/constructors.alc"]["initializers"])
	exec(root["bootstrap/object_operations.alc"]["initializers"])
	exec(root["core/mini_modify.alc"]["initializers"])
	exec(root["bootstrap/model_management.alc"]["initializers"])
	exec(root["bootstrap/ramify.alc"]["initializers"])
	exec(root["bootstrap/transform.alc"]["initializers"])
	exec(root["bootstrap/conformance_scd.alc"]["initializers"])
	exec(root["core/core_algorithm.alc"]["initializers"])

	// Load in a hard-reference to the previously created model
	core = import_node(core_model_location)

	while (True):
		output("Log on as which user?")
		username = input()

		user_id = get_user_id(username)
		if (user_id == ""):
			// New user
			// Add user to Core Formalism
			user_id = instantiate_node(core, "User", "")
			instantiate_attribute(core, user_id, "name", username)
			instantiate_attribute(core, user_id, "admin", False)

			output("This is a new user: please give password!")
			password = hash(input())

			output("Please repeat the password")
			if (password == hash(input())):
				output("Passwords match!")
				instantiate_attribute(core, user_id, "password", password)
				break!
			else:
				output("Not the same password!")
		else:
			if (check_login(user_id)):
				break!
			else:
				output("Wrong password!")

	user_function_skip_init(user_id)

	// User destroyed already, so just stop execution
	// TODO return a fresh node as otherwise the compiler doesn't take this
	return create_node()!

String function get_model_id(name : String):
	Element models
	String model

	models = allInstances(core, "Model")
	while (read_nr_out(models) > 0):
		model = set_pop(models)
		if (value_eq(name, read_attribute(core, model, "name"))):
			return model!
	
	return ""!

String function get_user_id(name : String):
	Element users
	String user

	users = allInstances(core, "User")

	while (read_nr_out(users) > 0):
		user = set_pop(users)
		if (value_eq(read_attribute(core, user, "name"), name)):
			return user!
	
	return ""!

String function get_group_id(name : String):
	Element groups
	String group

	groups = allInstances(core, "Group")
	while (read_nr_out(groups) > 0):
		group = set_pop(groups)
		if (value_eq(read_attribute(core, group, "name"), name)):
			return group!
	
	return ""!

Void function model_create(model : Element, name : String, user_id : String, type_id : String, kind : String):
	String location
	String model_id
	String instance_of

	location = "models/" + cast_id2s(model)
	export_node(location, model["model"])

	// Manage meta-info
	model_id = instantiate_node(core, kind, "")
	instantiate_attribute(core, model_id, "name", name)
	instantiate_attribute(core, model_id, "location", location)
	instantiate_attribute(core, model_id, "permissions", "200")
	instantiate_link(core, "owner", "", model_id, user_id)
	instantiate_link(core, "group", "", model_id, get_group_id("nobody"))
	instance_of = instantiate_link(core, "instanceOf", "", model_id, type_id)
	instantiate_attribute(core, instance_of, "type_mapping", model["type_mapping"])

	return!

Void function model_overwrite(model : Element, model_id : String):
	String location
	String instanceOf_link

	location = "models/" + cast_id2s(model)
	export_node(location, model["model"])

	// Change location in meta-data
	unset_attribute(core, model_id, "location")
	instantiate_attribute(core, model_id, "location", location)

	instanceOf_link = get_instanceOf_link(model_id)
	unset_attribute(core, instanceOf_link, "type_mapping")
	instantiate_attribute(core, instanceOf_link, "type_mapping", model["type_mapping"])

	return!

Boolean function check_is_typed_by(model_id : String, metamodel_id : String):
	// TODO check if there is actually an instanceOf link between them
	//    --> quick check!

	return True!

Boolean function check_conformance(model_id : String):
	// TODO check if it actually conforms, considering that instanceOf link
	//    --> in-depth check

	return True!

Boolean function pm_finished(worklist : Element, pm : String):
	Element finished
	Integer cnt
	Integer i

	// Check if any of the "finish" elements are in the worklist
	// If so, we can already finish, and therefore will stop immediately
	finished = allInstances(pm, "Finish")
	i = 0
	cnt = read_nr_out(finished)

	while (i < cnt):
		// Check each finished element individually
		if (set_in(finished, dict_read(read_edge_dst(read_out(worklist, i)), 0))):
			return True!
		i = i + 1

	return False!

Element function execute_operation(operation_id : String, input_models : Element, output_metamodels : Element, tracability_model : Element):
	// Operations are always in-place and uses only a single metamodel
	// Therefore, we must:
	//		1) Find merged metamodel
	// 		2) Merge the different source models and retype
	//		3) Perform the operation on the merged model
	//		4) Split the resulting model based on the target formalisms; if operation successful
	
	Element input_model
	String trace_link_id
	Element merged_model
	String merged_metamodel_id
	String ramified_metamodel_id
	Boolean result
	String exact_type
	Element trace_links
	String linktype
	String model_ID
	String key
	Element keys
	Element input_keys
	Element output_keys
	Element model_tuples
	String metamodel_name
	Element metamodel
	String metamodel_ID
	Boolean tracability

	// 1) Find merged metamodel

	exact_type = read_type(core, operation_id)

	if (exact_type == "ModelTransformation"):
		linktype = "RAMified"
		ramified_metamodel_id = set_pop(allAssociationDestinations(core, operation_id, "instanceOf"))
		trace_links = allOutgoingAssociationInstances(core, ramified_metamodel_id, "tracability")
	elif (exact_type == "ManualOperation"):
		linktype = "operatesOn"
		trace_links = allOutgoingAssociationInstances(core, operation_id, "tracability")
	elif (exact_type == "ActionLanguage"):
		linktype = "operatesOn"
		trace_links = allOutgoingAssociationInstances(core, operation_id, "tracability")
	else:
		// Don't know how to execute this operation!
		return read_root()!

