extends Object

class_name YarnRunner

var yarnScript : YarnScript

var say_func : FuncRef = null
var choices_func : FuncRef = null

var commands := {}

signal resume_workaround

func run_all():
	var next_node = yarnScript.nodes["Start"]
	while next_node != null:
		print("-> Jump to " + next_node["title"])
		var next_node_key = yield(run_body(next_node["body"]), "completed")
		if (yarnScript.nodes.has(next_node_key)):
			next_node = yarnScript.nodes[next_node_key]
		else:
			next_node = null

func run_body(body):
	yield(Controller.get_tree(), "idle_frame") # workaround before await
	for element in body:
		if element["type"] == "jump":
			return element["node"]
		elif element["type"] == "command":
			yield(run_command(element["command"], element["args"]), "completed")
		elif element["type"] == "choice_blocks":
			var block = yield(decide_choice_block(element["blocks"]), "completed")
			print(block)
			return block["node"] # todo change later with "-> choices"
		elif element["type"] == "condition_blocks":
			var block = decide_condition_block(element["blocks"])
			var next_node_key = yield(run_body(block["body"]), "completed")
			if next_node_key != "":
				return next_node_key
		else:
			if say_func == null or !say_func.is_valid():
				printerr("no say_func provided")
			else:
				yield(say_func.call_func(element), "completed")
	return ""

func add_command(command_key, function):
	commands[command_key] = function

func run_command(command_key, args):
	if (commands.has(command_key)):
		var command : FuncRef = commands[command_key]
		yield(command.call_func(args), "completed")

func decide_choice_block(blocks):
	if choices_func == null or !choices_func.is_valid():
		printerr("no choices_func provided")
	else:
		return yield(choices_func.call_func(blocks), "completed")

func decide_condition_block(blocks):
	for block in blocks:
		var expr := Expression.new()
		var err := expr.parse(block["condition"])
		
		if err == OK and expr.execute():
			return block
	return null