ricochet/server/ricochet.js

const uuid = require('uuid');
const UrlParser = require('url');
const DEBUG = (process.env.NODE_ENV !== "production");

const STATE = {
    COUNTDOWN: 'COUNTDOWN',
    PLAY: 'PLAY',
    WIN: 'WIN'
};

const COLORS = [
    '#FF6200',  // Orange
    '#06E746',  // Green
    '#E370FF',  // Purple
    '#06D6C4',  // Turq
    '#ff217c'   // Pink
];

const ICONS = [
    'assets/comet.svg', 
    'assets/moon.svg', 
    'assets/planet.svg', 
    'assets/rocket.svg', 
    'assets/spacesuit.svg',
    'assets/spider.svg', 
    'assets/ufo.svg'
];

const Ricochet = function({ messenger }) {
    this.messenger = messenger;
    this.squaresPerSide = 20;

    // Reference lookups
    this.robotIds = Array.from(Array(5).keys()).map(_ => uuid.v4());
    
    const shuffledColors = this.shuffle(COLORS);
    this.colors = this.robotIds.reduce((acc, id, i) => {
        acc[id] = shuffledColors[i];
        return acc;
    }, {});

    const shuffledIcons = this.shuffle(ICONS);
    this.icons = this.robotIds.reduce((acc, id, i) => {
        acc[id] = shuffledIcons[i];
        return acc;
    }, {});

    // Properties that will be emitted
    this.players = {};
    this.robots = this.freshRobots();
    this.state = STATE.PLAY;
    this.walls = this.freshWalls();
    this.objective = this.freshObjective();

    this.countdownDuration = 60;
    this.countdownTimer = null;
    this.countdownTimestamp = null;

    this.winningPlayerId = null;
    this.winningStack = null;
};

//===== Connection management

Ricochet.prototype.onConnect = function(ws, req) {
    if (Object.keys(this.players).length >= 10) {
        this.messenger.messageOne(ws, { type: 'full' });
        return;
    }

    const url = UrlParser.parse(req.url, true);
    const query = url.query;
    const santizedName = (query.name || 'Unknown').replace(/[^\w ]/g, '');

    DEBUG && console.log(`Connected: ${santizedName} (${ws.id.substr(0, 8)}) via ${req.url}`);

    this.addPlayer(ws.id, santizedName);

    this.messenger.messageAll({ type: 'players', body: this.players });

    this.messenger.messageOne(ws, { type: 'connected', body: { player_id: ws.id, player_name: santizedName } });
    this.messenger.messageOne(ws, { type: 'robots', body: this.robots});
    this.messenger.messageOne(ws, { type: 'objective', body: this.objective});
    this.messenger.messageOne(ws, { type: 'state', body: this.state});
    this.messenger.messageOne(ws, { type: 'walls', body: this.walls});

    if (this.state === STATE.COUNTDOWN) {
        this.messenger.messageOne(ws, { type: 'countdown', body: this.getCountdownStateBody() });
    }

    if (this.state === STATE.WIN) {
        this.messenger.messageOne(ws, { type: 'win', body: this.getWinStateBody() });
    }
};

Ricochet.prototype.onDisconnect = function(ws) {
    DEBUG && console.log(`Disconnected: ${this.players[ws.id]} (${ws.id.substr(0, 8)})`);      

    this.removePlayer(ws.id);
    
    this.messenger.messageAll({ type: 'players', body: this.players });
};

Ricochet.prototype.addPlayer = function(id, name) {
    if (!this.players[id]) {
        this.players[id] = name;
    }
};

Ricochet.prototype.removePlayer = function(id) {
    this.players[id] = undefined;
    delete this.players[id];
};


//===== State generators

Ricochet.prototype.freshRobots = function() {
    const result = [];

    for (let k = 0; k < this.robotIds.length; k++) {
        const id = this.robotIds[k];
        const { i, j } = this.randomUnoccupiedSquare();

        result.push({ 
            i,
            j,
            color: this.colors[id], 
            id, 
            icon: this.icons[id] 
        });
    }

    return result;
};

