import Code from '@hapi/code';   // assertion library
import Lab from '@hapi/lab';
import Serpentity, { Component, Entity, Node, System } from '../lib/serpentity.js';

const internals = {
  context: {},
  system: class TestSystem extends System {
    added(engine) {

      this.testNodes = engine.getNodes(internals.node);
      this.addedCalled = true;
      this.addedEngine = engine;
    }

    removed(engine) {

      this.testNodes = null;
      this.removedCalled = true;
      this.removedEngine = engine;
    }

    update(dt) {

      this.updateCalled = Date.now();
      this.updateDt = dt;

      for (const node of this.testNodes) {
        node.test.called = true;
        node.entity.called = true;
      }

      while (Date.now() === this.updateCalled) { /* pass some time */ }
    }
  },
  component: class TestComponent extends Component {
    constructor(config) {

      super(config);

      this.called = false;
    }
  },
  node: class TestNode extends Node {},
  delta: 10
};

// adds a component to the node
internals.node.types = {
  test: internals.component
};

const lab = Lab.script({
  schedule: false
});

const { beforeEach, experiment, test } = lab;
const { expect } = Code;

experiment('loading', () => {

  test('Serpentity should be exported', () => {

    expect(typeof Serpentity).to.not.be.undefined();
  });

  test('Serpentity should include the Entity class', () => {

    expect(typeof Entity).to.not.be.undefined();
  });

  test('Serpentity should include the Component class', () => {

    expect(typeof Component).to.not.be.undefined();
  });

  test('Serpentity should include the System class', () => {

    expect(typeof System).to.not.be.undefined();
  });

  test('Serpentity should include the Node class', () => {

    expect(typeof Node).to.not.be.undefined();
  });

  test('Serpentity should include the NodeCollection class', () => {

    expect(typeof NodeCollection).to.not.be.undefined();
  });
});

experiment('Engine Tests', () => {

  beforeEach(() => {

    internals.context.engine = new Serpentity();

    internals.context.regularSystem = new internals.system();
    internals.context.highPrioritySystem = new internals.system();
    internals.context.lowPrioritySystem = new internals.system();

    internals.context.firstEntity = new Entity();
    internals.context.firstEntity.addComponent(new internals.component());
    internals.context.secondEntity = new Entity();
    internals.context.secondEntity.addComponent(new internals.component());
    internals.context.emptyEntity = new Entity();

    // Add entity before the systems
    internals.context.engine.addEntity(internals.context.firstEntity);

    internals.context.engine.addSystem(internals.context.regularSystem, 100);
    internals.context.engine.addSystem(internals.context.highPrioritySystem, 0);
    internals.context.engine.addSystem(internals.context.lowPrioritySystem, 1000);

    // Add entity after the systems
    internals.context.engine.addEntity(internals.context.secondEntity);
    internals.context.engine.addEntity(internals.context.emptyEntity);
  });

  test('Engine should call added callback on added systems', () => {

    // Ensure the added callback is being called
    expect(internals.context.regularSystem.addedCalled).to.be.true();
    expect(internals.context.highPrioritySystem.addedCalled).to.be.true();
    expect(internals.context.lowPrioritySystem.addedCalled).to.be.true();
  });

  test('Engine should send the engine instance in added callback', () => {

    // Ensure the added callback is sending the engine
    expect(internals.context.regularSystem.addedEngine instanceof Serpentity).to.be.true();
    expect(internals.context.highPrioritySystem.addedEngine instanceof Serpentity).to.be.true();
    expect(internals.context.lowPrioritySystem.addedEngine instanceof Serpentity).to.be.true();
  });

  test('Engine should not add duplicate systems', () => {

    const originalSystemsLength = internals.context.engine.systems.length;
    const added = internals.context.engine.addSystem(internals.context.regularSystem, 0);
    const newSystemsLength = internals.context.engine.systems.length;

    // Ensure we don't add the same system twice
    expect(added).to.be.false();
    expect(originalSystemsLength).to.be.equal(newSystemsLength);
  });

  test('Engine should call update callback on added systems', () => {

    internals.context.engine.update(internals.delta);

    // Ensure update function called
    expect(!!internals.context.regularSystem.updateCalled).to.be.true();
    expect(!!internals.context.highPrioritySystem.updateCalled).to.be.true();
    expect(!!internals.context.lowPrioritySystem.updateCalled).to.be.true();
  });

  test('Engine should call update callback in the order of priorities', () => {

    internals.context.engine.update(internals.delta);

    // Ensure order of priorities
    expect(internals.context.regularSystem.updateCalled).to.be.lessThan(internals.context.lowPrioritySystem.updateCalled);
    expect(internals.context.regularSystem.updateCalled).to.be.greaterThan(internals.context.highPrioritySystem.updateCalled);
  });

  test('Engine should send the delta in the update callback', () => {

    internals.context.engine.update(internals.delta);

