MapComplete/Logic/FeatureSource/Sources/GeoJsonSource.ts

/**
 * Fetches a geojson file somewhere and passes it along
 */
import { UIEventSource } from "../../UIEventSource"
import FilteredLayer from "../../../Models/FilteredLayer"
import { Utils } from "../../../Utils"
import { FeatureSourceForLayer, Tiled } from "../FeatureSource"
import { Tiles } from "../../../Models/TileRange"
import { BBox } from "../../BBox"
import { GeoOperations } from "../../GeoOperations"

export default class GeoJsonSource implements FeatureSourceForLayer, Tiled {
    public readonly features: UIEventSource<{ feature: any; freshness: Date }[]>
    public readonly state = new UIEventSource<undefined | { error: string } | "loaded">(undefined)
    public readonly name
    public readonly isOsmCache: boolean
    public readonly layer: FilteredLayer
    public readonly tileIndex
    public readonly bbox
    private readonly seenids: Set<string>
    private readonly idKey?: string

    public constructor(
        flayer: FilteredLayer,
        zxy?: [number, number, number] | BBox,
        options?: {
            featureIdBlacklist?: Set<string>
        }
    ) {
        if (flayer.layerDef.source.geojsonZoomLevel !== undefined && zxy === undefined) {
            throw "Dynamic layers are not supported. Use 'DynamicGeoJsonTileSource instead"
        }

        this.layer = flayer
        this.idKey = flayer.layerDef.source.idKey
        this.seenids = options?.featureIdBlacklist ?? new Set<string>()
        let url = flayer.layerDef.source.geojsonSource.replace("{layer}", flayer.layerDef.id)
        if (zxy !== undefined) {
            let tile_bbox: BBox
            if (zxy instanceof BBox) {
                tile_bbox = zxy
            } else {
                const [z, x, y] = zxy
                tile_bbox = BBox.fromTile(z, x, y)

                this.tileIndex = Tiles.tile_index(z, x, y)
                this.bbox = BBox.fromTile(z, x, y)
                url = url
                    .replace("{z}", "" + z)
                    .replace("{x}", "" + x)
                    .replace("{y}", "" + y)
            }
            let bounds: { minLat: number; maxLat: number; minLon: number; maxLon: number } =
                tile_bbox
            if (this.layer.layerDef.source.mercatorCrs) {
                bounds = tile_bbox.toMercator()
            }

            url = url
                .replace("{y_min}", "" + bounds.minLat)
                .replace("{y_max}", "" + bounds.maxLat)
                .replace("{x_min}", "" + bounds.minLon)
                .replace("{x_max}", "" + bounds.maxLon)
        } else {
            this.tileIndex = Tiles.tile_index(0, 0, 0)
            this.bbox = BBox.global
        }

        this.name = "GeoJsonSource of " + url

        this.isOsmCache = flayer.layerDef.source.isOsmCacheLayer
        this.features = new UIEventSource<{ feature: any; freshness: Date }[]>([])
        this.LoadJSONFrom(url)
    }

    private LoadJSONFrom(url: string) {
        const eventSource = this.features
        const self = this
        Utils.downloadJsonCached(url, 60 * 60)
            .then((json) => {
                self.state.setData("loaded")
                // TODO: move somewhere else, just for testing
                // Check for maproulette data
                if (url.startsWith("https://maproulette.org/api/v2/tasks/box/")) {
                    console.log("MapRoulette data detected")
                    const data = json
                    let maprouletteFeatures: any[] = []
                    data.forEach((element) => {
                        maprouletteFeatures.push({
                            type: "Feature",
                            geometry: {
                                type: "Point",
                                coordinates: [element.point.lng, element.point.lat],
                            },
                            properties: {
                                // Map all properties to the feature
                                ...element,
                            },
                        })
                    })
                    json.features = maprouletteFeatures
                }

                if (json.features === undefined || json.features === null) {
                    return
                }

                if (self.layer.layerDef.source.mercatorCrs) {
                    json = GeoOperations.GeoJsonToWGS84(json)
                }

                const time = new Date()
                const newFeatures: { feature: any; freshness: Date }[] = []
                let i = 0
                let skipped = 0
                for (const feature of json.features) {
                    const props = feature.properties
                    for (const key in props) {
                        if (props[key] === null) {
                            delete props[key]
                        }

                        if (typeof props[key] !== "string") {
                            // Make sure all the values are string, it crashes stuff otherwise
                            props[key] = JSON.stringify(props[key])
                        }
                    }

                    if (self.idKey !== undefined) {
                        props.id = props[self.idKey]
                    }

                    if (props.id === undefined) {
                        props.id = url + "/" + i
                        feature.id = url + "/" + i
                        i++
                    }
                    if (self.seenids.has(props.id)) {
                        skipped++
                        continue
                    }
                    self.seenids.add(props.id)

                    let freshness: Date = time
                    if (feature.properties["_last_edit:timestamp"] !== undefined) {
                        freshness = new Date(props["_last_edit:timestamp"])
                    }

                    newFeatures.push({ feature: feature, freshness: freshness })
                }

                if (newFeatures.length == 0) {
                    return
                }

                eventSource.setData(eventSource.data.concat(newFeatures))
            })
            .catch((msg) => {
                console.debug("Could not load geojson layer", url, "due to", msg)
                self.state.setData({ error: msg })
            })
    }
}