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 = ?

Void function main():
	// Initialize the Core Formalism
	String core_location
	String core_model
	String core_model_location
	String core_formalism_model
	String scd_location
	String scd_model
	String admin_group
	String admin_user
	String nobody_group

	scd_location = "models/SimpleClassDiagrams"
	core_location = "models/CoreFormalism"
	core_model_location = "models/core"

	// Create the Model itself and make public
	core = instantiate_model(import_node(core_location))
	export_node(core_model_location, core)

	// 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)

	// 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)
	instantiate_attribute(core, scd_model, "permissions", "221")
	instantiate_link(core, "instanceOf", "", scd_model, scd_model)

	// 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 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)
	instantiate_attribute(core, core_formalism_model, "permissions", "221")
	instantiate_link(core, "instanceOf", "", core_formalism_model, scd_model)

	// 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", core_model_location)
	instantiate_attribute(core, core_model, "permissions", "200")
	instantiate_link(core, "instanceOf", "", core_model, core_formalism_model)

	// 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)

	// 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"])

	// Call this for ourselves as well
	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 !

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):
	// TODO
	return False!

Element function user_function():
	String username
	String user_id

	output("Log on as which user?")

	// 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"])
	core = import_node("models/core")

	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)

		// Now call with user created
		user_function_skip_init(user_id)
	else:
		if (check_login(user_id)):
			user_function_skip_init(user_id)

	// User destroyed already, so just stop execution
	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):
	String location
	String model_id

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

	// Manage meta-info
	model_id = instantiate_node(core, "Model", "")
	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"))
	instantiate_link(core, "instanceOf", "", model_id, type_id)

	return!

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

	location = "/models/" + cast_id2s(model)
	export_node(location, model)
	log("Got model ID: " + model_id)

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

	return!

Void function user_function_skip_init(user_id : String):
	Boolean do_continue
	String cmd

	do_continue = True

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

	while (do_continue):
		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_delete                    -- [TODO] Delete a model and all related transformations")
			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("")
			output("Transformation-specific operations")
			output("    transformation_add_MT_language  -- Create a RAMified metamodel")
			output("    transformation_add_MT           -- Initialize a new model transformation")
			output("    transformation_add_AL           -- [TODO] Initialize a new action language transformation")
			output("    transformation_add_EXT          -- [TODO] Initialize a new external tool transformation")
			output("    transformation_execute          -- Execute a transformation on a set of input models")
			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("    account_delete                  -- Remove current user and revoke all permissions ")

		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_id = get_model_id(input())
			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...")

						// TODO Update construct_model call to this interface
						new_model = construct_model_raw(import_node(read_attribute(core, type_id, "location")))
						model_create(new_model, name, user_id, type_id)
						output("Model upload success!")
					else:
						output("Model with that name already exists!")
				else:
					output("Permission denied")
			else:
				output("Could not find type 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

			output("Which transformation do you want to execute?")
			transformation_id = get_model_id(input())
			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(source) > 0):
							source = set_pop(sources)
							output(string_join("Which model to bind for source element ", read_attribute(core, source, "name")))
							name_id = get_model_id(input())
							if (name_id != ""):
								if (allow_read(user_id, name_id)):
									dict_add(inputs, read_attribute(core, source, "name"), name_id)
								else:
									output("Permission denied")
									set_add(sources, source)
							else:
								output("No such model")
								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 element ", read_attribute(core, target, "name")))
							name_id = get_model_id(input())
							dict_add(outputs, read_attribute(core, target, "name"), name_id)

						exact_type = read_type(core, transformation_id)
						if (exact_type == "ModelTransformation"):
							// Model transformation is always in-place and uses only a single metamodel
							// Therefore, we must:
							//		1) Create an empty model, instance of merged metamodel
							// 		2) Merge the different source models and retype
							//		3) Perform the transformation on the merged model
							//		4) Split the resulting model based on the target formalisms
							//
							// There is one exception: if the target model is bound to a source model, that model is overwritten
							// This allows for some optimizations when it is a simple in-place transformation (skip model copy, join, and split)
							// First check for this exception, as it is much faster
							Element input_model
							Element schedule_model
							String trace_link_id
							Element merged_model
							String merged_metamodel_id
							String ramified_metamodel_id

							schedule_model = import_node(read_attribute(core, transformation_id, "location"))
							if (bool_and(bool_and(read_nr_out(inputs) == 1, read_nr_out(outputs) == 1), set_equality(inputs, outputs))):
								// inputs and outputs have the same values and there is only one: keep in-place without additional bookkeeping
								input_model = import_node(read_attribute(core, set_pop(inputs), "location"))
								transform(input_model, schedule_model)
							else:
								// Need to fall back to the default approach, which is way slower
								// 1) Create empty instance of merged metamodel

								ramified_metamodel_id = set_pop(followAssociation(core, transformation_id, "instanceOf"))
								trace_links = allOutgoingAssociationInstances(core, ramified_metamodel_id, "tracability")
								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"), "ramified")):
										merged_metamodel_id = readAssociationDestination(core, trace_link_id)
								if (merged_metamodel_id != ""):
									merged_model = instantiate_model(import_node(read_attribute(core, merged_metamodel_id, "location")))

