Add code of Decorator Pattern: The Long Night

Author: Joao Paulo Monteiro

decorator/Character.js

@@ -0,0 +1,40 @@
+class Character{
+ constructor(name){
+ this._name = name;
+ this._life = 0;
+ }
+
+ set life(life){
+ this._life = (life > 0 ) ? life : 0;
+ }
+
+ get life(){
+ return this._life;
+ }
+
+ get name(){
+ return this._name;
+ }
+
+ attack(){
+ throw new Error('Este método precisa ser implementado nas subclasses');
+ }
+
+ defend(){
+ throw new Error('Este método precisa ser implementado nas subclasses');
+ }
+
+ receiveHit(attack){
+ throw new Error('Este método precisa ser implementado nas subclasses');
+ }
+
+ isAlive(){
+ throw new Error('Este método precisa ser implementado nas subclasses');
+ }
+
+ toString(){
+ throw new Error('Este método precisa ser implementado nas subclasses');
+ }
+}
+
+export default Character;

decorator/CharacterDecorator.js

@@ -0,0 +1,42 @@
+import { Character } from "./Character";
+
+class CharacterDecorator{
+ constructor(character){
+ this._character = character;
+ }
+
+ attack(){
+ return this._character.attack();
+ }
+
+ defend(){
+ return this._character.defend();
+ }
+
+ isAlive(){
+ return this._character.isAlive();
+ }
+
+ set life(life){
+ this._character.life = life;
+ }
+
+ get life(){
+ return this._character.life;
+ }
+
+ get name(){
+ return this._character.name;
+ }
+
+ receiveHit(hit){
+ this._character.receiveHit(hit);
+ }
+
+
+ toString(){
+ return `${this._character.name} - ${this._character.life}`;
+ }
+}
+
+export default CharacterDecorator;

decorator/SimpleCharacter.js

@@ -0,0 +1,33 @@
+import Character from './Character';
+
+class SimpleCharacter extends Character{
+ constructor(name){
+ super(name);
+ this._life = 100;
+ }
+
+ attack(){
+ return 1;
+ }
+
+ defend(){
+ return 1;
+ }
+
+ receiveHit(hit){
+ const damage = ( hit * Math.random() ) - ( this.defend() * Math.random() );
+ if(damage > 0){
+ this.life = this.life - damage;
+ }
+ }
+
+ isAlive(){
+ return this.life > 0;
+ }
+
+ toString(){
+ return `Simple Character. Name: ${this.name}`;
+ }
+}
+
+export default SimpleCharacter;

decorator/WhiteWalkerDecorator.js

@@ -0,0 +1,27 @@
+import CharacterDecorator from './CharacterDecorator';
+
+class WhiteWalkerDecorator extends CharacterDecorator{
+ constructor(character){
+ super(character);
+ this._power = Math.random();
+ }
+
+ set power(power){
+ this._power = power;
+ }
+
+ _whiteWalkerModifier(){
+ return Math.random() * this._power;
+ }
+
+ attack(){
+ return this._whiteWalkerModifier() * super.attack();
+ }
+
+ defend(){
+ return this._whiteWalkerModifier() * super.defend();
+ }
+
+}
+
+export default WhiteWalkerDecorator;

decorator/main.js

@@ -0,0 +1,76 @@
+import CharacterDecorator from './CharacterDecorator';
+import SimpleCharacter from './SimpleCharacter';
+import WhiteWalkerDecorator from './WhiteWalkerDecorator';
+
+const NUM_HUMANS = 20;
+const humans = Array.from(
+ Array(NUM_HUMANS),
+ (_, index) => new CharacterDecorator(new SimpleCharacter(`Human${index}`))
+);
+
+const nightKing = createNightKing();
+
+const whiteWalkers = [nightKing];
+
+console.log('The War started!');
+
+let human;
+let whiteWalker;
+
+while(!isWarFinished(humans, whiteWalkers)){
+ human = humans.pop();
+ whiteWalker = whiteWalkers.pop();
+
+ while(human.isAlive() && whiteWalker.isAlive()){
+ whiteWalker.receiveHit(human.attack());
+ human.receiveHit(whiteWalker.attack());
+ }
+
+ if(human.isAlive()){
+ console.log('Human Win!');
+ log(human, whiteWalker);
+ }
+
+ if(whiteWalker.isAlive()){
+ console.log('WhiteWalker Win!...');
+ whiteWalkers.push(whiteWalker);
+ console.log('... Human now is a White Walker:', human.name);
+ whiteWalkers.push(
+ new WhiteWalkerDecorator(
+ new SimpleCharacter(`White Walker: ${human.name}`)
+ )
+ );
+
+ console.log('----WhiteWalkers----');
+ console.table(whiteWalkers);
+ console.log('----Humans----');
+ console.table(humans);
+
+ }
+}
+
+console.log('The War is Finished');
+
+if(humans.length > 0){
+ console.log('The long night is over!');
+}else{
+ console.log('The long night stands forever!');
+}
+
+function isWarFinished(humans, whiteWalkers){
+ return humans.length == 0 || whiteWalkers.length == 0;
+}
+
+function log(human, whiteWalker){
+ console.log('--------------------');
+ console.log(`${human.toString()} Vs ${whiteWalker.toString()}`);
+ console.log();
+ console.log('--------------------');
+}
+
+function createNightKing(){
+ const nightKing = new WhiteWalkerDecorator(new SimpleCharacter('Night King'));
+ nightKing.life = 500;
+ nightKing.power = 2;
+ return nightKing;
+}

package.json

@@ -5,7 +5,8 @@
  },
  "scripts": {
  "strategy": "nodemon strategy/main.js",
- "observer": "nodemon observer/main.js"
+ "observer": "nodemon observer/main.js",
+ "decorator": "nodemon decorator/main.js"
  },
  "name": "design_patterns",
  "version": "1.0.0",