	merged_metamodel_id = ""
	while (read_nr_out(trace_links) > 0):
		trace_link_id = set_pop(trace_links)
		if (value_eq(read_attribute(core, trace_link_id, "type"), linktype)):
			merged_metamodel_id = readAssociationDestination(core, trace_link_id)

	if (merged_metamodel_id != ""):
		// 2) Merge source models

		model_tuples = create_node()
		while (read_nr_out(input_models) > 0):
			model_ID = get_model_id(set_pop(input_models))
			input_model = get_full_model(model_ID)
			metamodel_name = read_attribute(core, set_pop(allAssociationDestinations(core, model_ID, "instanceOf")), "name")
			set_add(model_tuples, create_tuple(metamodel_name, input_model))

		merged_model = model_join(model_tuples, get_full_model(merged_metamodel_id), read_root())

		// 3) Transform

		if (exact_type == "ModelTransformation"):
			result = transform(merged_model, get_full_model(operation_id))
		elif (exact_type == "ManualOperation"):
			output("Please perform manual operation " + cast_v2s(read_attribute(core, operation_id, "name")))
			modify(merged_model, True)
			result = True
		elif (exact_type == "ActionLanguage"):
			Element func
			func = get_func_AL_model(get_full_model(operation_id))
			result = func(merged_model)
		else:
			log("ERROR")

		// 4) Split in different models depending on type

		if (element_neq(tracability_model, read_root())):
			tracability = True
		else:
			tracability = False

		if (result):
			model_tuples = create_node()
			while (read_nr_out(output_metamodels) > 0):
				metamodel_ID = get_model_id(set_pop(output_metamodels))
				metamodel_name = read_attribute(core, metamodel_ID, "name")
				metamodel = get_full_model(metamodel_ID)
				set_add(model_tuples, create_tuple(metamodel_name, metamodel))

			result = model_split(merged_model, model_tuples, tracability)

			if (tracability):
				Element new_tracability_model
				new_tracability_model = result["__tracability"]
				dict_overwrite(tracability_model, "model", new_tracability_model["model"])
				dict_overwrite(tracability_model, "type_mapping", new_tracability_model["type_mapping"])
				dict_overwrite(tracability_model, "metamodel", new_tracability_model["metamodel"])
				dict_delete(result, "__tracability")

			return result!
		else:
			return read_root()!

	else:
		output("Could not resolve intermediate merged metamodel")
		return read_root()!

Boolean function enact_action(pm : Element, element : String, prefix : String, user_id : String):
	Boolean result
	String transformation_id
	Element lst
	String elem
	Element inputs
	Element outputs
	String type_name
	String exact_type
	Element trace_links
	Element output_mms
	Element consumes_link
	String name
	String value
	String elem_name
	Element keys
	String key

	inputs = create_node()
	outputs = create_node()

	// Read out the referenced element from the MvC
	transformation_id = get_model_id(read_attribute(pm, element, "name"))

	// Find all input model names
	lst = allOutgoingAssociationInstances(pm, element, "Consumes")
	while (read_nr_out(lst) > 0):
		value = read_attribute(pm, readAssociationDestination(pm, set_pop(lst)), "name")
		set_add(inputs, prefix + value)

	// Find all output model names and their metamodel
	lst = allAssociationDestinations(pm, element, "Produces")
	while (read_nr_out(lst) > 0):
		elem = set_pop(lst)
		type_name = read_attribute(pm, elem, "type")
		elem_name = read_attribute(pm, elem, "name")
		dict_add(outputs, type_name, prefix + elem_name)

	result = execute_operation(transformation_id, inputs, dict_keys(outputs), read_root())

	if (element_eq(result, read_root())):
		// Something went wrong!
		return False!
	else:
		keys = dict_keys(result)
		while (read_nr_out(keys) > 0):
			key = set_pop(keys)
			if (get_model_id(outputs[key]) == ""):
				// New model
				model_create(result[key], outputs[key], user_id, get_model_id(key), "Model")
			else:
				model_overwrite(result[key], get_model_id(outputs[key]))
		return True!

Void function enact_PM(pm : Element, prefix : String, user_id : String):
	Element worklist
	String element
	String start
	String type
	Boolean result
	Element tuple
	Element counters
	Element join_nodes

	// Initialize Join counters
	counters = create_node()
	join_nodes = allInstances(pm, "Join")
	while (read_nr_out(join_nodes) > 0):
		dict_add(counters, set_pop(join_nodes), 0)

	// Create the worklist with the Start instance as first element
	worklist = create_node()
	set_add(worklist, create_tuple(set_pop(allInstances(pm, "Start")), True))

	while (bool_not(pm_finished(worklist, pm))):
		// Pop a random element from the list and execute it
		tuple = set_pop(worklist)
		element = tuple[0]
		result = tuple[1]

		log("Enacting " + cast_v2s(element))

		// Find the type (to see what to do with it)
		//   this does not yet yield the type of transformation, if it is an Execution
		type = read_type(pm, element)

		if (type == "Start"):
			// Initial node, just progress to the next elements
			// Nothing to do here though, as we have just started
			result = True
		elif (type == "Finish"):
			// Should be impossible, as we would have ended...
			result = result
		elif (type == "Fork"):
			result = result
		elif (type == "Join"):
			// Only do this if all dependencies are fullfilled
			// So add to the counter of this Join
			dict_overwrite(counters, element, integer_addition(counters[element], 1))

			// Now check whether we have enough tokens to execute the Join itself
			Integer required
			Integer got
			required = read_nr_out(allIncomingAssociationInstances(pm, element, "Next")) + read_nr_out(allIncomingAssociationInstances(pm, element, "Else"))
			got = counters[element]
			if (got == required):
				// Reset counter to 0
				dict_overwrite(counters, element, 0)

				// And continue
			else:
				// We haven't gotten all yet, so we wait (i.e., continue without adding Next link to worklist)
				continue!

		elif (type == "Exec"):
			// Execute a transformation
			// This the difficult part!

			result = enact_action(pm, element, prefix, user_id)

		elif (type == "Decision"):
			// If the previous result is true, we add the normal one, otherwise the false one
			// in this context, that means that if it is false, we should add it manually to the list, and then continue the simulation loop
			if (bool_not(result)):
				// Apparently it is False, so map this to the "Else" branch
				set_add(worklist, create_tuple(set_pop(allAssociationDestinations(pm, element, "Else")), True))
				continue!
			else:
				// Apparently it is True, so map this to the "Then" branch
				set_add(worklist, create_tuple(set_pop(allAssociationDestinations(pm, element, "Then")), True))
				continue!

