import react from 'react';
import TiledLayer from './TiledLayer';

interface Point {
  x: number;
  y: number;
}

interface TiledLayerConductorProperties {
  height: number;
  width: number;
  shift: Point;
  zoom: number;
  tileSize: number;
  numberOfZoomLevels?: number;
  baseZoomLevel: number;
  setBaseZoomLevel: (baseZoomLevel: number) => void;
}

const TiledLayerConductor: react.FC<TiledLayerConductorProperties> = (
  props: TiledLayerConductorProperties
) => {
  const nbTiles =
    Math.ceil((Math.max(props.width, props.height) * 2) / 256) + 2;

  const numberOfZoomLevels =
    props.numberOfZoomLevels === undefined
      ? 1
      : props.numberOfZoomLevels % 2 === 0
      ? props.numberOfZoomLevels + 1
      : props.numberOfZoomLevels;

  const layers = [];
  const zoomLevel = Math.min(
    Math.max(Math.round(Math.log2(props.zoom)), 0),
    numberOfZoomLevels - 1
  );

  const getTiledLayer = (i: number, isActive: boolean) => {
    return (
      <TiledLayer
        key={`layer${i + props.baseZoomLevel}`}
        height={props.height * 2 ** i}
        width={props.width * 2 ** i}
        shift={{ x: props.shift.x * 2 ** i, y: props.shift.y * 2 ** i }}
        zoom={props.zoom}
        layerZoom={2 ** -i}
        tileSize={256}
        nbTiles={nbTiles * 2 ** i}
        active={isActive}
      />
    );
  };

  // First (ie last) dispay layers with less details (ascending order)
  for (let i = 0; i < zoomLevel; i++) {
    layers.push(getTiledLayer(i, false));
  }
  // then dispay layers with more details (descending order)
  for (let i = numberOfZoomLevels - 1; i > zoomLevel; i--) {
    layers.push(getTiledLayer(i, false));
  }
  // And then, of course, the active one
  layers.push(getTiledLayer(zoomLevel, true));

  return <>{layers}</>;
};

export default TiledLayerConductor;