									// 2) Merge source models

									String key
									Element keys
									Element input_keys
									Element output_keys

									input_keys = dict_keys(inputs)
									while (read_nr_out(input_keys) > 0):
										key = set_pop(input_keys)
										model_join(merged_model, import_node(read_attribute(core, inputs[key], "location")), key)

									// 3) Transform

									transform(merged_model, schedule_model)

									// 4) Split in different files depending on type

									String desired_metamodel_id
									Element split_off_model

									output_keys = dict_keys(outputs)
									while (read_nr_out(output_keys) > 0):
										key = set_pop(output_keys)
										desired_metamodel_id = set_pop(followAssociation(core, outputs[key], "instanceOf"))
										split_off_model = model_split(merged_model, import_node(read_attribute(core, desired_metamodel_id, "location")), key)

										// Check if the destination model already exists
										if (get_model_id(outputs[key]) == ""):
											// New model
											model_create(split_off_model, outputs[key], user_id, desired_metamodel_id)
										else:
											// Model exists, so we overwrite
											model_overwrite(split_off_model, outputs[key])

								else:
									output("Could not resolve intermediate merged metamodel")
						elif (exact_type == "ActionLanguage"):
							output("Not Implemented yet!")
						else:
							output("Did not know how to interpret model of type " + exact_type)
					else:
						output("Model is not an executable transformation")
				else:
					output("Permission denied")
			else:
				output("No such transformation")

		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(followAssociation(core, model_id, "instanceOf")))):
						output("Waiting for model constructors...")
						new_model = construct_model_raw(import_node(read_attribute(core, set_pop(followAssociation(core, model_id, "instanceOf")), "location")))
						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(import_node(read_attribute(core, model_id, "location")), 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(followAssociation(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
			String size

			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")
				size = cast_i2s(read_nr_out(dict_read(import_node(read_attribute(core, m, "location")), "model")))
				type = read_attribute(core, set_pop(allAssociationDestinations(core, m, "instanceOf")), "name")
				output((((((((((("  " + permissions) + "  ") + owner) + " ") + group) + "    ") + size) + "   ") + 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 + "/", import_node(read_attribute(core, model_id, "location"))))
							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 both 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(all_formalisms)
					model_create(merged_formalism, "__merged_" + name, user_id, type_id)
					merged_formalism_id = get_model_id("__merged_" + name)

					// Add tracability links at this level
					while (read_nr_out(all_formalisms) > 0):
						source_formalism_id = list_read(set_pop(all_formalisms), 1)
						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)
					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_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

			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)
						if (value_eq(read_attribute(core, link_id, "type"), "merged")):
							output(string_join("  ", read_attribute(core, readAssociationDestination(core, link_id), "name")))
							set_add(supported, readAssociationDestination(core, link_id))

					output("")
					output("Which ones do you want to use as source (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)
									output("Model added as source")
								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 ones do you want to use as target (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)
									output("Model added as target")
								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 transformation?")
					name = input()

					if (get_model_id(name) == ""):
						String new_model
						// Finished with all information, now create the model itself!
						new_model = instantiate_model(import_node(read_attribute(core, ramified_metamodel_id, "location")))

						model_create(new_model, name, user_id, ramified_metamodel_id)
						model_id = get_model_id(name)

						// Extend metadata with info on source and target
						while (read_nr_out(source) > 0):
							instantiate_link(core, "transformInput", "", new_model_id, set_pop(source))
						while (read_nr_out(target) > 0):
							instantiate_link(core, "transformOutput", "", new_model_id, set_pop(target))

						output("Meta-info correctly set!")
					else:
						output("Model already exists")
				else:
					output("Permission denied")
			else:
				output("No such model")

		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 (bool_and(bool_not(fail), i < 3)):
						permission = cast_s2i(string_get(permissions, i))
						if (bool_or(permission < 0, permission > 2)):
							fail = True

					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, user_id, "owner"), allOutgoingAssociationInstances(core, group_id, "owner"))
						if (read_nr_out(overlap) == 0):
							instantiate_link(core, "owner", "", group_id, user_id)

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

							if (read_nr_out(overlap) == 0):
								instantiate_link(core, "belongsTo", "", 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, user_id, "belongsTo"), allIncomingAssociationInstances(core, group_id, "belongsTo"))
						if (read_nr_out(overlap) > 0):
							overlap = set_overlap(allIncomingAssociationInstances(core, 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, user_id, "belongsTo"), allIncomingAssociationInstances(core, group_id, "belongsTo"))
						if (read_nr_out(overlap) == 0):
							instantiate_link(core, "belongsTo", "", 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, 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, 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 (True):
				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 == "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
			do_continue = False
		else:
			output("Unknown command: " + cmd)

	// Delete user from Core Formalism
	model_delete_element(core, user_id)
	output("Goodbye!")

	return !