import {expect, test} from 'vitest';

import Ecs from './ecs.js';
import System from './system.js';

const Empty = {};

const Name = {
  name: 'string',
};

const Position = {
  x: {type: 'int32', defaultValue: 32},
  y: 'int32',
  z: 'int32',
};

test('adds and remove systems at runtime', () => {
  const ecs = new Ecs();
  let oneCount = 0;
  let twoCount = 0;
  const oneSystem = () => {
    oneCount++;
  };
  ecs.addSystem(oneSystem);
  ecs.tick();
  expect(oneCount)
    .to.equal(1);
  const twoSystem = () => {
    twoCount++;
  };
  ecs.addSystem(twoSystem);
  ecs.tick();
  expect(oneCount)
    .to.equal(2);
  expect(twoCount)
    .to.equal(1);
  ecs.removeSystem(oneSystem);
  ecs.tick();
  expect(oneCount)
    .to.equal(2);
  expect(twoCount)
    .to.equal(2);
});

test('creates entities with components', () => {
  class CreateEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new CreateEcs();
  const entity = ecs.create({Empty: {}, Position: {y: 128}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {y: 128}}));
});

test("removes entities' components", () => {
  class RemoveEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new RemoveEcs();
  const entity = ecs.create({Empty: {}, Position: {y: 128}});
  ecs.remove(entity, ['Position']);
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}}));
});

test('gets entities', () => {
  class GetEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new GetEcs();
  const entity = ecs.create({Empty: {}, Position: {y: 128}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {y: 128}}));
});

test('destroys entities', () => {
  class DestroyEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new DestroyEcs();
  const entity = ecs.create({Empty: {}, Position: {y: 128}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {y: 128}}));
  expect(ecs.get(entity))
    .to.not.be.undefined;
  ecs.destroyAll();
  expect(ecs.get(entity))
    .to.be.undefined;
  expect(() => {
    ecs.destroy(entity);
  })
    .to.throw();
});

test('inserts components into entities', () => {
  class InsertEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new InsertEcs();
  const entity = ecs.create({Empty: {}});
  ecs.insert(entity, {Position: {y: 128}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {y: 128}}));
  ecs.insert(entity, {Position: {y: 64}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {y: 64}}));
});

test('ticks systems', () => {
  const Momentum = {
    x: 'int32',
    y: 'int32',
    z: 'int32',
  };
  class TickEcs extends Ecs {
    static Types = {Momentum, Position};
  }
  const ecs = new TickEcs();
  class Physics extends System {

    static queries() {
      return {
        default: ['Position', 'Momentum'],
      };
    }

    tick(elapsed) {
      for (const [position, momentum] of this.select('default')) {
        position.x += momentum.x * elapsed;
        position.y += momentum.y * elapsed;
        position.z += momentum.z * elapsed;
      }
    }

  }
  ecs.addSystem(Physics);
  const entity = ecs.create({Momentum: {}, Position: {y: 128}});
  const position = JSON.stringify(ecs.get(entity).Position);
  ecs.tick(1);
  expect(JSON.stringify(ecs.get(entity).Position))
    .to.deep.equal(position);
  ecs.get(1).Momentum.y = 30;
  ecs.tick(1);
  expect(JSON.stringify(ecs.get(entity).Position))
    .to.deep.equal(JSON.stringify({y: 128 + 30}));
});

test('creates many entities when ticking systems', () => {
  const ecs = new Ecs();
  class Spawn extends System {
    tick() {
      this.createManyEntities(Array.from({length: 5}).map(() => []));
    }
  }
  ecs.addSystem(Spawn);
  ecs.create();
  expect(ecs.get(5))
    .to.be.undefined;
  ecs.tick(1);
  expect(ecs.get(5))
    .to.not.be.undefined;
});

test('creates entities when ticking systems', () => {
  const ecs = new Ecs();
  class Spawn extends System {
    tick() {
      this.createEntity();
    }
  }
  ecs.addSystem(Spawn);
  ecs.create();
  expect(ecs.get(2))
    .to.be.undefined;
  ecs.tick(1);
  expect(ecs.get(2))
    .to.not.be.undefined;
});

