const rMin = 2; //min=1 max=5 step=.5
const rMax = 7; //min=5 max=10 step=.5
const bigR = 70; //min=40 max=90 step=5

// You can find the Turtle API reference here: https://turtletoy.net/syntax
Canvas.setpenopacity(-1);

// Global code will be evaluated once.
const turtle = new Turtle();
const polygons = new Polygons();

const circles = [];

// The walk function will be called until it returns false.
function walk(i) {
    if(i == 0) {
        //set up outer rim of circles
        let startA = Math.random() * 2 * Math.PI;
        for(let j = 0; j < Math.PI * 2;) {
            let r = rMin + (Math.random() * (rMax - rMin));
            let dJ = (r / bigR);
            let a = startA + j + dJ;
            
            if(circles.length > 0) {
                let realR = .1;
                while(!intersects(a, realR, bigR)) {
                    realR += .1;
                }
                r = realR - .1;
            }
            circles.push(new Circle([Math.cos(a) * bigR, Math.sin(a) * bigR], r, a));
            j += dJ * 2;
        }
        
        //remove last circle added and add a new one to fill the potential gap created by randomly filling outer rim
        circles.pop();
        let a = (startA + (circles[circles.length - 1].a + (circles[circles.length - 1].radius / bigR)) + (2 * Math.PI)) / 2;
        let realR = .1;
        while(!intersects(a, realR, bigR)) { realR += .1; }
        r = Math.max(rMin, realR - .1);
        let d = bigR;
        while(intersects(a, r, d)) { d -= .1; }
        circles.push(new Circle([Math.cos(a) * d, Math.sin(a) * d], r, a));

        //fill the circle with random circles
        for(let j = 0; j < 20000; j++) {
            let a = Math.random() * 2 * Math.PI;
            let r = rMin + (Math.random() * (rMax - rMin));
        
            let d = getDistance(a, r);
            if(d + r < bigR) {
                circles.push(new Circle([Math.cos(a) * d, Math.sin(a) * d], r, a));
            }
        }
        
        //randomize drawing order
        circles.sort((a,b) => Math.random()-.5);
    }
    
    //draw the circles
    if(circles.length > 0) {
        let c = circles.pop();
        c.draw(turtle);
        return true;
    }
    
    //and finally draw the background
    let p = polygons.create();
    addCirclePoints(p, [0,0], bigR, 0, 2 * Math.PI, 40);
    p.addHatching(0, .1);
    polygons.draw(turtle, p);
    return false;
}

function getDistance(a, r) {
    let d = 0;
    while(d + r < bigR && intersects(a, r, d)) {
        d+=.1;
    }
    return d;
}

function intersects(a, r, d) {
    for(let i = 0; i < circles.length; i++) {
        let x = Math.cos(a) * d;
        let y = Math.sin(a) * d;
        let distanceSquared = Math.pow(circles[i].position[0] - x, 2) + Math.pow(circles[i].position[1] - y, 2);
        let requiredDistanceSquared = Math.pow(circles[i].radius + r, 2);
        if(distanceSquared < requiredDistanceSquared) {
            return true;
        }
    }
    return false;
}
const add = (a, b) => [a[0]+b[0], a[1]+b[1]];
class Circle {
    constructor(position, radius, a) {
        this.position = position;
        this.radius = radius;
        this.a = a;
    }
    draw(turtle) {
        turtle.jump(this.position[0], this.position[1] - this.radius);
//        turtle.circle(this.radius);
        let cs = [this.radius - (Math.max(2, rMin) * .95), this.radius - (Math.max(2, rMin) * .70), this.radius - (Math.max(2, rMin) / 2), this.radius];
        for(let i = 0; i < cs.length; i++) {
            let p = polygons.create();
            addCirclePoints(p, this.position, cs[i], 0, 2 * Math.PI);
            if(i % 2 == 1) {
                p.addHatching(0, .1);
            }
            polygons.draw(turtle, p);
        }
    }
}
function addCirclePoints(p, position, r, s, e, f = 40) {
    for (let i=0; i<=f; i++) {
        p.addPoints(add([Math.cos(s+(e-s)*i/f)*r, Math.sin(s+(e-s)*i/f)*r], position));
    }
    return p;
}