		// We have finished the execution, so add all outgoing edges to the worklist
		Element all_next
		all_next = allAssociationDestinations(pm, element, "Next")
		String next
		while (read_nr_out(all_next) > 0):
			next = set_pop(all_next)
			set_add(worklist, create_tuple(next, result))

	// Reached a finish element, so stop
	return !

Void function user_function_skip_init(user_id : String):
	String cmd

	output("Welcome to the Model Management Interface v2.0!")
	output("Use the 'help' command for a list of possible commands")

	while (True):
		output("Ready for command...")
		cmd = input()
		if (cmd == "help"):
			output("Model operations")
			output("    model_add                       -- Add a new model")
			output("    model_modify                    -- Modify an existing model")
			output("    model_list                      -- List all models")
			output("    model_list_full                 -- List all models with full info")
			output("    model_overwrite                 -- Overwrites a model with an uploaded model, leaving all metadata")
			output("    model_render                    -- Render a given model with a specified mapper")
			output("    verify                          -- Check whether a model conforms to its metamodel")
			output("")
			output("Transformation-specific operations")
			output("    transformation_add_MT_language  -- Create a RAMified metamodel of a set of models")
			output("    transformation_add_MT           -- Initialize a new model transformation")
			output("    transformation_add_AL           -- Initialize a new action language transformation")
			output("    transformation_add_MANUAL       -- Initialize a new manual transformation")
			output("    transformation_execute          -- Execute a transformation on a set of input models")
			output("    transformation_list             -- List all model transformations")
			output("    transformation_list_full        -- List all model transformations with permissions")
			output("    transformation_detail           -- List transformation details")
			output("    transformation_RAMify           -- RAMify a metamodel (again)")
			output("")
			output("Process operations")
			output("    process_execute                 -- Execute a process model")
			output("")
			output("Model permission operations")
			output("    permission_modify               -- Change model permissions")
			output("    permission_owner                -- Change model owner")
			output("    permission_group                -- Change model group")
			output("")
			output("Group operations")
			output("    group_create                    -- Create a group")
			output("    group_delete                    -- Delete a group")
			output("    group_owner_add                 -- Add group owner")
			output("    group_owner_delete              -- Remove group owner")
			output("    group_join                      -- Add someone to your group")
			output("    group_kick                      -- Kick someone from your group")
			output("    group_list                      -- List all groups you are a member of")
			output("")
			output("Admin operations")
			output("    admin_promote                   -- Promote a user to admin status")
			output("    admin_demote                    -- Demote a user to normal status")
			output("")
			output("General operations")
			output("    self-destruct                   -- Remove current user and revoke all permissions ")
			output("    exit                            -- Kill the current task, while retaining user")

		elif (cmd == "model_add"):
			// Model addition operation, which uses model upload commands of the compiler
			String name
			String type
			String location
			String type_id
			Element new_model
			String new_model_id

			output("Creating new model!")
			output("Model type?")
			type = input()
			type_id = get_model_id(type)
			if (type_id != ""):
				// Type exists
				if (allow_read(user_id, type_id)):
					// And is readable
					output("Model name?")
					name = input()
					if (get_model_id(name) == ""):
						// Model doesn't exist yet
						output("Waiting for model constructors...")

						new_model = construct_model_raw(get_full_model(type_id))

						model_create(new_model, name, user_id, type_id, "Model")
						output("Model upload success!")
					else:
						output("Model with that name already exists!")
				else:
					output("Permission denied")
			else:
				output("Could not find type model: " + type)

		elif (cmd == "process_execute"):
			// Execute a process model until it reaches termination
			String process_id

			output("Which process model do you want to execute?")
			process_id = get_model_id(input())
			if (process_id != ""):
				if (allow_read(user_id, process_id)):
					output("Model prefix to use?")
					enact_PM(get_full_model(process_id), input(), user_id)
				else:
					output("Permission denied")
			else:
				output("No such model")

		elif (cmd == "model_render"):
			String model_name
			String model_ID
			String mapper_name
			String mapper_ID
			String rendered_name
			String tracability_name
			String type_ID
			Element inputs
			Element outputs
			Element rendered_model
			Element tracability_model
			Element result

			output("Model to render?")
			model_name = input()
			model_ID = get_model_id(model_name)

			if (model_ID != ""):
				output("Mapper to use?")
				mapper_name = input()
				mapper_ID = get_model_id(mapper_name)

				if (allow_read(user_id, model_ID)):
					if (mapper_ID != ""):
						if (allow_read(user_id, mapper_ID)):
							// Everything is fine; start the actual operation
							// Find metamodel to render to
							rendered_name = (("__RENDERED_" + model_name) + "__") + mapper_name
							tracability_name = (("__TRACABILITY_" + model_name) + "__") + mapper_name

							// Take the abstract syntax model and the previously rendered model
							inputs = create_node()
							set_add(inputs, model_name)
							set_add(inputs, rendered_name)

							// Generate a new rendered model only (no write to original model!)
							outputs = create_node()
							type_ID = set_pop(allAssociationDestinations(core, mapper_ID, "transformOutput"))
							set_add(outputs, read_attribute(core, type_ID, "name"))