test('schedules entities to be deleted when ticking systems', () => {
  const ecs = new Ecs();
  let entity;
  class Despawn extends System {

    finalize() {
      entity = ecs.get(1);
    }

    tick() {
      this.destroyEntity(1);
    }

  }
  ecs.addSystem(Despawn);
  ecs.create();
  ecs.tick(1);
  expect(entity)
    .to.not.be.undefined;
  expect(ecs.get(1))
    .to.be.undefined;
});

test('adds components to and remove components from entities when ticking systems', () => {
  class TickingEcs extends Ecs {
    static Types = {Foo: {bar: 'uint8'}};
  }
  const ecs = new TickingEcs();
  let addLength, removeLength;
  class AddComponent extends System {
    static queries() {
      return {
        default: ['Foo'],
      };
    }
    tick() {
      this.insertComponents(1, {Foo: {}});
    }
    finalize() {
      addLength = Array.from(this.select('default')).length;
    }
  }
  class RemoveComponent extends System {
    static queries() {
      return {
        default: ['Foo'],
      };
    }
    tick() {
      this.removeComponents(1, ['Foo']);
    }
    finalize() {
      removeLength = Array.from(this.select('default')).length;
    }
  }
  ecs.addSystem(AddComponent);
  ecs.create();
  ecs.tick(1);
  expect(addLength)
    .to.equal(1);
  expect(ecs.get(1).Foo)
    .to.not.be.undefined;
  ecs.removeSystem(AddComponent);
  ecs.addSystem(RemoveComponent);
  ecs.tick(1);
  expect(removeLength)
    .to.equal(0);
  expect(ecs.get(1).Foo)
    .to.be.undefined;
});

test('generates coalesced diffs for entity creation', () => {
  const ecs = new Ecs();
  let entity;
  entity = ecs.create();
  expect(ecs.diff)
    .to.deep.equal({[entity]: {}});
});

test('generates diffs for adding and removing components', () => {
  class DiffedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new DiffedEcs();
  let entity;
  entity = ecs.create();
  ecs.setClean();
  ecs.insert(entity, {Position: {x: 64}});
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Position: {x: 64}}});
  ecs.setClean();
  expect(ecs.diff)
    .to.deep.equal({});
  ecs.remove(entity, ['Position']);
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Position: false}});
});

test('generates diffs for empty components', () => {
  class DiffedEcs extends Ecs {
    static Types = {Empty};
  }
  const ecs = new DiffedEcs();
  let entity;
  entity = ecs.create({Empty});
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Empty: {}}});
  ecs.setClean();
  ecs.remove(entity, ['Empty']);
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Empty: false}});
});

test('generates diffs for entity mutations', () => {
  class DiffedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new DiffedEcs();
  let entity;
  entity = ecs.create({Position: {}});
  ecs.setClean();
  ecs.get(entity).Position.x = 128;
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Position: {x: 128}}});
  ecs.setClean();
  expect(ecs.diff)
    .to.deep.equal({});
});

test('generates coalesced diffs for components', () => {
  class DiffedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new DiffedEcs();
  let entity;
  entity = ecs.create({Position});
  ecs.remove(entity, ['Position']);
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Position: false}});
  ecs.insert(entity, {Position: {}});
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Position: {}}});
});

test('generates coalesced diffs for mutations', () => {
  class DiffedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new DiffedEcs();
  let entity;
  entity = ecs.create({Position});
  ecs.setClean();
  ecs.get(entity).Position.x = 128;
  ecs.get(entity).Position.x = 256;
  ecs.get(entity).Position.x = 512;
  expect(ecs.diff)
    .to.deep.equal({[entity]: {Position: {x: 512}}});
});

test('generates diffs for deletions', () => {
  const ecs = new Ecs();
  let entity;
  entity = ecs.create();
  ecs.setClean();
  ecs.destroy(entity);
  expect(ecs.diff)
    .to.deep.equal({[entity]: false});
});

