class SpaceInvadersGame {
    constructor(ctx) {
        this.new_game();
        this.ctx = ctx
    }

    new_game()
    {
        this.width = 600;
        this.height = 600;

        this.enemies = [];
        for(let i = 75; i < 550 ; i += 50)
        {
            for( let j = 75; j < 250; j+= 50)
            {
                this.enemies.push({x: i, y:j});
            }
        }

        this.spaceship = {x:300, y: 600};
        this.spanceship_direction = 0;
        this.enemies_x_position = 5;
        this.enemies_move_orientation = 1;

        this.game_started = false;
    }

    check_game_end()
    {
        for (let enemy of this.enemies)
        {
            if (enemy.y > this.spaceship.y - 27 )
            {
                return true;
            }
        }
        return false;
    }

    tick() {
        if (this.game_started) {

            if(this.check_game_end())
            {
                alert("You lose");
                this.new_game();
            }

            // Move the spaceship
            this.spaceship.x += this.spanceship_direction * 5;
            this.spanceship_direction = 0;

            // move the enemies
            this.enemies_x_position += this.enemies_move_orientation;
            let offset_x = this.enemies_move_orientation * 10;
            let offset_y = 0;
            if (this.enemies_x_position === 0) {
                this.enemies_move_orientation = 1;
                offset_y = 20;
            }
            else if (this.enemies_x_position === 10) {
                this.enemies_move_orientation = -1;
                offset_y = 20;
            }
            for (let enemy of this.enemies) {
                enemy.x += offset_x;
                enemy.y += offset_y;
            }
            
        }
    }

    draw()
    {
        this.ctx.clearRect(0, 0, this.width, this.height);
        this.ctx.fillStyle = "black";
        this.ctx.strokeStyle = "black 2px solid";
        this.ctx.fillRect(0, 0, this.width, this.height);

        this.ctx.fillStyle = "red";
        this.ctx.strokeStyle = "red 2px solid";
        for (let enemy of this.enemies)
        {
            this.ctx.fillRect(enemy.x-12, enemy.y-12, 25, 15);
        }

        this.ctx.fillStyle = "blue";
        this.ctx.strokeStyle = "blue 2px solid";

        this.ctx.fillRect(this.spaceship.x - 25, this.spaceship.y -15, 50, 15)
    }

    keypress(event)
    {
        this.spanceship_direction = {
                37: -1, // Left
                39: 1, // Right
            }[event.keyCode] || 0;
        this.game_started = {
            13: true,
            27: true
        }[event.keyCode] ? !this.game_started: this.game_started;
    }
}