							// Rendered model doesn't exist yet, so create first
							if (get_model_id(rendered_name) == ""):
								// Rendered model doesn't exist yet, so create first!
								rendered_model = instantiate_model(get_full_model(type_ID))
								model_create(rendered_model, rendered_name, user_id, type_ID, "Model")
								
								// Tracability model won't exist either
								tracability_model = instantiate_model(get_full_model(get_model_id("Tracability")))
								model_create(tracability_model, tracability_name, user_id, get_model_id("Tracability"), "Model")

							else:
								// Read out tracability model
								tracability_model = get_full_model(get_model_id(tracability_name))

							// Do the operation itself!
							result = execute_operation(mapper_ID, inputs, outputs, tracability_model)

							// Overwrite the previous rendered model; tracability updated in-place
							model_overwrite(result[read_attribute(core, type_ID, "name")], get_model_id(rendered_name))

							// Also output the resulting model
							output("Mapping success")
							output(JSON_print(get_full_model(get_model_id(rendered_name))))

						else:
							output("Permission denied")
					else:
						output("No such mapper")
				else:
					output("Permission denied")
			else:
				output("No such model")
			
		elif (cmd == "transformation_execute"):
			// Execute a transformation, whatever type it is
			// First we detect the type, so we know how to prepare for invocation
			String transformation_id
			String exact_type
			Element sources
			Element targets
			String source
			String target
			String name_id
			Element inputs
			Element outputs
			Element trace_links
			String target_model_name
			String source_model_name
			String source_model_ID
			Element result
			Element keys
			String key

			output("Which transformation do you want to execute?")
			transformation_id = input()
			transformation_id = get_model_id(transformation_id)
			if (transformation_id != ""):
				if (allow_read(user_id, transformation_id)):
					if (is_nominal_instance(core, transformation_id, "Transformation")):
						// Read out source and target links
						sources = allOutgoingAssociationInstances(core, transformation_id, "transformInput")
						inputs = create_node()
						while (read_nr_out(sources) > 0):
							source = set_pop(sources)
							output(string_join("Which model to bind for source type ", read_attribute(core, readAssociationDestination(core, source), "name")))
							source_model_name = input()
							source_model_ID = get_model_id(source_model_name)
							if (name_id != ""):
								if (allow_read(user_id, name_id)):
									// Check for conformance to the requested metamodel
									if (check_is_typed_by(source_model_ID, source)):
										if (check_conformance(source_model_ID)):
											set_add(inputs, source_model_name)
											continue!
										else:
											output("Model has correct type but does not conform completely!")
									else:
										output("Model has different type!")
								else:
									output("Permission denied")
							else:
								output("No such model")

							// Retry this model type
							set_add(sources, source)

						targets = allOutgoingAssociationInstances(core, transformation_id, "transformOutput")
						outputs = create_node()
						while (read_nr_out(targets) > 0):
							target = set_pop(targets)
							output(string_join("Which model to create for target type ", read_attribute(core, readAssociationDestination(core, target), "name")))
							target_model_name = input()

							if (get_model_id(target_model_name) == ""):
								// Doesn't exist yet, so we can easily create
								dict_add(outputs, read_attribute(core, readAssociationDestination(core, target), "name"), target_model_name)
							else:
								// Already exists, so we need to check for write access
								if (allow_write(user_id, get_model_id(target_model_name))):
									dict_add(outputs, read_attribute(core, readAssociationDestination(core, target), "name"), target_model_name)
								else:
									output("Permission denied; try again")
									set_add(targets, target)

						result = execute_operation(transformation_id, inputs, dict_keys(outputs), read_root())

						// Now write out the models again
						if (element_eq(result, read_root())):
							// Something went wrong!
							log("Transformation failed; discarding changes")

						else:
							keys = dict_keys(result)
							while (read_nr_out(keys) > 0):
								key = set_pop(keys)
								
								if (get_model_id(outputs[key]) == ""):
									// New model
									model_create(result[key], outputs[key], user_id, get_model_id(key), "Model")
								else:
									model_overwrite(result[key], get_model_id(outputs[key]))

					else:
						output("Model is not an executable transformation")
				else:
					output("Permission denied")
			else:
				output("No such transformation")

		elif (cmd == "verify"):
			// Check whether a model conforms to its specification (with the selected type mapping)
			String model_id
			String result

			output("Which model to verify?")
			model_id = get_model_id(input())
			if (model_id != ""):
				if (allow_read(user_id, model_id)):
					output("Verifying model...")
					result = conformance_scd(get_full_model(model_id))
					output(result)
				else:
					output("Permission denied")
			else:
				output("No such model")

		elif (cmd == "model_overwrite"):
			// Overwrites an existing model without changing any metadata
			String model_id
			Element new_model

			output("Which model to overwrite?")
			model_id = get_model_id(input())
			if (model_id != ""):
				if (allow_write(user_id, model_id)):
					if (allow_read(user_id, set_pop(allAssociationDestinations(core, model_id, "instanceOf")))):
						output("Waiting for model constructors...")
						new_model = construct_model_raw(get_full_model(set_pop(allAssociationDestinations(core, model_id, "instanceOf"))))
						model_overwrite(new_model, model_id)
						output("Model overwrite success!")
					else:
						output("Permission denied")
				else:
					output("Permission denied")
			else:
				output("No such model")

		elif (cmd == "model_modify"):
			// Model modify operation, which uses the mini_modify.alc operations, though with extensions for access control
			String model_id
			String type_id

			output("Which model do you want to modify?")
			model_id = get_model_id(input())

			if (model_id != ""):
				if (allow_read(user_id, model_id)):
					type_id = set_pop(allAssociationDestinations(core, model_id, "instanceOf"))
					if (allow_read(user_id, type_id)):
						modify(get_full_model(model_id), allow_write(user_id, model_id))
					else:
						output("Permission denied")
				else:
					output("Permission denied")
			else:
				output("Could not find model!")

