MapComplete/Logic/FeatureSource/FilteringFeatureSource.ts

import FeatureSource from "./FeatureSource";
import { UIEventSource } from "../UIEventSource";
import LayerConfig from "../../Customizations/JSON/LayerConfig";
import Loc from "../../Models/Loc";
import Hash from "../Web/Hash";
import { TagsFilter } from "../Tags/TagsFilter";

export default class FilteringFeatureSource implements FeatureSource {
  public features: UIEventSource<{ feature: any; freshness: Date }[]> =
    new UIEventSource<{ feature: any; freshness: Date }[]>([]);
  public readonly name = "FilteringFeatureSource";

  constructor(
    layers: UIEventSource<
      {
        isDisplayed: UIEventSource<boolean>;
        layerDef: LayerConfig;
        appliedFilters: UIEventSource<TagsFilter>;
      }[]
    >,
    location: UIEventSource<Loc>,
    selectedElement: UIEventSource<any>,
    upstream: FeatureSource
  ) {
    const self = this;

    function update() {
      const layerDict = {};
      if (layers.data.length == 0) {
        console.warn("No layers defined!");
        return;
      }
      for (const layer of layers.data) {
        layerDict[layer.layerDef.id] = layer;
      }

      const features: { feature: any; freshness: Date }[] =
        upstream.features.data;

      const missingLayers = new Set<string>();

      const newFeatures = features.filter((f) => {
        const layerId = f.feature._matching_layer_id;

        if (
          selectedElement.data?.id === f.feature.id ||
          f.feature.id === Hash.hash.data
        ) {
          // This is the selected object - it gets a free pass even if zoom is not sufficient
          return true;
        }

        if (layerId !== undefined) {
          const layer: {
            isDisplayed: UIEventSource<boolean>;
            layerDef: LayerConfig;
            appliedFilters: UIEventSource<TagsFilter>;
          } = layerDict[layerId];
          if (layer === undefined) {
            missingLayers.add(layerId);
            return true;
          }

          const isShown = layer.layerDef.isShown;
          const tags = f.feature.properties;
          if (isShown.IsKnown(tags)) {
            const result = layer.layerDef.isShown.GetRenderValue(
              f.feature.properties
            ).txt;
            if (result !== "yes") {
              return false;
            }
          }

          if (FilteringFeatureSource.showLayer(layer, location)) {
            const tagsFilter = layer.appliedFilters.data;
            if (tagsFilter) {
              const properties = f.feature.properties;
              if (!tagsFilter.matchesProperties(properties)) {
                return false;
              }
            }

            return true;
          }
        }
        // Does it match any other layer - e.g. because of a switch?
        for (const toCheck of layers.data) {
          if (!FilteringFeatureSource.showLayer(toCheck, location)) {
            continue;
          }
          if (
            toCheck.layerDef.source.osmTags.matchesProperties(
              f.feature.properties
            )
          ) {
            return true;
          }
        }
        return false;
      });
      console.log(
        "Filtering layer source: input: ",
        upstream.features.data?.length,
        "output:",
        newFeatures.length
      );
      self.features.setData(newFeatures);
      if (missingLayers.size > 0) {
        console.error(
          "Some layers were not found: ",
          Array.from(missingLayers)
        );
      }
    }

    upstream.features.addCallback(() => {
      update();
    });
    location
      .map((l) => {
        // We want something that is stable for the shown layers
        const displayedLayerIndexes = [];
        for (let i = 0; i < layers.data.length; i++) {
          const layer = layers.data[i];
          if (l.zoom < layer.layerDef.minzoom) {
            continue;
          }
          if (l.zoom > layer.layerDef.maxzoom) {
            continue;
          }
          if (!layer.isDisplayed.data) {
            continue;
          }
          displayedLayerIndexes.push(i);
        }
        return displayedLayerIndexes.join(",");
      })
      .addCallback(() => {
        update();
      });

    layers.addCallback(update);

    const registered = new Set<UIEventSource<boolean>>();
    layers.addCallbackAndRun((layers) => {
      for (const layer of layers) {
        if (registered.has(layer.isDisplayed)) {
          continue;
        }
        registered.add(layer.isDisplayed);
        layer.isDisplayed.addCallback(() => update());
        layer.appliedFilters.addCallback(() => update());
      }
    });

    update();
  }

  private static showLayer(
    layer: {
      isDisplayed: UIEventSource<boolean>;
      layerDef: LayerConfig;
    },
    location: UIEventSource<Loc>
  ) {
    return (
      layer.isDisplayed.data &&
      layer.layerDef.minzoom <= location.data.zoom &&
      layer.layerDef.maxzoom >= location.data.zoom
    );
  }
}