MapComplete/src/UI/BigComponents/GeolocationControl.ts

import { Store, UIEventSource } from "../../Logic/UIEventSource"
import GeoLocationHandler from "../../Logic/Actors/GeoLocationHandler"
import Constants from "../../Models/Constants"
import { MapProperties } from "../../Models/MapProperties"

/**
 * Does the user interaction state with a geolocation button, such as keeping track of the last click,
 * and lock status + moving the map when clicked
 */
export class GeolocationControlState {
    public readonly lastClick = new UIEventSource<Date>(undefined)
    public readonly lastClickWithinThreeSecs: Store<boolean>
    private readonly _geolocationHandler: GeoLocationHandler
    private readonly _mapProperties: MapProperties

    constructor(
        geolocationHandler: GeoLocationHandler,
        state: MapProperties,
        lastGeolocationRequestByUser: UIEventSource<Date> = undefined
    ) {
        const lastClick = lastGeolocationRequestByUser ?? new UIEventSource<Date>(undefined)
        lastClick.addCallbackD((date) => {
            geolocationHandler.geolocationState.requestMoment.setData(date)
        })
        const lastClickWithinThreeSecs = lastClick.map((lastClick) => {
            if (lastClick === undefined) {
                return false
            }
            const timeDiff = (new Date().getTime() - lastClick.getTime()) / 1000
            return timeDiff <= 3
        })
        const lastRequestWithinTimeout = geolocationHandler.geolocationState.requestMoment.map(
            (date) => {
                if (date === undefined) {
                    return false
                }
                const timeDiff = (new Date().getTime() - date.getTime()) / 1000
                return timeDiff <= Constants.zoomToLocationTimeout
            }
        )

        this._geolocationHandler = geolocationHandler
        this._mapProperties = state

        this.lastClick = lastClick
        this.lastClickWithinThreeSecs = lastClickWithinThreeSecs

        lastClick.addCallbackAndRunD((_) => {
            window.setTimeout(() => {
                if (lastClickWithinThreeSecs.data) {
                    lastClick.ping()
                }
            }, 500)
        })
        geolocationHandler.geolocationState.requestMoment.addCallbackAndRunD((_) => {
            window.setTimeout(() => {
                if (lastRequestWithinTimeout.data) {
                    geolocationHandler.geolocationState.requestMoment.ping()
                }
            }, 500)
        })
    }

    public async handleClick() {
        const geolocationHandler = this._geolocationHandler
        const geolocationState = this._geolocationHandler.geolocationState
        const lastClick = this.lastClick
        const state = this._mapProperties
        if (
            geolocationState.permission.data !== "granted" &&
            geolocationState.currentGPSLocation.data === undefined
        ) {
            lastClick.setData(new Date())
            geolocationState.requestMoment.setData(new Date())
            await geolocationState.requestPermission()
        }

        if (geolocationState.allowMoving.data === false) {
            // Unlock
            geolocationState.allowMoving.setData(true)
            return
        }

        const currentLocation = geolocationState.currentGPSLocation.data
        if (currentLocation === undefined) {
            // No location is known yet, not much we can do
            lastClick.setData(new Date())
            return
        }
        // A location _is_ known! Let's move to this location
        const inBounds = state.bounds.data.contains([
            currentLocation.longitude,
            currentLocation.latitude,
        ])
        geolocationHandler.MoveMapToCurrentLocation()
        if (inBounds) {
            state.zoom.update((z) => z + 3)
        }

        if (this.lastClickWithinThreeSecs.data) {
            geolocationState.allowMoving.setData(false)
            lastClick.setData(undefined)
            return
        }

        lastClick.setData(new Date())
    }
}