workadventure/front/src/Phaser/Game/SharedVariablesManager.ts

import type { RoomConnection } from "../../Connexion/RoomConnection";
import { iframeListener } from "../../Api/IframeListener";
import type { GameMap } from "./GameMap";
import type {ITiledMapLayer, ITiledMapObject, ITiledMapObjectLayer} from "../Map/ITiledMap";

interface Variable {
    defaultValue: unknown;
    readableBy?: string;
    writableBy?: string;
}

/**
 * Stores variables and provides a bridge between scripts and the pusher server.
 */
export class SharedVariablesManager {
    private _variables = new Map<string, unknown>();
    private variableObjects: Map<string, Variable>;

    constructor(
        private roomConnection: RoomConnection,
        private gameMap: GameMap,
        serverVariables: Map<string, unknown>
    ) {
        // We initialize the list of variable object at room start. The objects cannot be edited later
        // (otherwise, this would cause a security issue if the scripting API can edit this list of objects)
        this.variableObjects = SharedVariablesManager.findVariablesInMap(gameMap);

        // Let's initialize default values
        for (const [name, variableObject] of this.variableObjects.entries()) {
            if (variableObject.readableBy && !this.roomConnection.hasTag(variableObject.readableBy)) {
                // Do not initialize default value for variables that are not readable
                continue;
            }

            this._variables.set(name, variableObject.defaultValue);
        }

        // Override default values with the variables from the server:
        for (const [name, value] of serverVariables) {
            this._variables.set(name, value);
        }

        roomConnection.onSetVariable((name, value) => {
            this._variables.set(name, value);

            // On server change, let's notify the iframes
            iframeListener.setVariable({
                key: name,
                value: value,
            });
        });

        // When a variable is modified from an iFrame
        iframeListener.registerAnswerer("setVariable", (event, source) => {
            const key = event.key;

            const object = this.variableObjects.get(key);

            if (object === undefined) {
                const errMsg =
                    'A script is trying to modify variable "' +
                    key +
                    '" but this variable is not defined in the map.' +
                    'There should be an object in the map whose name is "' +
                    key +
                    '" and whose type is "variable"';
                console.error(errMsg);
                throw new Error(errMsg);
            }

            if (object.writableBy && !this.roomConnection.hasTag(object.writableBy)) {
                const errMsg =
                    'A script is trying to modify variable "' +
                    key +
                    '" but this variable is only writable for users with tag "' +
                    object.writableBy +
                    '".';
                console.error(errMsg);
                throw new Error(errMsg);
            }

            // Let's stop any propagation of the value we set is the same as the existing value.
            if (JSON.stringify(event.value) === JSON.stringify(this._variables.get(key))) {
                return;
            }

            this._variables.set(key, event.value);

            // Dispatch to the room connection.
            this.roomConnection.emitSetVariableEvent(key, event.value);

            // Dispatch to other iframes
            iframeListener.dispatchVariableToOtherIframes(key, event.value, source);
        });
    }

    private static findVariablesInMap(gameMap: GameMap): Map<string, Variable> {
        const objects = new Map<string, Variable>();
        for (const layer of gameMap.getMap().layers) {
            this.recursiveFindVariablesInLayer(layer, objects);
        }
        return objects;
    }

    private static recursiveFindVariablesInLayer(layer: ITiledMapLayer, objects: Map<string, Variable>): void {
        if (layer.type === "objectgroup") {
            for (const object of layer.objects) {
                if (object.type === "variable") {
                    if (object.template) {
                        console.warn(
                            'Warning, a variable object is using a Tiled "template". WorkAdventure does not support objects generated from Tiled templates.'
                        );
                        continue;
                    }

                    // We store a copy of the object (to make it immutable)
                    objects.set(object.name, this.iTiledObjectToVariable(object));
                }
            }
        } else if (layer.type === "group") {
            for (const innerLayer of layer.layers) {
                this.recursiveFindVariablesInLayer(innerLayer, objects);
            }
        }
    }

    private static iTiledObjectToVariable(object: ITiledMapObject): Variable {
        const variable: Variable = {
            defaultValue: undefined,
        };

        if (object.properties) {
            for (const property of object.properties) {
                const value = property.value;
                switch (property.name) {
                    case "default":
                        variable.defaultValue = value;
                        break;
                    case "writableBy":
                        if (typeof value !== "string") {
                            throw new Error(
                                'The writableBy property of variable "' + object.name + '" must be a string'
                            );
                        }
                        if (value) {
                            variable.writableBy = value;
                        }
                        break;
                    case "readableBy":
                        if (typeof value !== "string") {
                            throw new Error(
                                'The readableBy property of variable "' + object.name + '" must be a string'
                            );
                        }
                        if (value) {
                            variable.readableBy = value;
                        }
                        break;
                }
            }
        }

        return variable;
    }

    public close(): void {
        iframeListener.unregisterAnswerer("setVariable");
    }

    get variables(): Map<string, unknown> {
        return this._variables;
    }
}