humus-old/server/traits/informed.trait.js

import * as I from 'immutable';
import immutablediff from 'immutablediff';
import isPlainObject from 'is-plain-object';

import {compose} from '@avocado/core';
import {Trait} from '@avocado/entity';
import {Rectangle, Vector} from '@avocado/math';
import {
  Packer,
  StateKeysPacket,
  StatePacket,
  Synchronizer,
} from '@avocado/state';

const decorate = compose(
);

export class Informed extends decorate(Trait) {

  initialize() {
    this._packer = new Packer();
    this._rememberedEntities = {};
    this._socket = undefined;
    this._state = I.Map();
  }

  destroy() {
    if (this._socket) {
      delete this._socket.entity;
      delete this._socket;
    }
  }

  reduceState(state) {
    // Set client's self entity.
    state = state.set('selfEntity', this.entity.instanceUuid);
    // Reduce entity list to visible.
    const room = this.entity.room;
    const camera = this.entity.camera;
    // Blow up camera rectangle to compensate for camera desync.
    const position = Rectangle.position(camera.rectangle);
    const size = Rectangle.size(camera.rectangle);
    const visibleArea = Rectangle.compose(
      Vector.sub(
        position,
        Vector.scale(size, 0.25),
      ),
      Vector.scale(size, 1.5),
    );
    // Write over entity list for every layer.
    for (const {index, layer} of room.layers) {
      const visibleEntities = layer.visibleEntities(visibleArea);
      let reducedEntityList = I.Map();
      for (const entity of visibleEntities) {
        reducedEntityList = reducedEntityList.set(
          entity.instanceUuid,
          entity.state,
        );
      }
      const entityListPath = ['room', 'layers', index, 'entityList'];
      state = state.setIn(entityListPath, reducedEntityList);
    }
    return state;
  }

  get socket() {
    return this._socket;
  }

  set socket(socket) {
    socket.entity = this.entity;
    this._socket = socket;
  }

  methods() {
    return {

      inform: (state) => {
        // Reduce state.
        const reducedState = this.reduceState(state);
        // Take a pure JS diff.
        const steps = immutablediff(this._state, reducedState).toJS();
        // Rewrite entity removals.
        const entityRemovals = steps.filter((step) => {
          return 'remove' === step.op && step.path.match(
            /\/room\/layers\/.*\/entityList\/[a-z0-9-]+/
          );
        });
        for (const entityRemoval of entityRemovals) {
          // Remember the entity.
          const parts = entityRemoval.path.split('/');
          parts.shift();
          const uuid = parts[4];
          this._rememberedEntities[uuid] = state.getIn(parts);
          // Swap out the removal op for replaces to hide the entity.
          const index = steps.indexOf(entityRemoval);
          steps.splice(index, 1);
          const pathOverrides = [
            ['physical', 'state', 'addedToPhysics'],
            ['visible', 'state', 'isVisible'],
            // Ticking change last.
            ['existent', 'state', 'isTicking'],
          ]
          for (const pathOverride of pathOverrides) {
            steps.push({
              op: 'replace',
              path: entityRemoval.path + '/' + pathOverride.join('/'),
              value: false,
            });
          }
        }
        // Rewrite entity adds.
        const entityAdds = steps.filter((step) => {
          return 'add' === step.op && step.path.match(
            /\/room\/layers\/.*\/entityList\/[a-z0-9-]+/
          );
        });
        for (const entityAdd of entityAdds) {
          // Remembered entity?
          const parts = entityAdd.path.split('/');
          parts.shift();
          const uuid = parts[4];
          if (!(uuid in this._rememberedEntities)) {
            continue;
          }
          const rememberedEntity = this._rememberedEntities[uuid];
          // Take a diff from what the client remembers to now.
          const currentState = state.getIn(parts);
          const addSteps = immutablediff(
            rememberedEntity,
            currentState,
          ).toJS();
          // Translate step paths to full state location.
          const fullAddSteps = addSteps.map((addStep) => {
            return {
              op: addStep.op,
              path: entityAdd.path + addStep.path,
              value: addStep.value,
            };
          });
          // Swap out the add op for replaces to show the entity.
          const index = steps.indexOf(entityAdd);
          steps.splice(index, 1);
          steps.push(...fullAddSteps);
          const pathOverrides = [
            ['physical', 'state', 'addedToPhysics'],
            ['visible', 'state', 'isVisible'],
            // Ticking change last.
            ['existent', 'state', 'isTicking'],
          ]
          for (const pathOverride of pathOverrides) {
            steps.push({
              op: 'replace',
              path: entityAdd.path + '/' + pathOverride.join('/'),
              value: rememberedEntity.getIn(pathOverride),
            });
          }
          delete this._rememberedEntities[uuid];
        }
        // Remember state.
        this._state = reducedState;
        if (0 === steps.length) {
          return;
        }
        // Emit!
        const keys = this._packer.computeNewKeys(steps);
        if (0 !== keys[0].length) {
          this._socket.send(new StateKeysPacket(keys));
        }
        const packed = this._packer.pack(steps);
        this._socket.send(new StatePacket(packed));
      },

    };
  }

}