import Component from '@/ecs/component.js';
import {CHUNK_SIZE} from '@/util/constants.js';
import {floodwalk2D, ortho, removeCollinear} from '@/util/math.js';

import vector2d from './helpers/vector-2d';

class LayerProxy {
  $$chunks = [];
  $$sourceJson = {};
  constructor(instance, Component, index) {
    this.instance = instance;
    this.Component = Component;
    this.index = index;
    this.$$chunks = Array(
      Math.ceil(this.area.x / CHUNK_SIZE) * Math.ceil(this.area.y / CHUNK_SIZE)
    ).fill(0).map(() => ({}));
  }
  get area() {
    return this.layer.area;
  }
  clone() {
    const {$$chunks, $$sourceJson} = this.instance.$$layersProxies[this.index];
    const proxy = new LayerProxy(this.instance, this.Component, this.index);
    proxy.$$chunks = [...$$chunks];
    proxy.$$sourceJson = $$sourceJson;
    return proxy;
  }
  compute(index) {
    const cx = Math.floor((index % this.area.x) / CHUNK_SIZE);
    const cy = Math.floor(Math.floor(index / this.area.x) / CHUNK_SIZE);
    const ax = Math.ceil(this.area.x / CHUNK_SIZE);
    return cy * ax + cx;
  }
  get data() {
    return this.layer.data;
  }
  get hulls() {
    const {data, area, tileSize} = this;
    const hulls = [];
    const seen = {};
    const n = data.length;
    const {x: w, y: h} = area;
    let x = 0;
    let y = 0;
    for (let i = 0; i < n; ++i) {
      if (data[i]) {
        if (!seen[i]) {
          const indices = floodwalk2D(new Set([data[i]]), data, {x, y, w, h});
          if (indices.size > 0) {
            const pointHash = Object.create(null);
            const points = [];
            const seePoint = ({x, y}) => {
              if (pointHash[y]?.[x]) {
                return false;
              }
              if (!pointHash[y]) {
                pointHash[y] = Object.create({});
              }
              return pointHash[y][x] = true;
            };
            for (const index of indices) {
              seen[index] = true;
              const op = {
                x: tileSize.x * (index % area.x),
                y: tileSize.y * (Math.floor(index / area.x)),
              };
              let p;
              const tsq = {x: tileSize.x / 4, y: tileSize.y / 4};
              p = {x: op.x + tsq.x, y: op.y + tsq.y};
              if (seePoint(p)) {
                points.push(p);
              }
              p = {x: op.x + tileSize.x - tsq.x, y: op.y + tsq.y};
              if (seePoint(p)) {
                points.push(p);
              }
              p = {x: op.x + tileSize.x - tsq.x, y: op.y + tileSize.y - tsq.y};
              if (seePoint(p)) {
                points.push(p);
              }
              p = {x: op.x + tsq.x, y: op.y + tileSize.y - tsq.y};
              if (seePoint(p)) {
                points.push(p);
              }
            }
            hulls.push(removeCollinear(ortho(points, {x: tileSize.x / 2, y: tileSize.y / 2})));
          }
        }
      }
      x += 1;
      if (x === w) {
        x -= w;
        y += 1;
      }
    }
    return hulls;
  }
  get layer() {
    return this.instance.layers[this.index];
  }
  async load() {
    this.$$sourceJson = this.layer.source
      ? await this.Component.ecs.readJson(this.layer.source)
      : {};
  }
  get source() {
    return this.layer.source;
  }
  get sourceJson() {
    return this.$$sourceJson;
  }
  stamp(at, data) {
    const changes = {};
    for (const row in data) {
      const columns = data[row];
      for (const column in columns) {
        const tile = columns[column];
        const x = at.x + parseInt(column);
        const y = at.y + parseInt(row);
        if (x < 0 || y < 0 || x >= this.layer.area.x || y >= this.layer.area.y) {
          continue;
        }
        const calculated = y * this.layer.area.x + x;
        this.layer.data[calculated] = tile;
        changes[calculated] = tile;
      }
    }
    this.Component.markChange(this.instance.entity, 'layerChange', {[this.index]: changes});
  }
  tile({x, y}) {
    if (x < 0 || y < 0 || x >= this.layer.area.x || y >= this.layer.area.y) {
      return undefined;
    }
    return this.layer.data[y * this.layer.area.x + x];
  }
  get tileSize() {
    return this.layer.tileSize;
  }
}

export default class TileLayers extends Component {
  async createMany(entities) {
    for (const [, {layerChange, layers}] of entities) {
      if (layers) {
        for (const layer of layers) {
          const area = layer.area.x * layer.area.y;
          if (layer.data.length < area) {
            for (let i = 0; i < area; ++i) {
              if (!layer.data[i]) {
                layer.data[i] = 0;
              }
            }
          }
        }
      }
      if (layerChange) {
        for (const layerIndex in layerChange) {
          for (const calculated in layerChange[layerIndex]) {
            const tile = layerChange[layerIndex][calculated];
            layers[layerIndex].data[calculated] = tile;
          }
        }
      }
    }
    return super.createMany(entities);
  }
  async insertMany(entities) {
    for (const [, {layers}] of entities) {
      if (layers) {
        for (const layer of layers) {
          const area = layer.area.x * layer.area.y;
          if (layer.data.length < area) {
            for (let i = 0; i < area; ++i) {
              if (!layer.data[i]) {
                layer.data[i] = 0;
              }
            }
          }
        }
      }
    }
    await super.insertMany(entities);
    for (const [id, {layerChange}] of entities) {
      if (layerChange) {
        const component = this.get(id);
        const {layers} = component;
        for (const layerIndex in layerChange) {
          const proxy = component.$$layersProxies[layerIndex].clone();
          const chunksChanged = new Set();
          for (const tileIndex in layerChange[layerIndex]) {
            chunksChanged.add(proxy.compute(tileIndex));
            const tile = layerChange[layerIndex][tileIndex];
            layers[layerIndex].data[tileIndex] = tile;
          }
          for (const chunkChanged of chunksChanged) {
            proxy.$$chunks[chunkChanged] = {};
          }
          component.$$layersProxies[layerIndex] = proxy;
        }
      }
    }
  }
  instanceFromSchema() {
    return class TileLayersInstance extends super.instanceFromSchema() {
      $$layersProxies = {};
      layer(index) {
        return this.$$layersProxies[index];
      }
    }
  }
  async load(instance) {
    for (const index in instance.layers) {
      instance.$$layersProxies[index] = new LayerProxy(instance, this, index);
      await instance.$$layersProxies[index].load();
    }
  }
  mergeDiff(original, update) {
    if (!update.layerChange) {
      return super.mergeDiff(original, update);
    }
    const layerChange = {
      ...original.layerChange,
    };
    for (const index in update.layerChange) {
      layerChange[index] = {
        ...layerChange[index],
        ...update.layerChange[index],
      };
    }
    return {layerChange};
  }
  static properties = {
    layers: {
      type: 'array',
      subtype: {
        type: 'object',
        properties: {
          area: vector2d('float32'),
          data: {
            type: 'array',
            subtype: {
              type: 'uint16',
            },
          },
          source: {type: 'string'},
          tileSize: vector2d('float32'),
        },
      },
    },
  };
}