MapComplete/Logic/ContributorCount.ts

/// Given a feature source, calculates a list of OSM-contributors who mapped the latest versions
import { Store, UIEventSource } from "./UIEventSource"
import FeaturePipeline from "./FeatureSource/FeaturePipeline"
import Loc from "../Models/Loc"
import { BBox } from "./BBox"

export default class ContributorCount {
    public readonly Contributors: UIEventSource<Map<string, number>> = new UIEventSource<
        Map<string, number>
    >(new Map<string, number>())
    private readonly state: {
        featurePipeline: FeaturePipeline
        currentBounds: Store<BBox>
        locationControl: Store<Loc>
    }
    private lastUpdate: Date = undefined

    constructor(state: {
        featurePipeline: FeaturePipeline
        currentBounds: Store<BBox>
        locationControl: Store<Loc>
    }) {
        this.state = state
        const self = this
        state.currentBounds.map((bbox) => {
            self.update(bbox)
        })
        state.featurePipeline.runningQuery.addCallbackAndRun((_) =>
            self.update(state.currentBounds.data)
        )
    }

    private update(bbox: BBox) {
        if (bbox === undefined) {
            return
        }
        const now = new Date()
        if (
            this.lastUpdate !== undefined &&
            now.getTime() - this.lastUpdate.getTime() < 1000 * 60
        ) {
            return
        }
        this.lastUpdate = now
        const featuresList = this.state.featurePipeline.GetAllFeaturesWithin(bbox)
        const hist = new Map<string, number>()
        for (const list of featuresList) {
            for (const feature of list) {
                const contributor = feature.properties["_last_edit:contributor"]
                const count = hist.get(contributor) ?? 0
                hist.set(contributor, count + 1)
            }
        }
        this.Contributors.setData(hist)
    }
}