import {performance} from 'perf_hooks';

import * as I from 'immutable';
import immutablediff from 'immutablediff';

import {compose} from '@avocado/core';
import {EntityCreatePacket, EntityPacket, EntityRemovePacket, Trait} from '@avocado/entity';
import {Rectangle, Vector} from '@avocado/math';
import {BundlePacket} from '@avocado/net';
import {Synchronizer} from '@avocado/state';

const decorate = compose(
);

export class Informed extends decorate(Trait) {

  static type() {
    return 'informed';
  }

  constructor(entity, params, state) {
    super(entity, params, state);
    this.seenEntities = [];
    this._socket = undefined;
  }

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

  get areaToInform() {
    // 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 size = Rectangle.size(camera.rectangle);
    return Rectangle.expand(
      camera.rectangle,
      Vector.scale(size, 0.5),
    );
  }

  filterInvisibleEntityPackets(packets) {
    return packets.filter((packet) => {
      const entity = packet.entity;
      if (!entity) {
        return true;
      }
      // Removes could be on destroyed entities, so pass them.
      if (packet instanceof EntityRemovePacket) {
        return true;
      }
      return entity.is('visible');
    });
  }

  filterKnownEntityCreatePackets(packets) {
    return packets.filter((packet) => {
      if (!packet.entity) {
        return true;
      }
      if (!(packet instanceof EntityCreatePacket)) {
        return true;
      }
      return !this.hasSeenEntity(packet.entity);
    });
  }

  filterOutOfRangeEntityPackets(packets, outOfRangeEntities) {
    return packets.filter((packet) => {
      const entity = packet.entity;
      if (!entity) {
        return true;
      }
      // Send removes even if they're out of range, if client knows about
      // them.
      if (
        packet instanceof EntityRemovePacket
        && this.hasSeenEntity(entity)
      ) {
        return true;
      }
      return -1 === outOfRangeEntities.indexOf(packet.entity);
    });
  }

  hasSeenEntity(entity) {
    return -1 !== this.seenEntities.indexOf(entity);
  }

  injectEntityCreatePackets(packets, visibleEntities) {
    // Get a list of all visible but not yet seen entities.
    const visibleButNotYetSeen = [];
    for (let i = 0; i < visibleEntities.length; i++) {
      const entity = visibleEntities[i];
      if (!this.hasSeenEntity(entity)) {
        visibleButNotYetSeen.push(entity);
      }
    }
    // Get a list of all existing created entities.
    const allExistingCreatedEntities = packets.filter((packet) => {
      return packet instanceof EntityCreatePacket;
    }).map((packet) => {
      return packet.entity;
    })
    // JIT inject creates before any unknown updates.
    for (let i = 0; i < packets.length; i++) {
      const packet = packets[i];
      // Only care about entity packets.
      if (!(packet instanceof EntityPacket)) {
        continue;
      }
      // Only unknown.
      const entity = packet.entity;
      if (this.hasSeenEntity(entity)) {
        continue;
      }
      if (-1 !== allExistingCreatedEntities.indexOf(entity)) {
        continue;
      }
      // Not creates nor removes.
      if (
        packet instanceof EntityCreatePacket
        || packet instanceof EntityRemovePacket
      ) {
        // This does count as seen.
        const index = visibleButNotYetSeen.indexOf(entity);
        if (-1 !== index) {
          visibleButNotYetSeen.splice(index, 1);
        }
        continue;
      }
      // Inject.
      packets.splice(
        i,
        0,
        new EntityCreatePacket(entity.mergeDiff(), entity)
      );
      i += 1;
      // We've seen it.
      const index = visibleButNotYetSeen.indexOf(entity);
      if (-1 !== index) {
        visibleButNotYetSeen.splice(index, 1);
      }
      allExistingCreatedEntities.push(entity);
    }
    // Append creates for any visible-but-not-yet-seen entities.
    for (let i = 0; i < visibleButNotYetSeen.length; i++) {
      const entity = visibleButNotYetSeen[i];
      // Skip any existing creates.
      if (-1 === allExistingCreatedEntities.indexOf(entity)) {
        packets.push(new EntityCreatePacket(entity.mergeDiff(), entity));
      }
    }
    return packets;
  }

