import * as I from 'immutable';

import {compose, EventEmitter} from '@avocado/core';
import {Rectangle, Vector} from '@avocado/math';
import {Synchronized} from '@avocado/state';

import {TileUpdatePacket} from './packets/tile-update.packet';

const decorate = compose(
  EventEmitter,
  Vector.Mixin('size', 'width', 'height', {
    default: [0, 0],
  }),
  Synchronized,
);

export class Tiles extends decorate(class {}) {

  constructor(json) {
    super();
    this.data = [];
    this.updatePackets = [];
    if ('undefined' !== typeof json) {
      this.fromJSON(json);
    }
  }

  acceptPacket(packet) {
    if (packet instanceof TileUpdatePacket) {
      const unpackedPosition = [
        packet.data.position & 0xFFFF,
        packet.data.position >> 16,
      ];
      this.setTileAt(unpackedPosition, packet.data.tile);
    }
  }

  forEachTile(fn) {
    let [x, y] = [0, 0];
    let [width, height] = this.size;
    let i = 0;
    for (let k = 0; k < height; ++k) {
      for (let j = 0; j < width; ++j) {
        fn(this.data[i], x, y, i);
        ++i;
        ++x;
      }
      x = 0;
      ++y;
    }
  }

  fromJSON(json) {
    if (json.size) {
      this.size = json.size;
    }
    if (json.data) {
      this.data = json.data.slice(0);
    }
    return this;
  }

  packetsForUpdate() {
    const packetsForUpdate = this.updatePackets;
    this.updatePackets = [];
    return packetsForUpdate;
  }

  get rectangle() {
    return Rectangle.compose([0, 0], this.size);
  }

  setTileAt(position, tile) {
    const oldTile = this.tileAt(position);
    if (oldTile === tile) {
      return;
    }
    const index = position[1] * this.width + position[0];
    if (index < 0 || index >= this.data.length) {
      return;
    }
    this.data[index] = tile;
    const packedPosition = position[1] << 16 | position[0];
    this.updatePackets.push(new TileUpdatePacket({
      position: packedPosition,
      tile,
    }));
    this.emit('dataChanged');
  }

  slice(rectangle) {
    const tilesRectangle = this.rectangle;
    // Get intersection.
    if (!Rectangle.intersects(rectangle, tilesRectangle)) {
      return [];
    }
    let [x, y, sliceWidth, sliceHeight] = Rectangle.intersection(
      rectangle,
      tilesRectangle,
    );
    // No muls in the loop.
    let sliceRow = y * sliceWidth;
    const dataWidth = this.width;
    let dataRow = y * dataWidth;
    // Copy slice.
    const slice = new Array(sliceWidth * sliceHeight);
    for (let j = 0; j < sliceHeight; ++j) {
      for (let i = 0; i < sliceWidth; ++i) {
        slice[sliceRow + x] = this.data[dataRow + x];
        x++;
      }
      sliceRow += sliceWidth;
      dataRow += dataWidth;
      x -= sliceWidth;
    }
    return slice;
  }

  tileAt(position) {
    return this.data[position[1] * this.width + position[0]];
  }

  toJSON() {
    return {
      size: Vector.copy(this.size),
      data: this.data.slice(0),
    };
  }

}