first drop

.eslintignore

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+# /node_modules/* and /bower_components/* ignored by default
+
+# Ignore built files except build/index.js
+coverage/*
+build/*
+builds/*
+bundle.js

.eslintrc

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+{
+  "extends": [
+    "airbnb-base"
+  ],
+  "plugins": [
+    "promise"
+  ],
+  "rules": {
+    "no-param-reassign": 0
+  }
+}

.gitignore

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+# directories
+.idea/*
+.vscode/*
+local
+
+# generated files
+.DS_Store
+.vscode
+Desktop.ini
+Thumbs.db
+
+# specific file types
+*.backup
+*.bak
+*.log
+*.log.*
+*.tmp
+*.backup
+
+# node specific
+node_modules
+coverage
+*/config/local.js
+package-lock.json

README.md

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+# rools

package.json

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+{
+  "name": "rools",
+  "version": "1.0.0-alpha.0",
+  "description": "A small business rules engine for Node",
+  "main": "src/index.js",
+  "author": "Frank Thelen",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/frankthelen/rools"
+  },
+  "keywords": [
+    "rules",
+    "business",
+    "rule",
+    "engine"
+  ],
+  "scripts": {
+    "lint": "eslint . --ignore-path ./.eslintignore",
+    "test": "NODE_ENV=test mocha --recursive test",
+    "cover": "NODE_ENV=test istanbul cover _mocha -- --recursive test",
+    "coveralls": "npm run cover -- --report lcovonly && cat ./coverage/lcov.info | coveralls",
+    "preversion": "npm run lint && npm test"
+  },
+  "engines": {
+    "node": ">=8.9.0"
+  },
+  "devDependencies": {
+    "chai": "^4.1.2",
+    "chai-as-promised": "^7.1.1",
+    "coveralls": "^3.0.0",
+    "eslint": "^4.14.0",
+    "eslint-config-airbnb-base": "^12.1.0",
+    "eslint-plugin-import": "^2.8.0",
+    "eslint-plugin-promise": "^3.6.0",
+    "eslint-plugin-should-promised": "^2.0.0",
+    "istanbul": "^0.4.5",
+    "mocha": "^4.0.1",
+    "mocha-lcov-reporter": "^1.3.0",
+    "sinon": "^4.1.3",
+    "sinon-chai": "^2.14.0"
+  },
+  "dependencies": {
+    "md5": "^2.2.1",
+    "uuid": "^3.1.0"
+  }
+}

src/Rools.js

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+class Rools {
+  constructor() {
+    this.actions = [];
+    this.premises = [];
+  }
+
+  register(...rules) {
+    rules.forEach((rule) => {
+      const action = {
+        name: rule.name,
+        then: rule.then,
+        premises: [],
+        ready: false, // ready to fire
+        fired: false, // not yet fired
+      };
+      this.actions.push(action);
+      const whens = Array.isArray(rule.when) ? rule.when : [rule.when];
+      whens.forEach((when) => {
+        const premise = {
+          when,
+          value: undefined, // not yet evaluated
+        };
+        action.premises.push(premise);
+        this.premises.push(premise);
+      });
+    });
+  }
+
+  execute(facts) {
+    this.actions.forEach((action) => { // init
+      action.ready = false;
+      action.fired = false;
+    });
+    let iteration = 0;
+    do {
+      this.premises.forEach((premise) => {
+        premise.value = premise.when(facts);
+      });
+      this.actions.filter(action => !action.fired).forEach((action) => {
+        const num = action.premises.length;
+        const tru = action.premises.filter(premise => premise.value).length;
+        action.ready = tru === num;
+      });
+      const actionsToBeFired = this.actions.filter(action => !action.fired && action.ready);
+      if (actionsToBeFired.length === 0) {
+        break; // for --> all done
+      }
+      if (actionsToBeFired.length > 1) {
+        console.error('conflict resolution missing!');
+      }
+      actionsToBeFired.forEach((action) => {
+        console.log(`firing ${action.name}`);
+        action.fired = true;
+        action.then(facts);
+      });
+      iteration += 1;
+    } while (iteration < 100);
+    return facts;
+  }
+}
+
+module.exports = Rools;

src/index.js

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+const Rools = require('./Rools');
+
+module.exports = Rools;

test/.eslintrc

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+{
+  "extends": "../.eslintrc",
+  "env": {
+    "mocha": true
+  },
+  "globals" : {
+    "assert": false,
+    "expect": false,
+    "should": false,
+    "sinon": false
+  },
+  "plugins": [
+    "should-promised"
+  ]
+}

test/simple.spec.js

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+const chai = require('chai');
+const chaiAsPromised = require('chai-as-promised');
+const sinon = require('sinon');
+const sinonChai = require('sinon-chai');
+const Rools = require('../src');
+
+chai.use(chaiAsPromised);
+chai.use(sinonChai);
+
+global.chai = chai;
+global.sinon = sinon;
+global.expect = chai.expect;
+global.should = chai.should();
+
+describe('Simple tests', () => {
+  const frank = {
+    name: 'frank',
+    stars: 347,
+  };
+
+  const michael = {
+    name: 'michael',
+    stars: 156,
+  };
+
+  const weatherGood = {
+    temperature: 20,
+    windy: true,
+    rainy: false,
+  };
+
+  const weatherBad = {
+    temperature: 9,
+    windy: true,
+    rainy: true,
+  };
+
+  const ruleMoodGreat = {
+    name: 'mood is great if stars is greater than 200',
+    when: facts => facts.user.stars >= 200,
+    then: (facts) => {
+      facts.user.mood = 'great';
+    },
+  };
+
+  const ruleMoodSad = {
+    name: 'mood is sad if stars is lower or equals 200',
+    when: facts => facts.user.stars < 200,
+    then: (facts) => {
+      facts.user.mood = 'sad';
+    },
+  };
+
+  const ruleGoWalking = {
+    name: 'go for a walk if mood is great and the weather is fine',
+    when: [
+      facts => facts.user.mood === 'great',
+      facts => facts.weather.temperature >= 20,
+      facts => !facts.weather.rainy,
+    ],
+    then: (facts) => {
+      facts.goWalking = true;
+    },
+  };
+
+  const ruleStayAtHome = {
+    name: 'stay at home if mood is sad or the weather is bad',
+    when: [
+      facts => facts.weather.rainy || facts.user.mood === 'sad',
+    ],
+    then: (facts) => {
+      facts.stayAtHome = true;
+    },
+  };
+
+  let rools;
+
+  before(() => {
+    rools = new Rools();
+    rools.register(ruleMoodGreat, ruleMoodSad, ruleGoWalking, ruleStayAtHome);
+  });
+
+  after(() => {
+  });
+
+  it('test 1', () => {
+    const result = rools.execute({ user: frank, weather: weatherGood });
+    console.log(result);
+    expect(result.user.mood).to.be.equal('great');
+    expect(result.goWalking).to.be.equal(true);
+  });
+
+  it('test 2', () => {
+    const result = rools.execute({ user: michael, weather: weatherGood });
+    console.log(result);
+    expect(result.user.mood).to.be.equal('sad');
+    expect(result.stayAtHome).to.be.equal(true);
+  });
+
+  it('test 3', () => {
+    const result = rools.execute({ user: frank, weather: weatherBad });
+    console.log(result);
+    expect(result.user.mood).to.be.equal('great');
+    expect(result.stayAtHome).to.be.equal(true);
+  });
+});