class Sensor{
    constructor(){
        this.rayCount=5;
        this.rayLength=150;
        this.raySpread=Math.PI/4;

        this.rays=[];
        this.readings=[];
    }

    update(x,y,angle,roadBorders,traffic){
        this.#castRays(x,y,angle);
        this.readings=[];
        for(let i=0;i<this.rays.length;i++){
            this.readings.push(
                this.#getReading(this.rays[i],roadBorders,traffic)
            );
        }
    }

    #getReading(ray,roadBorders,traffic){
        let touches=[];

        roadBorders.forEach(border => {
            for(let i=1;i<border.length;i++){
                const touch=getIntersection(
                    ray[0],
                    ray[1],
                    border[i-1],
                    border[i]
                );
                if(touch){
                    touches.push(touch);
                }
            }
        });

        for(let i=0;i<traffic.length;i++){
            const poly=traffic[i].polygon;
            for(let j=0;j<poly.length;j++){
                const value=getIntersection(
                    ray[0],
                    ray[1],
                    poly[j],
                    poly[(j+1)%poly.length]
                );
                if(value){
                    touches.push(value);
                }
            }
        }

        if(touches.length==0){
            return null;
        }else{
            const offsets=touches.map(e=>e.offset);
            const minOffset=Math.min(...offsets);
            return touches.find(e=>e.offset==minOffset);
        }
    }

    #castRays(x,y,angle){
        this.rays=[];
        for(let i=0;i<this.rayCount;i++){
            const rayAngle=lerp(
                this.raySpread/2,
                -this.raySpread/2,
                this.rayCount==1?0.5:i/(this.rayCount-1)
            )+angle;

            const start={x,y};
            const end={
                x:x-Math.sin(rayAngle)*this.rayLength,
                y:y-Math.cos(rayAngle)*this.rayLength
            };
            this.rays.push([start,end]);
        }
    }

    draw(ctx){
        for(let i=0;i<this.rayCount;i++){
            let end=this.rays[i][1];
            if(this.readings[i]){
                end=this.readings[i];
            }
            ctx.beginPath();
            ctx.lineWidth=2;
            ctx.strokeStyle="yellow";
            ctx.moveTo(
                this.rays[i][0].x,
                this.rays[i][0].y
            );
            ctx.lineTo(
                end.x,
                end.y
            );
            ctx.stroke();
            /*
            ctx.strokeStyle="black";
            ctx.moveTo(
                this.rays[i][1].x,
                this.rays[i][1].y
            );
            ctx.lineTo(
                end.x,
                end.y
            );
            ctx.stroke();*/
        }
    }
}