		elif (cmd == "model_delete"):
			// Delete a model and all of its related transformations
			String model_id

			output("=================================================")
			output("WARNING: Deletion is a very destructive operation")
			output("         as it also deletes all transformations  ")
			output("         defined which make use of this model!   ")
			output("=================================================")

			output("")
			output("Currently not supported!")

		elif (cmd == "model_list"):
			// List all models
			Element models
			String m

			models = allInstances(core, "Model")
			while (read_nr_out(models) > 0):
				m = set_pop(models)
				output(string_join((string_join("  ", read_attribute(core, m, "name")) + " : "), read_attribute(core, set_pop(allAssociationDestinations(core, m, "instanceOf")), "name")))

		elif (cmd == "model_list_full"):
			// List all models with full info
			Element models
			String m
			String permissions
			String owner
			String group
			String name
			String type

			models = allInstances(core, "Model")
			while (read_nr_out(models) > 0):
				m = set_pop(models)
				permissions = read_attribute(core, m, "permissions")
				owner = read_attribute(core, set_pop(allAssociationDestinations(core, m, "owner")), "name")
				group = read_attribute(core, set_pop(allAssociationDestinations(core, m, "group")), "name")
				name = read_attribute(core, m, "name")
				type = read_attribute(core, set_pop(allAssociationDestinations(core, m, "instanceOf")), "name")
				output((((((((("  " + permissions) + " ") + owner) + " ") + group) + " ") + name) + " : ") + type)

		elif (cmd == "transformation_add_MT_language"):
			// Create a model transformation language from a set of input and output formalisms
			String name
			String model_id
			Element source
			Element target
			Element all_formalisms
			Element merged_formalism
			Element ramified_formalism
			String old_type_id
			String type_id
			String location
			String new_model_id

			old_type_id = ""

			// Read involved formalisms
			all_formalisms = create_node()
			output("Formalisms to include (terminate with empty string)?")
			name = input()
			while (name != ""):
				model_id = get_model_id(name)
				if (model_id != ""):
					if (allow_read(user_id, model_id)):
						type_id = set_pop(allAssociationDestinations(core, model_id, "instanceOf"))
						if (bool_or(old_type_id == "", type_id == old_type_id)):
							set_add(all_formalisms, create_tuple(name, get_full_model(model_id)))
							old_type_id = type_id
						elif (old_type_id != type_id):
							// Already have a previous type_id and now another: CLASH
							output("Cannot add model as types not compatible with previous models; try again")
					else:
						output("Model not readable; try again")
				else:
					output("No such model; try again")
				
				name = input()

			// Merge all into a single metamodel
			if (read_nr_out(all_formalisms) > 0):
				output("Name of the RAMified transformation metamodel?")
				name = input()
				if (get_model_id(name) == ""):
					String merged_formalism_id
					String ramified_formalism_id
					String source_formalism_id
					String tracability_link

					// New location is available, so write
					merged_formalism = model_fuse(set_copy(all_formalisms))
					model_create(merged_formalism, "__merged_" + name, user_id, type_id, "Model")
					merged_formalism_id = get_model_id("__merged_" + name)

					// Add tracability links at this level
					while (read_nr_out(all_formalisms) > 0):
						source_formalism_id = get_model_id(list_read(set_pop(all_formalisms), 0))
						tracability_link = instantiate_link(core, "tracability", "", merged_formalism_id, source_formalism_id)
						instantiate_attribute(core, tracability_link, "type", "merged")

					// Merge complete, now RAMify!
					ramified_formalism = ramify(merged_formalism)
					model_create(ramified_formalism, name, user_id, type_id, "Model")
					ramified_formalism_id = get_model_id(name)

					// Add tracability link at this level
					tracability_link = instantiate_link(core, "tracability", "", ramified_formalism_id, merged_formalism_id)
					instantiate_attribute(core, tracability_link, "type", "RAMified")

				else:
					output("Model already exists!")
			else:
				output("At least one formalism is required")

		elif (cmd == "transformation_RAMify"):
			// RAMify a metamodel
			String merged_model_id
			String target_model_name
			String target_model_id
			Element target_model
			String tracability_link

			output("Which metamodel do you want to RAMify?")
			merged_model_id = get_model_id(input())
			if (merged_model_id != ""):
				if (allow_read(user_id, merged_model_id)):
					output("Where do you want to store the RAMified metamodel?")
					target_model_name = input()
					target_model_id = get_model_id(target_model_name)
					if (target_model_id == ""):
						// New model, so everything is fine
						target_model = ramify(get_full_model(merged_model_id))
						model_create(target_model, target_model_name, user_id, set_pop(allAssociationDestinations(core, merged_model_id, "instanceOf")), "Model")
						target_model_id = get_model_id(target_model_name)
						tracability_link = instantiate_link(core, "tracability", "", target_model_id, merged_model_id)
						instantiate_attribute(core, tracability_link, "type", "RAMified")
					else:
						// Existing model, so overwrite
						if (allow_write(user_id, target_model_id)):
							target_model = ramify(get_full_model(merged_model_id))
							model_overwrite(target_model, target_model_id)
							model_delete_element(core, set_pop(allOutgoingAssociationInstances(core, target_model_id, "tracability")))
							tracability_link = instantiate_link(core, "tracability", "", target_model_id, merged_model_id)
							instantiate_attribute(core, tracability_link, "type", "RAMified")
						else:
							output("Permission denied")
				else:
					output("Permission denied!")
			else:
				output("No such model")