    // Ensure delta is being sent
    expect(internals.context.regularSystem.updateDt).to.be.equal(internals.delta);
    expect(internals.context.highPrioritySystem.updateDt).to.be.equal(internals.delta);
    expect(internals.context.lowPrioritySystem.updateDt).to.be.equal(internals.delta);
  });

  test('System remove callback', () => {

    const originalSystemLength = internals.context.engine.systems.length;
    const originalRemoved = internals.context.engine.removeSystem(internals.context.lowPrioritySystem);
    const intermediateSystemLength = internals.context.engine.systems.length;
    const finalRemoved = internals.context.engine.removeSystem(internals.context.lowPrioritySystem);
    const finalSystemLength = internals.context.engine.systems.length;
    internals.context.engine.update(internals.delta);

    // Check for return value
    expect(originalRemoved).to.be.true();
    expect(finalRemoved).to.be.false();

    // Confirm that only removed if found by checking length of systems
    // array
    expect(originalSystemLength).to.be.above(intermediateSystemLength);
    expect(finalSystemLength).to.be.equal(intermediateSystemLength);

    // Ensure callback is sent
    expect(!!internals.context.regularSystem.removedCalled).to.be.false();
    expect(!!internals.context.highPrioritySystem.removedCalled).to.be.false();
    expect(!!internals.context.lowPrioritySystem.removedCalled).to.be.true();

    // Ensure update is no longer sent
    expect(!!internals.context.regularSystem.updateCalled).to.be.true();
    expect(!!internals.context.highPrioritySystem.updateCalled).to.be.true();
    expect(!!internals.context.lowPrioritySystem.updateCalled).to.be.false();
  });

  test('Entity node selection', () => {

    internals.context.engine.update(internals.delta);

    // Ensure component is called for each entity
    expect(!!internals.context.firstEntity._components[0].called).to.be.true();
    expect(!!internals.context.secondEntity._components[0].called).to.be.true();

    // Ensure entity not in node collection not called
    expect(!!internals.context.firstEntity.called).to.be.true();
    expect(!!internals.context.secondEntity.called).to.be.true();
    expect(!!internals.context.emptyEntity.called).to.be.false();
  });

  test('Entity node removal', () => {

    internals.context.engine.removeEntity(internals.context.secondEntity);
    internals.context.engine.update(internals.delta);

    expect(!!internals.context.firstEntity._components[0].called).to.be.true();
    expect(!!internals.context.secondEntity._components[0].called).to.be.false();

    expect(!!internals.context.firstEntity.called).to.be.true();
    expect(!!internals.context.secondEntity.called).to.be.false();
    expect(!!internals.context.emptyEntity.called).to.be.false();
  });

  test('Entity should not add duplicate components', () => {

    const originalComponentsLength = internals.context.secondEntity._components.length;
    const result = internals.context.secondEntity.addComponent(new internals.component());
    const newComponentsLength = internals.context.secondEntity._components.length;

    expect(result).to.be.false();
    expect(originalComponentsLength).to.be.equal(newComponentsLength);
  });

  test('Entity should allow access to components by class', () => {

    const firstComponent = internals.context.firstEntity.getComponent(internals.component);
    const emptyComponent = internals.context.emptyEntity.getComponent(internals.component);

    expect(firstComponent instanceof internals.component).to.be.true();
    expect(emptyComponent).to.be.equal(undefined);
  });

  test('Engine should not add duplicate entities', () => {

    const originalEntitiesLength = internals.context.engine.entities.length;
    const added = internals.context.engine.addEntity(internals.context.firstEntity);
    const finalEntitiesLength = internals.context.engine.entities.length;

    expect(added).to.be.false();

    expect(originalEntitiesLength).to.be.equal(finalEntitiesLength);
  });

  test('Engine should remove entities', () => {

    const originalEntityLength = internals.context.engine.entities.length;
    const originalRemoved = internals.context.engine.removeEntity(internals.context.firstEntity);
    const intermediateEntityLength = internals.context.engine.entities.length;
    const finalRemoved = internals.context.engine.removeEntity(internals.context.firstEntity);
    const finalEntityLength = internals.context.engine.entities.length;
    internals.context.engine.update(internals.delta);

    // Check for return value
    expect(originalRemoved).to.be.true();
    expect(finalRemoved).to.be.false();

    // Confirm that only removed if found by checking length of systems
    // array
    expect(originalEntityLength).to.be.above(intermediateEntityLength);
    expect(finalEntityLength).to.be.equal(intermediateEntityLength);

    // Ensure callback is sent
    expect(!!internals.context.firstEntity.called).to.be.false();
    expect(!!internals.context.secondEntity.called).to.be.true();
  });
});

Lab.report(lab).then((result) => process.exit(result.code));