include "primitives.alh"
include "object_operations.alh"
include "modelling.alh"

Element function make_matching_schedule(LHS_model : Element):
	Element schedule
	Element workset
	Element all_elements
	Element full_all_elements
	Integer required_size
	String new_element
	Integer counter
	String next

	// Initialize
	schedule = create_node()
	workset = create_node()
	all_elements = allInstances(LHS_model, "Pre_Element")
	full_all_elements = set_copy(all_elements)
	required_size = read_nr_out(all_elements)

	// Need to keep adding to the schedule
	while (read_nr_out(schedule) < required_size):

		// workset is empty, but we still need to add to the list
		// Therefore, we pick a random, unbound node, and add it to the workset
		new_element = set_pop(all_elements)
		while (bool_or(set_in(schedule, new_element), is_edge(LHS_model["model"][new_element]))):
			// Element is not usable, so pick another one
			new_element = set_pop(all_elements)
		set_add(workset, new_element)

		// Handle the workset
		while (read_nr_out(workset) > 0):
			// Still elements in the workset, so pop from these first
			next = set_pop(workset)

			// Check if element might not be already used somewhere
			if (bool_not(set_in(schedule, next))):
				if (set_in(full_all_elements, next)):
					list_append(schedule, next)

					// If it is an edge, we should also add the target and source
					if (is_edge(LHS_model["model"][next])):
						// Add the target/source to the schedule
						set_add(workset, reverseKeyLookup(LHS_model["model"], read_edge_src(LHS_model["model"][next])))
						set_add(workset, reverseKeyLookup(LHS_model["model"], read_edge_dst(LHS_model["model"][next])))

					// Also add all outgoing links
					counter = read_nr_out(LHS_model["model"][next])
					while (counter > 0):
						counter = counter - 1
						if (set_in_node(LHS_model["model"], read_out(LHS_model["model"][next], counter))):
							set_add(workset, reverseKeyLookup(LHS_model["model"], read_out(LHS_model["model"][next], counter)))

	return schedule!

Element function get_possible_bindings(host_model : Element, LHS_model : Element, current_element : String, map : Element):
	Element options

	output("FIND BINDING")
	options = create_node()

	return options!

Element function match(host_model : Element, LHS_model : Element):
	// Match the LHS_model to the host_model, returning all possible mappings from LHS_model elements to host_model elements

	// Make the schedule first
	Element schedule
	schedule = make_matching_schedule(LHS_model)

	// Now follow the schedule, incrementally building all mappings
	Element mappings
	Element new_mappings
	Element new_map
	String current_element
	Element map
	String option
	Element options

	mappings = create_node()
	set_add(mappings, create_node())
	while (bool_and(read_nr_out(schedule) > 0, read_nr_out(mappings) > 0)):
		current_element = list_pop(schedule, 0)
		log("Finding options for " + current_element)
		new_mappings = create_node()

		while (read_nr_out(mappings) > 0):
			map = set_pop(mappings)
			log("In context " + set_to_string(map))
			options = get_possible_bindings(host_model, LHS_model, current_element, map)
			log("Found options " + set_to_string(options))

			while (read_nr_out(options) > 0):
				option = set_pop(options)
				new_map = set_copy(map)
				dict_add(new_map, current_element, option)
				log(" --> adding mapping " + set_to_string(new_map))
				set_add(new_mappings, new_map)

		mappings = new_mappings

	return mappings!

Void function rewrite(host_model : Element, RHS_model : Element, mapping : Element):
	output("TODO: rewrite!")

	return!

Void function transform(host_model : Element, LHS_model : Element, RHS_model : Element):
	Element mapping
	Element mappings

	// Get all possible mappings
	mappings = match(host_model, LHS_model)

	// Select one such mapping and rewrite it
	if (read_nr_out(mappings) > 0):
		// Mapping found, so can rewrite it
		mapping = set_pop(mappings)
		rewrite(host_model, RHS_model, mapping)
	else:
		output("No mapping found!")

	return!