Ricochet.prototype.freshWalls = function() {
    // Corner count relates quadratically to squares per side.
    const numberOfCorners = Math.ceil(Math.pow((this.squaresPerSide / 4), 2));
    const corners = [];
    let shortCircuitCounter = 0;

    while (corners.length < numberOfCorners && shortCircuitCounter < numberOfCorners * 5) {
        const { i, j } = this.randomSquare();

        const isTooClose = corners.reduce((acc, v) => {  
            const delta = Math.abs(v.i - i) + Math.abs(v.j - j);
            
            return acc || (delta < 3);
        }, false);

        if (isTooClose === false) {
            corners.push({ i, j });
        }   
    }

    // Edge IDs are of the form [i1-j1-i2-j2]. Top left is 0, 0.
    const horizontalEdges = corners.map(({ i, j }) => {
        const isLeftward = i > 0 && i < this.squaresPerSide && (Math.random() < 0.5);
        const i1 = isLeftward ? i - 1 : i;
        const i2 = isLeftward ? i : i + 1;
        
        return { i1, j1: j, i2, j2: j};
    });  

    const verticalEdges = corners.map(({ i, j }) => {
        const isUpward = j > 0 && j < this.squaresPerSide && (Math.random() < 0.5);
        const j1 = isUpward ? j - 1 : j;
        const j2 = isUpward ? j : j + 1;

        return { i1: i, j1, i2: i, j2 };
    });  

    const edges = horizontalEdges.concat(verticalEdges);

    return edges.reduce((acc, { i1, j1, i2, j2 }) => {
        // Remove walls along all edges
        const onLeft = (i1 === 0 && i2 === 0);
        const onRight = (i1 === this.squaresPerSide && i2 === this.squaresPerSide);
        const onTop = (j1 === 0 && j2 === 0);
        const onBottom = (j1 === this.squaresPerSide && j2 === this.squaresPerSide);

        if (onLeft || onRight || onTop || onBottom) {
            return acc;
        }

        // Remove some walls randomly
        if (Math.random() < 0.3) {
            return acc;
        }

        return acc.concat(`${i1}-${j1}-${i2}-${j2}`);
    }, []);
};

Ricochet.prototype.freshObjective = function() {
    const getRandomWall = () => {
        if (!this.walls.length) {
            this.randomUnoccupiedSquare();
        }

        const wall = this.walls[Math.floor((Math.random() * this.walls.length))];

        const [i1, j1, i2, j2] = wall.split('-');

        return (Math.random() < 0.5) ? { i: i1, j: j1 } : { i: i2, j: j2 };
    };

    const rand = Math.floor(Math.random() * this.robotIds.length);
    const id = this.robotIds[rand];

    const { i, j } = getRandomWall();

    return {
        i,
        j,
        id,
        color: this.colors[id],
    };
};

Ricochet.prototype.onMessage = function(ws, rawBody) {
    try {
        const message = JSON.parse(rawBody);

        DEBUG && console.log('Received message: ');
        DEBUG && console.log(message);

        if (!message.type) {
            DEBUG && console.warn("Unprocessable message: ")
            DEBUG && console.warn(message);
            return;
        }

        switch (message.type) {
            case 'heartbeat': this.msgHeartbeat(ws); break;
            case 'newround': this.msgNewRound(); break;
            case 'objective': this.msgObjective(); break;
            case 'robots': this.msgRobots(); break;
            case 'skip': this.msgSkip(); break;
            case 'solve': this.msgSolve(message.rawBody); break;
            case 'walls': this.msgWalls(); break;
            default: console.warn("Unknown message type: ", message.type)
        }
    } catch (error) {
        console.error(error);
    }
};

//===== Message handlers
Ricochet.prototype.msgHeartbeat = function(ws) {
    this.messenger.messageOne(ws, { type: 'heartbeat' });
};

Ricochet.prototype.msgNewRound = function() {
    this.objective = this.freshObjective();
    this.state = STATE.PLAY;

    const lastPositions = this.winningStack.reduce((acc, v) => {
        acc[v.id] = v;
        return acc;
    }, {})

    this.robots = Object.values(lastPositions).map(({ i, j, id }) => ({
        i,
        j,
        id,
        color: this.colors[id],
        icon: this.icons[id]
    }));

    this.countdownTimer = null;
    this.countdownTimestamp = null;

    this.winningPlayerId = null;
    this.winningStack = null;

    this.messenger.messageAll({ type: 'newround' });
    this.messenger.messageAll({ type: 'objective', body: this.objective});
    this.messenger.messageAll({ type: 'state', body: this.state});
    this.messenger.messageAll({ type: 'robots', body: this.robots});
};

