the-forest/server/interpreter.js

const sqlite = require('better-sqlite3');
const db = new sqlite('the_big_db.db', { verbose: console.log });

var sockets = new Map();

function interpret(context, player, command) {
	// interpret and execute a command entered by a player.
	//
	// context: the location the player has entered the command in from. 
	//		may be null if it's executing from a script?
	// player: the id of the player object who typed in the command. 
	//		may? be null if it's executing from a script? used for output.
	//		so arguably 
	// command: the full string typed in by the player

	const socket = sockets.get(player)
	const words = command.trim().split(' ');

	try {
		socket?.send(`interpreting and executing the received command: ${command}`);
		
		//for the moment we'll only allow statements of the form "go north" with implicit subject: the player
		const [first, second, third, ...rest] = words;

		const verb = findVerb(first, context, player);

		console.log(`executing verb ${verb} towards ${player} on ${player} ${second} ${third}`);
		executeVerb(player, verb, player, second, third, ...rest)
	} catch (error) {
		socket?.send(`got an error! ${error.mesage}`);
	}

	/*
	// if the second word is a verb, but the first word is also a verb, what do we do?
	if (second in verbs) {
		// for now, assume that if the second word is a verb, it's the verb we want.
		executeVerb(player, verbs.get(second), first, third, ...rest);
	} else {
		// if the second word is not a verb, then the first word is the verb, and the player is the implied subject.
		executeVerb(player, verbs.get(first), player, second, third, ...rest)
	}
	*/
}

function findVerb(word, location, actor) {
	// returns the number of a verb which matches the requested word.
	// check for verbs on actor
	let verb = findVerbOnObject(word, actor);
	if (verb) return verb;

	const actorContents = getAttribute(actor, "contents");
	for (const obj of (actorContents || [])) {
		verb = findVerbOnObject(word, obj);
		if (verb) return verb;
	}

	const locationContents = getAttribute(location, "contents");
	for (const obj of (locationContents || [])) {
		verb = findVerbOnObject(word, obj);
		if (verb) return verb;
	}

	verb = findVerbOnObject(word, location);
	if (verb) return verb;

	return undefined;
}

function findVerbOnObject(word, object) {
	// check for verbs on a single object, and its chain of parents. return a matching verbId, or undefined
	if (!word) return undefined;

	let focus = object;
	while (focus) {
		const focusVerbs = getAttribute(focus, "verbs");
		for (const verbId of (focusVerbs || [])) {
			const fullVerb = lookUpObject(verbId);

			if (!fullVerb) continue;

			// test our word against 
			if (word.toLowerCase() == fullVerb.title.toLowerCase()) {
				return verbId;
			}
		}
		focus = getAttribute(focus, "parent");
	}

	return undefined;
}

function executeVerb(outputObject, verbId, subject, object, ...rest) {
	const fullVerb = lookUpObject(verbId);
	if (!fullVerb) {
		return sockets.get(outputObject)?.send(`verb not found`);
	}
	sockets.get(outputObject)?.send(`verb found as ${fullVerb.name}`);
	const func = fullVerb.fn;
	if (!func) {
		return sockets.get(outputObject)?.send(`verb was found but didn't have a fn attribute`);
	}
	return fullVerb.fn(outputObject, subject, object, ...rest);
}

const objectQuery = db.prepare('select * from pages where number=? order by time desc');
function lookUpObject(number) {
	return hardCodedObjects(number) || objectQuery.get(number);
}

const attributeQuery = db.prepare(`select * from attributes where number=?`);
function lookUpObjectAttributes(number) {
	return JSON.parse(attributeQuery.get(number).contents);
}


function hardCodedObjects(id) {
	// return objectQuery.get(id);
	if (id == 29) return {
		title: "look", 
		verb: true,
		description: "send description of direct object to subject's socket", 
		fn: (logReceiver, subject, object, ...rest) => {
			sockets.get(logReceiver)?.send(`you looked around! subject ${subject} object: ${object} args: ${rest}`);
			console.log(`${subject} looked at ${object} with args ${rest}, and output was directed to ${logReceiver}`);
		}
	}
	if (id == 31) return {
		title: "warp",
		verb: true,
		description: "this built-in function changes the player's location, as well as telling their client to move",
		fn: (logReceiver, subject, object, ...rest) => {
			const objectNum = verifyObjectReference(object);
			const subjectNum = verifyObjectReference(subject);
			setAttribute(subjectNum, "location", objectNum);

			sockets.get(logReceiver)?.send(`location change to: ${object}`);
		}
	}
}




const pullAttribute = db.prepare(`select * from attributes where number=?`);
function getAttribute(obj, attributeName) {
	const attributeStore = pullAttribute.get(verifyObjectReference(obj));
	const contents = JSON.parse(attributeStore.contents);

	if (contents.hasOwnProperty(attributeName)) {
		return contents[attributeName];
	}

	if (contents.hasOwnProperty("parent")) {
		return getAttribute(contents.parent, attributeName);
	}

	return undefined;
}

function hasOwnAttribute(obj, attributeName) {
	const attributeStore = pullAttribute.get(verifyObjectReference(obj));
	const contents = JSON.parse(attributeStore.contents);
	
	return contents.hasOwnProperty(attributeName);
}

const insertAttribute = db.prepare(`update or replace attributes set contents=:contents where number=:number`);
function setAttribute(obj, attributeName, value) {
	const attributeStore = pullAttribute.get(verifyObjectReference(obj));
	const contents = JSON.parse(attributeStore.contents);

	contents[attributeName] = value;
	
	insertAttribute.run({...attributeStore, contents: JSON.stringify(contents)});
}

function deleteAttribute(obj, attributeName) {
	const attributeStore = pullAttribute.get(verifyObjectReference(obj));
	const contents = JSON.parse(attributeStore.contents);
	
	delete contents["attributeName"];
	
	insertAttribute.run({...attributeStore, contents: JSON.stringify(contents)});
}

function verifyObjectReference(obj) {
	try {
		if (typeof(obj) === "string") {
			return Number(obj.replace("#", ""));
		} else if (typeof(obj) === "number") {
			return obj;
		} else if (typeof(obj.number) == "number") {
			return obj.number;
		}
	} catch (error) {
		throw new Error("Tried to get an attribute from something which wasn't an object");
	}
}

module.exports = { interpret, sockets, lookUpObject, getAttribute, setAttribute, deleteAttribute, hasOwnAttribute };