import {UIEventSource} from "../UIEventSource";
import UserDetails, {OsmConnection} from "./OsmConnection";
import {Utils} from "../../Utils";

export class OsmPreferences {

    public preferences = new UIEventSource<any>({}, "all-osm-preferences");
    private readonly preferenceSources = new Map<string, UIEventSource<string>>()
    private auth: any;
    private userDetails: UIEventSource<UserDetails>;
    private longPreferences = {};

    constructor(auth, osmConnection: OsmConnection) {
        this.auth = auth;
        this.userDetails = osmConnection.userDetails;
        const self = this;
        osmConnection.OnLoggedIn(() => self.UpdatePreferences());
    }

    /**
     * OSM preferences can be at most 255 chars
     * @param key
     * @param prefix
     * @constructor
     */
    public GetLongPreference(key: string, prefix: string = "mapcomplete-"): UIEventSource<string> {

        if (this.longPreferences[prefix + key] !== undefined) {
            return this.longPreferences[prefix + key];
        }


        const source = new UIEventSource<string>(undefined, "long-osm-preference:" + prefix + key);
        this.longPreferences[prefix + key] = source;

        const allStartWith = prefix + key + "-combined";
        // Gives the number of combined preferences
        const length = this.GetPreference(allStartWith + "-length", "");

       if( (allStartWith + "-length").length > 255){
           throw "This preference key is too long, it has "+key.length+" characters, but at most "+(255 - "-length".length - "-combined".length - prefix.length)+" characters are allowed"
       }

        const self = this;
        source.addCallback(str => {
            if (str === undefined || str === "") {
                return;
            }
            if (str === null) {
                console.error("Deleting " + allStartWith);
                let count = parseInt(length.data);
                for (let i = 0; i < count; i++) {
                    // Delete all the preferences
                    self.GetPreference(allStartWith + "-" + i, "")
                        .setData("");
                }
                self.GetPreference(allStartWith + "-length", "")
                    .setData("");
                return
            }

            let i = 0;
            while (str !== "") {
                if (str === undefined || str === "undefined") {
                    throw "Long pref became undefined?"
                }
                if (i > 100) {
                    throw "This long preference is getting very long... "
                }
                self.GetPreference(allStartWith + "-" + i, "").setData(str.substr(0, 255));
                str = str.substr(255);
                i++;
            }
            length.setData("" + i); // We use I, the number of preference fields used
        });


        function updateData(l: number) {
            if(Object.keys(self.preferences.data).length === 0){
                // The preferences are still empty - they are not yet updated, so we delay updating for now 
                return
            }
            const prefsCount = Number(l);
            if (prefsCount > 100) {
                throw "Length to long";
            }
            let str = "";
            for (let i = 0; i < prefsCount; i++) {
                const key = allStartWith + "-" + i
                if(self.preferences.data[key] === undefined){
                    console.warn("Detected a broken combined preference:", key, "is undefined", self.preferences)
                }
                str += self.preferences.data[key] ?? "";
            }

            source.setData(str);
        }

        length.addCallback(l => {
            updateData(Number(l));
        });
        this.preferences.addCallbackAndRun(_ => {
            updateData(Number(length.data));
        })

        return source;
    }

    public GetPreference(key: string, prefix: string = "mapcomplete-"): UIEventSource<string> {
        key = prefix + key;
        key = key.replace(/[:\\\/"' {}.%]/g, '')
        if (key.length >= 255) {
            throw "Preferences: key length to big";
        }
        const cached = this.preferenceSources.get(key)
        if (cached !== undefined) {
            return cached;
        }
        if (this.userDetails.data.loggedIn && this.preferences.data[key] === undefined) {
            this.UpdatePreferences();
        }
                
        const pref = new UIEventSource<string>(this.preferences.data[key], "osm-preference:" + key);
        pref.addCallback((v) => {
            this.UploadPreference(key, v);
        });

        
        this.preferenceSources.set(key, pref)
        return pref;
    }

    public ClearPreferences() {
        let isRunning = false;
        const self = this;
        this.preferences.addCallback(prefs => {
            console.log("Cleaning preferences...")
            if (Object.keys(prefs).length == 0) {
                return;
            }
            if (isRunning) {
                return
            }
            isRunning = true
            const prefixes = ["mapcomplete-"]
            for (const key in prefs) {
                const matches = prefixes.some(prefix => key.startsWith(prefix))
                if (matches) {
                    console.log("Clearing ", key)
                    self.GetPreference(key, "").setData("")

                }
            }
            isRunning = false;
            return;
        })
    }

    private UpdatePreferences() {
        const self = this;
        this.auth.xhr({
            method: 'GET',
            path: '/api/0.6/user/preferences'
        }, function (error, value: XMLDocument) {
            if (error) {
                console.log("Could not load preferences", error);
                return;
            }
            const prefs = value.getElementsByTagName("preference");
            for (let i = 0; i < prefs.length; i++) {
                const pref = prefs[i];
                const k = pref.getAttribute("k");
                const v = pref.getAttribute("v");
                self.preferences.data[k] = v;
            }
            
            // We merge all the preferences: new keys are uploaded
            // For differing values, the server overrides local changes
            self.preferenceSources.forEach((preference, key) => {
                const osmValue = self.preferences.data[key]
                if(osmValue === undefined && preference.data !== undefined){
                    // OSM doesn't know this value yet
                    self.UploadPreference(key, preference.data)
                } else {
                    // OSM does have a value - set it
                    preference.setData(osmValue)
                }
            })
            
            self.preferences.ping();
        });
    }

    private UploadPreference(k: string, v: string) {
        if (!this.userDetails.data.loggedIn) {
            console.debug(`Not saving preference ${k}: user not logged in`);
            return;
        }

        if (this.preferences.data[k] === v) {
            return;
        }
        console.debug("Updating preference", k, " to ", Utils.EllipsesAfter(v, 15));

        if (v === undefined || v === "") {
            this.auth.xhr({
                method: 'DELETE',
                path: '/api/0.6/user/preferences/' + encodeURIComponent(k),
                options: {header: {'Content-Type': 'text/plain'}},
            }, function (error) {
                if (error) {
                    console.warn("Could not remove preference", error);
                    return;
                }
                console.debug("Preference ", k, "removed!");

            });
            return;
        }


        this.auth.xhr({
            method: 'PUT',
            path: '/api/0.6/user/preferences/' + encodeURIComponent(k),
            options: {header: {'Content-Type': 'text/plain'}},
            content: v
        }, function (error) {
            if (error) {
                console.warn(`Could not set preference "${k}"'`, error);
                return;
            }
            console.debug(`Preference ${k} written!`);
        });
    }


}