Snake/sources/js/Tile.js

import {Game} from "./Game.js";

export class Tile {
    /**
     * A tile of the game grid
     * @param {int} x
     * @param {int} y
     * @param {tiles} type
     * @param {Game} game
     */
    constructor(x, y, type = tiles.EMPTY, game) {
        if (typeof x === "number" && x >= 0 && x % 1 === 0)
            this.x = x;
        else
            throw new InvalidTileOption("x");

        if (typeof y === "number" && y >= 0 && y % 1 === 0)
            this.y = y;
        else
            throw new InvalidTileOption("y");

        if (type && Object.values(tiles).find(t => t === type))
            this.type = type;
        else
            throw new InvalidTileOption("type");

        if (game && game instanceof Game)
            this.game = game;
        else
            throw new InvalidTileOption("game");
    }

    /**
     * Draw the tile on the grid
     */
    draw() {
        const canvasPos = this.getCanvasPos(), size = this.getSize();

        this.game.ctx.beginPath();

        this.game.ctx.globalCompositeOperation = "destination-out";
        this.game.ctx.fillRect(...canvasPos, ...size);
        this.game.ctx.globalCompositeOperation = "source-over";

        switch (this.type) {
            case tiles.EMPTY:
                this.game.ctx.strokeStyle = "#999999";
                this.game.ctx.rect(...canvasPos, ...size);
                break;
            case tiles.APPLE:
                this.game.ctx.fillStyle = "#ff0000";
                this.game.ctx.fillRect(...canvasPos, ...size);
                break;
            case tiles.SNAKE:
                this.game.ctx.fillStyle = "#00ff5f";
                this.game.ctx.fillRect(...canvasPos, ...size);
                break;
        }

        this.game.ctx.stroke();
    }

    /**
     * Get the tile position on the canvas
     * @returns {[int, int]}
     */
    getCanvasPos() {
        return [this.getSize()[0]*this.x, this.getSize()[1]*this.y]
    }

    /**
     * Get the tile size on the canvas
     * @returns {[int, int]}
     */
    getSize() {
        const s = Math.min(Math.round(this.game.ctx.canvas.width/this.game.size[0]), Math.round(this.game.ctx.canvas.height/this.game.size[1]));
        return [s, s]
    }
}

export class InvalidTileOption extends Error {
    /**
     * @param {string} name
     */
    constructor(name) {
        super(`Invalid Tile option: ${name}`);
    }
}

export const tiles = {
    EMPTY: "empty",
    APPLE: "apple",
    SNAKE: "snake"
};