////////////////////////////////////////////////////////////////
// Polygon Clipping utility code - Created by Reinder Nijhoff 2019
// (Polygon binning by Lionel Lemarie 2021)
// https://turtletoy.net/turtle/a5befa1f8d
////////////////////////////////////////////////////////////////
function Polygons(){const t=[],s=25,e=Array.from({length:s**2},t=>[]),n=class{constructor(){this.cp=[],this.dp=[],this.aabb=[]}addPoints(...t){let s=1e5,e=-1e5,n=1e5,h=-1e5;(this.cp=[...this.cp,...t]).forEach(t=>{s=Math.min(s,t[0]),e=Math.max(e,t[0]),n=Math.min(n,t[1]),h=Math.max(h,t[1])}),this.aabb=[s,n,e,h]}addSegments(...t){t.forEach(t=>this.dp.push(t))}addOutline(){for(let t=0,s=this.cp.length;t<s;t++)this.dp.push(this.cp[t],this.cp[(t+1)%s])}draw(t){for(let s=0,e=this.dp.length;s<e;s+=2)t.jump(this.dp[s]),t.goto(this.dp[s+1])}addHatching(t,s){const e=new n;e.cp.push([-1e5,-1e5],[1e5,-1e5],[1e5,1e5],[-1e5,1e5]);const h=Math.sin(t)*s,o=Math.cos(t)*s,a=200*Math.sin(t),i=200*Math.cos(t);for(let t=.5;t<150/s;t++)e.dp.push([h*t+i,o*t-a],[h*t-i,o*t+a]),e.dp.push([-h*t+i,-o*t-a],[-h*t-i,-o*t+a]);e.boolean(this,!1),this.dp=[...this.dp,...e.dp]}inside(t){let s=0;for(let e=0,n=this.cp.length;e<n;e++)this.segment_intersect(t,[.1,-1e3],this.cp[e],this.cp[(e+1)%n])&&s++;return 1&s}boolean(t,s=!0){const e=[];for(let n=0,h=this.dp.length;n<h;n+=2){const h=this.dp[n],o=this.dp[n+1],a=[];for(let s=0,e=t.cp.length;s<e;s++){const n=this.segment_intersect(h,o,t.cp[s],t.cp[(s+1)%e]);!1!==n&&a.push(n)}if(0===a.length)s===!t.inside(h)&&e.push(h,o);else{a.push(h,o);const n=o[0]-h[0],i=o[1]-h[1];a.sort((t,s)=>(t[0]-h[0])*n+(t[1]-h[1])*i-(s[0]-h[0])*n-(s[1]-h[1])*i);for(let n=0;n<a.length-1;n++)(a[n][0]-a[n+1][0])**2+(a[n][1]-a[n+1][1])**2>=.001&&s===!t.inside([(a[n][0]+a[n+1][0])/2,(a[n][1]+a[n+1][1])/2])&&e.push(a[n],a[n+1])}}return(this.dp=e).length>0}segment_intersect(t,s,e,n){const h=(n[1]-e[1])*(s[0]-t[0])-(n[0]-e[0])*(s[1]-t[1]);if(0===h)return!1;const o=((n[0]-e[0])*(t[1]-e[1])-(n[1]-e[1])*(t[0]-e[0]))/h,a=((s[0]-t[0])*(t[1]-e[1])-(s[1]-t[1])*(t[0]-e[0]))/h;return o>=0&&o<=1&&a>=0&&a<=1&&[t[0]+o*(s[0]-t[0]),t[1]+o*(s[1]-t[1])]}};return{list:()=>t,create:()=>new n,draw:(n,h,o=!0)=>{reducedPolygonList=function(n){const h={},o=200/s;for(var a=0;a<s;a++){const c=a*o-100,r=[0,c,200,c+o];if(!(n[3]<r[1]||n[1]>r[3]))for(var i=0;i<s;i++){const c=i*o-100;r[0]=c,r[2]=c+o,n[0]>r[2]||n[2]<r[0]||e[i+a*s].forEach(s=>{const e=t[s];n[3]<e.aabb[1]||n[1]>e.aabb[3]||n[0]>e.aabb[2]||n[2]<e.aabb[0]||(h[s]=1)})}}return Array.from(Object.keys(h),s=>t[s])}(h.aabb);for(let t=0;t<reducedPolygonList.length&&h.boolean(reducedPolygonList[t]);t++);h.draw(n),o&&function(n){t.push(n);const h=t.length-1,o=200/s;e.forEach((t,e)=>{const a=e%s*o-100,i=(e/s|0)*o-100,c=[a,i,a+o,i+o];c[3]<n.aabb[1]||c[1]>n.aabb[3]||c[0]>n.aabb[2]||c[2]<n.aabb[0]||t.push(h)})}(h)}}}