  injectEntityRemovePackets(packets, visibleEntities) {
    const alreadyRemovedEntities = packets.filter((packet) => {
      return packet instanceof EntityRemovePacket;
    }).map((packet) => {
      return packet.entity;
    });
    for (let i = 0; i < this.seenEntities.length; i++) {
      const entity = this.seenEntities[i];
      if (-1 === visibleEntities.indexOf(entity)) {
        if (-1 === alreadyRemovedEntities.indexOf(entity)) {
          packets.push(new EntityRemovePacket({}, entity));
        }
      }
    }
    return packets;
  }

  markEntitiesSeen(visibleEntities) {
    for (let i = 0; i < visibleEntities.length; i++) {
      const entity = visibleEntities[i];
      if (-1 === this.seenEntities.indexOf(entity)) {
        this.seenEntities.push(entity);
      }
    }
  }

  markEntitiesUnseen(packets) {
    const removedEntities = packets.filter((packet) => {
      return packet instanceof EntityRemovePacket;
    }).map((packet) => {
      return packet.entity;
    });
    for (let i = 0; i < removedEntities.length; i++) {
      const entity = removedEntities[i];
      const index = this.seenEntities.indexOf(entity)
      if (-1 !== index) {
        this.seenEntities.splice(index, 1);
      }
    }
  }

  reducePacketEntitiesByRange(packets) {
    // Unique packet entities.
    const packetEntitiesMap = new Map();
    for (let i = 0; i < packets.length; i++) {
      const entity = packets[i].entity;
      if (entity && !packetEntitiesMap.has(entity)) {
        packetEntitiesMap.set(entity, true);
      }
    }
    // Locate visible entities.
    const areaToInform = this.areaToInform;
    const visibleEntities = this.entity.room.visibleEntities(areaToInform);
    // Document out of range entities.
    const inRangeEntities = [];
    const outOfRangeEntities = [];
    let it = packetEntitiesMap.keys();
    for (let value = it.next(); !value.done; value = it.next()) {
      const entity = value.value;
      if (-1 === visibleEntities.indexOf(entity)) {
        if (-1 === outOfRangeEntities.indexOf(entity)) {
          outOfRangeEntities.push(entity);
        }
      }
      else {
        if (-1 === inRangeEntities.indexOf(entity)) {
          inRangeEntities.push(entity);
        }
      }
    }
    return [inRangeEntities, outOfRangeEntities, visibleEntities];
  }

  get socket() {
    return this._socket;
  }

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

  methods() {
    return {

      inform: (packets) => {
        if (0 === packets.length) {
          return;
        }

        // TODO: filter packets that are only delivered to self entity.

        // Filter invisible entities.
        packets = this.filterInvisibleEntityPackets(packets);
        // Reduce entities by range.
        const [
          inRangeEntities,
          outOfRangeEntities,
          visibleEntities,
        ] = this.reducePacketEntitiesByRange(packets);

        // TODO? Upgrade seen entity packets that are out of range to entity
        // remembers.

        // Filter the out of range entity updates.
        packets = this.filterOutOfRangeEntityPackets(
          packets,
          outOfRangeEntities
        );
        // Filter known creates.
        packets = this.filterKnownEntityCreatePackets(packets);
        // Inject create packets.
        packets = this.injectEntityCreatePackets(packets, visibleEntities);
        // Inject removes for any previously seen entity that isn't visible
        // anymore.
        packets = this.injectEntityRemovePackets(packets, visibleEntities);
        // "See" entities.
        this.markEntitiesSeen(visibleEntities);
        // Unsee any removed entities.
        this.markEntitiesUnseen(packets);
        // Ship it!
        if (this._socket) {
          this._socket.send(new BundlePacket(packets));
        }
      },

      seesEntity: (entity) => {
        return Rectangle.isTouching(
          this.entity.areaToInform,
          entity.visibleAabb
        );
      }

    };
  }

}