mapcomplete/Logic/Web/Hash.ts

import { UIEventSource } from "../UIEventSource"
import { Utils } from "../../Utils"

/**
 * Wrapper around the hash to create an UIEventSource from it
 */
export default class Hash {
    public static hash: UIEventSource<string> = Hash.Get()

    /**
     * Gets the current string, including the pound sign if there is any
     * @constructor
     */
    public static Current(): string {
        if (Hash.hash.data === undefined || Hash.hash.data === "") {
            return ""
        } else {
            return "#" + Hash.hash.data
        }
    }

    private static Get(): UIEventSource<string> {
        if (Utils.runningFromConsole) {
            return new UIEventSource<string>(undefined)
        }
        const hash = new UIEventSource<string>(window.location.hash.substr(1))
        hash.addCallback((h) => {
            if (h === "undefined") {
                console.warn("Got a literal 'undefined' as hash, ignoring")
                h = undefined
            }

            if (h === undefined || h === "") {
                window.location.hash = ""
                return
            }

            history.pushState({}, "")
            window.location.hash = "#" + h
        })

        window.onhashchange = () => {
            let newValue = window.location.hash.substr(1)
            if (newValue === "") {
                newValue = undefined
            }
            hash.setData(newValue)
        }

        window.addEventListener("popstate", (_) => {
            let newValue = window.location.hash.substr(1)
            if (newValue === "") {
                newValue = undefined
            }
            hash.setData(newValue)
        })

        return hash
    }
}