		elif (bool_or(cmd == "transformation_add_MANUAL", cmd == "transformation_add_AL")):
			// Add a manual transformation model
			String model_id
			Element models
			Element source
			Element target
			String name
			Element all_formalisms
			Element merged_formalism
			String merged_formalism_id
			String source_formalism_id
			String tracability_link
			String type_id
			String old_type_id

			source = create_node()
			target = create_node()
			all_formalisms = create_node()

			type_id = ""
			old_type_id = ""

			output("Which metamodels do you want to use as source for the operation (empty string to finish)?")
			name = input()
			while (name != ""):
				model_id = get_model_id(name)
				if (model_id != ""):
					if (allow_read(user_id, model_id)):
						if (bool_not(set_in(source, model_id))):
							type_id = set_pop(allAssociationDestinations(core, model_id, "instanceOf"))
							if (bool_or(old_type_id == "", type_id == old_type_id)):
								old_type_id = type_id
								set_add(source, model_id)
								set_add(all_formalisms, create_tuple(name, get_full_model(model_id)))
							elif (old_type_id != type_id):
								// Already have a previous type_id and now another: CLASH
								output("Cannot add model as types not compatible with previous models; try again")
						else:
							output("Model already selected as source")
					else:
						output("Permission denied")
				else:
					output("No such model; try again")
				
				name = input()

			output("Which metamodels do you want to use as target for the operation (empty string to finish)?")
			name = input()
			while (name != ""):
				model_id = get_model_id(name)
				if (model_id != ""):
					if (allow_read(user_id, model_id)):
						if (bool_not(set_in(target, model_id))):
							type_id = set_pop(allAssociationDestinations(core, model_id, "instanceOf"))
							if (bool_or(old_type_id == "", type_id == old_type_id)):
								old_type_id = type_id
								set_add(target, model_id)
								set_add(all_formalisms, create_tuple(name, get_full_model(model_id)))
							elif (old_type_id != type_id):
								// Already have a previous type_id and now another: CLASH
								output("Cannot add model as types not compatible with previous models; try again")
						else:
							output("Model already selected as target")
					else:
						output("Permission denied")
				else:
					output("No such model; try again")
				
				name = input()

			output("Name of operation model?")
			name = input()

			if (get_model_id(name) == ""):
				if (cmd == "transformation_add_MANUAL"):
					// Finished with all information, now create the model itself!
					model_create(instantiate_model(get_full_model(get_model_id("ManualOperation"))), name, user_id, get_model_id("ManualOperation"), "ManualOperation")
					model_id = get_model_id(name)

				elif (cmd == "transformation_add_AL"):
					// Finished with all information, now create the model itself!
					output("Waiting for model constructors...")
					add_code_model(get_full_model(get_model_id("ActionLanguage")), "AL/" + name, construct_function())
					model_create(import_node("AL/" + name), name, user_id, get_model_id("ActionLanguage"), "ActionLanguage")
					model_id = get_model_id(name)

				// Write out a merged metamodel containing all these models: this is the MM for the manual operation
				// New location is available, so write
				merged_formalism = model_fuse(set_copy(all_formalisms))
				model_create(merged_formalism, "__merged_" + name, user_id, type_id, "Model")
				merged_formalism_id = get_model_id("__merged_" + name)

				// Add tracability links at this level
				while (read_nr_out(all_formalisms) > 0):
					source_formalism_id = get_model_id(list_read(set_pop(all_formalisms), 0))
					tracability_link = instantiate_link(core, "tracability", "", merged_formalism_id, source_formalism_id)
					instantiate_attribute(core, tracability_link, "type", "merged")

				tracability_link = instantiate_link(core, "tracability", "", model_id, merged_formalism_id)
				instantiate_attribute(core, tracability_link, "type", "operatesOn")

				// Extend metadata with info on source and target
				String link
				String dst

				while (read_nr_out(source) > 0):
					dst = set_pop(source)
					link = instantiate_link(core, "transformInput", "", model_id, dst)

				while (read_nr_out(target) > 0):
					dst = set_pop(target)
					link = instantiate_link(core, "transformOutput", "", model_id, dst)
			else:
				output("Model already exists")

		elif (cmd == "transformation_add_MT"):
			// Add a model transformation model
			// Just a usual model instantiation, but need to add the source and target links based on user info
			String ramified_metamodel_id
			String model_id
			Element models
			Element links
			String link_id
			Element supported
			Element source
			Element target
			String name
			String new_model_id
			String merged_link_id
			Element links_merged
			String merged_metamodel_id

			source = create_node()
			target = create_node()
			supported = create_node()
			output("RAMified metamodel to use?")
			ramified_metamodel_id = get_model_id(input())
			if (ramified_metamodel_id != ""):
				if (allow_read(user_id, ramified_metamodel_id)):
					output("Supported metamodels:")
					links = allOutgoingAssociationInstances(core, ramified_metamodel_id, "tracability")
					while (read_nr_out(links) > 0):
						link_id = set_pop(links)
						merged_metamodel_id = readAssociationDestination(core, link_id)
						if (value_eq(read_attribute(core, link_id, "type"), "RAMified")):
							links_merged = allOutgoingAssociationInstances(core, merged_metamodel_id, "tracability")
							while (read_nr_out(links_merged) > 0):
								merged_link_id = set_pop(links_merged)
								if (value_eq(read_attribute(core, merged_link_id, "type"), "merged")):
									output(string_join("  ", read_attribute(core, readAssociationDestination(core, merged_link_id), "name")))
									set_add(supported, readAssociationDestination(core, merged_link_id))

					output("Which metamodels do you want to use as source for the operation (empty string to finish)?")
					name = input()
					while (name != ""):
						model_id = get_model_id(name)
						if (model_id != ""):
							if (set_in(supported, model_id)):
								if (bool_not(set_in(source, model_id))):
									set_add(source, model_id)
								else:
									output("Model already selected as source")
							else:
								output("Model is not supported by RAMified metamodel!")
						else:
							output("No such model; try again")
						
						name = input()

					output("Which metamodels do you want to use as target for the operation (empty string to finish)?")
					name = input()
					while (name != ""):
						model_id = get_model_id(name)
						if (model_id != ""):
							if (set_in(supported, model_id)):
								if (bool_not(set_in(target, model_id))):
									set_add(target, model_id)
								else:
									output("Model already selected as target")
							else:
								output("Model is not supported by RAMified metamodel!")
						else:
							output("No such model; try again")
						
						name = input()

					output("Name of new operation?")
					name = input()

					if (get_model_id(name) == ""):
						String new_model
						// Finished with all information, now create the model itself!
						output("Waiting for model constructors...")
						new_model = construct_model_raw(get_full_model(ramified_metamodel_id))
						model_create(new_model, name, user_id, ramified_metamodel_id, "ModelTransformation")
						model_id = get_model_id(name)