test('applies creation patches', () => {
  class PatchedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new PatchedEcs();
  ecs.apply({16: {Position: {x: 64}}});
  expect(Array.from(ecs.entities).length)
    .to.equal(1);
  expect(ecs.get(16).Position.x)
    .to.equal(64);
});

test('applies update patches', () => {
  class PatchedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new PatchedEcs();
  ecs.createSpecific(16, {Position: {x: 64}});
  ecs.apply({16: {Position: {x: 128}}});
  expect(Array.from(ecs.entities).length)
    .to.equal(1);
  expect(ecs.get(16).Position.x)
    .to.equal(128);
});

test('applies entity deletion patches', () => {
  class PatchedEcs extends Ecs {
    static Types = {Position};
  }
  const ecs = new PatchedEcs();
  ecs.createSpecific(16, {Position: {x: 64}});
  ecs.apply({16: false});
  expect(Array.from(ecs.entities).length)
    .to.equal(0);
});

test('applies component deletion patches', () => {
  class PatchedEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new PatchedEcs();
  ecs.createSpecific(16, {Empty: {}, Position: {x: 64}});
  expect(ecs.get(16).constructor.types)
    .to.deep.equal(['Empty', 'Position']);
  ecs.apply({16: {Empty: false}});
  expect(ecs.get(16).constructor.types)
    .to.deep.equal(['Position']);
});

test('calculates entity size', () => {
  class SizingEcs extends Ecs {
    static Types = {Empty, Position};
  }
  const ecs = new SizingEcs();
  ecs.createSpecific(1, {Empty: {}, Position: {}});
  // ID + # of components + Empty + Position + x + y + z
  // 4  + 2               + 2     + 2        + 4 + 4 + 4 = 22
  expect(ecs.get(1).size())
    .to.equal(22);
});

test('serializes and deserializes', () => {
  class SerializingEcs extends Ecs {
    static Types = {Empty, Name, Position};
  }
  const ecs = new SerializingEcs();
  // ID + # of components + Empty + Position + x + y + z
  // 4  + 2               + 2     + 2        + 4 + 4 + 4 = 22
  ecs.createSpecific(1, {Empty: {}, Position: {x: 64}});
  // ID + # of components + Name + 'foobar' + Position + x + y + z
  // 4  + 2               + 2    + 4 + 6    + 2        + 4 + 4 + 4 = 32
  ecs.createSpecific(16, {Name: {name: 'foobar'}, Position: {x: 128}});
  const view = SerializingEcs.serialize(ecs);
  // # of entities + Entity(1) + Entity(16)
  // 4             + 22        + 32         = 58
  expect(view.byteLength)
    .to.equal(58);
  // Entity values.
  expect(view.getUint32(4 + 22 - 12, true))
    .to.equal(64);
  expect(view.getUint32(4 + 22 + 32 - 12, true))
    .to.equal(128);
  const deserialized = SerializingEcs.deserialize(view);
  // # of entities.
  expect(Array.from(deserialized.entities).length)
    .to.equal(2);
  // Composition of entities.
  expect(deserialized.get(1).constructor.types)
    .to.deep.equal(['Empty', 'Position']);
  expect(deserialized.get(16).constructor.types)
    .to.deep.equal(['Name', 'Position']);
  // Entity values.
  expect(JSON.stringify(deserialized.get(1)))
    .to.equal(JSON.stringify({Empty: {}, Position: {x: 64}}))
  expect(JSON.stringify(deserialized.get(1).Position))
    .to.equal(JSON.stringify({x: 64}));
  expect(JSON.stringify(deserialized.get(16).Position))
    .to.equal(JSON.stringify({x: 128}));
  expect(deserialized.get(16).Name.name)
    .to.equal('foobar');
});

test('deserializes empty', () => {
  class SerializingEcs extends Ecs {
    static Types = {Empty, Name, Position};
  }
  const ecs = SerializingEcs.deserialize(new DataView(new Uint32Array([0]).buffer));
  expect(ecs)
    .to.not.be.undefined;
});