MapComplete/Logic/Actors/BackgroundLayerResetter.ts

import { UIEventSource } from "../UIEventSource"
import BaseLayer from "../../Models/BaseLayer"
import AvailableBaseLayers from "./AvailableBaseLayers"
import Loc from "../../Models/Loc"
import { Utils } from "../../Utils"

/**
 * Sets the current background layer to a layer that is actually available
 */
export default class BackgroundLayerResetter {
    constructor(
        currentBackgroundLayer: UIEventSource<BaseLayer>,
        location: UIEventSource<Loc>,
        availableLayers: UIEventSource<BaseLayer[]>,
        defaultLayerId: string = undefined
    ) {
        if (Utils.runningFromConsole) {
            return
        }

        defaultLayerId = defaultLayerId ?? AvailableBaseLayers.osmCarto.id

        // Change the baselayer back to OSM if we go out of the current range of the layer
        availableLayers.addCallbackAndRun((availableLayers) => {
            let defaultLayer = undefined
            const currentLayer = currentBackgroundLayer.data.id
            for (const availableLayer of availableLayers) {
                if (availableLayer.id === currentLayer) {
                    if (availableLayer.max_zoom < location.data.zoom) {
                        break
                    }

                    if (availableLayer.min_zoom > location.data.zoom) {
                        break
                    }
                    if (availableLayer.id === defaultLayerId) {
                        defaultLayer = availableLayer
                    }
                    return // All good - the current layer still works!
                }
            }
            // Oops, we panned out of range for this layer!
            console.log(
                "AvailableBaseLayers-actor: detected that the current bounds aren't sufficient anymore - reverting to OSM standard"
            )
            currentBackgroundLayer.setData(defaultLayer ?? AvailableBaseLayers.osmCarto)
        })
    }
}