						// Extend metadata with info on source and target
						String link
						String dst

						while (read_nr_out(source) > 0):
							dst = set_pop(source)
							link = instantiate_link(core, "transformInput", "", model_id, dst)

						while (read_nr_out(target) > 0):
							dst = set_pop(target)
							link = instantiate_link(core, "transformOutput", "", model_id, dst)
					else:
						output("Model already exists")
				else:
					output("Permission denied")
			else:
				output("No such model")

		elif (cmd == "transformation_list"):
			// List all models
			Element models
			String m
			String type

			models = allInstances(core, "Transformation")
			while (read_nr_out(models) > 0):
				m = set_pop(models)
				output(string_join(("[" + read_type(core, m)) + "]", string_join((string_join(" ", read_attribute(core, m, "name")) + " : "), read_attribute(core, set_pop(allAssociationDestinations(core, m, "instanceOf")), "name"))))

		elif (cmd == "transformation_list_full"):
			// List all models with full info
			Element models
			String m
			String permissions
			String owner
			String group
			String name
			String type

			models = allInstances(core, "Transformation")
			while (read_nr_out(models) > 0):
				m = set_pop(models)
				permissions = read_attribute(core, m, "permissions")
				owner = read_attribute(core, set_pop(allAssociationDestinations(core, m, "owner")), "name")
				group = read_attribute(core, set_pop(allAssociationDestinations(core, m, "group")), "name")
				name = read_attribute(core, m, "name")
				type = read_attribute(core, set_pop(allAssociationDestinations(core, m, "instanceOf")), "name")
				output((((((((("  " + permissions) + " ") + owner) + " ") + group) + " ") + ((("[" + read_type(core, m)) + "] ") + name)) + " : ") + type)

		elif (cmd == "permission_modify"):
			String permissions
			Integer permission
			String model_id

			output("Which model do you want to change permissions of?")
			model_id = get_model_id(input())
			if (model_id != ""):
				if (get_relation_to_model(user_id, model_id) == 0):
					output("New permissions?")
					permissions = input()

					Boolean fail
					Integer i
					i = 0
					if (string_len(permissions) != 3):
						fail = True

					while (i < 3):
						permission = cast_s2i(string_get(permissions, i))
						if (bool_or(permission < 0, permission > 2)):
							fail = True
							break!
						i = i + 1

					if (bool_not(fail)):
						unset_attribute(core, model_id, "permissions")
						instantiate_attribute(core, model_id, "permissions", permissions)
					else:
						output("Permissions must be a string of three characters with each character being a digit between 0 and 2")
				else:
					output("Permission denied!")
			else:
				output("No such model!")
			
		elif (cmd == "permission_owner"):
			String permissions
			String model_id
			String user_id

			output("Which model do you want to change owner of?")
			model_id = get_model_id(input())
			if (model_id != ""):
				if (bool_or(get_relation_to_model(user_id, model_id) == 0, is_admin(user_id))):
					output("New owner?")
					user_id = get_user_id(input())
					if (user_id != ""):
						model_delete_element(core, set_pop(allOutgoingAssociationInstances(core, model_id, "owner")))
						instantiate_link(core, "owner", "", model_id, user_id)
					else:
						output("No such user!")
				else:
					output("Permission denied!")
			else:
				output("No such model!")

		elif (cmd == "permission_group"):
			String permissions
			String model_id
			String group_id

			output("Which model do you want to change permissions of?")
			model_id = get_model_id(input())
			if (model_id != ""):
				if (bool_or(get_relation_to_model(user_id, model_id) == 0, is_admin(user_id))):
					output("New group?")
					group_id = get_group_id(input())
					if (group_id != ""):
						model_delete_element(core, set_pop(allOutgoingAssociationInstances(core, model_id, "group")))
						instantiate_link(core, "group", "", model_id, group_id)
					else:
						output("No such group!")
				else:
					output("Permission denied!")
			else:
				output("No such model!")

		elif (cmd == "group_create"):
			// Create a new group and become its owner
			String group_id
			String name

			output("Which group do you want to create?")
			name = input()
			group_id = get_group_id(name)
			if (group_id == ""):
				group_id = instantiate_node(core, "Group", "")
				instantiate_attribute(core, group_id, "name", name)
				instantiate_link(core, "belongsTo", "", user_id, group_id)
				instantiate_link(core, "owner", "", group_id, user_id)
				output("Group created!")
			else:
				output("Group already exists")

		elif (cmd == "group_delete"):
			// Delete an existing group
			String group_id
			String name

			output("Which group do you want to delete?")
			name = input()
			group_id = get_group_id(name)
			if (group_id != ""):
				if (allow_group_modify(user_id, group_id)):
					model_delete_element(core, group_id)
				else:
					output("Permission denied")
			else:
				output("No such group")

		elif (cmd == "group_owner_add"):
			// Add an owner to your group
			String group_id
			String other_user_id

