"use strict";

const StarsBackground = (function(){

    const StarsBackground = function(xgravity){

        const self = this;
        const stars = [];

        const init_stars = (width, height) => {
            stars.length = 0;
            for(let i = 0; i < xgravity.values.bg_stars_count; i++)
                stars.push({
                    x : Math.random() * width,
                    y : Math.random() * height,
                    size : Math.random() * (xgravity.values.bg_stars_size_maximum - xgravity.values.bg_stars_size_minimum) + xgravity.values.bg_stars_size_minimum,
                    speed : Math.random() * (xgravity.values.bg_stars_speed_maximum - xgravity.values.bg_stars_speed_minimum) + xgravity.values.bg_stars_speed_minimum,
                    alpha : Math.random() * 0.8 + 0.2
                });
        };

        this.resize = (width, height) => {
            init_stars(width, height);
        };

        this.render = (ctx, width, height, delta_time) => {

            ctx.fillStyle = "#020408";
            ctx.fillRect(0, 0, width, height);

            stars.length || init_stars(width, height);

            for(const star of stars){

                star.x += xgravity.values.bg_stars_direction_x * star.speed * (delta_time * 60);
                star.y += xgravity.values.bg_stars_direction_y * star.speed * (delta_time * 60);

                if(star.y > height){
                    star.y = 0;
                    star.x = Math.random() * width;
                }else if(star.y < 0){
                    star.y = height;
                    star.x = Math.random() * width;
                };

                if(star.x > width){
                    star.x = 0;
                    star.y = Math.random() * height;
                }else if(star.x < 0){
                    star.x = width;
                    star.y = Math.random() * height;
                };

                ctx.fillStyle = Common.string_variables(xgravity.values.bg_stars_color, {
                    alpha : star.alpha.toFixed(2)
                });
                ctx.fillRect(star.x, star.y, star.size, star.size);

            };

        };

    };

    return StarsBackground;
})();