Ricochet.prototype.msgObjective = function() {
    this.objective = this.freshObjective();
    this.messenger.messageAll({ type: 'objective', body: this.objective });
};

Ricochet.prototype.msgRobots = function() {
    this.robots = this.freshRobots();
    this.messenger.messageAll({ type: 'robots', body: this.robots});
};

Ricochet.prototype.msgWalls = function() {
    this.walls = this.freshWalls();
    this.messenger.messageAll({ type: 'walls', body: this.walls });
};

Ricochet.prototype.msgSkip = function() {
    this.onCountdownComplete();
};

Ricochet.prototype.msgSolve = function(message) {
    clearTimeout(this.countdownTimer);

    this.countdownTimer = setTimeout(this.onCountdownComplete.bind(this), this.countdownDuration * 1000);
    this.countdownTimestamp = Date.now();

    this.state = STATE.COUNTDOWN;
    
    this.winningStack = this.sanitizeStack(message.stack);

    this.winningPlayerId = this.sanitizeId(message.id);

    this.messenger.messageAll({ type: 'state', body: this.state });

    this.messenger.messageAll({ type: 'countdown', body: this.getCountdownStateBody() });
};

//===== Helper functions

Ricochet.prototype.randomSquare = function() {
    return {
        i: Math.floor(Math.random() * this.squaresPerSide),
        j: Math.floor(Math.random() * this.squaresPerSide)
    };
};

Ricochet.prototype.randomUnoccupiedSquare = function() {
    let result = this.randomSquare();
    let CONTROL_COUNTER = 0;

    while (this.isSquareOccupied(result) && CONTROL_COUNTER < 20) {
        CONTROL_COUNTER++;
        result = this.randomSquare();
    }

    if (CONTROL_COUNTER > 19) {
        console.log(`==================\n\nCRITICAL ERROR!\n\nrandomUnoccupiedSquare() while() short-circuited!\n\n==================`);
    }

    return result;
};

Ricochet.prototype.isSquareOccupied = function({ i, j }) {
    if (i < 0 || i > this.squaresPerSide) {
        return true;
    }

    if (j < 0 || j > this.squaresPerSide) {
        return true;
    }

    if (this.robots) {
        for (let k = 0; k < this.robots.length; k++) {
            if (this.robots[k].i === i && this.robots[k].j === j) {
                return true;
            }
        }
    }

    if (this.objective && i === this.objective.i && j === this.objective.j) {
        return true;
    }

    return false;
};

Ricochet.prototype.sanitizeStack = function(rawMoveStack) {
    const sanitizedStack = rawMoveStack.map(move => {
        const sanitizedRobotId = this.sanitizeId(move.id);
        const sanitizedI = move.i * 1;
        const sanitizedJ = move.j * 1;

        return {
            i: sanitizedI,
            j: sanitizedJ,
            id: sanitizedRobotId
        };
    });

    return sanitizedStack;
};

Ricochet.prototype.sanitizeId = function(id) {
    return id.replace(/[^0-9a-zA-Z\-]/g, '');
};

Ricochet.prototype.shuffle = function(arr) {
    const result = [];
    let CONTROL_COUNTER = 0;

    while (arr.length && CONTROL_COUNTER < 50) {
        const x = Math.floor(Math.random() * arr.length);
        result.push(arr[x]);
        arr.splice(x, 1);
    }

    if (CONTROL_COUNTER > 39) {
        console.log(`==================\n\nCRITICAL ERROR!\n\shuffle()() while() short-circuited!\n\n==================`);
    }

    return result;
};

Ricochet.prototype.onCountdownComplete = function() {
    clearTimeout(this.countdownTimer);

    this.countdownTimestamp = null;
    this.state = STATE.WIN;

    this.messenger.messageAll({ type: 'state', body: this.state });
    this.messenger.messageAll({ type: 'win', body: this.getWinStateBody() });
};

Ricochet.prototype.getCountdownStateBody = function() {
    return { 
        duration: this.countdownDuration,
        id: this.winningPlayerId, 
        moveCount: this.winningStack.length - this.robots.length,
        timestamp: this.countdownTimestamp 
    };
};

Ricochet.prototype.getWinStateBody = function() {
    return { 
        moveCount: this.winningStack.length - this.robots.length,
        player_id: this.winningPlayerId, 
        stack: this.winningStack 
    }; 
};

module.exports = Ricochet;