			output("Which group do you want to add an owner to?")
			group_id = get_group_id(input())
			if (group_id != ""):
				if (allow_group_modify(user_id, group_id)):
					output("Which user do you want to make an owner?")
					other_user_id = get_user_id(input())
					if (other_user_id != ""):
						Element overlap

						overlap = set_overlap(allIncomingAssociationInstances(core, other_user_id, "owner"), allOutgoingAssociationInstances(core, group_id, "owner"))
						if (read_nr_out(overlap) == 0):
							instantiate_link(core, "owner", "", group_id, other_user_id)

							overlap = set_overlap(allOutgoingAssociationInstances(core, other_user_id, "belongsTo"), allIncomingAssociationInstances(core, group_id, "belongsTo"))

							if (read_nr_out(overlap) == 0):
								instantiate_link(core, "belongsTo", "", other_user_id, group_id)

							output("New owner added to group!")
						else:
							output("User is already an owner!")
					else:
						output("No such user")
				else:
					output("Permission denied!")
			else:
				output("No such group")

		elif (cmd == "group_owner_delete"):
			// Remove an owner from your group
			String group_id
			String other_user_id

			output("Which group do you want to disown someone from?")
			group_id = get_group_id(input())
			if (group_id != ""):
				if (allow_group_modify(user_id, group_id)):
					output("Which user do you want to disown?")
					other_user_id = get_user_id(input())
					if (other_user_id != ""):
						Element overlap

						overlap = set_overlap(allOutgoingAssociationInstances(core, other_user_id, "belongsTo"), allIncomingAssociationInstances(core, group_id, "belongsTo"))
						if (read_nr_out(overlap) > 0):
							overlap = set_overlap(allIncomingAssociationInstances(core, other_user_id, "owner"), allOutgoingAssociationInstances(core, group_id, "owner"))
							if (read_nr_out(overlap) > 0):
								model_delete_element(core, set_pop(overlap))
								output("Disowned group from user!")
							else:
								output("User is not even an owner of the group!")
						else:
							output("User is not even a member of the group!")
					else:
						output("No such user")
				else:
					output("Permission denied!")
			else:
				output("No such group")

		elif (cmd == "group_join"):
			// Add someone to your group
			String group_id
			String other_user_id

			output("Which group do you want to add someone to?")
			group_id = get_group_id(input())
			if (group_id != ""):
				if (allow_group_modify(user_id, group_id)):
					output("Which user do you want to add?")
					other_user_id = get_user_id(input())
					if (other_user_id != ""):
						Element overlap

						overlap = set_overlap(allOutgoingAssociationInstances(core, other_user_id, "belongsTo"), allIncomingAssociationInstances(core, group_id, "belongsTo"))

						if (read_nr_out(overlap) == 0):
							instantiate_link(core, "belongsTo", "", other_user_id, group_id)
							output("User added to the group!")
						else:
							output("User is already a member of the group!")
					else:
						output("No such user")
				else:
					output("Permission denied!")
			else:
				output("No such group")

		elif (cmd == "group_kick"):
			// Remove someone from your group
			String group_id
			String other_user_id

			output("Which group do you want to kick someone from?")
			group_id = get_group_id(input())
			if (group_id != ""):
				if (allow_group_modify(user_id, group_id)):
					output("Which user do you want to kick?")
					other_user_id = get_user_id(input())
					if (other_user_id != ""):
						Element overlap

						overlap = set_overlap(allOutgoingAssociationInstances(core, other_user_id, "belongsTo"), allIncomingAssociationInstances(core, group_id, "belongsTo"))
						if (read_nr_out(overlap) > 0):
							model_delete_element(core, set_pop(overlap))

							// Check if user was an owner as well
							overlap = set_overlap(allIncomingAssociationInstances(core, other_user_id, "owner"), allOutgoingAssociationInstances(core, group_id, "owner"))
							if (read_nr_out(overlap) > 0):
								model_delete_element(core, set_pop(overlap))

							output("User kicked!")
						else:
							output("User is not even a member of the group!")
					else:
						output("No such user")
				else:
					output("Permission denied!")
			else:
				output("No such group")

		elif (cmd == "group_list"):
			// List all groups you are a member of (and whether you are admin or not!)
			Element groups
			String group_id
			String admin
			
			groups = allAssociationDestinations(core, user_id, "belongsTo")
			while (read_nr_out(groups) > 0):
				group_id = set_pop(groups)
				if (set_in(allOutgoingAssociationInstances(core, group_id, "owner"), user_id)):
					admin = " A "
				else:
					admin = "   "

				output(string_join(admin, read_attribute(core, group_id, "name")))

		elif (cmd == "admin_promote"):
			// Promote a user to admin status
			if (is_admin(user_id)):
				String other_user_id

				output("Which user do you want to promote?")
				other_user_id = get_user_id(input())
				if (other_user_id != ""):
					unset_attribute(core, other_user_id, "admin")
					instantiate_attribute(core, other_user_id, "admin", True)
					output("Permissions granted!")
				else:
					output("No such user!")
			else:
				output("Permission denied!")

		elif (cmd == "admin_demote"):
			// Demote a user to normal status
			if (is_admin(user_id)):
				String other_user_id

				output("Which user do you want to demote?")
				other_user_id = get_user_id(input())
				if (other_user_id != ""):
					unset_attribute(core, other_user_id, "admin")
					instantiate_attribute(core, other_user_id, "admin", False)
					output("Permissions revoked!")
				else:
					output("No such user!")
			else:
				output("Permission denied!")

		elif (cmd == "self-destruct"):
			// Delete user from Core Formalism
			model_delete_element(core, user_id)
			return !

		elif (cmd == "exit"):
			// Exit by actually removing the user and decoupling it from all of its models
			// Restarting with the same user name will NOT grant you access to anything of the previous user with that same name
			// as the current user will have been deleted
			return !

		else:
			output("Unknown command: " + cmd)

	// We never get here!
	return !