"use strict";

module.exports = class Generator {

	constructor(parsed) {
		this.systems = parsed.systems;
		this.behaviors = parsed.behaviors;
		this.interactions = parsed.interactions;
		this.triggers = parsed.triggers;
	}

	*generate(obj, scope=1, n=0, i=0) {
		let min = obj.scope && typeof obj.scope.min === "number" ? obj.scope.min : 1;
		let max = obj.scope && typeof obj.scope.max === "number" ? obj.scope.max : scope;
		console.log(`t=${obj.type}	id=${obj.id || `...${obj.body.length}`}	n=${n}	i=${i}	s=${scope}	min=${min}	max=${max}`);

		let id = null;
		switch (obj.type) {

			case "Behavior":
				if (!obj.body) { // Behavior reference
					let realObj = this.behaviors[obj.id];
					if (!realObj || !realObj.body) throw new Error(`Unable to find referenced behavior: ${obj.id}`);
					Object.defineProperty(obj, "body", { // use real body but keep it hidden (for debugging the AST mainly)
						value: realObj.body,
					});
				}
				/* falls through */
			case "System": // or Behavior
				if (!obj.body) throw new Error(`Unexpected empty ${obj.type}`);
				id = `${obj.id}_${n + 1}of${max}`;
				/* falls through */
			case "Sequence": // or System or Behavior
				let outs = [];
				if (i === 0 && id !== null) outs.push(id);
				if (i < obj.body.length) {
					for (let evts of this.generate(obj.body[i], scope)) {
						for (let nextEvts of this.generate(obj, scope, n, i + 1)) {
							yield outs.concat(evts, nextEvts);
						}
					}
				} else {
					if (n >= min - 1) yield outs;
					if (n < max - 1) {
						for (let nextEvts of this.generate(obj, scope, n + 1, 0))
							yield outs.concat(nextEvts);
					}
				}
				break;

			default:
				throw new Error(`UNIMPLEMENTED TYPE: ${obj.type}`);

		}
	}

};