// Node.
import {performance} from 'perf_hooks';
// 3rd party.
import immutablediff from 'immutablediff';
// 2nd party.
import {
  create as createEntity,
  EntityList,
  registerTrait,
} from '@avocado/entity';
import {World} from '@avocado/physics/dummy';
import {StateSynchronizer} from '@avocado/state';
// Create game.
export default function(avocadoServer) {
  avocadoServer.on('connect', createConnectionListener(avocadoServer));
  setInterval(createMainLoop(avocadoServer), 1000 / 80);
}
// Entity tracking.
const entityList = new EntityList();
entityList.world = new World();
const informables = [];
const stateSynchronizer = new StateSynchronizer({
  entityList,
});
for (let i = 0; i < 20; ++i) {
  const x = Math.floor(Math.random() * 1000) + 100;
  const y = Math.floor(Math.random() * 500) + 100;
  const flowerBarrel = createFlowerBarrelEntity([x, y]);
  entityList.addEntity(flowerBarrel);
}
// Connection listener.
function createConnectionListener(avocadoServer) {
  return (socket) => {
    // Create and track a new entity for the connection.
    const entity = createEntityForConnection(socket);
    entityList.addEntity(entity);
    // Listen for events.
    socket.on('message', createMessageListener(avocadoServer, socket));
    socket.on('disconnect', createDisconnectionListener(avocadoServer, socket));
  }
}
// Handle incoming messages.
function createMessageListener(avocadoServer, socket) {
  const {entity} = socket;
  return ({type, payload}) => {
    switch (type) {
      case 'input':
        entity.inputState = payload;
        break;
    }
  };
}
// Handle disconnection.
function createDisconnectionListener(avocadoServer, socket) {
  const {entity} = socket;
  return () => {
    entity.destroy();
  };
}
// Create an entity for a new connection.
function createEntityForConnection(socket) {
  let entity = createEntity();
  entity = entity.fromJSON({
    traits: {
      animated: {
        params: {
          animations: {
            idle: {
              offset: [0, -48],
              uri: '/idle.animation.json',
            },
            moving: {
              offset: [0, -48],
              uri: '/moving.animation.json',
            },
          }
        },
      },
      controllable: {},
      directional: {
        params: {
          directionCount: 4,
        },
      },
      existent: {},
      graphical: {},
      informed: {},
      mobile: {
        state: {
          speed: 400,
        },
      },
      physical: {
        params: {
          shape: {
            type: 'rectangle',
            position: [0, 0],
            size: [32, 32],
          }
        }
      },
      positioned: {
        state: {
          x: 100,
          y: 100,
        },
      },
    },
  });
  // Track informables.
  informables.push(entity);
  entity.on('destroyed', () => {
    const index = informables.indexOf(entity);
    if (-1 !== index) {
      informables.splice(index, 1);
    }
  });
  // Embed socket.
  entity.socket = socket;
  return entity;
}
// Create a flower barrel.
function createFlowerBarrelEntity(position) {
  const entity = createEntity();
  return entity.fromJSON({
    traits: {
      pictured: {
        params: {
          images: {
            initial: {
              offset: [0, -32],
              size: [128, 128], // Derive?
              uri: '/flower-barrel.png',
            },
          }
        },
      },
      existent: {},
      graphical: {},
      physical: {
        params: {
          shape: {
            type: 'rectangle',
            position: [0, 0],
            size: [32, 32],
          }
        }
      },
      positioned: {
        state: {
          x: position[0],
          y: position[1],
        },
      },
    },
  });
}
// Main loop.
let lastTime = performance.now();
function createMainLoop(avocadoServer) {
  return () => {
    const now = performance.now();
    const elapsed = (now - lastTime) / 1000;
    lastTime = now;
    entityList.tick(elapsed);
    const diff = stateSynchronizer.diff();
    if (StateSynchronizer.noChange === diff) {
      return;
    }
    // All informed entities get their own slice.
    for (const entity of informables) {
      const CAMERA_LOCATION = [640, 360];
      const reduced = entity.reduceStateDiff(diff, CAMERA_LOCATION);
      entity.inform(reduced);
    }
  }
}